R-TOT RIVER
TIME-OF-TRAVEL MODEL:
COMPUTER PROGRAM EXTENSION,
ENHANCEMENT, DISTRIBUTION, AND
TRAINING

Michael Gene Waldon, Ph.D., P.E.

Center for Louisiana Inland Water Studies

University of Southwestern Louisiana

Technical Report Series
97-010

DISCLAIMER

This report was prepared under a contract
between the University of Southwestern Louisiana and the Louisiana Applied Oil
Spill Research and Development Program (OSRADP). The contents of this report do
not necessarily reflect the views and policies of the Louisiana Oil Spill
Coordinator's Office-Office of the Governor or that of the Louisiana Applied Oil
Spill Research and Development Program, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use by the
state of Louisiana.

REPORT
AVAILABILITY

Additional copies of this report can be obtained by writing to:

Louisiana Applied Oil Spill Research and Development Program

1997 Deliverables
258 A/B Military Science Building
Baton Rouge,
Louisiana 70803
Telephone: (225) 388-3477 FAX: (225)
388-0403

or from

The Louisiana Oil Spill Coordinator/Office of the Governor

Natural Resources Building 625 N. 4th Street, Room 800
Baton Rouge,
Louisiana 70802
Telephone: (225) 219-5800 FAX: (225)
219-5802

CITATION

Waldon, M.G. 1998. R-TOT: River time-of-travel model. Louisiana Applied Oil
Spill Research and Development Program. OSRADP Technical Report Series
97-010.

TABLE OF
CONTENTS

1.0
Introduction

2.0
Model Development

2.1
Technical Approach

2.1.1
Travel Time

2.1.2
Peak Concentration

3.0
Model Application

3.1
Data Availability

3.2
Mississippi River

3.2.1
Calibration

3.2.2
Application

3.3
Bayou Lafourche

3.3.1
Calibration

3.3.2
Application

4.0
Training and Distribution

5.0
Conclusions

6.0
References

ATTACHMENT
A - R-TOT River Time-of-Travel Computer Program User's Manual

ATTACHMENT
B - R-TOT River Time-of-Travel Computer Programmer's Manual

LIST OF
FIGURES

Figure
1 Mississippi River industrial corridor and EWOCDS monitoring sites

Figure
2 Mississippi River model calibration, observed and predicted travel times
in hours of dye leading edge

Figure
3 Mississippi River model calibration, observed and predicted travel times
in hours of dye peak

Figure
4 Mississippi River model calibration, observed and predicted travel times
in hours of dye trailing edge

Figure
5 Mississippi River model calibration, observed and predicted times in hours
of dye duration

Figure
6 Predicted and observed unit concentrations from dye tracer studies

Figure
7 EDC concentrations observed at three monitoring stations. Model-predicted
leading edge arrival time and trailing edge passage are marked by solid and
dashed vertical lines, respectively

Figure
8 Comparison of observed and modeled EDC spill occurrence. Solid lines
indicate model-projected leading edge, peak, and trailing edge travel

LIST OF
TABLES

Table
1 Number of dye time-of-travel studies which have been performed on
Louisiana streams, and for which data are available

Table
2 Rivermile locations of selected Mississippi River landmarks above Baton
Rouge

Table
3 Rivermile locations of selected Mississippi River landmarks at and below
Baton Rouge

Table
4 Monitored spill events to which the model has been applied

Table
5 Parameters used in calibrated Mississippi River time-of-travel program

Table
6 EDC mass estimated from observed peak concentration, model calculated
duration, and discharge of 6,090 cms (215,000 cfs)

Table
7 Fresh water intakes on Bayou Lafourche

Table
8 Major landmarks along Bayou Lafourche

Table
9 R-TOT projections for a spill originating at Baton Rouge, rivermile 232,
and ending at New Orleans, rivermile 104. Travel times for leading edge (LE),
peak (PK), and trailing edge (TE) are presented. Duration is the time from
leading edge to trailing edge, and spill length is the distance from trailing
edge to leading edge when leading edge reaches mile 104

ACKNOWLEDGMENTS

Initial development and funding for the time-of-travel model was provided by
the Louisiana Department of Environmental Quality (LDEQ). The model utilizes
data that were collected by personnel from the Office of Water Resources, LDEQ,
by the U.S. Geological Survey in cooperation with the Louisiana Department of
Transportation and Development, by the U.S. Army corps of Engineers, and by
staff members of the University of Southwestern Louisiana. These previous data
collection studies have provided a basis for the project described here. Funding
for the work presented in this report was provided by the Louisiana Applied Oil
Spill Research and Development Program. USL graduate students Sarah Kuchipudi
and Louis Landesman assisted in development of the OSRADP funded model described
here. Dr. Paul Richards, Director of the USL Center for Louisiana Inland Water
Studies, has provided unselfish support and assistance throughout this project.
His contribution is gratefully acknowledged.

R-TOT River Time-of-Travel Model: Computer Program Extension,
Enhancement, Distribution, and Training

Abstract

Following the spill of potentially toxic material into a river, rapid
decisions must be made in order to protect human health and natural resources.
For example, municipal and industrial water intakes must often be shut down, and
water storage for drinking and fire protection may be limited. Water control
structures may need to be operated and other protective measures taken to
minimize damage to infrastructure and ecosystems. In order to support this
decision making, knowledge of the arrival and passage times of waterborne
contaminants is vital.

A time-of-travel model (R-TOT) has been developed for the Mississippi River.
A version of this program was recently extended to include Bayou Lafourche, a
controlled distributary of the Mississippi River. More than a million people
receive drinking water from the Mississippi River below Baton Rouge, and a
quarter of a million people obtain their drinking water from Bayou Lafourche.
The model predicts a spill's time of arrival and the duration of its passage.
Additionally, if the quantity of material spilled is known or estimated, the
model predicts peak concentrations at any downstream location.

The R-TOT time-of-travel parameters are calculated from observations of
non-toxic dye tracer transport and dispersion. A number of these dye studies
have been performed in Louisiana waterbodies, but the additional studies
identified in this report are needed to credibly extend the time-of-travel model
to more Louisiana waterways.

1.0 Introduction

The major objective of the
time-of-travel model presented here is to help provide timely and accurate
warnings of spills to downstream water users, which will allow emergency
shutdown of water intakes and reduction of risk and resource damage. Predicting
the arrival and passage times of a river spill is of crucial importance for
Louisiana's environmental resource managers. More than a million people receive
drinking water from the Mississippi River below Baton Rouge (Bostock, et
al. 1991), and a quarter of a million people obtain their drinking water
from Bayou Lafourche, a small distributary of the river (Figure 1). Typical
water supply systems have less than a day's supply of water in storage. Drinking
water and industrial water intakes can usually be shut down for a limited period
to allow spill passage, but lengthy shutdowns may interrupt drinking water
supplies, reduce fire protection, interrupt industrial processes, and increase
liability for the responsible party.

The model has been utilized in
conjunction with volatile organic compound monitoring performed by the Louisiana
Early Warning Organic Contaminant Detection System (EWOCDS) on the Mississippi
River (Romanowsky, 1985). Other uses for a river time-of-travel model include
spill contingency planning, surveillance, and enforcement. For example, the
model has been used for the following applications:

by the Louisiana Department of Environmental Quality (LDEQ) for spill
monitoring, quantification, and management.

by an environmental consulting company for spill contingency planning and
for real time spill sample location planning during an actual spill.

by a chemical industry located on the river to aid their spill planning
efforts.

as a tool for assessing the EWOCDS monitoring network sampling frequency
and site selection (Waldon and Bostock, 1989). This assessment formed the
basis for proposals to increase sampling frequency at some sites.

for identifying possible stream reaches where spills of unknown origin may
have originated, and similarly, for excluding other reaches.

The Lower Mississippi River
industrial corridor is at high risk for hazardous contaminant spills from
transportation accidents and industrial releases. River ports from Baton Rouge
to New Orleans are some of the largest in the U.S. More than 70 major industries
line this corridor, using river water for once-through-cooling and for process
water supply.

Concern over the potential impacts
of spills in the Mississippi River has spurred studies and monitoring activities
since at least the early 1970s. Dye tracer studies, performed to measure time of
travel and dispersion in streams (Hubbard, et al. 1982; Wilson, et
al. 1984), have been performed on the lower Mississippi River (Calandro,
1976, 1978; Schexnayder, 1990; Hebel, et al. 1991). Based on early
dye studies, McQuivey and Keefer (1976a, 1976b) developed a dispersion modeling
methodology and applied it to the Mississippi River below Baton Rouge.

Figure
1       Mississippi River
industrial corridor and EWOCDS monitoring sites

Based on published dye tracer
studies (Calandro, 1978), environmental managers have attempted to graphically
project time of arrival and passage of spills in the river. These graphical
techniques illustrated the value of the data for spill management, but proved to
be impractical in real time situations. The need for a better tool inspired two
collaborators, Ken O'Hara of the LDEQ and Duane Everett of the University of
Southwestern Louisiana, to develop a computer program that automated the
graphical approach. The modeling approach presented here was developed for
subsequent versions of this computer program (Waldon, 1997a, 1997b).

