Study on the performance of contour vegetative barriers in an arid region using numerical models

The purpose of the study was to evaluate and derive the optimum spacing of contour vegetative barriers (CVB) of locally adapted, drought resistant plant species as soil and water conservation measures for rainfed crop-fields in an arid region. Adapted perennial grasses performed the best and formed effective barriers against soil erosion. Runoff volume and specific peak discharge were reduced by 28 to 97% and 22 to 96%, respectively using CVB with negligible soil loss. The resultant increase in soil moisture storage increased pearl millet crop yield by 35%. Hydrologic processes with respect to crop response for digitally generated CVB layouts were simulated using the distributed numerical models SWAMREG (rainfall-runoff) and SWACROP (moisture storage-plant transpiration-crop yield), and a personal computer-based geographic information system (GIS) for designing optimum CVB spacing. Inputs needed for these models are soil hydraulic parameters, daily meteorological data, and crop characteristics. Simulated outputs were validated with the observed runoff soil moisture storage and pearl millet yield data. At an optimum simulated vertical spacing of CVB between 0.5 and 0.6 m, 24% reduction in runoff resulted in better moisture regime and crop yield improvement by 70% over control. (C) 1999 Elsevier Science B.V. All rights reserved.