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Page A-3 <br /> TASK 2. Drought Analysis <br /> Defining the design drought as quickly as possible is critical to the project so that we can define 1) <br /> the drought demand, 2)the drought supply, and 3)the drought"gap" (the difference between drought <br /> demand and supply).The drought gap is what must be achieved through additional supply alternatives <br /> to provide Decatur drought supply assurance.The "10-month drought" was used as a design basis in <br /> RFP. However, a different drought duration can be considered if such a drought can be quickly and <br /> decisively determined to be more critical to Lake Decatur. <br /> Subtasks: <br /> 1. Review drought records; consult with Vern Knapp,and define the critical drought <br /> 2. Generate lake inflow,daily precipitation,and evaporation rate time series for the critical drought,or the <br /> 10-month drought <br /> 3. Develop new stage-volume-area relationship for Lake Decatur <br /> 4. Determine Lake Decatur drought yield <br /> Products and Results: <br /> • Assessment of drought relationship:flow at Monticello and inflow to Lake Decatur <br /> • 10-month drought conditions defined: <br /> o Sangamon inflow time series <br /> o Friends Creek inflow time series <br /> o Big/Long Creek inflow time series <br /> o Lake evaporation rate time series <br /> o Daily precipitation time series <br /> • Full time series hydrologic data sets defining 10-month drought, ready for inclusion in the Systems <br /> Model (Task 6) <br /> • Comparison of 10-month drought inputs/outputs with ISWS water budget model <br />