Bear River Basin Water Plan
Technical Memoranda

SUBJECT:	Appendix H Speadsheet Modeling Support - Efficiencies and Return Flow Patterns
PREPARED BY:	Bear River Basin Planning Team

Introduction

The spreadsheet model determines the mass balance at locations along the river. Therefore, historic or estimated river headgate diversions are used as the demands that drive the model. However, only a portion of the headgate diversion is actually available to satisfy crop consumptive use requirements, municipal demands, or industrial demands. The unused portion of the headgate diversions is either lost in route to the farm or treatment plant (conveyance loss) or lost during crop application (application or on-farm loss).

Efficiencies and Return Flow Patterns

This unused portion of headgate diversion either returns to the river as surface runoff during the month it is diverted, or "deep percolates" into the alluvial aquifer. The deep percolation portion returns to the river through the aquifer but generally lags the time of diversion by several months, or even years. It is important for the model to simulate both the percent of headgate diversions that return to the river, and the timing of which this unused portion returns. In the Bear River Basin, water from the river is reused many times from the headwaters to the Great Salt Lake.

Diversion efficiency for agricultural use is the common measure of the portion of headgate diversion that is consumed, and therefore not returned to the river. Diversion efficiency for municipal and industrial use is the percent of headgate diversion that makes it to the treatment plant or industrial site. The remaining percent is lost during conveyance, and returns to the river as surface runoff or deep percolation. Diversions for agricultural use experience both conveyance losses and application losses, and both these loss percents return to the river as surface runoff or deep percolation.

Conveyance Efficiency

Factors that affect conveyance efficiencies include:

• Frequency and duration of diversion. More losses occur during the first month of the irrigation season due to canal "wetting".

• Underlying soil characteristics. More permeable soil will experience greater conveyance losses.

• Canal capacity and length. Larger canals generally serve more lands and have more opportunity to "lose" water in route to the farm.

• Location of water table relative to the canal. Canals running through areas with high water tables can actually "gain" water in route to the farm.

• Canal evaporation. Water evaporates from the surface of canals. The amount of is generally small and depends on the width and length of canals.

• Phreatophyte occurance. Phreatophytes, such as willows and cottonwood trees that grow unchecked along canals, can use a portion of diverted water.

The report "Irrigation Conveyance Systems - Working Paper for the Bear River Basin Type IV Study", USDA and SCS, April 1976, estimated conveyance efficiencies throughout the Bear River Basin. The conveyance efficiencies for the Unita County irrigation systems ranged from 30 percent to 75 percent. The conveyance efficiencies for Lincoln County ranged from 50 percent to 85 percent. Tables are provided in that report showing conveyance efficiencies by major ditch system, however, there is no documentation provided on how these estimates were developed. Therefore, we estimated conveyance efficiencies based on main canal length and the proximity of irrigated acreage to the main canal. The maps provided in the Type IV Study report were used to measure canal lengths. In most cases, our estimated conveyance efficiencies were consistent with the efficiencies summarized in the Type IV Study report. Note that the ditch systems in the Bear River basin in Wyoming have changed very little since 1976.

Table 1 shows the conveyance efficiencies estimated for the key ditch systems represented in the modeling effort for the upper division. The upper division aggregate ditch systems were assigned a conveyance efficiency of 60 percent, because they represent smaller ditches generally irrigating lands close to the river.

Table 2 shows the conveyance efficiencies estimated for the key ditch systems represented in the modeling effort for the central division. The central division aggregate ditch systems were assigned a conveyance efficiency of 65 percent, again because they represent smaller ditches generally irrigating lands close to the river. The exception is the aggregate diversion representing the irrigated lands in Utah between Woodruff Narrows and Pixley Dam. These lands are dependent on each other's return flows for diversion supply, but because of the aggregation, all diversion will be modeled at one location. A conveyance efficiency of 45 percent was used to represent these diversions.

Application (on-farm) Efficiencies

Factors that affect application efficiencies include:

• Irrigation practice. Flood irrigation techniques require more water to be applied than the crops require. Flood irrigation causes much more runoff and deep percolation than sprinkler irrigation. Sprinkler irrigation is generally applied more frequently and directly to the crops.

