Submitted to: Proceedings International Water Research Conference United Arab Emirates
Publication Type: Proceedings
Publication Acceptance Date: 7/12/2000
Publication Date: N/A
Interpretive Summary: A major problem in water-deficient, or arid, areas is to account for the recharge of ground-water from infiltration in ephemeral stream channels. These infiltration losses to the channel bed and banks are called transmission losses. The form and structure (geomorphic features) of ephemeral stream channels are related to the rates and amounts of streamflow experienced by them following infrequent rainfall events. Mathematical models have been developed and implemented on personal computers to calculate runoff, streamflow, and transmission losses in arid areas. We combined the approaches of using channel geomorphic features and computer simulation modeling to estimate transmission losses and recharge to ground-water in arid areas. The resulting estimates of streamflow, transmission losses, and ground-water recharge are improvements over previously available estimates. Because of this research, better estimates sof water resources will be available in arid areas.
Technical Abstract: In water-deficient areas, recharge to the ground-water reservoir by infiltration of streamflow (transmission losses) along ephemeral-stream channels is estimated as an unmeasured residual of a water budget or balance. This value is poorly constrained and alternative approaches are needed. By combining channel-morphology techniques inferred from downstream changes in streamflow with a simple, distributed simulation model, estimates of ground-water recharge from transmission losses are made from direct measurements of watershed variables. Inputs to the distributed transmission-loss model may be determined geomorphically using estimates of outflow from selected basins or by estimating downstream changes in discharge as related to channel geometry. Recharge also can be estimated by routing discharge from an index, or representative, storm downstream, accounting for channel losses, and adjusting for inter-channel recharge during low-frequency precipitation events.