Updates to Watershed Modeling in the Potholes Reservoir 

Basin, Washington—a Supplement to Scientific 

Investigations Report 2009–5081

By Mark Mastin

Open File Report 2012–1251

U.S. Department of the Interior

U.S. Geological Survey
Cover: “A concrete-lined head ditch caries water for gravity-flow irrigation on a farm in Winchester, Washington, Columbia Basin Project” 

Photograph taken May 30, 1973. (Photograph number C222-100-349, obtained with permission from the Bureau of Reclamation, accessed

July 18, 2012, at: http://www.usbr.gov/lc/region/g5000/photolab/gallery_detail.cfm?PICIDTYPE=8561).
iii

U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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its natural and living resources, natural hazards, and the environment—visit 

http://www.usgs.gov or call 1–888–ASK–USGS

For an overview of USGS information products, including maps, imagery, and publications,

visit http://www.usgs.gov/pubprod

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Suggested citation:

Mastin, M.C, 2012, Updates to watershed modeling in the Potholes Reservoir basin, Washington—a supplement to 

Scientific Investigation Report 2009-5081: U.S. Geological Survey Open-File Report 2012-1251, 52 p. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report.
iv

Contents

Abstract ......................................................................................................................................................................... 1

Introduction.................................................................................................................................................................... 1

Purpose and Scope ....................................................................................................................................................... 3

Updating the Watershed Model to Incorporate Two New Meteorological Sites ............................................................. 3

Comparisons of Measured Hydrologic Data with Simulations by the 2009 and 2012 Models.................................... 4

New Real-Time Data-Retrieval Program, the Potholes Data Chimp .......................................................................... 5

Object User Interface for Making Watershed Model Runs and Viewing Data................................................................ 6

Major Tree Nodes ...................................................................................................................................................... 7

Basin Maps Major Tree Node................................................................................................................................. 7

Model Unit Maps Major Tree Node......................................................................................................................... 7

Models & Data Major Tree Node............................................................................................................................ 8

Method for Collecting Snow Data and Incorporating the Data into the Watershed Model ............................................10

Measurements of Snow ............................................................................................................................................10

Snow-Survey Methodology....................................................................................................................................10

Distributing Snow-Course Information throughout the Watershed ............................................................................12

Adding Distributed Snow Information to the Current Watershed Model ....................................................................13

Summary ......................................................................................................................................................................15

References Cited..........................................................................................................................................................16

Appendix A. Potholes Watershed Model Background .................................................................................................35

Appendix B. Snow-Course Locations ..........................................................................................................................36

Figures 

Figure 1. Locations of streamflow-gaging stations and boundaries of the Columbia Basin Project and study area in 

the Potholes Reservoir basin, Washington .................................................................................................................. 17

Figure 2. Watershed modeling units, streamflow-gaging stations and new and existing meteorological sites that 

provide input data to the watershed models, Potholes Reservoir basin, Washington.................................................. 18

Figure 3. Comparison of measured discharge and discharge simulated with the 2009 and 2012 models at three 

streamflow-gaging stations, upper Crab Creek basin, Washington water years 2010-11............................................ 19

Figure 4. Measured hydrologic variables and hydrologic variables simulated using the 2009 and 2012 models at 

Hydrologic Response Unit (HRU) 148 near Davenport, Washington, water years 2010-11 ........................................ 20

Figure 5. Screen capture showing the Potholes Data Chimp data information window. ............................................ 21

Figure 6. Object User Interface (OUI) directory structure for the Potholes watershed model, Potholes Reservoir 

basin, Washington ....................................................................................................................................................... 22

Figure 7. Screen shot of the Object User Interface (OUI) opening screen showing the tree nodes under the three 

major tree nodes (left panel) and the Map Mode panel (right panel) showing maps of two selected tree node 

elements, “Models” and “Crab Ck MRUs” from the “Model Unit Maps” tree node........................................................ 23

Figure 8. Screen shot of the Object User Interface (OUI) main window showing the real-time stations in the Map 

Mode window with the Davenport, Washington, station selected (top), and the Time Series Tool window with a 

zoomed-in plot of precipitation input data .................................................................................................................... 24

Figure 9. Screen capture of the ESP report, Run MMS Model in ESP Mode, and OUI ESP Tool windows............... 25

Figure 10. Screen capture of the opening window for the Modular Modeling System (MMS) traditional user interface 

for the Crab Creek model, Potholes Reservoir basin, Washington.............................................................................. 26

Figure 11. Screen capture of the MMS Run Control - Single Run window for the Modular Modeling System traditional 

user interface for the Crab Creek model, Potholes Reservoir basin, Washington ....................................................... 27
v 

Figure 12. Existing network of snow courses in and near the watershed model boundaries, Potholes Reservoir basin, 

Washington ............................................................................................................................................................. 28

Figure 13. Snow-water equivalent measured at nine locations during January 8-9, 2004, and snow-water equivalent 

throughout the model domain estimated based on the measured values, Potholes Reservoir basin, Washington. .... 29

Figure 14. A proposed field-sheet layout for collecting snow-survey information....................................................... 30

Figure 15. Screen capture of spreadsheet used to calculate variables freeh2o, pk_ice, and pk_depth..................... 31

Figure 16. Screen capture of Ensemble Streamflow Prediction (ESP) update window with start and end date and 

variable file entered for the example ESP model run updated with snow-survey data................................................. 31

Tables

Table 1. Comparison of measured runoff volumes and runoff volumes simulated with the 2012 model at three 

streamflow-gaging stations, upper Crab Creek basin, Washington, January 1-June 30, water years (WY) 2010-11. . 32

Table 2. Comparison of measured runoff volumes and the Ensemble Streamflow Prediction (ESP) 50-percentexceedance-probability runoff volumes generated by the 2009 and 2012 models at three streamflow-gaging 

stations, upper Crab Creek basin, Washington, for runoff season January 1-June 30, water years (WY) 2010-11..... 32

Table 3. Meteorological sites, data sources, and sequence numbers indicating the order of data items in the

input file for the real-time Potholes watershed model, Potholes Reservoir basin, Washington................................... 33

Table 4. Point identification numbers and related snow-course names for the input file, sno_crs_pts.txt, used to 

generate a snow-water equivalent grid for the Potholes Reservoir basin, Washington. .............................................. 33

Table 5. Example of first six rows of data in the spreadsheet showing (A) GIS output; (B) values of snow-water 

equivalent (SWE), sorted by Hydrologic Response Unit (HRU); (C) imported area values that are used to compute 

SWE volume; and (D) SWE volume for each HRU...................................................................................................... 34
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Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

Area

acre 4,047 square meter (m2)

Volume

cubic foot (ft3) 0.02832 cubic meter (m3) 

acre-foot (acre-ft) 1,233 cubic meter (m3)

Flow rate

cubic foot per second (ft3/s) 0.02832 Cubic meter per second (m3/s)

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Datums

Vertical coordinate information is referenced to the “North American Vertical Datum of 1988 (NAVD 88).”

Horizontal coordinate information is referenced to the “North American Datum of 1983 (NAD 83).”

Elevation, as used in this report, refers to distance above the vertical datum.
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1 

Updates to Watershed Modeling in the Potholes Reservoir 

Basin, Washington—a Supplement to Scientific 

Investigations Report 2009–5081

By Mark Mastin

Abstract

A previous collaborative effort between the U.S. Geological Survey and the Bureau of 

Reclamation resulted in a watershed model for four watersheds that discharge into Potholes Reservoir, 

Washington. Since the model was constructed, two new meteorological sites have been established that 

provide more reliable real-time information. The Bureau of Reclamation was interested in incorporating

this new information into the existing watershed model developed in 2009, and adding measured

snowpack information to update simulated results and to improve forecasts of runoff. This report 

includes descriptions of procedures to aid a user in making model runs, including a description of the 

Object User Interface for the watershed model with details on specific keystrokes to generate model 

runs for the contributing basins. A new real-time, data-gathering computer program automates the 

creation of the model input files and includes the new meteorological sites. The 2009 watershed model 

was updated with the new sites and validated by comparing simulated results to measured data. As in 

the previous study, the updated model (2012 model) does a poor job of simulating individual storms, but 

a reasonably good job of simulating seasonal runoff volumes. At three streamflow-gaging stations, the 

January 1 to June 30 retrospective forecasts of runoff volume for years 2010 and 2011 were within 40 

percent of the measured runoff volume for five of the six comparisons, ranging from -39.4 to 60.3 

percent difference. A procedure for collecting measured snowpack data and using the data in the 

watershed model for forecast model runs, based on the Ensemble Streamflow Prediction method, is 

described, with an example that uses 2004 snow-survey data. 

