Deterministic watershed model for evaluating the effects of surface mining on hydrology

Abstract

Natural hydrologic factors help limit the extent to which land disturbed by man's activities, such as surface mining, can be returned to a productive state. In the western United States the available moisture is frequently the most important factor. This factor causes soil moisture to be low and ground water contributions to runoff to be miniscule. A deterministic watershed model is developed by which estimates of soil moisture, peak flows, runoff volumes and erosion can be obtained. With this information, decisions regarding recontouring and revegetation can be made with greater confidence. The watershed model is designed to readily accept changes in topography, which allows proposed surface configurations to be evaluated without physically recontouring. The model is composed of five components: evapotranspiration, interception, soil moisture movement (infiltration and evaporation), surface runoff routing, and sedimentation. On a 2.2 ha watershed on Black Mesa, Arizona, actual infiltration and runoff rates were compared to simulated infiltration and runoff rates. The results were very good.