• Crop types. Row crops generally cause more runoff than field crops, such as irrigated meadow.

Ranges of irrigation application efficiencies are widely published. For this study, we used efficiency percents presented by Duane D. Klamm and John S. Brenner in the 1995 Evapotranspiration and Irrigation Efficiency Seminar sponsored by the American Consulting Engineers Council of Colorado and the Colorado Division of Water Resources. Flood irrigation application efficiencies were estimated to be 55 percent basin wide for the modeling effort. Center pivot and side-roll sprinkler application efficiencies were estimated at 85 percent, and hand-line sprinklers were estimated at 80 percent.

Most crop acreage in the upper division of the Bear River basin is irrigated using flood application techniques. There is only one sprinkler irrigated quarter-section shown in the 1993 irrigated acreage assessment. The local water administrator further verified that all other farms use flood irrigation in the upper division.

The central division is also mostly flood irrigated, however, there has been a greater trend towards sprinkler irrigation. Through interviews with water administrators and users, we have estimated the percent of acreage under the key ditch systems that apply water through sprinklers. Center pivot and side-roll sprinklers are most common; however there are a few hand-line sprinklers.

In addition to conveyance efficiencies, Table 1 shows the suggested application efficiency for the key ditch systems in the upper division. Because lands in the upper division are flood irrigated, the application efficiencies are all 55 percent. An application efficiency of 55 percent is also used for aggregated ditch systems.

Table 2 shows the suggested application efficiency for the key ditch systems in the central division. An application efficiency of 65 percent was used for aggregated ditch systems in the central division, which represents an average of key ditch system efficiencies.

The model uses a diversion efficiency that represents the actual amount of headgate diversion used to satisfy crop consumptive use demands. It is calculated as the product of conveyance efficiency and application efficiency. The diversion efficiency is also provided in Tables 1 and 2.

Table 1
Upper Division Diversion Efficiencies

Model Node ID	Diversion Name	Conveyance Efficiency	Application Efficiency	Diversion Efficiency	Irrigation Methods
1.01	Lannon and Lone Mountain	45 %	55 %	25 %	100 % Flood
1.02	Hilliard West Side	40 %	55 %	22 %	100 % Flood
1.03	Bear Canal	40 %	55 %	22 %	100 % Flood
1.04	Crown and Pine Grove	50 %	55 %	27 %	100 % Flood
1.05	McGraw (and Big Bend)	55 %	55 %	30 %	100 % Flood
1.06	Lewis	55 %	55 %	30 %	100 % Flood
1.07	Myers No 2	50 %	55 %	27 %	100 % Flood
1.08	Myers No 1	50 %	55 %	27 %	100 % Flood
1.09	Myers Irrigation	55 %	55 %	30 %	100 % Flood
1.11	Booth	50 %	55 %	27 %	100 % Flood
1.12	Anel	55 %	55 %	30 %	100 % Flood
1.13	Evanston Water Supply	50 %	55 %	27 %	100 % Flood
3.01	Evanston Water Ditch	65 %	55 %	36 %	100 % Flood
3.02	Rocky Mountain Blythe	65 %	55 %	36 %	100 % Flood
4.01	John Simms	65 %	55 %	36 %	100 % Flood
4.02	SP Ramsey	60 %	55 %	33 %	100 % Flood
5.01	Chapman (WY portion)	50 %	55 %	27 %	100 % Flood
5.02	Morris Brothers	65 %	55 %	36 %	100 % Flood
5.04	Tunnel	65 %	55 %	36 %	100 % Flood
7.01	Francis Lee	60 %	55 %	33 %	100 % Flood
7.02	Bear River Canal	60 %	55 %	33 %	100 % Flood
7.03	Utah Aggregate Ditches	45 %	65 %	30 %	67 % Flood 33 % Center Pivot
8.00	BQ Dam Diversions	55 %	60 %	33 %	90 % Flood 10 % Center Pivot
8.01	Pixley Dam	55 %	60 %	33 %	90 % Flood 10 % Center Pivot S
Varies	Aggregate Systems	60 %	55 %	33 %	100 % Flood

