Impact of River Valley Project in South Pennaiyar Catchment of Tamil Nadu, India

Aims: The impact of comprehensive interventions in erosion control, improving water availability, development of agro-forestry, sustainable management of natural resources, enhancement of agricultural productivity and socio-economic aspects of the farmers was studied. Assessment of effectiveness of watershed development programme, identification of major issues and lacunae in project implementation across the watersheds also has been studied.

Study Design: Multistage stratified sampling technique was adopted in selection of study watersheds (secondary sampling unit-SSU), farmers (primary sampling units-PSU) and structures for detailed surveys.

Place and Duration of the Study: The study was conducted in South Pennaiyar catchement in Dharmapuri, Salem, Villupuram, Vellore, Thiruvannamalai districts of Tamil Nadu. The study was conducted for three years period during 2012-14.

Methodology: Sample based before and after project evaluation approach, employing budgeting techniques. By employing stratified random sampling method 15 study watersheds (SWS) were selected and the benchmark data collected by the project implementing agency (PIA) at the time of project planning were used for the study. All the collected data were analyzed through budgeting techniques or appropriate statistics. The cash flow table was developed which were further aggregated along with other miscellaneous costs of the project to generate total cost and benefit stream of the project.

Results: The evaluation study reveals that runoff reduction of 8 to 10 percent and soil loss varies in the range of 1.1 to 1.9 t ha-1yr-1 after the project compare to 4.1 to 4.9 t ha-1yr-1 before the project shows the reduction of 3 t ha-1yr-1. Gully control structures made their impacts in terms of arresting silts at the rate of about 10.1 cum yr-1 in one watershed and stabilized the gullies. Increased water table in the range of 0.32 and 0.93 m with increased duration of water availability in wells for more than 9 months and increased recuperation rate (1.8 to 6.5 per cent) were observed. An additional surface storage capacity of 26.4 ha - m per watershed was created due to watershed interventions. The Net Present value of the project is about Rs. 52,238 lakhs without considering intangible benefits. The economic soundness of the project is also amply indicated by BCR (1.65:1) and IRR (53%) and the whole investment made in the project can be recovered within seven years. The NPV of the project further improved by inclusion of monetary value of the nutrient due to reduced soil erosion. The value of NPV was more than Rs. 63,968 Lakhs with 1.72 BCR and 65.5 % IRR.

Conclusion: River valley project in South Pennaiyar catchment of Tamil Nadu is economically viable and recommended to be taken on priority for sustainable agricultural growth in the river / reservoir catchments.