Performance evaluation and impact assessment of a small water-harvesting structure in the Shiwalik foothills of northern India

Abstract

AbstractConstruction of small water-harvesting structures (WHS) across seasonal streams, in the vicinity of cultivated areas, has proved to be a viable technique of water harvesting in the Shiwalik foothills of northern India. This paper reports on the performance and impact of one such structure in this area. Sufficient rainwater was available for harvesting because 86 ± 5.4% of monsoon rainstorms were runoff producing, resulting in collection of 29 ± 5% of the total monsoon rainfall. Out of this harvested water around 62% was available for irrigation at the start of the Rabi season (i.e., the dry season starting around 1 November). With time the water losses from the WHS declined from 66% in the first year of construction (1985) to 18% in 1996, because of sealing of soil pores from siltation of the reservoir bed. The life of the WHS was estimated to be 65 years at the observed average siltation rate of 47 Mg/ha/year. After construction of the WHS, the area under cultivation increased from 17 ha to 20 ha and the cropping intensity by 170 to 200%. The Rabi crop yields were approximately doubled. Assured availability of water and fodder increased milk production by 103%. Additional annual income of Rs. 7,015 per year was generated through fish culture. A rise in the groundwater level and higher growth of vegetation around the WHS were also observed. On the basis of increased crop production alone, the WHS proved to be an economically viable venture resulting in a benefit:cost ratio of greater than one. Socioeconomic considerations in the management of the WHS were also studied and showed that community involvement was essential to the success of this project.