ESTIMATING TRANSMISSION LOSSES IN AN ARID REGION

Flow volumes in ephemeral streams in and regions decrease significantl y in magnitude downstream. These transmission losses are important not only in their obvious effect on flow reduction, but also as a source of groundwater recharge to underlying alluvial aquifers. A distributed model for estimation of transmission losses described herein represen ts an attempt to develop a procedure for practical applications and is shown to produce reasonable estimates. The model is simplified and re quires a minimum of observed data for calibration. Based on available information obtained from Landsat Thematic Mapper False Colour Composi tes of bands 2, 3 and 4, published sources and regression analyses, th e model can be used to estimate transmission losses from ungauged chan nels in arid regions. Transmission loss data are compared with some pr eviously published data, and despite some scatter are generally consis tent with them.