MODELING THE EFFECTS OF TERRACING ON WATER SUPPLIES IN THE MEDICINE CREEK

摘要

Terraces can be used to conserve moisture and reduce erosion in the watershed. Conservation terraces are usually constructed with a ridge, and a wide, flat channel in which surface runoff from the contributing slope is stored in the terrace channel and slowly infiltrated into the soil under the channel. Assessing the impact of terraces on water supplies in a watershed is critical for accurate water balance calculations. It must include estimates of the rate of infiltration of water in the terrace channel and on the contributing slope portion of the inter-terrace area. Agricultural management practices used on terraced land must be determined to adequately represent the effect of terraces. This study describes our initial modeling efforts to determine the impact of terrace systems on the agricultural hydrology. The POTYLDR, a physically based, continuous time scale, model was used for predicting the effects of terraces on water balance parameters, in particular, percolation, runoff, and evapotranspiration. A case study for Medicine Creek watershed in Nebraska is given. The simulations were done using 50 years of historical weather data for two important crops grown under a silt loam soil: continuous corn and wheat-fallow rotation.