2.0 Model
Development

2.1 Technical
Approach

Literature on modeling longitudinal
dispersion in advective streams is extensive. Most of the approaches to spill
dispersion modeling (Elhadi, 1984) fall within the categories of Fickian and
modified Fickian formulations (Levenspiel and Smith, 1957; Benedict, 1979;
Bowie, et al. 1985) and "dead zone" formulations (Levich et
al. 1967; Beer and Young, 1983; Yu and Wenzhi, 1989). Fickian models, also
referred to in the literature as ADE models (advection-dispersion equation), are
most common, but they are seldom adequate for river spill modeling. Spills
exhibit a characteristic skewness that is not easily obtained from the ADE
formulation. In addition, many spills exhibit spreading and peak reduction over
time, phenomena that are inconsistent with the ADE formulation (Nordin and
Sabol, 1974; Nordin and Troutman, 1980). Dead zone formulations do predict
distributions that are appropriately skewed, but do not have the extensive
theoretical basis or history of documented application characteristic of the
Fickian approach.

In general, spill time-of-travel
models and computer programs should meet specific criteria:

(1) Dynamic-The model must be capable of describing the temporal transport
and dispersion of the spill. Steady-state models are utilized for analysis of
continuous discharges, and are not appropriate for modeling "instantaneous"
spills.

(2) Ease of use-For application in real time situations, the model must not
require extensive user interaction or input. The computer program should also
provide as many error messages and other forms of advice to the user as
possible.

(3) The model must be reliable and of adequate accuracy for the proposed
application.

Alternative models were considered
for travel time simulation. Specialized river oil spill models (Yapa and Shen,
1994) require considerable data, time, and effort for calibration and execution,
and are therefore less easily applied in real time spill management situations.
General dynamic water quality models and formulations also fall short of meeting
the necessary criteria. The U.S.E.P.A. WASP (Ambrose et al. 1993) model
and the U.S.G.S. BLT model (Jobson and Schoellhamer, 1987) are two popular
dynamic models that might be applicable to spill modeling. But as with the
specialized oil spill models, neither of these water quality models meet the
ease of use criterion, and both calculate dispersion based on a Fickian
formulation. Experience with WASP has shown that numerical dispersion and
lengthy computer run times can also seriously reduce the utility of this model
(Smythe, 1996). It is likely that similar problems would be encountered with
other general water quality models running in dynamic mode.

Some models do predict
time-of-travel from general stream properties. These more general models are
valuable in some applications, but have projection errors that are unacceptable
in real time spill tracking and management. Boning (1974) attempted to develop a
general time-of-travel model based on stream discharge, channel slope, and reach
length. Boning's analyses were based on dye studies of more than 300 streams
involving 20,000 stream kilometers and 1500 individual measurements. Based on a
log-transformed multiple regression, the standard error of estimate for these
general equations was found to be between 26 and 50% of observed velocities. For
a typical Mississippi River spill, errors from Boning's more general model are
unacceptably high. The typical calibration error of the Mississippi River model
presented here is roughly one hour or less, corresponding to a 1 to 10% error
for typical Mississippi River spill scenarios with travel times of 10 to 100
hours.

The approach described here, termed
the modified plug flow (MPF) model, calibrates time-of-travel for a stream using
site specific studies. The MPF model calculates travel time for the spill peak
and edges as though each were transported by plug flow at its own characteristic
velocity. This model is based on empirical equations that relate velocities to
stream discharge. Parameters for these relationships were established through
the use of rhodamine WT dye tracer studies. Dye time-of-travel study data are
often summarized by the time from dye injection to the passage of the dye
leading edge, peak, and trailing edge at specific locations. In practice, the
leading edge and trailing edge are often defined as the location at which
concentration is 5 to 10% of the peak concentration. Typically, the time of the
leading edge is quite sharp, while the trailing edge concentration recedes
gradually and has a less defined occurrence time.

2.1.1 Travel Time

Transport mechanisms of water and
solutes in a stream can be categorized as advective and dispersive. A stream
that exhibits purely advective flow is said to undergo "plug flow." Under ideal
plug flow, the length, shape, and peak concentration of a dye tracer cloud will
remain unchanged during transport downstream. Dispersive transport moves solutes
from areas of higher concentration to areas of lower concentration. Thus, with
dispersive transport, a dye tracer cloud will expand in length and reduce in
peak concentration over time.

A highly simplified but useful
conceptual model of dispersive transport (Levich et al. 1967) considers
the stream channel to be divided into a rapidly flowing "active area," and a
stagnant, slack water area or dead zone. The velocity of the leading edge of a
dye dump may then be associated with the velocity of water and solute within the
active flow area. During transport, this water and solute are dispersed
laterally between the active area and the dead zone. This lateral dispersion
results in an apparent longitudinal dispersion, as a part of the solute is
continuously stranded in the dead zone and recruited back into the active area
of the cross section velocity. Total travel time is the sum of travel time
within the active area to the given location plus a cumulative dead zone time.
For the peak, this dead zone time is the most probable cumulative value, given
the active area travel time at a downstream location.

The active area of the channel,
AL, may be approximated as stream discharge, Q,
divided by the velocity of the leading edge, vL, of
the dye cloud.

Analogously, areas may be defined
from the velocity of the dye peak and trailing edge. The physical interpretation
of these areas, however, is less clear:

where subscripts P and T denote the peak value, and trailing edge value,
respectively. Equations 1 through 3 form the central assumptions of the MPF
model.

Active area and velocity of the
leading edge of the spill are here assumed to be proportional to the total
stream discharge raised to a fractional power. This formulation is a variation
of the approach introduced by Leopold and Maddock (1953). The Leopold and
Maddock equation is commonly used for stream geometry and velocity projections
in water quality modeling (Mills, 1986; Ambrose et al. 1993; Brown and
Barnwell, 1987; Allen et al. 1994). Active area,
AL, is thus assumed to follow an exponential
relationship with discharge defined by:

and

where x is stream rivermile location, the parameters
aL(x) and bL(x) are
independent of discharge, and Qm is a typical river
discharge. Here Qm=11,327 cms ( 400,000 cfs),
approximately the median lower Mississippi River discharge below the Old River
Control Structure (ORCS). Normalizing the discharge by dividing by
Qm establishes the value of
aL(x) as the cross sectional area under typical
discharge conditions. From the above equations it follows that:

The parameter
bL(x) can adjust the sensitivity of the cross
sectional area and leading edge velocity to discharge. If
bL(x) is one, area is independent of discharge, and
velocity is proportional to discharge. If bL(x) is
zero, area is proportional to discharge, and velocity is independent of
discharge.

The peak area and trailing edge
areas are assumed to be related to AL through the
relationships:

Analogous to the active area, the
incremental areas of the peak and tail, AP and
AT, are assumed to be described by:

and

This model formulation assures that
AT AP
AL. In model calibration and use this formulation has
proven to be adequate for the lower Mississippi River; some modification,
however, may be required for application to other streams.

2.1.2 Peak
Concentration

Peak concentration projection is
based on the unit concentration concept (Boning, 1974; Calandro, 1978). The unit
concentration, cu, facilitates comparison of dye
tracer studies by normalizing concentration values for stream discharge, Q, and
tracer or contaminant mass, M:

where x0 is the initial spill or dye injection
location. Unit concentration has dimensions of reciprocal time; for convenience,
however, it is often reported as (ug/L)cfs/lb. A graph of unit concentration
versus rivermile may be determined experimentally from dye tracer data. To
ensure a uniform reach, this experimentally determined graph can project peak
spill concentrations for other values of Q, M, and other origins by translating
the graphical spill origin to the alternate location.

Concentration at time t and
rivermile x can be calculated from the unit concentration as:

where f is the dye time-concentration curve normalized to a peak value of
one, and z is a normalized linear function of time defined by the ratio:

Here, zL and zT are the
values of z that correspond to the leading edge and trailing edge of the
function f, respectively.

As an example, it may be assumed
that f is independent of x, and is related to a standard normal probability
function, G(z), by:

In this example, the function f has a peak value at z=0, is symmetrical about
z=0, has a value of 5% of the peak value at z=2.44, 7.5% of the peak at z=2.28,
and 10% of the peak at z=2.15. Because the leading and trailing edges occurr at
concentrations between 5 and 10 % of the peak concentration, z in the range
-2.44z-2.15 corresponds to the leading edge, and z in the range 2.15z2.44
corresponds to the trailing edge of the curve. In this example it is assumed that
zT=-zL=2.28.

Taking the derivative of z with
respect to t:

Integrating the product of flow and
concentration over time provides the total mass, M, passing the point:

Distribution number,
D*, is here defined to be the product of unit
concentration and duration,
tT-tL. Then from equation 16
it follows that:

In this example:

The distribution number can be
converted to more typical units by application of the appropriate conversion
factors:

Although this example is based on
the assumption of a specific function for f(z), similar results would be
anticipated for other reasonable concentration distributions. Actual dye tracer
curves are usually skewed, with a greater mass of tracer following the peak
concentration than would be predicted by a symmetrical distribution. In the most
extreme example, f could have an exponential distribution:

In this case,
zL=zP=0, and, assuming the
trailing edge to be 7.5% of the peak,
zT=D*=2.59. If the trailing
edge was defined as 5% or 10% of the peak, zT and
D* would have values of 2.30 or 2.99, respectively.

Actual concentration functions
should fall between these extremes of skewness and symmetry and be closer to the
normal distribution example. As described in the following sections, the value
of D* for the lower Mississippi River was estimated to
be 1.966 from reported dye studies and, therefore, is consistent with this
conjecture.