Introduction 

Since 2002, the U.S. Geological Survey (USGS) Washington Water Science Center has been 

working with the Ephrata, Washington, office of the Bureau of Reclamation (Reclamation) to develop a 

watershed model of the drainage basins that drain into Potholes Reservoir, Washington, in four streams: 

Rocky Ford Creek, Crab Creek, Rocky Coulee, and Lind Coulee. Previous work in these basins 

includes the development of a watershed model using the USGS Precipitation-Runoff Modeling System 

(Leavesley and others, 1983) that incorporates a graphical user interface to facilitate user operation, and 

a USGS report (Mastin, 2009) that documents the model. The model has been installed on computers at 

the Reclamation office in Ephrata, and the USGS provided training in its use. 
2 

Reclamation manages the Columbia Basin Project, a multipurpose project that provides

hydropower, recreation, irrigation, and flood protection. Pumps move water from Franklin D. Roosevelt 

Lake to Banks Lake for irrigation through canals to farmlands located mostly south of Banks Lake, and 

to feed Potholes Reservoir, which regulates discharges for irrigation of more lands farther south of the 

reservoir (fig. 1). Potholes Reservoir also receives runoff from the streams that feed Moses Lake, 

whose outflow feeds directly into Potholes Reservoir, and from Lind Coulee, which discharges directly 

into Potholes Reservoir (fig. 1). Management of this water-conveyance system may be improved if the 

natural spring runoff can be projected months or weeks in advance with real-time forecasts based on 

historical weather information and the current hydrologic conditions in the basin. Additionly, long-term 

studies of the hydrology of the system generally need historical runoff information that may not be 

available from the existing streamflow-gaging network. For these reasons, a set of watershed models 

(model units Crab Creek, including Rocky Ford Creek, Lind Coulee, and Rocky Coulee) was created as 

part of the original study to facilitate Reclamation’s water-conveyance decision-making process by 

providing forecasted and historical runoff information that affects the inflows to Potholes Reservoir. A 

group of long-term meteorological sites provides daily precipitation and daily minimum and maximum 

temperatures as input (file, pot_lt.data; see appendix A for more information on input files) to the set of 

long-term models. Not all the long-term meteorological sites have real-time telemetry, so the same 

model (that is, same process algorithms) is used with a slightly different group of meteorological sites

that have real-time telemetry. Therefore, the real-time model uses a different input file (pot_rt.data) 

than the long-term model. 

After working for several years with the model developed in 2009, Reclamation and the USGS 

discovered a few shortcomings and looked for ways to improve the real-time simulations. For example, 

the existing network of real-time meteorological and soil moisture sites included fewer sites than the 

number of sites used to calibrate the initial model, and incomplete data were collected at some of those 

sites. Since the initial model was completed, two new meteorological sites, Almira and Davenport (fig. 

2), were added to the network as Agrimet sites. The Almira and Davenport sites include monitoring of 

soil moisture and soil temperature, along with air temperature and precipitation. Agrimet is a satellitebased network of automated agricultural weather stations throughout the Pacific Northwest operated and 

maintained by Reclamation (Bureau of Reclamation, 2012a). The data collected by the new sites are 

maintained on the Hydromet real-time database system, a network of automated hydrological and 

meteorological monitoring systems also operated by Reclamation (Bureau of Reclamation, 2012b). Soil 

moisture and soil temperature are not inputs to the model, but provide useful information for the 

modeler. For example, frozen ground has the important function of dramatically increasing runoff 

during rain storms and soil-temperature information allows the modeler to monitor whether the model is 

correctly simulating frozen or non-frozen soil. Similarly, the ability of the model to simulate snow 

volumes accurately in the watershed at the time runoff forecasts are made is critical to the success of the 

forecasts. A modeler can distribute measured snow-water equivalents to the hydrologic modeling units 

that represent the watershed and substitute the information for simulated snow conditions to improve 

runoff forecasts.

Detailed information about the Potholes watershed model is available in the previously 

published model (hereafter called the “2009 model”) documentation (Mastin, 2009). Some details about 

the file names, flow-routing schematics, and model setup are available in appendix A of this report. 
3 

Purpose and Scope

The purpose of this report is to document changes to the previously published Potholes 

watershed 2009 model, to provide instructions for model use, and to describe protocols for collecting 

snowpack data in the watershed. This report specifically documents 1) the updated model parameters 

for new sets of input data from the two new meteorological sites, 2) verification of the updated model 

using the two new sites, 3) the upgraded real-time data retrieval program that includes the two new 

meteorological sites, 4) a guide for making snow measurements in the Potholes Reservoir basin to 

determine snow-water equivalents, and 5) the method used to update the watershed model with 

measured snow-water equivalents. 

Updating the Watershed Model to Incorporate Two New Meteorological Sites

Two new meteorological sites (fig. 2), one near Almira and one on the Wilke Experimental Farm 

in Davenport, were installed in January 2009 to provide meteorological and hydrological information in 

the headwaters of the Crab Creek basin to improve runoff simulations from the Potholes Watershed 

Model. 

The 2009 real-time model uses the National Weather Service (NWS) meteorological site at 

Davenport (NWS index number 2007), a Hydromet site at Dry Falls, and seven other meteorological 

sites. The NWS site at Davenport often was unreliable in providing real-time data and the Dry Falls site

was located outside the watershed boundaries. The new Hydromet sites, Davenport and Almira (fig. 2), 

continuously monitor real-time air temperature, precipitation, soil temperature, and soil moisture. 

It is important to have reliable, real-time meteorological sites because one of the purposes of the 

model is to forecast the upcoming runoff season (usually February through July) based on current 

watershed conditions. The watershed model uses daily maximum and minimum air temperature and 

daily precipitation as inputs. To simulate current conditions, the model must have current daily inputs; 

therefore, real-time, daily minimum and maximum air temperature and precipitation are needed. 

Soil temperature and soil moisture are not inputs to the watershed model, but they provide 

indicators for comparison with watershed-model simulation results. Measured and simulated soil 

moisture can be compared to give the user an indication of the reliability of the model. A similar 

comparison can be made between measured and simulated soil temperature. Soil temperature indicates 

whether the soil is frozen. The pathway of runoff can change substantially depending on whether the 

ground is frozen or not frozen (Mastin, 2009). The watershed model uses a simple threshold-type index 

to simulate frozen ground. Once the threshold is exceeded, all water available for runoff or infiltration is 

routed to the surface runoff pathway and quickly becomes runoff. This closure of the infiltration 

pathway for available water can result in dramatically high peak discharges with little input from 

snowmelt and precipitation. If the index is in agreement with the soil information measured at the new 

sites, a user will have more confidence in the runoff volumes forecasted by the model. 

The updated model (hereafter called the “2012 model”) was developed by creating a new 

parameter file to accommodate the new meteorological sites used for input to the model—Agrimet sites 

Davenport and Almira, in place of the Davenport NWS site and the Dry Falls Hydromet site. The 

location parameters for Almira were substituted for the Dry Falls location parameters and the location 

and mean monthly precipitation parameters were left the same for the two Davenport sites. These 

location parameters include the temperature station latitude, longitude (Universal Transverse Mercator

[UTM], zone 11 coordinates), and elevation (feet) (model parameters tsta_ylat, tsta_xlong, and 

tsta_elev, respectively), and the precipitation station latitude and longitude (model parameters psta_ylat, 
4 

and psta_xlong, respectively). One more precipitation parameter, psta_mon, which represents the longterm monthly precipitation at the meteorological site, was estimated from the 1961-90 mean monthly 

precipitation at Almira simulated by the Parameter-elevation Regressions on Independent Slopes Model 

(PRISM) (Daly and others, 1997). No new calibration model runs were made to adjust any of the 

process-related parameters previously calibrated in the 2009 model. 