Table 2
Central Division Diversion Efficiencies

Model Node ID	Diversion Name	Conveyance Efficiency	Application Efficiency	Diversion Efficiency	Irrigation Methods
10.02	Button Flat	65 %	55 %	36 %	100 % Flood
10.03	Emelle	65 %	55 %	36 %	100 % Hand-line Sprinkler
10.04	Cooper	65 %	55 %	36 %	100 % Flood
10.05	Covey	45 %	65 %	30 %	70 % Flood 30 % Center Pivot Sprinkler
10.06	VH Canal	55 %	85 %	47 %	100 % Center Pivot Sprinkler
10.07	Goodell	55 %	85 %	47 %	100 % Center Pivot Sprinkler
10.08	Whites Water	60 %	65 %	40 %	60 % Flood 40 % Hand-line Sprinkler
10.09	S. Branch Irrigating	60 %	70 %	42 %	40 % Flood 60 % Hand-line Sprinkler
11.02	Alonzo F. Sights	60 %	65 %	40 %	60 % Flood 40 % Hand-line Sprinkler
11.03	Oscar E. Snyder	73 %	55 %	40 %	100 % Flood
11.04	Cook Brothers	73 %	55 %	40 %	100 % Flood
Varies	Aggregate Systems	65 %	65 %	42 %	67 % Flood 33 % Center Pivot Sprinkler

Return Flow Patterns

As discussed above, the unused, or inefficient, portion of diversions are returned to the river either by direct surface runoff, or through the alluvial aquifer. For modeling purposes, an estimate must be made of both:

• the location or locations on the river where the unused portion of diversions will return, and
• the timing of those returns.

The location where unused water is returned to the river is based on the location of irrigated lands. Unless a "drain" has been constructed to remove excess water from lands with high water tables, return flows do not generally return to a specific point on the river. However, for modeling purposes, it needs to be returned to a specific node in the network. The return flows can be re-diverted at the return flow location node and any nodes downstream. For the larger ditch systems, unused water may return at more than one location. The irrigated acreage GIS theme was used to estimate these locations, shown in Table 3 for the upper division and Table 4 for the central division.

Return flow patterns represent the timing of return flows back to the river. Generally, the surface runoff portion of unused diversion returns to the river the same month as diversions, whereas the deep percolation portion may take much longer. The timing of return flows can be determined using standard Glover equations, basin water budgets, or more detailed ground water modeling techniques. Return flow patterns were estimated in the publication "Water Budget Studies - Utah, Bear River Study Area", State of Utah Natural Resources, September 1994. Return flow patterns were developed for several river reaches, including both the upper and central portion of the Bear River Basin in Wyoming. The following return flow patterns were adopted from this study for the modeling effort, and represent the timing of the return of unused diversions. Note that month 0 is the month of diversion, month 1 is the 1st month after diversion, etc.

Return Pattern 1 = 50 % month 0, 25 % month 1, 15 % month 2, 10 % month 3
Return Pattern 2 = 70 % month 0, 20 % month 1, 10 % month 2
Return Pattern 3 = 100 % month 0

Return flow pattern 1 is used to represent larger ditch systems that serve lands further from the river. Return flow pattern 2 is used to represent smaller ditch systems that serve lands adjacent to the river. Return flow pattern 3 is used to represent municipal and industrial nodes, where water is returned to the river from treatment plants or industrial processes directly. In addition to the return flow node location in the river, Tables 3 and 4 show the return flow pattern used to represent each ditch system.

Table 3
Upper Division Return Flow Locations and Patterns 50 % Ag-Sulphur Creek bl Reservoir