Although
D* is derived from cu, which
is a function of x, t, and x0, the value of
D* depends solely on the distribution function, f. The
value of D* is a constant if the function f is invariant, and, as shown above,
is not expected to vary greatly with time or location. The distribution number,
treated as a constant, provides the linkage between the time-of-travel estimates
of the MPF formulation and the peak concentration estimate:

3.0 Model
Application

3.1 Data
Availability

Adequacy of data for modeling the
Mississippi River and Bayou Lafourche is discussed in the following sections.
Table 1 summarizes the number of dye studies for which data on Louisiana streams
are available. At a minimum, two overlapping studies are currently required for
calibration of the R-TOT model.

3.2 Mississippi
River

Location on the Mississippi River
is denoted as rivermiles upstream from or above Head-of-Passes (AHP) where the
river channel divides into distributary channels that flow into the Gulf of
Mexico. Along the lower Mississippi River corridor, rivermiles AHP are familiar
units of river location, and are shown on both USGS quad maps, and Corps of
Engineers Mississippi River maps. New Orleans is approximately 104 rivermiles
AHP, and Baton Rouge is located approximately 232 miles AHP. The 885 kilometer
reach modeled here includes all of the Mississippi River within and bordering
the state of Louisiana from rivermile zero to 550. Tables 2 and 3 list major
landmarks along the Mississippi River by rivermile location. Note that in R-TOT,
rivermiles are assumed to increase downstream of the zero point, and decrease
upstream. Thus, rivermiles on the Mississippi River AHP are defined as negative
quantities.

There are no large tributaries
within the study reach, and the Atchafalaya River is the only major
distributary. The headwaters of the Atchafalaya River are formed by flows from
the Red River and the Mississippi River. Flow from the Mississippi River is
routed to the Atchafalaya River through the Old River Control Structure (ORCS)
at Mississippi rivermile 314. The ORCS was constructed and is operated by the
U.S. Army Corps of Engineers. Flow in the Atchafalaya River is regulated to
approximately 30% of the total flow of the Red and Mississippi Rivers. On
average, roughly 23% of the Mississippi River discharge is diverted to the
Atchafalaya River at the ORCS. Discharge of the Mississippi River below the ORCS
is measured or estimated on a daily basis. Because there are no large
tributaries or distributaries between rivermile zero and the ORCS, this observed
discharge is generally applied to this entire segment of the river.

Values for the Mississippi River
model parameters were estimated using the data from nine dye tracer studies
conducted over subsections of the river (Calandro, 1976, 1978; Schexnayder,
et al. 1990; Hebel et al. 1991). Additionally, the Mississippi
River model was tested using observations from six monitored chemical
contamination episodes (Table 4).

3.2.1 Calibration

Nine dye tracer time-of-travel
studies have been performed on the Mississippi River within the study area
(Waldon, 1991, 1997c) between the Louisiana-Arkansas border, rivermile 550, and
Head of Passes (rivermile 0). Seven of these studies were performed
cooperatively by the Louisiana Department of Public Works, the Louisiana
Department of Transportation and Development, and the U.S. Geological Survey
(Everett, 1971; Calandro, A.J., 1976, 1978; Wells, 1980). Two more recent
studies were performed by the LDEQ in cooperation with the University of
Southwestern Louisiana (Schexnayder et al.. 1990; Hebel et al.
1991).

Values for the model's travel time
parameters were estimated using the data from the nine dye tracer studies. A
heuristic approach was used to directly estimate parameter values for specific
river reaches. Initially, an attempt was made to develop analytical equations
for the parameter variation versus river mile. These equations were based on the
assumption that the active area of the river is a linear function of rivermile
at two river discharges, 10,194 and 22,427 cms (360,000 and 792,000 cfs).
Additionally, it was assumed that the active area at all discharges is equal at
rivermile zero. Calculated time-of-travel based on these simple assumptions was
fairly accurate, but was considered to be inadequate for spill surveillance and
warning. Parameter values were therefore estimated for specific river reaches. A
third alternative formulation for parameter calculation was also tested. Here,
the values of the parameters were interpolated to provide a continuous
functional relationship with rivermile. Very little improvement and even some
additional error was found using this formulation. As a result, this approach
was not pursued further. A piecewise constant parameterization was the method
chosen for the study. Travel time calibration (Figure 2-5) was in good agreement
with dye tracer study observations.

Figure
2        Mississippi River model
calibration, observed and predicted travel times in hours of dye leading
edge

Figure
3        Mississippi River model
calibration, observed and predicted travel times in hours of dye
peak

Figure
4        Mississippi River model
calibration, observed and predicted travel times in hours of dye trailing
edge

Figure
5        Mississippi River model
calibration, observed and predicted times in hours of dye duration

Data from a minimum of two studies
at different river discharge rates are available for all reaches of the river
between St. Francisville (rivermile 266) and Pointe a la Hache (rivermile 49).
Above St. Francisville, from rivermile 523 to 266, two studies have been
performed. Calibration in this reach is less reliable because there is little
overlap between these studies, and they were performed at nearly the same
discharge. In order to provide extrapolation of time-of-travel to other flows, a
reasonable exponent value has been assumed for flow adjustments within this
reach. Time-of-travel estimates in this reach may be unreliable when discharge
is considerably different from the calibration discharge. To forestall this
problem, the computer program developed by this project provides a warning if
the user requests projections that are not supported by an appropriate
calibration dataset.

Time-of-travel estimation in the
reach below Pointe a la Hache (rivermile 49) is similarly calibrated using a
single study performed at 13,337 cms (471,000 cfs). In this case, because the
active area appears to be relatively insensitive to flow in this lowest river
segment, a single study may be adequate. Added complexities may, however, also
exist in this region. Tidal influences may be significant at locations near Head
of Passes. Additionally, the presence of a salt water wedge in the lower river
may effectively reduce the active area at unusually low flows. Warnings of these
conditions are provided by the computer program.

The calibrated MPF model
demonstrates clear rivermile trends. Active (leading edge) area, peak area, and
trailing edge area as a function of rivermile at constant river discharge rates
can be easily calculated from the model parameters and equations. Areas at all
discharges exhibit a decreasing trend moving upriver. Below Baton Rouge, the
river is contained within levees and appears to have a relatively simple channel
geometry at all discharges. Within this segment, channel area increases
continuously in the downstream direction. Areas are less dependent on rivermile
at higher discharges, and areas are least sensitive to flow changes in the most
downstream reach. Near Head of Passes (rivermile zero), the area is relatively
insensitive to river discharge.

Active area
(aL in Table 5) increases in the downstream direction
in a nearly linear fashion for similar discharge magnitudes above and below the
ORCS. This observation reflects the river's decreased velocity as it approaches
base level. It is also apparent that the active area becomes less sensitive to
flow variations at downstream locations. Similarly, the river stage is less
sensitive to discharge as one moves downstream. The effect of the ORCS on
channel area is also apparent from the calibration parameters. The active area
of the Mississippi River just above the ORCS is larger than the active area just
below the structure. This again is consistent with the structure's partial
function as a base level for the river.

Between St. Francisville and Baton
Rouge, the values of bP and
bT were estimated to be negative. These unusual values
may be caused by the existence of islands. Islands do not significantly
influence travel times below Baton Rouge. Above Baton Rouge, however, Profit
Island apparently has a significant influence on travel times and dispersion.
This is particularly pronounced at higher river discharges. Data from the Baton
Rouge station of the 1991 dye study (study 9) showed a pronounced "shoulder"
following the peak concentration (Hebel et al. 1991). This was likely
caused by the existence of two separate routes around Profit Island. Above the
ORCS time-of-travel studies are only available at flows near 11,327 cms (400,000
cfs). Projections of travel times at discharges which are not near 400,000 cfs
are therefore questionable. Travel time estimates in this segment may
additionally be confounded at high water by points and backwater areas which
become inundated because they are not protected by levees.

Based on the derivation presented
earlier, it was hypothesized that the peak concentration distribution number is
approximately constant and insensitive to changes in travel time, rivermile, or
discharge. The mean value of the 25 observations of the distribution number was
1.966, with a standard deviation of 0.255 (Figure 6). Based on these findings,
the unit concentration in the modeled reach of the Mississippi River can be
estimated from duration:

Figure
6        Predicted and observed
unit concentrations from dye tracer studies

3.2.2 Application

The EWOCDS was established
primarily to warn lower Mississippi River drinking water providers of chemical
discharges that might adversely impact water quality (Romanowsky, 1985; Overton
et al. 1988). Ten sampling sites (Figure 1) are located between
rivermile 232 and rivermile 87.9. Water samples are collected and analyzed at
each site at least once a day. When elevated levels of one or more of the
chemical pollutants are found in a regular sample, downstream stations are
alerted and additional samples are collected at roughly hourly intervals.