Comparisons of Measured Hydrologic Data with Simulations by the 2009 and 2012 Models 

Comparisons were made by running the model with the 2009 and 2012 parameter files and 

comparing selected simulated and measured variables for water years (WY) 2010 and 2011 (a water 

year starts on October 1 of the previous year and ends September 30 of the current year). Because the 

streamflow-gaging station Crab Creek at Irby, USGS station number 12465000, generally is the focus of 

interest for forecast runoff, this study compares simulated and measured runoff and other hydrologic 

variables in this part of the upper Crab Creek basin upstream of Irby (fig. 1). 

The model does not simulate the peak discharges well for both water years, by under-simulating 

the WY 2010 peaks and over-simulating the WY 2011 peaks in Crab Creek (fig. 3). The runoff 

volumes are compared in table 1 for January 1 to June 30 (the runoff part of the year) and show undersimulation of runoff in five of the six comparisons and over-simulation in one comparison (Crab Creek 

at Irby in WY 2011). However, the differences between runoff simulated with the 2009 and 2012 

models are small relative to the differences between the simulated and measured runoff. Runoff 

simulated with the 2012 model closely follows the pattern of runoff simulated with the 2009 model, but 

the 2012 model simulates slightly less runoff overall and a significant difference in the peak runoff in 

WY 2011 (the daily peak at Crab Creek at Irby simulated by the 2009 and 2012 models is 837 and 554 

ft3

/s, respectively). The larger peak simulated by the 2009 model generally is due to the larger 

precipitation total (fig. 4A). Figure 4A shows a 2-year total of 29.60 in. for the 2009 model compared 

with 24.49 in. for the 2012 model for Hydrologic Response Unit (HRU, also known as MRU or Model 

Response Unit) 148, located near Davenport, Washington (fig. 2), and is representative of the highest

annual precipitation in the study area. Soil moisture values for HRU 148 show similar patterns between 

the simulated values for the 2009 and 2012 models (fig. 4B), but both models miss some large 

variations indicated by the measured record. The measured soil moisture represents only the average of 

the 4- and 20-in. depths at one point in the watershed, whereas the simulated soil moisture represents the 

entire soil column averaged for a large area (9,976 acres for HRU 148); therefore, a close match 

between simulated and measured time series is not expected. However, the general pattern between 

simulated and measured soil moisture should be similar. The simulated soil moisture showed higher 

winter moisture values relative to the beginning moisture on September 1, 2009, than the measured

moisture. However, the simulated soil moisture values returned to about the same initial September 

2009 value in September 2010 and September 2011 whereas the measured September values in 2010 

and 2011 were about 2 in. less than the September 2009 initial value. 

The Continuous Frozen Ground Index (CFGI, fig. 4C) indicates when the ground is frozen or 

not. Molnau and Bissel (1983) originally developed the index and it use in the Potholes watershed 

model is described by Mastin (2009). The index increases when the daily air temperature is below 32oF. 

Increasing snow-cover depth tends to reduce the CFGI value and a user-defined parameter sets the daily 

decay of the CFGI value. After a user-defined threshold value is exceeded (137 in the Potholes 

watershed model), all simulated liquid water at the land surface of that HRU becomes surface runoff. 

By directing all the liquid water to the surface runoff outlet, the simulated runoff hydrograph becomes 

flashy and the peak discharges are much larger than they would be otherwise. The simulated CFGI time 

series for the 2009 and 2012 models shows a similar pattern for water years 2010 and 2011 for HRU 
5 

148 (fig. 4C), and generally increases as the measured soil temperature approaches and is below 

freezing. As soil temperatures increase, the CFGI values decrease. The CFGI never reached the CFGI 

threshold during these water years, so no large, flashy peaks are simulated (fig. 3). 

It is apparent from the simulation of peak discharges in WYs 2010 and 2011 that the model 

cannot be relied on to accurately simulate peak discharges. This is consistent with the conclusions of 

Mastin (2009). Despite the poor performance in simulating peak discharges during the runoff season, 

the question remains whether the model can reasonably forecast seasonal runoff volumes, one of the 

primary uses of the model. The model has a forecast tool built into the programming of its Object User 

Interface (OUI; Markstrom and Koczot, 2008) that uses the Ensemble Streamflow Prediction (ESP) 

method (Day, 1985). ESP uses historical input data (beginning in WY 1950 for the Potholes models) to 

simulate an ensemble of possible runoff scenarios from the current point in time, and it orders the output 

by volume or peak discharge to create exceedance probabilities of the future runoff as a function of past 

climate (see Mastin [2009] for more detail). Generally, the 50-percent exceedance probability is 

considered the most likely runoff volume or peak discharge that can be expected to occur if model bias 

is ignored. To demonstrate the accuracy of the forecast tool, retrospective forecasts were made using 

the ESP method for the January 1 to June 30 runoff season for WYs 2010 and 2011 with input time 

series that ended on December 31, 2009, and December 31, 2010, respectively. The simulated 50-

percent-exceedance-probability runoff volumes generated by the 2009 and 2012 models are shown in 

table 2 for each water year along with the measured data. Percent differences between the 50-percentexceedance-probability runoff volume simulated by the 2012 model and the measured runoff volume 

are still high, with 5 of the 6 comparisons within 40 percent of the measured runoff volumes. One-half 

of the percent differences were within 17 percent of the measured runoff volumes and the extremes 

varied from -39.4 to 60.3 percent. These results are similar to the results of the comparisons between 

measured and simulated long-term mean monthly runoff values for January through June in the 2009 

long-term model, which simulated three monthly runoff volumes less than 15 percent different from 

measured values and three monthly runoff volumes greater than 26 percent different from measured 

values (Mastin, 2009, table 9). Despite the poor fit between simulated and measured runoff, the model 

provides some useful volumetric runoff information within relatively large error bands. 

New Real-Time Data-Retrieval Program, the Potholes Data Chimp

In addition to changes made to two meteorological data inputs to the model, the existing 

program to retrieve real-time data was revised completely and named the Potholes Data Chimp. The 

program, Potholes_Data_Chimp.exe, runs outside the model user interface, and must run prior to an 

ESP forecast to upload the latest data to the real-time data input file. Data specific to the Potholes 

watershed model are retrieved from several web sites and reformatted for model input (table 3). The 

first time the program is executed, it asks for the file name of the master data file. This file, called 

MasterDatafile.txt in the example in this report, contains data from October 1, 1949, to September 30, 

2009, or later, formatted in the model input data format for daily precipitation, daily maximum 

temperature, and daily minimum temperature for the nine real-time meteorological stations (one row of 

data for each day). The Potholes Data Chimp appends new data to the master data file when the new 

data has a time stamp after the most recent existing data. Data with the same time stamp overwrites 

existing data, but the program will not overwrite data before October 1, 2009. 
6 

The data information window (fig. 5) appears upon startup of the Potholes Data Chimp. The 

start and end dates of the existing data file are provided in the Data File Information block, and the user 

enters the start and end dates of the desired retrieval of new data in the Enter Start and End Dates block. 

The program defaults to a start date of the day after the last date in the master data file and an end date 

of the current day. The user may enter other dates, but the program will not overwrite any data in the 

master file prior to October 1, 2009. After the desired dates have been entered, the user clicks the Start 

button to initiate the data retrieval. A progress bar shows the progress of the retrieval and a small popup window appears informing the user that the retrieval has been completed. 

A recommended procedure is to locate the Potholes_Data_Chimp.exe file in the data 

directory along with the master data file. The data directory is located in the input directory, which is 

located in a directory path relative to the root directory (oui_potholes, fig. 6). The project 

directory potholes is located under the directory oui_potholes followed by the 

mms_work/input/data pathway showing the Potholes_Data_Chimp.exe, master data file

(MasterData.txt), and the input data file used for ESP model runs (pot_rt.data). 

 

After the data retrieval has been completed and the master data file has been updated, the user should 

delete the old pot_rt.data file and copy the updated master data file to a new pot_rt.data file. 

The model is then ready to run an ESP forecast. 

Object User Interface for Making Watershed Model Runs and Viewing Data

The Object User Interface (OUI) is a computer application that manages the watershed model 

and associated temporal and spatial data to facilitate use of the model. The OUI has been configured 

specifically for the Potholes watershed model with a control file, project_potholes.xml, written in 

eXtensible Markup Language (XML). A more detailed discussion of the OUI can be found in the OUI 

user manual (Markstom and Koczot, 2008). 

