Merced Irrigation District optimizes operations during California's "whiplash" of wet and dry years

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Real-time forecasting predicts short-term reservoir inflows and supports decisions

The fully automated MIDH2O decision-support model pulls quality-controlled data from its water information system, computes and every six hours reports on past, current and estimated future conditions that may impact operations.

Successful deployment of the MIDH2O Hydrologic and Hydraulic Optimization Model was a collaboration among environmental software developer KISTERS, water resource modeling firm Resource Management Associates (RMA), and consulting engineer firm Dewberry.

The District operates reservoirs for irrigation, flood control, water supply and hydropower generation as well as environmental stewardship and public recreation. Ranging from western slopes of the Central Sierra Nevada mountain range to the San Joaquin River, the District has a total drainage area of 1266 square miles. Furthermore, elevation ranges from 52 ft to 13,090 ft above sea level.

With increasing inconsistencies in precipitation and snowmelt, MID wanted to predict short-term and season reservoir inflows and take appropriate action.

Every six hours, a generated report covers precipitation and snowpack, status of reservoirs, diversion demand, and forecasted flow for key downstream locations. The appendix includes the current San Joaquin Valley Report from the National Weather Service; historical plots for San Joaquin Valley basin precipitation, California snow water content, and Lake McClure storage; as well as a Merced Watershed Report featuring historical snow water equivalent (SWE) time series for Ostrander and Tenaya lakes during years identified as critical as well as current conditions and precipitation at Lake McClure.

Data sources include flow data from a network of stream gauges and SCADA data from the District itself. Information from the California Department of Water Resources, California Data Exchange Center (CDEC) is imported into the water information system developed by KISTERS (WISKI).

Automated and manual quality assurance tasks are performed before data are passed through to a sequence of Hydrologic Engineering Center (HEC) models: Hydrologic Modeling System (HMS), Reservoir System Simulation (ResSim) and River Analysis System (RAS). The first model output becomes input for the subsequent model. After all models have run, resulting information is distributed back to WISKI and the report is generated.

The District uses two weeks of observed data, in order to simulate one week into the future.

From observed stream flow data and soil moisture deficit computations, HMS provides reservoir inflow and elevation releases, supplemental release and irrigation demand data to the ResSim model. Scripts and KISTERS’ web interoperability services ensure secure transfer of information and in a format appropriate for the decision-support system.

The HEC model has an interactive GIS-based interface. However a “headless” implementation may be integrated with other interfaces. The District uses the HEC Decision Storage System (DSS) interface, custom configured with the web services, to quickly and easily plot or visualize and tabulate data with the click of a few icons.

HEC – Real Time Simulation (RTS) is the free public version of the U.S. Army Corps of Engineers’ Corps Water Management System Control and Visualization Interface (CAVI). As such, all HEC models including those implemented in the MIDH2O optimization model are free to the public. WISKI integration is a standard feature available in HEC-RTS version 3.1.

Dewberry will also develop a long-term planning model to support new and refined delivery strategies for the district.

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