Although the primary purpose of the
EWOCDS is warning water providers, data from the system can be used for a
variety of other purposes. Many of the events monitored by the system provide
data analogous to dye tracer studies. As such, these data can provide valuable
test cases of the time-of-travel model. Monitoring data from these spills are
generally inadequate for model calibration or traditional model verification.
Spills are often not monitored at some sites because the daily monitoring
frequency is inadequate to assure detection of all events. Typically, an
elevated measurement at one site will trigger an alert, which will result in
more frequent sampling at downstream stations. Thus, a spill may be monitored
only once at a first station, a few times at the next downstream station, and
completely characterized at sites further downstream. In addition, each site
operates separate GC analytical equipment and may therefore have different
laboratory procedures, detection and quantification limits, and sampling
protocols. In spite of these limitations, the monitored events within the
historical database do provide an independent test of the time-of-travel model
in the real time situations for which the model was developed. Considerable
insight into the utility of this model can therefore be gained from examining
these spill events. Six chemical contamination episodes monitored on the river
(Table 4) have been utilized (Waldon, 1991) to test the time-of-travel model. In
all cases, the model adequately predicted downstream travel times. One of these
spills, designated "Event 1" by Overton et al. (1988) is described
below in detail. Carbon Tetrachloride spill, December, 1990. Bostock (1991)
documented a carbon tetrachloride spill which occurred on December 11, 1990,
rivermile 210. This spill was first monitored by the EWOCDS station at rivermile
209.6. Subsequently, the spill was monitored at four downstream stations. River
discharge on the day of the spill was 378000 cfs. Figure 21 graphs the observed
and calculated time-of-travel and estimated peak concentration for this event.
The peak concentration in this graph, plotted as a dashed line, was calculated
on a basis of a 650 pound spill. Hours for sampling times were calculated
relative to the estimated time of the spill. Samples for which observed carbon
tetrachloride was above 0.4 ppb are marked by a star symbol. Toluene spill, May,
1991. Freedman and Wagenecht (1991) documented a toluene spill resulting from a
barge accident which occurred on May 5, 1991. This data are specially
significant for comparison to the time-of-travel estimates because the River
discharge on the day of the spill was approximately 1,150,000 cfs. This is a
very high flow, and is considerably above any flow for which dye data are
available. The toluene spill originated near Port Allen, Louisiana, and was
detected at locations downstream. Data from the Monsanto EWOCDS site were
adequate to estimate passage of the trailing edge of the spill, and data from
the New Orleans Carrolton EWOCDS site were adequate to characterize the entire
toluene distribution as it passed the sampling station. Data from this spill are
compared to projected values in Figure 22. Projected peak concentration, graphed
as a dashed line, is based on a 20,000 pound toluene spill. Samples for which
the observed concentration exceeded 4 ppb are designated by a star symbol in
Figure 22. A hypothesized second spill is also outlined by second leading and
trailing edge lines in Figure 22. The figure demonstrates that such a spill
could have occurred several hours after the initial spill, and missed detection
at all stations except St. James EWOCDS sampling site. -->

1,2-Dichloroethane spill, August 1987.

This spill involved
1,2-Dichloroethane (EDC), and smaller concentrations of 1,1,2-Trichloroethane.
Following initial detection at rivermile 232, the contaminants were monitored at
downstream sites, with relatively complete observations at rivermiles 175.5,
152.2, and 104.7 (Figure 7-8). The higher peak concentration observed at
rivermile 152.2 compared to the concentration observed at rivermile 175.5 likely
results from differences in site lab procedures or sampling. Seventy hours
later, a second, much smaller spill followed the major spill. River discharge
over this period varied from 6,230 cms (220,000 cfs) on August 13, to 6,031 cms
(213,000 cfs) on August 16. Model projections were based on a constant discharge
of 6,088 cms (215,000 cfs).

Figure
7        EDC concentrations
observed at three monitoring stations. Model-predicted leading edge arrival time
and trailing edge passage are marked by solid and dashed vertical lines,
respectively

Figure
8        Comparison of observed and
modeled EDC spill occurrence. Solid lines indicate model-projected leading edge,
peak, and trailing edge travel

The initial time and rivermile of
the spill were determined through a trial and error procedure. This was done in
order to obtain a match with the timing of the observed excessive concentration
samples (Figures 7 and 8). The actual source of this spill was unknown, but
clearly was above the most upstream station at rivermile 232. Because the spill
time was uncertain, time in this discussion was measured in hours after 12AM on
August 1. This spill was estimated to start at rivermile 275 on August 10 at
7:00 P.M., or 235 hours. Origination at rivermile 275 assumes an instantaneous
release. If the duration of the major release was not short in comparison to the
duration projected at rivermile 232, then the actual origin of the spill was
estimated to be located at a point downstream of rivermile 275 and upstream of
rivermile 232.

The distribution number approach
provided a simple basis for estimating the total amount of contaminant involved
in this spill (Table 6). Model-calculated duration was used to estimate unit
concentration using Equation 21. Observed peak concentration and stream
discharge were then substituted into Equation 11 to determine spill mass, M.
Using this approach, spill mass was estimated to be between 950 and 1600 kg of
EDC. One might alternatively estimate the total spill amount by numerical
integration of the product of concentration and discharge over time, but this is
usually not practical because spill concentrations are seldom observed over a
sufficient period or with adequate frequency to estimate a complete distribution
curve at a single site. By using model calculated duration based on observations
at a number of sites, a better estimate is achieved.

Two samples at rivermile 232
detected EDC. Although these samples were taken after spill passage was
projected by the model, insight into the spill can be gained through comparison
with model projections. At rivermile 232, the model projected leading edge,
peak, and trailing edge arrival at 259.5, 261.2, and 264.4 hours, respectively.
Projected peak concentration at rivermile 232 was 25 g/L, and the first observed
concentration was 3.33 g/L observed 6.6 hours after projected trailing edge
passage. Thus, sampling at this site clearly missed the peak concentration, and
indicates that the spill trailing edge may have arrived at a slightly later time
than the model projected.

Sampling at rivermile 209.6, the
second monitoring site, detected EDC only once at 280.42 hours. Projected
leading edge, peak, and trailing edge arrival at this site were 273.9, 277.1,
and 282.8 hours, respectively. Peak concentration was projected to be 14 g/L.
The single observed concentration of 5.65 g/L was consistent with the projection
that this sample was taken after passage of the EDC peak.

3.3 Bayou Lafourche

Bayou Lafourche was historically a
distributary of the Mississippi River, and before this century was also known as
the west fork of the Mississippi River. Early in this century the bayou was
completely isolated from the river by flood control levees. Today, a small part
of the Mississippi River flow is diverted into the bayou via a pump station at
Donaldsonville. The study area for which the R-TOT model has been calibrated
extends 62 miles, from the headwaters of the bayou at Donaldsonville to
Valentine, Louisiana.

Bayou Lafourche is the source of
drinking water for a quarter of a million people in five parishes in southwest
Louisiana. The bayou is also the major artery through this region; highways,
cities, and industry line its banks from Donaldsonville in the north to Golden
Meadow near the Gulf of Mexico. Due to the proximity of developed areas, there
have been numerous contaminant spills into the bayou. In order to minimize the
public's risk from a spill, drinking water providers need timely warning of
approaching contaminants.

Locations and distances on the
bayou are conveniently represented as rivermiles downstream from the headwater
(pump station) at Donaldsonville. Fresh water intakes and their rivermile
locations are listed in Table 7. Prominent landmark locations (e.g. bridge
crossings) are listed in Table 8.

3.3.1 Calibration

The R-TOT computer model was
calibrated using data gathered during two tracer dye time-of-travel studies
conducted on the bayou in June, 1991 and May, 1994. These studies involved a
collaboration among the LDEQ, the Bayou Lafourche Freshwater District, and the
University of Southwestern Louisiana (USL). The studies were conducted utilizing
fluorescent rhodamine WT dye injected at an upstream site and observed passing a
downstream site. Discharge was determined utilizing bridge and boat measurement
techniques, along with gage readings. Dye concentrations were determined
utilizing Turner Designs model 10 fluorometers.

Development of a time-of-travel
model and program for Bayou Lafourche required that dye studies be conducted at
separate flow regimes. Discharge was measured at three sites for each of these
studies. Average discharge during the 1991 study was 138.8 cfs (cubic feet per
second); during the 1994 survey average discharge was determined at 327.0 cfs.
Dye was injected and recovered at predetermined sites, segmenting the bayou into
manageable reaches. Separate dye travel times were determined for each reach.

3.3.2 Application

No data are available to
independently test the calibrated R-TOT Bayou Lafourche time-of-travel model.
Changes in the bayou's hydraulics caused by rooted plant growth and
sedimentation may cause a reduction in present day velocities. A verification
time-of-travel study on Bayou Lafourche should be conducted. In the absence of
such a study, future spills should be carefully monitored in order to provide a
crucial test and verification of the model. Until further testing can be
accomplished, the credibility of the model is reduced.

4.0 Training and
Distribution

Three free river spill training
classes have been completed under OSRADP sponsorship. These classes were hosted
by the LDEQ (July 2 and July 9, 1997), and by the USL Department of Civil
Engineering (July 22, 1997). Each trainee was provided with a training manual
and an R-TOT diskette. Trainee response was generally positive. Depending on
demand, funding, and availability of resources, future training classes may be
offered.

Two R-TOT manuals were developed as
a part of the OSRADP supported research. A user's manual (Waldon, 1997a)
provides information on R-TOT model installation, utilization, parameter
estimation, and interpretation of output. The programmer's manual (Waldon,
1997b) provides information for individuals wishing to extend the R-TOT model to
new rivers, or change internal aspects of the model. A journal article (Waldon,
1997c) describing the model's development and application on the Mississippi
River has also been submitted.

To provide a wider distribution and
awareness of river spill modeling, and specifically, the R-TOT model, a web page
has been developed: http://www.ucs.usl.edu/~mgw0237/riverspill.html.
This page provides links to other river spill related internet resources,
information on training opportunities, a bibliography of river spill related
references, information on the current versions of R-TOT, and a download area
for the R-TOT model. The page has purposefully been designed to provide rapid
access and to accommodate text only browsers.