The OUI relies on model-input data, model-input variable, model-input parameter, spatial, and 

executable files maintained in a specific directory structure relative to the root directory named 

“oui_potholes” in the example shown in figure 6. The OUI files for the Potholes watershed model can 

be installed by extracting the files from the Win.zip file (potholes_model03_23_12.zip; file available 

from the author), which maintains the directory structure shown in figure 6. The OUI is written in Java 

and XML and it requires Java version 1.5.0_09 or later (accessed June 26, 2012, at 

http://www.oracle.com/technetwork/java/javase/downloads/index.html) to execute the program with a 

Windows operating system. To run the OUI, the user executes the oui_potholes.bat file in the 

oui_potholes/potholes directory by double-clicking the file name in the Windows Explorer program. 

The OUI project file, project_potholes.xml, organizes the different spatial, model-input data, and 

executable elements of the project into a project tree structure. The elements are defined as tree nodes 

that are arranged in a hierarchical manner within a project tree that is visible to the user when opening 

the OUI window. Any tree node may contain other tree nodes similar to a file system on a computer 

where the root directory contains all the other directories and files (described in more detail by 

Markstrom and Kozat, 2008). 
7 

Major Tree Nodes 

The following discussion about using the Potholes OUI program is arranged by the major tree 

nodes and their function in the order they appear in the opening window. 

The three major tree nodes under the Potholes Project shown by the OUI include “Basin Maps,” 

“Model Unit Maps,” and “Models & Data.” The nodes can be seen in the upper-left panel of the 

Potholes OUI window (fig. 7). Text in italics in this section refers to identical text in the OUI window 

pointing to various tree nodes and tree-node operations. 

Basin Maps Major Tree Node

Tree nodes under the Basin Maps major tree node are selected by clicking the right button on the 

mouse (right-clicking) to display background GIS coverages without active data (active data can 

generate a process or a new screen when the GIS feature is clicked). A good starting point is to display 

the model units by right-clicking the Models node and then clicking the Load tab (not shown in fig. 7). 

This method works for all the themes. The selected theme will be “loaded” in the lower left panel of the 

OUI window called Loaded Themes. Clicking the Visible check box makes it visible in the right Map 

Mode panel of the OUI Window. Clicking the Labels check box adds labels to the map. The Active and 

Query check boxes do not do anything for this theme, and checking the Attributes check box will open a 

new window showing the attributes for this theme (the new window may be hidden behind the main 

OUI window). The following are the tree nodes under the Basin Maps major tree node that contain the 

shape files that are used to display spatial themes: 

• Lakes uses shape file: oui\potholes\oui\work\shapes\all_lakes.shp

• Springs uses shape file: oui\potholes\oui\work\shapes\springs.shp

• Streams uses shape file: oui\potholes\oui\work\shapes\all_str.shp

• Models uses shape file: oui\potholes\oui\work\shapes\model_units.shp

• Met-lt uses shape file: oui\potholes\oui\work\shapes\met_lt.shp

Model Unit Maps Major Tree Node

Tree nodes under the Model Unit Maps major tree node provide additional GIS coverages 

without active data. Load and display these themes in the same manner as described under “Basin Maps 

Major Tree Node” for the Models theme. Substitute “Crab Ck,” “Lind,” or “Rocky” for <model> as 

follows for a description of the contents of these tree nodes under the Model Unit Maps major tree node: 

• <model> model Model unit subbasins

• <model> MRUs Model Response Units (MRUs) map for each model unit

• DEM digital elevation model display for each model unit

• Slope slope surfaces display computed from DEM for each model unit

• Aspect slope aspect display computed from DEM for each model unit
8 

Models & Data Major Tree Node

The Models & Data major tree node is the main section for viewing input and output data and 

for running the models. All the tree nodes under this major tree node have additional tree nodes under 

them, which are described below. 

Input Tree Node

The Input tree node is used to view the model input data. Tree node MMS Data Files (fig. 8)

contains sub-nodes listed in the hierarchical bullets at the end of the “Input Tree Node” section. Time 

series plots can be made using station data for sites displayed by these sub-node themes. For example, a 

plot of precipitation at the Davenport station can be made by first loading the Real-time Stations theme 

(right-click the node Real-time Stations under the Climate Data node, then click the Load tab), and then 

click the Visible, Labels, Active and Query check boxes for the Real-time Stations theme in the Loaded 

Themes panel. A set of labeled box symbols will be visible in the Map Mode panel. Using the Select

tool in the Map Mode panel, click the Davenport box (fig. 8). An informational pop-up box will appear, 

listing the three available variables (not shown). Select precipitation and a Time Series Tool window 

will appear (if the window is not visible, it may be hidden behind the main OUI window). Click precip

at Davenport in the Trace List of the Time Series Tool window, click the drop-down menu item Plots, 

and select Time Series. A time series plot for all the available data will appear. Missing meteorological 

data are coded as -9999; therefore, the range of the y-axis may be large and make it difficult to view the 

real values (“-9” is used for missing discharge data). A box defining a zoom area can be drawn using 

the mouse to view the range you wish to see. Right-click in the plot for more options (fig. 8). 

The hierarchical order of the tree nodes under the Input tree node follows the bulleted list below. 

These tree nodes allow the user to make graphs of climate data for real-time and long-term stations and 

of measured discharge using the method described above for precipitation at Davenport. 

Input 

• MMS Data Files

o Climate Data

 Real-time Stations

 Long-term Stations 

o Observed Runoff Data 

 Measured Discharge

Single Run Tree Node

The Single Run tree node is used to make single runs for all three model units using usersupplied model run dates. Right-clicking on this node pops up a small Run button. Clicking on Run will 

cause the Run MMS Model window to appear. A user can enter the run dates and start the model run by 

clicking the Run button. Note that 1) 2 years should be run for the initial or “warm-up” period when the 

model is run, but the results are not used; 2) the long-term data file, which ends on September 30, 2004, 

is used as input; and 3) all three models run for the same period. 

The sub-node Single run Model Output is used to plot the simulated discharge (variable 

segment_cfs) time series of selected locations of the last single model run. Right-clicking the sub-node 

displays the selected locations as point symbols in the Map Mode panel. After the Active and Query

check boxes in the Loaded Themes panel are checked and a point location in the Map Mode panel is 

selected, a drop-down menu will appear with all the variables (flow-routing nodes on the stream 

network) from the last single model run that are available for plotting. For example, clicking the point 
9 

symbol labeled “6” in the Map Mode will display a pop-up menu that asks “Which variable for 6?” and 

lists all the selected segment_cfs variables. Clicking the segment_cfs 6 in this pop-up menu will display 

the Time Series Tool window with “segment_cfs 6 at 6” in the Trace List. This plot is the simulated 

time series runoff for node 6 or Crab Creek at Irby. Appendix A provides a table and a map of the 

Potholes model flow-routing nodes, their identification numbers, and descriptions and locations of the 

stream-network points they represent (table A1 and fig. A1). 

ESP Run Tree Node

The ESP Run tree node is used to make ESP model runs for all three models for the purpose of 

forecasting streamflows during a user-supplied forecast period. Right-clicking this node will display a 

small Run button. Clicking Run will cause a Run MMS Model in ESP Mode window to appear (fig. 9). 

This window allows a user to enter the forecast dates and then start an ESP model run by clicking the 

Run button. A model run is made beginning 2 years prior to the user-supplied forecast start date. (The 

2 additional years serve to estimate initial antecedent conditions.) Each ESP run consists of a set of 

multiple model runs for the same period within the year, but uses different years of historical input data. 

The pot_rt.data file contains the historical input data for these model runs. Simulated results are saved 

in “statvar” files (files with “statvar” in the file name) in directory 

../oui/potholes/mms_work/output/esp. There is one output statvar file for each year of 

simulated runoff, such as crab_ESP_1950.statvar, which contains the output data for the ESP 

run for the Crab Creek Model Unit using WY 1950 input. The output statvar file lists the simulated 

runoff for all the selected routing nodes for each day in one row. The header of the file lists the order of 

the simulated discharge in each row by the segment_cfs index number. 

