Determining transit losses for water deliveries by use of stream-aquifer models

Hydrologic modeling of stream-aquifer interaction commonly has been used to quantify transit losses associated with water deliveries, such as those from reservoir storage. This technique requires estimation of model parameters that include stage-discharge relations, channel-storage coefficient, aquifer transmissivity, and aquifer-storage coefficient. Because data to reliably estimate or calibrate these parameters often may be lacking, it is beneficial to know how parameter errors will affect the determination of transit losses. In addition, transit loss varies considerably depending on the duration of the recovery period (time allowed for water to leave channel and bank storage) used in the calculation of hydrograph volume. Sensitivity analysis indicates that recovery period typically is more important to the determination of total transit loss than are errors in the estimated values of channel and aquifer characteristics.