| INFLOW Lake Idagon receives the flow of the Idagon after the river's flow has been increased by the ground water discharge at Big Springs. This flow averages around 13 MAF/year. The month by month variations in the inflow are illustrated in the chart. The inflow is rather constant over the 12 months in a year because the ground water discharge at Big Springs is relatively constant from one month to another. The slight decline in the May and June inflow arises from the upstream diversions to irrigators in Area 1. The slight increase in September and October arises from runoff from Area 1. OUTFLOW The reservoir is used to store water for summer irrigation. The chart shows that 30 MAF/year is released during the irrigation season. Since the irrigation season is one-third of the year, the total release during this season is 10 MAF. This is the amount typically needed to irrigate the one million acres in Area 3. |
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| During the other 8 months of the year, the outflow is subject
to a minimum flow requirement. In this example, the minimum flow is set
to zero. The chart shows that there would be no releases in the fall months
as the reservoir is refilled to prepare for the following year. There are
some releases in Jan, Feb and March, however. These releases indicate that
there is more than enough water flowing through Lake Idagon to meet the
irrigation needs in Area 3. Since there is usually ample water for Area
3, the model will always operate Lake Idagon to deliver the full amount
needed in Area 3. Lake Idagon Dimensions The reservoir storage capacity is 16 MAF which amounts to about 1.3 years of average annual flow. The lake's surface area is 80,000 acres when the lake is full. The height of water at the dam is 300 feet when the lake is full. The net evaporation rate in this region is 2 feet/year, so the evaporation losses amount to 160,000 AF/yr or somewhat more than 1% of the annual flow. The hydro-electric power production from the Lake Idagon dam depends on the flow through the turbines and the height of water at the dam. Most of the power is generated in the summer irrigation season. When experimenting with the model, you may open the graph "In_and_Out_Flow_2_Lake_Idagon" to see if the simulated flows are similar to the illustration shown above. And to see if the policy of serving 100% of the irrigators in Area 3 is feasible, you might open the graph "Fullness_of_Eastern_Reservoirs" and check if the reservoir is refilled each year. |
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