Clicking sub-node ESP Traces will display a map with the location of streamflow routing nodes 

with ESP output in the Map Mode panel. Selecting one of these locations will open up the OUI ESP 

Tool window (fig. 9), which lists the available time series of simulated daily discharge for the selected 

location within the Ensemble Traces window. The listing includes one time series for each year of 

simulated runoff, and the time series ranked by volume, peak discharge, or year as selected by the user. 

Selecting one or more of these time series creates a composite hydrograph. Each plotted time series is a 

hydrograph referred to here as a “trace.” The simulated 2-year-model-initiation hydrograph prior to the 

ESP period also is shown (the line labeled “init” in fig. 9). The user may right-click the graph for 

various zooming options, or may simply click and drag to define a zoom area. Functions under the Data 

Management Interface (DMI) drop-down menu are not operable at this time. By clicking drop-down 

menu Reports and Write Report (fig. 9), a summary report labeled ESP Report is generated that provides 

the runoff volume and peak discharge for each trace (year). 

MMS Runs Tree Node

The MMS Runs tree node has three sub nodes, one for each model, that emulate the traditional 

Modular Modeling System (MMS, Leavesley and others, 1996) interface when activated. The interface 

allows users to adjust individual parameters and to make custom model runs. Right-clicking one of the 

three sub-nodes (labeled Crab Creek MMS Model, Lind Coulee MMS Model, and Rocky Coulee MMS 

Model) displays the Run button that will initiate the MMS user interface for the selected model (fig. 10). 

Clicking the drop-down Run menu in the opening window provides the option for making a single 

model run. Clicking this option displays a new window, the MMS Run Control - Single Run window 

(fig. 11). In this example, the model run start date is October 1, 2000, the end date is September 1, 

2004, a variable file (crab.01.09.04) is being saved, the output statvar file is crab_swe_rt_statvar.dat, 

and one graph (runtime graph) that displays a user-selected variable time series while the model runs is 
10

being generated. The output Statistics file is checked, but this function currently is disabled in the OUI 

program. A variable file consists of variable values computed by the model for the end date of a model 

run. 

Additional background information about the Potholes watershed model and its OUI is provided 

in Appendix A. 

Method for Collecting Snow Data and Incorporating the Data into the Watershed 

Model

The watershed model simulates the density, depth, and snow-water equivalent (SWE) of snow 

on each HRU created for the model. However, the simulation of the current snowpack in the basin may 

be in error at the time the user wishes to make a runoff prediction. In order to check the accuracy of the 

model or to update the model with measured data, the actual snowpack in the basin can be estimated 

from readings at snow courses. Currently (2012), there are no snow pillows or weather stations in the 

basin that measure snow density or SWE. This section of the report describes a procedure for making 

measurements on an existing network of snow courses using a snow-measuring kit such as the 

SnowmetricsTM kit (Snowmetrics, 2012), converting the point measurements to a spatial estimate of 

snowpack in the basin, and incorporating the spatial estimate in the watershed model.

Measurements of Snow 

The goal of the snow survey is to measure snow depth and snow density and to combine the two

measurements to estimate SWE for the current snowpack in the Potholes Reservoir basin. Data 

measured at nine snow-course locations in or near the basin have been used previously to estimate the 

spatial extent of the three snow variables throughout the basin, and the snow-course locations continue 

to be the suggested sites for further snow surveys (fig. 12). After the spatial extent of the snow 

variables has been estimated, the data can be used to update the current snowpack conditions simulated 

by the watershed model to try to improve forecasts of runoff volumes. This type of “direct-insertion” 

approach has not always been successful in improving runoff forecasts. Clark and others (2006) provide 

a good review of various techniques that have been used to assimilate snow-covered area or SWE 

information into watershed models. As an example, figure 13 shows the SWE measured at nine 

locations in January 2004 and estimated values throughout the model domain. In this example, the data 

were entered into a GIS and, using an inverse-distance-weighted (IDW) interpolation method, the SWEs 

measured at the nine point locations were distributed throughout the model domain as gridded values. 

The gridded values were then assigned to HRUs in the watershed models to replace simulated SWE 

values. 

The nine locations of the snow-survey sites are documented in Appendix B of this report. 

Snow-Survey Methodology

The general method used to make a snow survey at a site in the study area has been adapted 

from a method by the U.S. Department of Agriculture (1984). The idea of a set snow course that 

generally has about 10 sample points along a line is retained, but the use of snow sampling tubes is not 

recommended because the snow generally is too shallow in the study area for accurate sampling with a 

snow tube. Instead of using snow tubes to sample the snow, a cutter or small tool (often used by 

avalanche forecasters to sample snow layers in a snow pit for snow density) is described in the 

following section as the recommended tool to sample the snow. The general method is:
11

1) Measure the snow depth. Use the folding ruler or tape measure to measure the snow depth 

at 10 equally spaced locations along a snow course that is documented in the site location 

maps in Appendix B. The snow course should be undisturbed and without drifts. In the 

snow course descriptions (Appendix B), the snow courses were generally 135-ft long and 

depths were measured every 15 ft beginning at the start of the snow course. Preferably, a 

cloth tape is placed along the course, but a well-defined pace by the surveyor also can be 

used. 

2) Measure the snow density. At two to four sites along the snow course, snow pits are dug 

and one or more snow samples are retrieved from each pit and measured for snow density. 

In the Crab Creek basin, the snow usually is not deep and a pit is dug simply with one swipe 

of a shovel. If distinct layers can be seen in the snow pit, a density sample is needed from 

each layer and the layer depth range needs to be recorded. At each layer where a density 

sample is collected, the SWE is calculated, averaged for the profile, and then averaged again 

with other profile densities for the snow course. The text in italics is from Snowmetrics

(2012) and describes how to sample a snow pit: 

Dig snow pit wall or surface to be sampled. Shave the wall or surface with a flatbladed shovel to give a smooth sampling surface. Surface must not be rough or sampling 

error will result. Position cutter perpendicular to surface in both vertical and horizontal 

directions.

Insert cutter at desired location. Be sure to insert cutter perpendicular to the surface 

so that the entire back of the cutter is flush with the snow surface when the cutter is all the 

way in. Do not attempt to straighten cutter after it is partially inserted or sampling error will 

result. It is better to move cutter and resample correctly. Do not push cutter in farther than 

snow surface or over sampling will occur. [It may be preferable to have a little snow come 

out the end of the cutter to ensure a full sample (E. Josberger, U.s. Geological Survey, oral 

commun., 2011)] 

Place lid adjacent to top edge of cutter at an angle close to the angle of the upper 

cutter surface.

Hold cutter in place with one hand while inserting cutter lid in with the other. Do not 

allow cutter to slide back as lid is pressed in as undersampling will occur.

In consolidated or wet snow, once the lid is pressed in and the sample has been 

isolated, the cutter and sample may be removed and weighted while the lid is left in. In 

new, unconsolidated, weak, or kinetic (depth hoar) snow, the lid should be removed from 

the pit wall with the cutter to insure no sample loss.

Transfer the snow sample to the plastic baggie hanging from your spring scale. The 

weight in grams is simply multiplied by 4 to get density in kilograms per meter cubed (kg m 

-3), because the sample size is 250 cc. For example: a weight in grams of 90 gives 90 x 4 

= 360 kg m-3. Percent density is calculated by dividing the number above by 1000 (36%). 

If you are using a digital top-loading scale, the lid is removed after the sample is turned 

upright, and the sample (still in the cutter) is placed directly on the scale. 

Best results are obtained by inserting the flat bottom of the cutter vertically into the 

snowpack because this insures that heterogeneous layers are sampled evenly by the wedge 

shaped cutter. Hold the cutter handle in your left hand as you would a key being inserted 

into a lock; and hold the lid in your right hand. Reverse this procedure if you are left 
12

handed. Since the lid perturbs the snow above and below the cutter, a continuous density 

should be sampled by staggering alternate samples to one side or the other. 

3) Collect miscellaneous data. The SnowmetricsTM kit includes a stem thermometer, a 

magnifying glass, and a millimeter grid for snow crystal measurements. Use the stem 

thermometer to collect air temperature, snow temperature for each layer at which a snowdensity sample is collected, and soil temperature. Using the magnifying glass and millimeter

grid, sprinkle a few snow grains under the magnifying glass to determine the shape and size 

of the snow crystals. Note the roundness or sharpness of the crystals and the shape—needlelike, prismatic, plate-like, star-like, and so on. Record the snow crystal data in the Remarks 

section of the field sheet. See the proposed field sheet layout (fig. 14). 