5.0 Conclusions

The simple model presented here
applies an MPF formulation of spill velocity in the calculation of spill
time-of-travel. The model combines the MPF calculated duration with the unit
concentration to provide a unified methodology for predicting peak
concentrations. This model is sufficiently accurate for most requirements of
hazardous materials spill monitoring and risk management, and is computationally
simple enough to be applied in real time spill management. The utility of this
model for spill identification, tracking, evaluation, and management has been
demonstrated through the analysis of six actual events (including the EDC spill
discussed here) on the river. The model does not require an extensive number of
parameters, and required parameters can be easily identified from dye
time-of-travel studies. Additionally, the equations for this model are
straightforward enough to allow calculations for time-of-travel and peak
concentration to be easily incorporated into simple computer programs or
spreadsheets.

Spill velocities are highly
sensitive to discharge. As an example, consider a spill originating in Baton
Rouge (Table 9). For a five-fold change in discharge, leading edge travel times
to New Orleans would vary by a factor of three. Both peak and trailing edge
travel times are similarly sensitive to variation in discharge. The spacial
extent of the spill is far less sensitive to discharge, increasing only 29%
under the same five-fold discharge increase. Without a model, estimation of
spill arrival time and duration is difficult and less certain.

A computer program implementing
these equations and providing advice on model applicability, warnings, and
errors has been used for several years and has recently been revised and
enhanced (Waldon 1997a, 1997b). The new version of the river time-of-travel
model (R-TOT, available from the author) was implemented using Microsoft Excel
worksheets and macros to improve the user interface and simplify support and
application to new rivers. Based on a previous implementation (Waldon and Hebel,
1995), the new model version has also been extended to Bayou Lafourche. Data
from thousands of dye time-of-travel studies on other streams are also available
(Boning, 1974), and extension of this model to additional streams would be of
value both for spill management, and as a preliminary integration of data in
support of more sophisticated model development. At this time, efforts of the
author and colleagues are being directed toward extending the model to
additional Louisiana streams.

The R-TOT computer program for the
Mississippi River has minimized unnecessary water supply interruptions.
Additionally, the program has identified possible stream reaches where spills of
unknown origin may have originated, and conversely, excluded other reaches where
spills did not occur. The R-TOT program has also been used for spill contingency
planning. The model considers only transport of materials that are dissolved or
entrained into the bulk water movement. Further data collection and research
into travel of buoyant materials and sheen producing contaminants are needed.

6.0 References

Allen, P.M., J.G. Arnold, and B.W. Byars, 1994. Downstream channel geometry
for use in planning-level models. Water Res. Bull. Vol. 30(4):663-671.

Ambrose, R.B., T.A. Wool, and J.L. Martin, 1993. The water quality analysis
simulation program, WASP5: Model documentation. Environmental Research
Laboratory, U.S. EPA, Athens, Georgia.

Beer, Tom, and Peter C. Young, 1983. Longitudinal dispersion in natural
streams. J. of Env. Engineering, ASCE. 109(5):1049-1067.

Benedict, B.A., 1979. Analytical models for mixing of toxic spills in rivers.
Proc. of the Hydrologic Trans. Modeling Symp., Am. Soc. of Agric. Eng., New
Orleans. pp. 108-117.

Boning, C.W., 1974. Generalization of stream travel rates and dispersion
characteristics from time-of-travel measurements. Jour. Research U.S. Geol.
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Bostock, H.H., and M.G. Waldon, 1989. EWOCDS: System analysis and evaluation.
Report No. WQR 89.11.

Bostock, H.H., 1991. Spill event assessment report: Mississippi River/carbon
tetrachloride, December 11-14, 1990. Univ. of Southwestern Louisiana Center for
Inland Water Studies, Report No. WQR 91.01.

Bostock, H.H., P.R. Richards, M.C. Rogers, and M.G. Waldon, 1991. A GIS
approach to potable water protection on the Mississippi River. Proceedings of
the AWRA symposium on "Resource Development in the Lower Mississippi," New
Orleans, Louisiana.

Brown, L.C., and T.O. Barnwell, Jr., 1987. The enhanced stream water quality
models QUAL2E and QUAL2E-UNCAS: Documentation and user's manual.
EPA/600/3-87/007, Environmental Research Laboratory, U.S. EPA, Athens, Georgia.

Bowie, G.L., et al. 1985. Rates, constants, and kinetics: Formulations in
surface water quality modeling (Second Edition). EPA/600/3-85/040.

Calandro, A.J., 1976. Time of travel of solutes in the Mississippi River from
Arkansas-Louisiana state line to Plaquemine, Louisiana. Louisiana Department of
Public Works, and U.S. Geological Survey, Technical Report 12.

Calandro, A.J., 1978. Time of travel of solutes in Louisiana streams.
Louisiana Department of Trans. and Dev. Office of Public Works, and U.S.
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Elhadi, N., A. Harrington, I. Hill, Y.L. Lau, and B.G. Krishnappan, 1984.
River mixing: A state-of-the-art report. Can. J. Civ. Eng. 11:585-609.

Everett, D.E., 1971. Hydrologic and quality characteristics of the lower
Mississippi River. Louisiana Department of Public Works, and U.S. Geological
Survey, Technical Report No. 5, 48p.

Freedman, J., and D. Wagenecht, 1991. An account of the toluene spill
resulting from a barge accident in the Mississippi River on May 5, 1991.
Louisiana Department of Environmental Quality, Office of Water Resources, May
10, 1991.

Hebel, M.T. Jr., M.J. Forbes, and D.E. Everett, 1991. Time of travel of
solutes in the Mississippi River from St. Francisville to Baton Rouge,
Louisiana. Louisiana Department of Environmental Quality in cooperation with the
Univ. of Southwestern Louisiana Center for Louisiana Inland Water Studies.

Hubbard, E.F., F.A. Kilpatrick, L.A. Martens, and J.F. Wilson, Jr., 1982.
Measurement of time of travel and dispersion in streams by dye tracing.
Techniques of Water-Resources Investigations of the United States Geological
Survey, Book 3, Chapter A9, 44 pp.

Jobson, H.E., and D.H. Schoellhamer, 1987. User's manual for a branched
Lagrangian transport model. U.S. Geological Survey, Water-Resources
Investigations Report 87-4163.

Leopold, L.B., and T. Maddock, 1953. The hydraulic geometry of stream
channels and some physiographic implications. U.S. Geological Survey
Professional Paper 252.

Levenspiel, O., and W.K. Smith, 1957. Notes on the diffusion-type model for
longitudinal mixing of fluids in flow. Chem. Eng. Sci. 6:227-233.

Levenspiel, O., and J.C.R. Turner, 1970. The interpretation of residence-time
experiments. Chem. Eng. Sci. 25:1605-1609.

Levenspiel, O., B.W. Lai, and C.Y. Chatlynne, 1970. Tracer curves and the
residence time distribution. Chem. Eng. Sci. 25:1611-1613.

Levich, V.G., V.S. Markin, and Y.A. Chismadzhev, 1967. On hydrodynamic mixing
in a model of a porous medium with stagnant zones. Chem. Eng. Sci. 22:1357-1367.

McQuivey, R.S., and T.A. Keefer, 1976a. Convective model of longitudinal
dispersion. J. Hydraulics Div., ASCE. HY10:1409-1424.

McQuivey, R.S., and T.A. Keefer, 1976b. Dispersion - Mississippi River below
Baton Rouge. J. Hydraulics Div., ASCE. HY10:1425-1437.

Mills, W.B., G.L. Bowie, T.M. Grieb, and K.M. Johnson, 1986. Handbook: Stream
sampling for waste load allocation applications. EPA/625/6-86/013, U.S. EPA
Office of Research and Development, Washington, D.C.

Nordin, C.F., Jr., and G.V. Sabol, 1974. Empirical data on longitudinal
dispersion in rivers. USGS Water-Resources Investigations 20-74, Report No.
USGS-WRD-74-035, 331.

Nordin, C.F., Jr., and B.M. Troutman, 1980. Longitudinal dispersion in
rivers: The persistence of skewness in observed data. Water Resources Bull.
16(1):123-8.

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early warning organic compound detection system: A descriptive data review.
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Romanowsky, Peter, 1985. Progress in the development of Louisiana's lower
Mississippi River Water Quality Management program. Louisiana DEQ.

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solutes in the Mississippi River from New Orleans to Pointe a la Hache,
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a conservative dye indicator. Report number CLIWS-WQR 93.01.

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River: Technical report. Report number WQR 91.04.

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ATTACHMENT A

R-TOT

River Time-of-Travel

Computer Program User's Manual

Michael Gene Waldon, Ph.D., P.E.

Center for Louisiana Inland Water Studies

Department of Civil Engineering

University of Southwestern Louisiana

Lafayette, Louisiana

June 1997

Preface

The R-TOT model
development is funded by the The Louisiana Applied And Educational Oil Spill
Research And Development Program (OSRADP). Previous funding was provided by the
State of Louisiana Department of Environmental Quality (LDEQ). The model
utilizes data which were collected by personnel of the Office of Water Resources
of the LDEQ, by the U.S. Geological Survey in cooperation with the Louisiana
Department of Transportation and Development, the U.S. Army Corps of Engineers,
and by staff members of the University of Southwestern Louisiana Center for
Louisiana Inland Water Studies (USL-CLIWS). These previous studies provide a
basis for the program described in this report.

Application of the procedures and programs presented here are solely the
responsibility of the user. Suggestions for corrections, extensions, or
clarifications of the computer program or this document would be appreciated.
Please address comments to the USL Center for Louisiana Inland Water Studies,
P.O. Box 42291, Lafayette, LA 70504-2291, or through our web page site, which is
currently:

http://www.ucs.usl.edu/~mgw0237/riverspill.html

Table of
Contents

Preface

Overview

Installation

Model
Execution and User Input

Determination
of User Input Parameters

Examples

Riverspill
Web Page

Bibliography

Glossary
of Selected Terms

List of
Figures

Figure
1 Example 1, Input Dialog Screen

Figure
2 Output Screen for Example 1

Figure
3 Example 2, Input Dialog Screen

Figure
4 Example 2, variable discharge input dialog sheet appears after user
presses the "Enter discharges" button.

