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 pla nt 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 di scharge were reduced by 28 to 97% and 22 to 96%, respectively using CVB wit h negligible soil loss. The resultant increase in soil moisture storage inc reased 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 (moistu re storage-plant transpiration-crop yield), and a personal computer-based g eographic information system (GIS) for designing optimum CVB spacing. Input s needed for these models are soil hydraulic parameters, daily meteorologic al data, and crop characteristics. Simulated outputs were validated with th e 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% reduct ion in runoff resulted in better moisture regime and crop yield improvement by 70% over control. (C) 1999 Elsevier Science B.V. All rights reserved.