Distributing Snow-Course Information throughout the Watershed

After point measurements of snow density and SWE have been made, the variables need to be 

estimated throughout the watershed model domain. The color-shaded information shown in figure 13

illustrates how the point measurements of SWE have been distributed throughout the Potholes Reservoir 

basin using an IDW interpolation method. 

The procedure to distribute the snow-course data to the watershed is best described by an 

example. The following example creates a grid of SWE values for the January 3-4, 2004, data for the 

basin using Arc and Grid commands for the Environmental Systems Research Institute ArcInfo® GIS in 

ArcInfo Workstation mode using an existing grid of the study area boundary (sa) and a grid of 

watershed model HRUs. 

1) The following is from an ASCII file (called sno_crs_pts.txt) of the point IDs, the X and Y 

coordinates for the snow course locations (UTM zone 11, datum NAD 83, units = meters) and the 

measured SWE (inches). This same file can be used in future snow surveys by updating the fourth 

column of data with current SWE values. Table 4 relates the point identifiers in this file to the snow 

courses.

 1 0.3094002E+06 0.5242992E+07 1.06 

 2 0.3271944E+06 0.5276113E+07 1.26 

 3 0.3428339E+06 0.5283372E+07 4.14 

 4 0.3730221E+06 0.5290695E+07 5.10 

 5 0.4149700E+06 0.5278735E+07 5.18 

 6 0.4058188E+06 0.5258474E+07 4.28 

 7 0.3943122E+06 0.5219253E+07 4.01 

 8 0.3580135E+06 0.5240782E+07 3.56 

 9 0.3413762E+06 0.5211914E+07 3.29 

END

2) Using the IDW grid command, the text file “sno_crs_pts.txt,” and an existing study area 

boundary grid, sa, the grid of SWE, swe_jan04_sa, was generated. The following three

commands at the GRID level were used: 

Grid: setwindow sa

Grid: swe_jan04 = IDW (sno_crs_pts.txt, #, #, 2, sample, 9, 50000, 90) 

Grid: jan04_sa = con( sa > 0, swe_jan04) 
13

The jan04_sa grid now can be plotted to show the distribution of SWE from the nine discrete points 

in the basin to the entire basin. 

Grid: gridp jan04_sa 

Adding Distributed Snow Information to the Current Watershed Model

Prior to adding the current condition of SWE to the watershed model, it should be determined 

whether conditions are meaningfully different from the simulated SWE, and thus whether the simulated 

SWE values need to be replaced. In the description that follows, steps 1 through 4 compute the upper 

Crab Creek basin SWE volume for the simulated and measured estimates. Steps 5 and 6 outline how a 

forecast model run using the ESP method can be made using the measured SWE values.

1) Using the “combine” and “zonalmean” grid commands, create a new grid that merges SWE data 

with an existing HRU grid for the Crab Creek modeling unit (crab_hru): 

Grid: out_jan04 = combine(crab_hru, zonalmean( crab_hru, (jan04_sa * 100))) 

NOTE: The 100 multiplier converts the SWE values expressed in fractions of inches (real 

number) to hundreds of inches (an integer) so that an attribute table can be generated (grid 

attribute tables only contain integers). 

2) Create a text file of SWE values ordered by HRU number. 

The grid attribute data should look like this: 

Grid: list out_jan04.vat 

Record VALUE COUNT CRAB_HRU XYXY027 

 1 1 8280 11 458 

 2 2 5077 50 500 

 3 3 1248 12 485 

 4 4 2825 15 503 

 . . . . . 

 . . . . . 

 . . . . . 

Write the HRU and SWE data to a file, swe_jan04.txt: 

Grid: listoutput swe_jan04.txt 

Grid: list out_jan04.vat CRAB_HRU XYXY027 

Grid: listoutput screen [return output to the screen] 

3) Import the text file (swe_jan04.txt) into a spreadsheet (table 5). Sort the SWE values of the last 

column of the text file by HRU number and convert values of hundreds of inches of SWE to inches 

of SWE. In the spreadsheet, the area in acres for each HRU (parameter hru_area in the parameter 

file of the model) has been imported and sorted by HRU number. Finally, the volume of SWE by 

HRU (table 5) and total SWE volume for the modeling unit can be computed in acre-feet and mean 

depth in inches. 

4) Compute the model-simulated basin SWE for the Crab Creek Modeling Unit and compare the 

results with measured snow-survey data. 

a) In the oui_potholes/potholes directory, click the file crab_swe_rt.bat to start the model 

b) Click the Run drop-down menu and Single Run.

c) Enter the Model End Date as the date of the snow survey, and enter a start date of September 1 

that is 3-4 years prior to the snow survey date (fig. 11). 
14

d) Check the Variable Save: check box and enter a file name for the variable file (fig. 11). The 

example uses the file name “crab.01.09.04” because this file will save all the variables on the 

end date of January 9, 2004. This file can be updated later with measured SWE data to make a 

forecast ESP model run. 

e) Click the Start button (fig. 11) to run the model. 

f) After the model has ended, exit the program, and open file crab_swe_rt_statvar.dat in the 

oui_potholes/potholes/mms_work/output directory. Read the last value for the snow survey date. 

This is the mean depth of the simulated SWE in inches for the Crab Creek Modeling Unit. 

g) Compare the snow-survey-derived mean depth with the simulated mean depth. In this example, 

the snow-survey-derived mean depth was 3.93 in. (about 5 times the simulated mean depth of 

0.744 in.). 

5) Edit the variable file if the simulated and measured SWE values are determined to be substantially 

different. If the measured SWE for the basin is much different from the simulated basin-wide SWE, 

as is evident in our example for January 2004, the measured snow-survey data can be used to update 

the variable file. These data will modify the simulated current conditions prior to making an ESP 

model run to forecast seasonal runoff volumes for the upper Crab Creek basin. This step begins the 

process of editing the variable file, crab.01.09.04, created in the last step. Four snow-related 

variables will be edited in the variable file: (1) SWE, in inches (pkwater_equiv); (2) free water in 

the snowpack, in inches (freeH20), computed as 2 percent of the SWE when the snowpack 

temperature is 0o

C; (3) snowpack ice (pk_ice), computed as SWE minus free water; and (4) 

snowpack depth (pk_depth), computed as SWE divided by snowpack density. The variable file is an 

ASCII file that consists of one long column of data ordered by HRU number (1-387, in the case of 

the Crab Creek model) with sets of data separated by a line with “####,” a line with the variable 

name, and four lines of header information. 

a) Begin by creating another sheet in the spreadsheet file created in step 3 and copying the SWE 

data sorted by HRU to the new sheet. If not done already, convert the units of the SWE data to 

inches. 

b) Open the variable file in directory oui_potholes/potholes/mms_work/input/vars (crab.01.09.04, 

in this example) in a text editor, search for “pk_temp” (snowpack temperature), select the data 

beginning five lines after “pk_temp,” and copy the data to the new sheet in the spreadsheet file. 

Be careful to align the data so that the SWE data for an HRU is aligned by row with the pk_temp 

data for the same HRU.

c) Calculate values for freeh2o for each HRU in a new spreadsheet as 2 percent of pkwater_equiv if 

the pk_temp is 0.0. If pk_temp is not 0.0, the freeh2o value is 0 (if the pkwater_equiv data is in 

column C and the pk_temp data is in column E, then the formula for freeh2o in row 5 is 

“=IF(E5=0, C5*0.02, 0)” (fig. 15). 

d) Create a column for pk_ice that is equal to pkwater_equiv minus freeh2o (fig. 15). 

e) Create a column for pk_depth that is equal to pk_water divided by density. The density is 

available from the snow survey (average = 0.204 in decimal percent for this example). Note that 

the density is not used in the calculations of runoff; therefore, it is not critical to assign an exact 

value to density. 
15

f) Replace the existing data in the variable file with new variable data for pkwater_equiv, freeh2o, 

pk_ice, and pk_depth. Be sure that all data in the spreadsheet are left justified. Update one 

variable at a time by first searching for the variable name in the variable file, copy the data from 

the spreadsheet, paste the data in the variable file beginning five rows below the variable name, 

and delete the old data for that variable.

6) Make an ESP run with the updated variable file. 