Figure
5 Example 2, output sheet

Overview

R-TOT, the River Time-of-Travel Model, is a model for predicting the time of
travel of a solute or entrained material. The current version of R-TOT is
implemented and programmed in Microsoft Excel, and Excel must be installed on
the computer in order to use the R-TOT system. The model provides a convenient
user interface for input, a summary output sheet, and easy user access to the
data analysis and graphical capabilities available within Excel.

This manual is intended to assist the user in application of the R-TOT
Time-of-Travel computer program. For a specified downstream location this
program projects:

the arrival time of the leading edge of a spill;

the arrival time of the peak concentration;

the time the trailing edge of the spilled material will pass;

the peak concentration if the amount of material spilled is known.

Time-of-travel models are useful in a number of water quality management
applications, including:

providing timely warning to donwstream water users so that water intakes
may be shut down to avoid risks of contamination;

predicting duration of a spill to minimize potential water shortages, loss
of fire protection, and so on;

spill contingency planning, spill prevention control and countermeasure
(SPCC) plans;

spill training simulation;

investigation of spills of unknown origin.

The model was designed to present a friendly and uncomplicated user
interface, and to provide a straightforward computational approach that
minimizes programming effort needed to incorporate new study data. The program
has been designed and tested to run under the Windows operating system. Assuming
that Excel has been installed, the user may run the program by activating the
appropriate spreadsheet file. More information will be found in the file named
"readme.txt" on the distribution disk. The user should then simply follow the
input requests provided by the program. Sections of this manual assist the user
in determining the appropriate input values. In many situations, the program
provides user advice at run-time to warn the user of unusual conditions or input
errors.

Installation

R-TOT has been run successfully
using Excel 5 under Windows 3.11, and Windows 95 using Excel version 7 for
Windows 95. Suggested minimum hardware requirements are 16 megabytes of
installed RAM, and 5 free megabytes of hard disk space available prior to
installation. The user should guard against introducing computer viruses during
installation by virus scanning the distribution files. Note that zipped
(compressed) files may need to be scanned before and after unzipping.

Installation is simple. The user
should create a subdirectory for the model (for example C:\R-TOT). Copy the
distribution file(s) to this directory, and follow the instructions provided in
the file "readme.txt."

To remove (or uninstall) R-TOT, the
user should simply delete the associated files that were copied during
installation. Version 5.0 of R-TOT should not require any other uninstall
procedure. Future versions may require additional uninstall steps. Consult the
distribution "readme.txt" file for any additional information on deleting future
versions.

Model execution and user
input

There are a number of ways to
execute the R-TOT program. One method is to simply view the R-TOT subdirectory
using File Manager or Windows 95 Explore, and double-click the desired
spreadsheet name. The screen appearance of the R-TOT program may vary between
computers depending on the operating system, monitor resolution, and application
options that the user has selected.

As the program runs, the user
should carefully read the online instructions, warnings, and error messages.
Warnings provide valuable suggestions and information concerning input
selections and values. After a warning, the user may return to the input dialog
window or ignore the warning and continue to the output screen. Each error that
is detected case an error message box to be displayed. The user is returned to
the input dialog window following error message displays.

Determination of user input
parameters

In order to calculate
time-of-travel, the user must enter a value for the starting rivermile, ending
rivermile, and discharge. Additionally, the amount of contaminant spilled, if
known, can be entered in order to estimate peak concentration at the ending
rivermile. Spill date and time are optional. If any of the keyed in parameters
are out of the model's range, the user will be prompted by warning or error
messages. Errors are "fatal" to the programs ability to run, and the program
will return to the parameter input dialog sheet.

RIVERMILE

In R-TOT, locations are determined
by distance termed in rivermiles (RM), which are downstream of a selected zero
point. Rivermiles upstream of this zero location are negative. By convention,
Mississippi River rivermiles are measured upstream from Head-of-Passes. Thus,
rivermiles for locations above head-of-passes (AHP) on the Mississippi River are
entered as negative numbers in R-TOT. In contrast, rivermiles on Bayou Lafourche
are measured in miles from the Mississippi River levee at Donaldsonville, and
are positive. The user receives rivermile locations by using a dropdown edit
feature that displays locations of selected sites along the modeled reach. The
user may enter a site description following the rivermile value by entering a
comma and a space after the number and appending the site description.

DISCHARGE

Discharge (or flow) is a required
input parameter. The model will accept a direct discharge value in cubic feet
per second (CFS) or cubic meters per second (CMS). Discharge may be entered as a
single value, in which case that value is applied to the entire reach.
Alternatively, a variable rivermile dependent discharge may be entered. In this
case, the discharge entered applies to the downstream reach of the corresponding
rivermile. The model assumes that increases in discharge do not contain
additional spill material, and therefore do not dilute the material
concentration. A reduction in discharge is assumed to represent a diversion or
distributary, and appropriate mass is removed to account for this removal of
flow. Example 2 below illustrates a variable discharge model scenario.

The most expedient method for
estimating discharge is to use values monitored by a government agency.
Discharges and stages monitored by the New Orleans District of the Corps of
Engineers may be obtained by calling a recorded message at (504)862-2461, or by
accessing the New Orleans District Corps of Engineers "Daily Stage and Discharge
Data" web page at:

http://www.lmn.usace.army.mil/eng/edhd/edhh_2.htm

Discharge and stage data collected
by the Louisiana District of the USGS in Baton Rouge may be obtained by
contacting Mr. Blackie Devillier at (504) 389-0281 Ext. 3131, or Ms. Chris
Resweber at the same number Ext. 3123.

Discharge may be measured or
estimated by utilizing any of the following techniques:

A direct physical measurement of discharge by boat or from a bridge - This
determination of discharge requires specialized equipment and trained
personnel. In this method, numerous velocity and depth measurements are
performed and used to calculate discharge.

Tapedown measurement - A tapedown is a measurement from the water surface
to a known mark on a fixed structure. As the measurement decreases, water
surface elevation and flow increases. A stage discharge (or tapedown
discharge) relationship must be quantified to allow estimation of discharge
from tapedown measurement.

Stage Gauge - Stage is the elevation of the water surface relative to some
datum. Discharge is determined using a stage-discharge relationship. A wire
weight gauge (USGS Water Supply Paper 2175) or similar device is typically
installed at an appropriate fixed location.

Time-of-travel - If time-of-travel data are available for a spill, the
discharge may be determined through trial and error using R-TOT.

SIZE OF SPILL

If the total weight (in pounds) of
the contaminant of interest can be estimated, then the peak concentration of the
contaminant at the downstream site will be projected. If the peak concentration
projection is not required, the contaminant mass may be left blank.

The most straightforward method of
estimating contaminant weight is, of course, to use a reported weight. For
example, if 50 pounds of solvent containing 10% benzene is reported spilled,
five pounds of benzene would be entered into the computer program. The Windows
calculator may be activated to assist the user in more complex calculations.
Calculated values may be copied from the calculator and pasted into the
appropriate edit box.

R-TOT alternatively allows for
input of spill volume in gallons or barrels. In this case, the specific gravity
(weight relative to a similar volume of water) of the material must also be
entered. A dropdown edit box provides some typical specific gravity values to
assist the user in estimating this parameter.

If the peak concentration has been
measured at one downstream site, a second mass estimation technique is to simply
utilize the program peak concentration projection. Projected peak concentration
is proportional to the amount spilled. If the amount spilled is unknown, the
user may simply enter a convenient mass, 100 pounds for example. The actual
spill mass may then be estimated by adjusting the input mass by the ratio of the
observed to projected peak concentration. For example, if a peak of 50
micro-grams per liter, mg/L, was observed, and the program projects 20 mg/L for
a 100 pound spill, the actual spill mass would be estimated to be 250 pounds
(100*50/20).

Note that R-TOT assumes no loss of
material. Because most spill materials will experience some loss, observed
concentrations should typically be lower than those projected by R-TOT.

Examples

Note: All examples are ficticious.

(1) On July 4, 1997, at 10:15 AM, a barge accident spills 2000 pounds of EDC
into the Mississippi River at rivermile 229.2, the I-10 bridge in Baton Rouge.
River discharge on that date is 792,000 cfs. What is the time of arrival and
durration at New Orleans, rivermile 104.7? What is the peak concentration?

The input dialog sheet and output sheet are displayed in Figures 1 and 2. The
user must perform the following tasks to complete this example:

enter a descriptive title;

select known date/time;

enter date and time;

select single value discharge, and cfs discharge units;

enter discharge value;

enter rivermiles and descriptions of locations

or select rivermiles from the location drop down boxes;

select units of spill size;

enter spill size value;

press "OK (run R-TOT)" button;

wait for computations to complete;

examine output screen.

The output screen appears in full
view. To return Excel to normal view simply click on the "View" dropdown menu at
the top of the screen, and then click on "Full Screen" to deselect this option.

