Losses of flood water from alluvial channels

Abstract

Transmission losses were estimated through a mass balance approach that accounted for the influence of tributary runoff contribution and evaporation loss in a typical arid catchment area of Tabalah basin in southwestern Saudi Arabia. Runoff variability played a dominant role in magnitude of transmission loss. Runoff events were classified into two groups. The first group consisted of 16 events, where the magnitudes of inflow ranged from 0.078 to 2.95 × 106 m3 and outflow from 0 to 1.97 x 106 m3. The transmission losses ranged from a minimum of 0.10 x 106 m3 to a maximum of 1.186 X 106 m3. The second group consisted of 11 events, where the magnitudes of inflow ranged between 0 and 1.26 x 106 m3 and outflow from 0.003 to 2.96 × 106 m3. The tributary runoff ranged from 0.1143 to 2.304 x 106 m3, with a consequent loss of 0.05–0.96 × 106 m3. Regression equations related the magnitude of transmission loss to the controlling parameters such as upstream inflow, channel flow width, and antecedent soil conditions. Other equations related upstream inflow to downstream outflow and provided a useful tool for estimating the transmission losses and flood volumes for channels having similar hydrological and morphological characteristics.