The ESP function in the OUI does not use the variable file for generating the individual traces as 

it did in earlier versions of the OUI. Instead, a Perl script for Windows has been developed to make an 

ESP model run using the variable file created in step 5 called crab.01.09.04.txt in this example.

(NOTE: ActivePerl for Windows is needed to run the script; it can be downloaded at no cost from the 

following web site, accessed June 26, 2012, at http://www.activestate.com/activeperl/downloads/thankyou?dl=http://downloads.activestate.com/ActivePerl/releases/5.14.2.1402/ActivePerl-5.14.2.1402-

MSWin32-x86-295342.msi) 

Prior to running the Perl script, it is important to make an ESP model run using the OUI for the 

same ESP start and end dates as will be used in the script. The Perl script will substitute the new data 

for the same period after the warm-up period in the original OUI-generated ESP files. 

In the directory oui_potholes/potholes, run the script called “crab_updated_swe_rt.pl” by 

double-clicking the file name in Windows Explorer. The opening screen for the script will appear (fig. 

16). In this example, a start date of January 10, 2004, and an end date of April 30, 2004, are used with 

the edited variable file crab.01.09.04.txt. The script runs the ESP model for the Crab Creek Model Unit 

and saves the output traces in a file name different than the output traces made running ESP with the 

OUI. After the script has run, the user can restart the OUI, display the ESP report (fig. 9) and generate 

new forecasts. The new forecasts are based on the measured snow-survey-derived data that replace the 

simulated current conditions of the snowpack for the Crab Creek Model Unit. 

Summary 

The U.S. Geological Survey (USGS) and the Bureau of Reclamation (Reclamation) have 

maintained a collaborative relationship in the development of watershed models for the drainage basins 

to Potholes Reservoir, Washington, which is managed by Reclamation along with a canal system to

irrigate thousands of acres in the Columbia Basin Project. A previous USGS Scientific Investigations 

Report documents the development of a watershed model (2009 model) for these drainage basins. Since 

2009, two new meteorological sites with real-time telemetry have been established in and near the study 

area. Adding these sites to the model required some updates to the model (2012 model) and the 

development of a new real-time data retrieval system. Model runs with the 2009 model and the 2012 

model show similar results, and comparisons with measured data confirm the conclusions in the 

previous report that the model is not reliable in simulating runoff from individual storms, but has been 

successful in forecasting runoff volumes over a season. Updates to the model were made and a new realtime retrieval program called the Potholes Data Chimp was created; both are described in this report. A 

method of collecting snow data at nine historical measurement locations is described along with a 

method of incorporating the data into forecast model runs. 
16

References Cited

Bureau of Reclamation, 2012a, AgriMet--The Pacific Northwest Cooperative Agricultural Weather 

Network: Bureau of Reclamation database, accessed May 14, 2012, at 

http://www.usbr.gov/pn/agrimet/. 

Bureau of Reclamation, 2012b, Hydromet: Bureau of Reclamation database, accessed May 14, 2012, at 

http://www.usbr.gov/pn/hydromet/. 

Clark, M.P., Slater, A.G., Barrett, A.P., Hay, L.E., McCabe, G.J., Rajogopalan, B. and Leavesley, G.H., 

2006, Assimilation of snow covered area information into hydrologic and land-surface models, 

Advances in Water Resources, v29, p. 1209-1221. 

Daly, Christopher, Taylor, George, and Gibson, Wayne, 1997, The PRISM approach to mapping 

precipitation and temperature: Proceeding of the 10th Conference on Applied Climatology, Reno, 

Nevada, American Meteorological Society, p. 10-12, accessed October 2011 at 

http://www.prism.oregonstate.edu/pub/prism/docs/appclim97-prismapproach-daly.html. 

Day, G.N., 1985, Extended streamflow forecasting using NWSRFS: American Society of Civil 

Engineers, Journal of Water Resources Planning and Management, v. 111, no.2, p.157—170. 

Leavesley, G.H., Lichty, R.W., Troutman, B.M., and Saindon, L.G., 1983, Precipitation-runoff 

modeling system—User’s manual: U.S. Geological Survey Water-Resources Investigation Report 

83-4238, 207 p. 

Leavesley, G.L., Restrepo, P.J., Markstrom, S.L., Dixon, Mike, and Stannard, L.G., 1996, The Modular 

Modeling System (MMS) user’s manual: U.S. Geological Survey Open-File Report 96-151, 175 p. 

Markstrom, S.L., and Koczot, K.M., 2008, User’s manual for the object user interface (OUI)—An 

environmental resource modeling framework: U.S. Geological Survey Open-File Report 2008-1120, 

39 p. 

Mastin, M.C., 2009 Watershed models for decision support for inflows to Potholes Reservoir, 

Washington: U.S. Geological Survey Scientific Investigations Report 2009-5081, 54 p. 

Molnau, M., and Bissel, 1983, A continuous frozen ground index for flood forecasting: Vancouver, 

Wash., Proceedings of the 51st Annual Meeting of the Western Snow Conference, p. 109-119. 

Snowmetrics, 2012, Tools for avalanche forecasting and snow research: Snowmetrics Web site, 

accessed August 13, 2012, at http//www.snowmetrics.com/store/. 

U.S. Department of Agriculture, 1984, Snow survey sampling guide: Soil Conservation Service 

Agricultural Handbook Number 169, 32 p. 
17

Figure 1. Locations of streamflow-gaging stations and boundaries of the Columbia Basin Project and study area 

in the Potholes Reservoir basin, Washington. 
18

Figure 2. Watershed modeling units, streamflow-gaging stations and new and existing meteorological sites that 

provide input data to the watershed models, Potholes Reservoir basin, Washington.
19

Figure 3. Comparison of measured discharge and discharge simulated with the 2009 and 2012 models at three 

streamflow-gaging stations, upper Crab Creek basin, Washington water years 2010-11.
20

Figure 4. Measured hydrologic variables and hydrologic variables simulated using the 2009 and 2012 models at 

Hydrologic Response Unit (HRU) 148 near Davenport, Washington, water years 2010-11. (A) Simulated daily 

precipitation, (B) simulated daily soil moisture and measured soil moisture at Davenport (measured soil 

moisture is the average of the soil moisture at 4 and 20 in. depths); and (C) Continuous Frozen Ground Index 

(CFGI) and measured soil temperature at Davenport.
21

Figure 5. Screen capture showing the Potholes Data Chimp data information window.
22

Figure 6. Object User Interface (OUI) directory structure for the Potholes watershed model, Potholes Reservoir 

basin, Washington. [MMS, Modular Modeling System; esp, ensemble streamflow prediction; PRMS, 

Precipitation Runoff Modeling System; GIS, Geographic Information System]
23

Figure 7. Screen shot of the Object User Interface (OUI) opening screen showing the tree nodes under the three 

major tree nodes (left panel) and the Map Mode panel (right panel) showing maps of two selected tree node 

elements, “Models” and “Crab Ck MRUs” from the “Model Unit Maps” tree node. 
24

Figure 8. Screen shot of the Object User Interface (OUI) main window showing the real-time stations in the Map 

Mode window with the Davenport, Washington, station selected (top), and the Time Series Tool window with a 

zoomed-in plot of precipitation input data. 
25

Figure 9. Screen capture of the ESP report, Run MMS Model in ESP Mode, and OUI ESP Tool windows. 
26

Figure 10. Screen capture of the opening window for the Modular Modeling System (MMS) traditional user 

interface for the Crab Creek model, Potholes Reservoir basin, Washington.
27

Figure 11. Screen capture of the MMS Run Control - Single Run window for the Modular Modeling System 

traditional user interface for the Crab Creek model, Potholes Reservoir basin, Washington.
28

Figure 12. Existing network of snow courses in and near the watershed model boundaries, Potholes Reservoir 

basin, Washington. Detailed descriptions of the snow courses are given in Appendix B.
29

Figure 13. Snow-water equivalent measured at nine locations during January 8-9, 2004, and snow-water 

equivalent throughout the model domain estimated based on the measured values, Potholes Reservoir basin, 

Washington. 
30

Figure 14. A proposed field-sheet layout for collecting snow-survey information.
31

Figure 15. Screen capture of spreadsheet used to calculate variables freeh2o, pk_ice, and pk_depth.