Model Node ID	Diversion Name	Return Nodes	Return Pattern
1.01	Lannon and Lone Mountain	30 % Lewis Ditch 70 % Confluence with Mill Ck	1
1.02	Hilliard West Side	100 % Sulphur Creek Reservoir	1
1.03	Bear Canal	60 % Sulphur Creek Reservoir 40 % Ag-Sulphur Creek bl Reservoir	1
1.04	Crown and Pine Grove	25 % Lewis 25 % Confluence with Mill Ck 50 % Myers No 2	2
1.05	McGraw (and Big Bend)	100 % Lewis	2
1.06	Lewis	100 % Myers No 1	2
1.07	Myers No 2	100 % Myers No 1	2
1.08	Myers No 1	50 % Booth	2
1.09	Myers Irrigation	100 % Anel	2
1.11	Booth	100% Evanston Water Ditch	2
1.12	Anel	100 % Ag-Bear River between Mill Creek and Sulphur Creek	2
1.13	Evanston Water Supply	50 % Rocky Mountain Blythe 50 % John Simms	2
1.15	Ag-Bear River between Mill Creek and Sulphur Creek	100 % Confluence Bear and Sulphur Creek	2
2.01	Ag-Sulphur Creek Above Res	100 % Sulphur Creek Res.	2
2.03	Ag-Sulphur Creek Below Reservoir	100 % Confluence Bear and Sulphur Creek	2
3.01	Evanston Water Ditch	100 % Rocky Mountain Blythe	2
3.02	Rocky Mountain Blythe	70 % John Simms 30 % SP Ramsey	2
4.01	John Simms	50 % SP Ramsey 50 % Ag-Bear River between Sulphur and Yellow Creeks	2
4.02	SP Ramsey (also called Adin Brown)	50 % Ag-Bear River between Sulphur and Yellow Creeks 50 % Chapman	2
4.03	Ag-Bear River between Sulphur and Yellow Creeks	100 % Chapman	2
5.01	Chapman	100 % Ag-Bear River between Yellow Creek and Woodruff	2
5.02	Morris Brothers	30 % Ag-Bear River between Yellow Creek and Woodruff 70 % Woodruff Narrows	2
5.03	Ag-Bear River between Yellow Creek and Woodruff Narrows	100 % Tunnel	2
5.04	Tunnel	100 % Woodruff Narrows	2
7.01	Francis Lee	100 % Ag- Utah Diversions	1
7.02	Bear River Canal	100 % Ag-Utah Diversion	1
7.03	Ag-Utah diversion	70 % USGS Gage 10026500 5 % Pixley 25 % Return Flow Node 7.04	2
8.02	BQ Dam Diversions	100 % Pixley	2
8.01	Pixley Dam	100 % Confluence with Smiths Fork	2

Table 4
Central Division Return Flow Locations and Patterns Fork and Smiths Fork

Model Node ID	Diversion Name	Return Nodes	Return Pattern
9.02	Ag-Bear River between Twin	100 % Confluence with Smiths Fork	2
10.01	Quinn Bourne	100 % Button Flat	2
10.02	Button Flat	100 % Emelle	2
10.03	Emelle	50 % Cooper Ditch 50 % Covey	2
10.04	Cooper	100% Covey	2
10.05	Covey	10 % White Water 90 % Ag-Bear River below Smiths Fork	1
10.06	VH Canal	100 % White Water	1
10.07	Goodell	100 % White Water	1
10.08	Whites Water	100 % Ag-Bear River below Smiths Fork	2
10.09	S. Branch Irrigating	100 % Ag-Bear River below Smiths Fork	2
10.10	Ag-Smiths Fork	100 % Confluene Bear and Smiths Fork	2
11.01	Ag-Bear River below Smiths Fork	40 % Alonzo F. Sights 40 % Oscar E. Snyder 20 % Cook Brothers	2
11.02	Alonzo F. Sights	50 % Oscar E. Snyder 50 % Cook Brothers	2
11.03	Oscar E. Snyder	50 % Cook Brothers 50 % Bear River at Border Gage (1003950)	2
11.04	Cook Brothers	50 % Bear River at Border Gage 50% Ag-Idaho Diversions	2

Sources

USDA and SCS, Irrigation Conveyance Systems - Working Paper for the Bear River Basin Type IV Study, April 1976,

State of Utah Natural Resources, Water Budget Studies - Utah, Bear River Study Area, September 1994.

Duane D. Klamm and John S. Brenner, excerpts from the 1995 Evapotranspiration and Irrigation Efficiency Seminar sponsored by the American Consulting Engineers Council of Colorado and the Colorado Division of Water Resources.