Comprehensive impact assessment of watershed development projects in lower Bhavani catchments of Tamil Nadu

Abstract

Watershed development projects are generally evaluated to assess their social, economic and ecological benefits. The evaluation of 17 sub-watersheds implemented under River Valley Project in lower Bhavani catchments during 1996-2000 on hydrology, bio-physical and socio-economic aspects has been carried out. Participatory evaluation, random sampling technique and detailed data on different socio-economic aspects were adopted to assess the comprehensive impact of watershed interventions. Appropriate scientific tools and techniques were employed to evaluate the water harvesting structures, silt detention structures and soil conservation structures in the watershed. The study revealed that runoff and soil loss reduction was ranges from 4 to 18% and from 4 to 5 Mg ha-1 yr-1, respectively. The water table has increased in the range of 0.3 to 0.5 m in the influence zone of percolation ponds. The value of net present value was more than Rs. 107 crore with 1.69 BCR and 63.7% internal rate of return. The criteria of economic evaluation indicate that such projects are highly economically sound to be taken on priority for sustainable agricultural growth in the region. The evaluation concluded that such projects should be carried out with more concentration and coordination guided by technological requirement.