Figure
1        Example 1 input dialog
screen

Figure
2       Output screen for
Example1

(2) On August 19, 2001, at 9:00 AM, a dye time-of-travel study on the
Mississippi River was performed using 200 gallons of 20% dye solution having a
specific gravity of 1.19. The dye was injected at rivermile 381, Waterproof,
Louisiana. River discharge at the injection point on that date was 682,000 cfs.
Note that the injection point is above the Old River Control Structure
(rivermile 314 AHP) where roughly 23% of the Mississippi River discharge is
diverted to the Atchafalaya River. On this date, the discharge of the
Mississippi River below the Old River Control Structure is 514,000 cfs. What is
the time of arrival and duration at the Highway 190 Bridge in Baton Rouge,
rivermile 233.9? What is the peak concentration?

Execution of this example is
similar to Example 1. In this case the "Advanced" river discharge option is
selected, and the "Enter Discharges" button is pressed. The multiple input
dialog sheet then appears. Rivermile locations and descriptions are entered, cfs
or cms discharges are entered, and the "Add" button is depressed until all
discharge variations are described. After the user presses the "OK" button,
Excel will process the new information for several seconds, perhaps as long as a
half minute, without displaying the hourglass icon. When the update is
completed, the user is returned to the main input dialog window.

(NOTE: Version 5 requires that
discharge be defined from the most upstream modeled rivermile, -555 for the
Mississippi River. Do not delete this discharge. If it is deleted, the user
should reenter this value. This restriction may be corrected in future
versions.)

Figure
3       Example 2, input dialog
sheet

Figure
4       Example 2, variable
discharge input dialog sheet appears after user presses the "Enter discharges"
button.

Figure
5       Example 2, output
sheet

Riverspill web
page

More current and comprehensive
information about the program can be found on the riverspill web page. This page
is located at the URL:

http://www.ucs.usl.edu/~mgw0237/riverspill.html

The page is indexed by major search engines, and may be located on Yahoo by
simply searching the term "R-TOT."

Bibliography

Waldon, M.G., 1997a. Time-of-travel in the Lower Mississippi River: Model
development, calibration, and verification" Manuscript submitted to Water
Environment Research.

Waldon, M.G., 1997b. R-TOT, River Time-of-Travel Computer Programmer's
Manual. Center for Louisiana Inland Water Studies, June 1997.

Glossary of selected
terms

The following list of terms and
definitions is provided to assist the user in spill modeling, and specifically
in the use of the R-TOT models. The definitions presented here are specifically
provided for these purposes, and therefore may not provide the most general or
alternative meanings.

ADE Advection dispersion equation, also called the heat
equation. Typically in river spill modeling, the one-dimensional form of this
equation is applied.

advection Transport of water or material in water through
the bulk water movement.

ADZ Aggregated dead zone model, an alternative to the ADE
model. This model assumes that a dead zone(s) of constant volume causes the
delay and dispersion observed in spill and tracer studies.

barrel A unit of volume measurement. For petroleum, a barrel
is 42 gallons.

buoyancy The tendency of a material to float. Positively
buoyant materials tend to float, negatively buoyant materials tend to sink.

cfs Cubic feet per second, a conventional unit of measure of
volumetric discharge of a stream.

CLIWS Center for Louisiana Inland Water Studies, a research
center under the Department of Civil Engineering, University of Southwestern
Louisiana.

(http://www.ucs.usl.edu/~mgw0237/cliws.html)

cms Cubic meters per second, a metric unit measuring
volumetric discharge of a stream.

diffusion Transport that results from the random movement of
molecules.

dispersion Transport of material in water through mixing.
Dispersion always moves material from locations with higher concentrations to
areas of lower concentration.

distribution number The product of unit concentration and
duration. Often this dimensionless number is nearly constant, and has a value
slightly less than two. R-TOT assumes a constant value for the distribution
number and uses the duration, discharge, spill mass, and this distribution
number value to calculate peak concentration.

duration In R-TOT the duration of a spill is the length of
time between the leading edge and the trailing edge. Also termed the
time-of-passage.

edge The time at which a concentration-time curve (observed
or modeled) is at a percentage of the peak concentration value. Values between 5
and 10% are used, with 7.5% a good compromise if no value is given.

emulsion A stable colloidal suspension consisting of an
immiscible liquid dispersed and held in water.

entrainment The process by which a material is carried along
with the water flow. An entrained material is not dissolved, but moves with the
water flow like a solute.

estuary For the purpose of river mixing and spill modeling,
the tidal part of a river.

Eulerian Referring to a fixed frame of reference that does
not move along with water movement (see Lagrangian). Named after Joseph-Louis
Euler (1707-83), a great Swiss mathematician and physicist.

Excel A spreadsheet application program published by
Microsoft Corp. R-TOT 5 is implemented under Excel for windows.

Fick's law This law states that the rate of change of
concentration with time is proportional to the second derivative of
concentration with respect to distance. For molecular diffusion in the
x-direction the governing differential equation is:

Fickian dispersion It is often assumed that dispersion can
be modeled in a manner analogous to molecular diffusion described by Fick's law.

gamma distribution A family of probability distribution
functions that are skewed (asymmetrical). The distribution has two parameters
(compared to the Gaussian distribution with only one parameter). Depending on
parameter values, the distribution may vary from exponential to Gaussian. Also
termed a Pearson Type II distribution.

Lagrangian Referring to a frame of reference that moves
along with water movement down a river (see Eulerian). Named after the great
Italian mathematician named Joseph-Louis Lagrange (1736-1813).

LDEQ Louisiana Department of Environmental Quality (http://www.deq.state.la.us/).

leading edge The pre-peak time at which a spill
concentration is a small percentage (5 to 10%) of the peak concentration.

mg/L A unit of concentration, milligram per liter. One mg/L
is one thousand mg/L, and is approximately one part per million.

MPF Modified plug flow, the term used in R-TOT to describe
the velocity based model of transport of the leading edge, peak, and trailing
edge of a spill.

OSRADP Louisiana OSRADP is "The Louisiana Applied And
Educational Oil Spill Research And Development Program," under the Office of the
Governor

(http://atlas.lsu.edu/osradp).

photooxidation The chemical oxidation of a material induced
by exposure to sunlight.

plug flow Water transport in which no mixing occurs.

solute A material that is dissolved in water.

specific gravity The ratio of the weight or mass of a given
volume of a substance to that of an equal volume of water.

stage The surface elevation of a waterbody at a specific
location.

surfacing The movement of a positively buoyant material to
the water surface. This process may occur in a river in areas of low velocity
and turbulence.

tapedown A measurement from the water surface to a known
mark on a fixed structure (a scribe marked bridge rail, for example). As the
measurement decreases, water surface elevation and flow increases.

time-of-passage See duration.

trailing edge The pre-peak time at which a spill
concentration is a small percentage (5 to 10%) of the peak concentration.

mg/L Unit of concentration, micrograms per liter. One part
per billion, ppb, is approximately equal to one mg/L.

unit concentration The peak concentration of a spill at a
location and time scaled by discharge and spill size. Unit concentration is the
peak concentration multiplied by discharge and divided by spill weight. Often
reported in units of (mg/L)-cfs/lb, the units may be reduced to reciprocal time.

VBA A term that stands for "Visual Basic for Applications."

Visual Basic for Applications A version of Visual Basic,
used in Microsoft applications, such as Excel, for macro programming.

Visual Basic A dialect (or version) of the Basic
computer programming language. The Visual Basic (VB) compiler, written by
Microsoft, provides extensions of Basic that allow Windows applications
to more easily interface with users.

ATTACHMENT B

R-TOT

River Time-of-Travel

Computer Programmer's Manual

Michael Gene Waldon, Ph.D., P.E.

Center for Louisiana Inland Water Studies

Department of Civil Engineering

University of Southwestern Louisiana

Lafayette, Louisiana

June 1997

Table of
Contents

Overview

Theoretical
Background and Calculations

Description
of Sheets

Description
of Macros

Modification
for Simulation of a New Stream

Bibliography

Overview

R-TOT, the River Time-of-Travel
Model, predicts the time-of-travel of a solute or entrained material. The
current version of R-TOT is implemented and programmed in Microsoft Excel, and
Excel must be installed on the computer in order to use the R-TOT system. The
model provides a convenient user interface for input, a summary output sheet,
and easy user access to the data analysis and graphical capabilities available
within Excel.

Theoretical background and
calculations

R-TOT calculates time-of-travel and
peak concentration using a formulation termed the Modified Plug Flow (MPF) model
(Waldon, 1997). This model assumes that the leading edge, peak, and trailing
edge of a spill all travel at constant velocities depending on stream discharge
and parameters specific to stream location. The peak concentration in this model
is assumed to fall in inverse proportion to spill duration.

Most calculations are performed on
the worksheet named ValueArrays. Columns in this worksheet are described in the
following table.

Column name

Description

Rivermile

Location for calculations on this row starting at the most
upstream rivermile and continuing by steps of DeltaMile to the most
downstream rivermile

Discharge

Value of discharge is either single valued or is calculated
from lookup table by rivermile from Discharge Values worksheet.

a-Lead

Parameter a for leading edge

b-Lead

Parameter b for leading edge

Area-Lead

Leading edge area in square feet

v-Lead fps

Velocity of leading edge in feet per second

v-Lead mph

Velocity of leading edge in miles per hour

TOT-Lead

Time of travel of the leading edge from the most upstream
rivermile to the current rivermile in hours

a-Peak

Parameter a for peak

b-Peak

Parameter b for peak

Area-Peak

Peak area in square feet

v-Peak fps

Velocity of peak in feet per second

v-Peak mph

Velocity of peak in miles per hour

TOT-Peak

Time-of-travel of the peak from the most upstream rivermile
to the current rivermile in hours

a-Trail

Parameter a for trailing edge

b-Trail

Parameter b for trailing edge

Area-Trail

Trailing edge area in square feet

v-Trail fps

Velocity of trailing edge in feet per second

v-Trail mph

Velocity of trailing edge in miles per hour

TOT-Trail

Time of travel of the trailing edge from the most upstream
rivermile to the current rivermile in hours

Mass (Rel)

Initially 1.00 at the most upstream rivermile, this
relative mass is reduced when discharge reduces (i.e. is diverted).

