A Simple Model for Estimating Water Balance and Salinity of Reservoirs and Outflow
Date
2010-08-23Metadata
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Reservoir storage reduces fluctuation in streamflow salinity, yet increases outflow salinity
because of water evaporation. These processes are highly relevant to developing water
management strategy, yet the method to predict outflow salinity has not been adequately
examined. The study reported here examined the water and salt balance in a reservoir using a
two-layer model. This model assumes that inflow blends with the storage, but the water
evaporation takes place from the surface layer, and the percolation losses from the subsurface.
The thickness of the first layer where salinity increases with evaporation was estimated through
calibration against the measured outflow salinity. The changes in salinity were computed using a
moving average method on a monthly time step. This model was applied first to Red Bluff
Reservoir of the Middle Pecos River, then to Elephant Butte, Amistad, and Falcon along the Rio
Grande. The outflow salinity projected by the model was in good agreement with the measured,
except under a few circumstances where mixing of inflow and reservoir storage was suspected to
be incomplete. The accuracy of prediction can be improved by improving the estimate of initial
salinity of reservoir storage, which is currently taken as being equal to outflow salinity at the onset
of the simulation.
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Citation
Miyamoto, S; Yuan, F; Anand, Shilpa (2010). A Simple Model for Estimating Water Balance and Salinity of Reservoirs and Outflow. Texas Water Resources Institute. Available electronically from https : / /hdl .handle .net /1969 .1 /92273.