River Basin Simulation with WEAP Water Evaluation and Planning System David Rosenberg CEE 5460 – Water Resources Engineering

Learning Objectives Describe reasons to model priority-based water allocations Draw a system schematic (that includes water sources, demand sites, and return flows) Calculate allocations given available water and delivery priorities Add reservoir storage and release priorities Use the WEAP system to set up the schematic, enter data, obtain results, and define + analyze scenarios 2CEE

Motivation To determine water availability, need to track inflows, reservoir storage, groundwater, return flows, and soil moisture Then determine demands, deliveries, and shortages Also need to consider allocation priorities –Appropriation doctrine (first in time, first in right) –By purpose (e.g.: urban demands before environmental) –By location (e.g.: upstream, then downstream, or reverse) WEAP History –First developed in 1992 –WEAP21 version in 2005 –Already 119 published applications (33 in 2010) CEE 5460David Rosenberg 3

Draw a System Schematic Identify the major system components –Water sources (surface and groundwater) –Demand sites (agricultural, urban, etc..) –Source connections to demand sites –Outflows from demand sites after use Example 1: A river can supply water to a city and an agricultural district. The outfalls from agricultural drain pipes and the city’s wastewater treatment plant are located downstream of both diversion intakes. CEE 5460David Rosenberg 4

Drawing a System Schematic (cont.) Example 2: A river can supply water to a city and an agricultural district. The city is located upstream of the agricultural district. 40% of the city’s withdrawals are collected, treated, returned to the river, and available for downstream use by the agricultural district. CEE 5460David Rosenberg 5

Calculate Allocations 1.Draw the schematic (previous slides) 2.Determine delivery targets for demand sites (demands) 3.Assign priorities to demand sites (delivery preferences) 4.Determine water availability  Sources  Return flows 5.Allocate remaining available water to meet delivery target of highest priority demand site 6.Repeat Steps 4 and 5 for next highest priority site. CEE 5460David Rosenberg 6

Calculate Allocations (cont.) Example 3: A river can supply water to a city and an agricultural district. The outfalls from agricultural drain pipes and the city’s wastewater treatment plant are located downstream of both diversion intakes. CEE 5460David Rosenberg 7 Demand Site Priority [rank] Delivery Target [ac-ft/yr] City 2 (lower)30 Agricultural 1 (high)60 70 ac-ft is available in the river this year. The table shows demand site priorities and delivery targets. What water volume is allocated to each demand site?

Calculate Allocations (cont.) Example 4: A river can supply water to a city and an agricultural district. The city is located upstream of the agricultural district. 40% of the city’s withdrawals are collected, treated, returned to the river, and available for downstream use by the agricultural district. CEE 5460David Rosenberg 8 Demand Site Priority [rank] Delivery Target [ac-ft/yr] City 2 (lower)30 Agricultural 1 (high)60 70 ac-ft is available in the river this year. The table shows demand site priorities and delivery targets. What water volume is allocated to each demand site?

Calculate Allocations (cont.) Always use mass balance to determine water available to a user (or at model node) Allocation calculations get more complicated as add demand sites and return flows Computer modeling can really help! CEE 5460David Rosenberg 9

Adding Reservoirs Reservoirs are just another supply source Reservoir source availability determined by –Storage at end of previous time step –Reservoir release rules –Reservoir inflows, evaporation losses, etc. Recall storage partition CEE 5460David Rosenberg 10

Adding Reservoirs (cont.) In WEAP 1.First use in-stream flows to meet Demand Site targets 2.If in-stream flows inadequate, withdraw from reservoirs 3.Withdrawal a function of reservoir storage 4.Can also assign priorities to refill reservoirs CEE 5460David Rosenberg 11 Withdraw to meet full delivery target Withdraw reduced amount (buffer coefficient)

WEAP Allocation Math In each time step, WEAP solves a small linear program Maximize Demand Satisfaction 1.Meet supply priorities 2.Obey demand site preferences 3.Mass balance 4.Other constraints Embed the LP in a time-series simulation (psuedo code) CEE 5460David Rosenberg 12 Such that:

Using WEAP Major Modules –Schematic –Data –Results –Scenario Explorer Introduce modules today Apply & practice through on-your-own lab exercise and PBL-3 CEE 5460David Rosenberg 13

WEAP Schematic Drag and drop system node components –Demand sites –Reservoirs, etc. Drag, click, and drop system link components –Rivers –Transmission links –Return flows Add GIS layers to help place components Must include all infrastructure you plan to test in Scenario Explorer CEE 5460David Rosenberg 14

Weaping River Example Schematic CEE 5460David Rosenberg 15

New Cache Cache Valley Bear River Canal Company New Box Elder County Reservoir, proposed Wetland Ag. Use Urban Use Box Elder County Bird Refuge Schematic for the Lower Bear River Cutler Above Cutler QX15-South Cache QX54-Little Bear QX5-Lower Bear QX6-Cache GW QX22- Malad Reach Gain QX27-Box Elder GW QX61-Malad River

Hypothesized Cross Section for Above-Cutler Site 1,700 ft Current river channel 10 ft 30 ft 1:1 slope bank 150 ft

Example 5. Complete the Lower Bear River Schematic Open the partially complete WEAP Area for the Lower Bear River Add the required demand sites, reservoirs, transmission links and return flows to the schematic. –What reservoir(s) did you add? –What demand sites did you add? CEE 5460David Rosenberg 18

WEAP Data Module Enter data for each schematic component –Rivers: Headflows for each month of the simulation –Demand sites: activity levels, use rates, losses, consumption, demand priority (1=highest; 99=lowest) –Transmission links: Max flows, supply preference –Return flows: routing (percent returned) –Reservoirs: storage capacity, initial storage, volume- elevation curve, evaporation, pool definitions, buffer coefficients, priority Enter data for a base case or a scenario Enter data or read from input file CEE 5460David Rosenberg 19

Alternatively, right-click any schematic component to also get to the Data module CEE

CEE Tree view, Buttons, and Tabs to navigate to desired data

CEE Graphical and tabular views of Demand Site Priority

WEAP Results Module Click the Results icon and recalculate (all scenarios) Choose results from schematic or dropdown lists Numerous options to view, tabulate, and export CEE 5460David Rosenberg 23

Water demands by Demand Site CEE 5460David Rosenberg 24

WEAP Scenario Explorer Define and manage scenarios from the Data module Enter input data here too CEE 5460David Rosenberg 25

WEAP Scenario Explorer (cont.) Use Scenario Explorer icon to open scenario dashboard CEE 5460David Rosenberg 26

Conclusions WEAP can simulate priority-based water allocations Drag and drop interface to draw system schematic Enter variety of data for river, demand site, reservoir, return flow, and other system components View results in numerous formats Use scenario tool to test and view results for changes in model inputs Apply principles in Thursday’s lab exercise for the Weber Basin, Utah CEE 5460David Rosenberg 27