Peak Conc

ug/L

Peak concentration as the spill passes the current
rivermile

Rivermile

Rivermile value of this row if rivermile is between the
user specified starting and ending rivermiles. Otherwise, a value of #N/A
(in Excel this means no value is available) is assigned

Travel time from start

Lead

Leading edge time-of-travel in hours from starting mile. If
rivermile is outside the starting-ending rivermile reach a #N/A value is
assigned

Peak

Peak time of travel as described above

Trail

Trailing edge time-of-travel as described
above

Description of sheets

Sheet Name: Input

Type: Dialog, normally hidden

Description:

This is the main user input interface.

Associated macros:

InitInSheet, UnknownDate, QsimpleOption, QadvancedOption, AllUnHide,
HideSpGravity, UnHideSpGravity, ShowVersion.

Stream specific features:

None.

Sheet Name: RTOT Help

Type: Dialog, normally hidden

Description:

Provides user with options for help.

Associated macros:

ShowRTOTHelpPict, TextButton, wwwButton

Stream specific features:

None.

Sheet Name: Discharge Input

Type: Dialog, normally hidden

Description:

This sheet provides the advanced,
multiple discharge-location, user input interface. The four input list boxes for
rivermile, location description, discharge (cfs), and discharge (cms), are
synchronized through associated macros.

Associated macros:

Qboxcfs, Qboxcms, CoordinateQln, QinSheetOK, AddToQList, DeleteFromQlist.

Stream specific features:

None.

Sheet Name: Output

Type: Worksheet, normally unhidden

Description:

Final report of travel times and concentration projections. This is the sheet
that the user views following model calculation (OK selection on Input dialog
sheet). This may also be the sheet initially viewed by the user.

Associated macros:

ShowInput, RTOTHelp, ExitRtot.

Stream specific features:

None.

Sheet Name: General

Type: Worksheet, normally hidden

Description:

General information concerning the model and the modeled stream.

Associated macros:

None.

Stream specific features:

Stream/river name, most upstream rivermile, revision date, most downstream
rivermile, and (possibly) distribution number.

Sheet Name: InSheet

Type: Worksheet, normally hidden

Description:

This sheet contains input
information for the specific model run. Input data is placed on the sheet by
various macros processing input from the input dialog sheet. Some values are
calculated on this sheet by parsing comma delimited user input of rivermile and
location, for example. Interpolation of starting and ending hours of travel is
also performed here.

Associated macros:

None directly.

Stream specific features:

None.

Sheet Name: Errors

Type: Worksheet, normally hidden except when error detected

Description:

This sheet contains error
conditions and error messages. Column B contains the error conditions, and
column C contains the associated error messages. Column A is written by a macro
during each calculation and is a text version of the condition in column B. If
errors are inactive, i.e. TRUE, their corresponding conditions are green. Active
errors, i.e. FALSE, are red. This formatting is performed by a macro function,
ShowErrors(), which loops through rows on this sheet until a blank is
encountered.

Associated macros:

Function ShowErrors.

Stream specific features:

Stream specific error conditions must be entered or edited.

Sheet Name: Warnings

Type: Worksheet, normally hidden except when warning is detected

Description:

This sheet contains warning
conditions and messages. Column B contains the warning conditions, and column C
contains the associated warning messages. Column A is written by a macro during
each calculation, and is a text version of the condition in column B. If
warnings are inactive, i.e. TRUE, their corresponding conditions are green.
Active warnings, i.e. FALSE, are red. This formatting is performed by a macro
function, ShowWarnings(), which loops through rows on this sheet until a blank
is encountered.

Associated macros:

Function ShowWarnings.

Stream specific features:

Stream specific warning conditions must be entered or edited.

Sheet Name: TOT Graph

Type: Chart sheet, normally unhidden

Description:

Graph of travel time versus
rivermile. This sheet provides the user with a convenient way to view
projections through a stream reach or to compare predicted and observed travel
times. Users are encouraged to enhance this sheet as a basis for spill/study
specific purposes. Axis scales, chart data series, and chart symbols might be
manipulated by the user.

Associated macros:

None.

Stream specific features:

None.

Sheet Name: Conc Graph

Type: Chart sheet, normally unhidden

Description:

Similar to TOT Graph sheet, this sheet graphs peak projected concentration
versus rivermile.

Associated macros:

None.

Stream specific features:

None.

Sheet Name: ValueArrays

Type: Worksheet, normally hidden

Description:

Most model calculations are performed here.

Associated macros:

None.

Stream specific features:

Cell B1, named DeltaMile, is the
rivermile step size used in this table. Alternative time-of-travel formulas
could be placed here to create specialized models that take into account unusual
site specific features. Note that the relative mass column is calculated so that
discharge reductions are assumed to remove mass. This assumption could be
eliminated by replacing this column by a constant value of 1.00.

Sheet Name: Discharge Values

Type: Worksheet, normally hidden

Description:

Table of rivermile and discharge
(cfs) values created from user input. Discharge values are piecewise constant,
that is, each discharge value is constant over the rivermiles from the current
row to the next row down. Rivermile values must be sorted in ascending order,
and this ordering must begin upstream and go downstream. For example, the
following sequence is in ascending order: -232, -209, -104, -52, 0, 50, 120.

Associated macros:

None.

Sheet Name: Parameter Values

Type: Worksheet, normally hidden

Description:

Lookup table of parameter values.
That is, a, b, and c values for the leading edge, peak, and trailing edge areas.
Rivermile values must be in ascending numerical order. Values are assumed to be
piecewise constant over the rivermile interval from the value on the current row
to the value on the next row down.

Associated macros:

None.

Stream specific features:

Rivermile and parameter values must
be entered for a new stream. Range name "Parameters" must be given to this
lookup table, and must be redefined if the number of rows in the table is
changed.

Stream specific features:

None.

Sheet Name: Locations

Type: Worksheet, normally hidden

Description:

This sheet lists rivermile
locations for a number of predefined sites. These values are used in the dialog
drop down boxes. Values are entered into column A of this sheet. Format is
rivermile, followed by a comma and a space, then the location description. The
range name "Location Table" must be set to refer to this column of information.
Entries should be sorted from upstream to downstream, that is, in ascending
rivermile order. The rivermile location can also be calculated in column B. This
optional value can than be used with the sort data/sort selection to properly
sort the locations.

Associated macros:

None.

Stream specific features:

All locations are stream specific.

Sheet Name: Sp Gravity

Type: Worksheet, normally hidden

Description:

This sheet lists specific gravity
values for a number of predefined materials. These values are used in the dialog
drop down box in the input sheet. Values are entered into column A of this
sheet. Format is specific gravity value, followed by a comma, a space, and the
material description. The range name "SpGravity Table" must be set to refer to
this column of information. Values in this table may be typical values and only
represent an approximation.

Associated macros:

None.

Stream specific features:

None.

Sheet Name: Help Picture

Type: Dialog Sheet, normally hidden

Description:

Used in the display of the help information from the sheet "Help Sheet."

Associated macros:

None.

Stream specific features:

None.

Sheet Name: Help Sheet

Type: Worksheet, normally hidden

Description:

Information on the input dialog box is listed here. This information is
displayed on the dialog sheet named "Help Picture."

Associated macros:

None.

Stream specific features:

None.

Sheet Name: Timings

Type: Worksheet, normally hidden

Description:

Timings to various macro locations
are stored here by the macros as they run. Time of day, description of process,
and elapsed time is displayed. This worksheet may be useful to the programmer
for optimizing the time used by R-TOT in calculation.

Associated macros:

As determined by the programmer.

Stream specific features:

None.

Sheet Name: R-TOT Macros

Type: Macro module sheet, normally hidden

Description:

This module contains all the macros
used in the R-TOT program. None of these macros are intended to be
stream-specific. If stream-specific macros are required in a future application,
these should be placed on a separate module sheet.

Associated macros:

N/A.

Stream specific features:

None.

Description of
Macros

All R-TOT macros are located on the
module sheet named "R-TOT Macros." These macros should be self-documented
through comments that are liberally included in the macro code. Any program
changes made to these macros that include purpose, name of programmer, and date
of modification should be documented.

The "Option Explicit" statement
included at the top of this module sheet means that all user defined
variables must be explicitly declared, typically in a Dim statement. This option
forces more complete documentation and reduces potential errors caused by
misspelled variable names within the program.

Modification for simulation of a new
stream

Simulating a new stream is
relatively straightforward. One objective of this version of R-TOT was to keep
all stream specific data on worksheets. Thus, no knowledge of Visual Basic
programming should be required by the user who is simply updating a current
stream's parameters or seeking to simulate a new stream. The section of this
report titled "Description of Sheets" should provide the outline of changes
required.

Bibliography

Waldon, M.G., 1997. "Time-of-travel in the Lower Mississippi River: Model
development, calibration, and verification." Manuscript submitted to Water
Environment Research.

Walkenbach, John, 1996. Excel for Windows 95 Power Programming with VBA,
2nd Edition. IDG Books Worlwide, Inc, Foster City, CA, 687 pages.