Figure 16. Screen capture of Ensemble Streamflow Prediction (ESP) update window with start and end date and 

variable file entered for the example ESP model run updated with snow-survey data.
32

Table 1. Comparison of measured runoff volumes and runoff volumes simulated with the 2012 model at three 

streamflow-gaging stations, upper Crab Creek basin, Washington, January 1-June 30, water years (WY) 2010-

11.

January-June, WY 2010 January-June, WY 2011

Streamflowgaging stationMeasured 

runoff

(acre-feet)

Simulated

runoff

(acre-feet)

Percent 

difference

Measured 

runoff

(acre-feet)

Simulate 

runoff

(acre-feet)

Percent 

difference

Crab Creek at 

Rocky Ford Road 21,889 7,196 -67.1 31,966 25,574 -20.0

Coal Creek at 

Mohler 2,538 147 -94.2 2,731 1,334 -51.2

Crab Creek at 

Irby 19,745 7,085 -64.1 26,761 32,466 21.3

Table 2. Comparison of measured runoff volumes and the Ensemble Streamflow Prediction (ESP) 50-percentexceedance-probability runoff volumes generated by the 2009 and 2012 models at three streamflow-gaging 

stations, upper Crab Creek basin, Washington, for runoff season January 1-June 30, water years (WY) 2010-

11. 

January 1 through June 30, WY 2010 January 1 through June 30, WY 2011

Streamflowgaging stationESP 50-

percentexceedanceprobability 

runoff 

volume, 

2009 model 

(acre-feet)

ESP 50-

percentexceedanceprobability 

runoff 

volume, 

2012 model 

(acre-feet)

Measured 

runoff 

volume 

(acrefeet)

Percent 

difference

between 

simulated 

and 

measured 

runoff 

volume, 

2012 

model

ESP 50-

percentexceedanceprobability 

runoff 

volume, 

2009 model 

(acre-feet)

ESP 50-

percentexceedanceprobability 

runoff 

volume, 

2012 model 

(acre-feet)

Measured 

runoff 

volume 

(acre-feet)

Percent 

difference

between 

simulated 

and 

measured 

runoff 

volume, 

2012 

model

Crab Creek at 

Rocky Ford 

Road 17,636 15,806 21,889 -27.8 40,811 31,891 31,966 -0.2

Coal Creek at 

Mohlar

1,292 1,537 2,538 -39.4 3,496 3,171 2,731 16.1

Crab creek at 

Irby 

21,400 20,224 19,745 2.4 48,283 42,888 26,761 60.3
33

Table 3. Meteorological sites, data sources, and sequence numbers indicating the order of data items in the input 

file for the real-time Potholes watershed model, Potholes Reservoir basin, Washington. 

Meteorological 

Site

Data Source Sequence Number

Daily 

Precipitation 

Daily Minimum 

Temperature 

Daily Maximum 

Temperature 

Davenport Hydromet 1 10 19 

Ephrata AP NWS 2 11 20 

Harrington NWS 3 12 21 

Almira Hydromet 4 13 22 

Lind Hydromet 5 14 23 

Moses Lake NWS 6 15 24 

Odessa Hydromet 7 16 25 

Ritzville NWS 8 17 26 

Wilbur NWS 9 18 27 

Table 4. Point identification numbers and related snow-course names for the input file, sno_crs_pts.txt, used to 

generate a snow-water equivalent grid for the Potholes Reservoir basin, Washington.

POINT ID Snow-Course Name

1 Ephrata

2 Dry Falls

3 Hartline

4 Wilber

5 Davenport

6 Harrington

7 Ritzville

8 Odessa

9 Bassett Junction
34

Table 5. Example of first six rows of data in the spreadsheet showing (A) GIS output; (B) values of snow-water 

equivalent (SWE), sorted by Hydrologic Response Unit (HRU); (C) imported area values that are used to 

compute SWE volume; and (D) SWE volume for each HRU.

from Jan 04 GIS output Sorted by HRU Hru_area SWE volume

Record CRAB_HRU XYXY027 CRAB_HRU

XYXY027, 

inches HRU Area, acres in ac-ft

1 11 458 1 4.18 1 4965.59 1729.68

2 50 500 2 4 2 3260.50 1086.833

3 12 485 3 4.05 3 1164.35 392.9681

4 15 503 4 4.2 4 1886.63 660.3205

5 13 492 5 4.33 5 1560.15 562.9541

6 16 504 6 3.99 6 6305.93 2096.722
35

Appendix A. Potholes Watershed Model Background

Three modeling units in the Potholes watershed-modeling project are simulated in separate 

models: Crab Creek (21 flow-routing nodes), Rocky Coulee (11 flow-routing nodes), and Lind Coulee 

(14 flow-routing nodes). All models use the executable file PRMSIV_dev.exe and the same data file, 

either pot_rt.data (water years 1950-current) or pot_lt.data (water years 1950-2004). The long term data 

file (pot_lt.data) has nine weather-station inputs and the real-time data file (pot_rt.data) has seven

weather-station inputs (with some different stations) and missing values (-9999.00) for the other two 

stations. All weather stations measure maximum and minimum daily temperature and daily 

precipitation. The Potholes Object User Interface (OUI) has been set up to allow the user to run longterm model runs (Single Run) and to get the simulated discharge time series at all 46 flow-routing nodes 

for the three models. The OUI also includes the ability to run real-time Ensemble Streamflow 

Prediction (ESP) model runs and generate output at nine specific nodes. All the runoff routing is done 

within the PRMSIV_dev.exe executable between flow-routing nodes (fig. A1, table A1). 
36

Appendix B. Snow-Course Locations

The hand-drawn maps and photographs included in this appendix provide additional location 

information about the proposed network of nine snow courses. Refer to figure 12 in the main text for 

the general location of these snow courses. Latitude and longitude of the snow-course locations are 

included in the hand-drawn maps. The hand-drawn maps and photographs were made during a snow 

survey during January 8-9, 2004. The snow-water equivalents measured at nine locations are shown in 

figure 13. 

The following are hand-drawn maps and some topographic maps for the nine snow-course 

locations (fig. 12), listed in alphabetical order:

1. Bassett Junction

2. Davenport 

3. Dry Falls

4. Ephrata Airport

5. Harrington

6. Hartline

7. Odessa Agrimet

8. Ritzville Airport

9. Wilbur 
37
38
39
40
41
42
43
44
45
46
47
48
49

Appendix figure and table:

Figure A1. Potholes model units and flow-routing nodes.
50

Table A1. Flow-routing nodes.

Node 

ID

Model Subbasin USGS streamflow-gaging station and 

number

1 Crab Crab abv. Lords

2 Crab Crab abv Rockyford Rd

3 Crab Coal Creek Coal Creek at Mohler, 12464800

4 Crab Duck Creek

5 Crab Lake Creek

6 Crab Odessa Crab Creek at Irby, 1246500

7 Crab Martin Hollow

8 Crab Canniwai

9 Crab Corbett

10 Crab Upper Wilson

11 Crab Corbett + Upper Wilson Wilson Creek blw Corbett Draw, 12465400

12 Crab Wilson

13 Crab Stratford

14 Crab Arbuckle

15 Crab Below Brooks Lake

16 Crab Upper Irrigated

17 Crab Middle Irrigated

18 Crab Broken Rock

19 Crab Black Lake

20 Crab Crab near Moses Lake Crab Creek near Moses Lake, 1246700

21 Crab Rocky Ford

1 Rocky Upper Rocky

2 Rocky Rocky

3 Rocky Cemetary

4 Rocky Sand

5 Rocky Black Rock

6 Rocky Block 40

7 Rocky Rocky at East Low Canal

8 Rocky Rocky near mouth

9 Rocky Block 41

10 Rocky Block 42 trib

11 Rocky Block 42

1 Lind McElroy Coulee

2 Lind Paha Coulee

3 Lind Upper Lind

4 Lind Lind Coulee

5 Lind Bauer Coulee

6 Lind Farrier Coulee Farrier Coulee near Schrag, 12471270

7 Lind Upper Weber Coulee
51

8 Lind Farrier at mouth

9 Lind Weber

10 Lind North Fork

11 Lind Mid-Weber

12 Lind Lower Lind

13 Lind Lower Lind-North

14 Lind Lind near mouth Lind Coulee Wasteway at SR17, 12471400
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