Ecological Services of Irrigation Tanks and Canals in the Management of Groundwater and Welfare Implications in Hard Rock Areas of Karnataka

Abstract

"Ecological services of irrigation tanks and canals in groundwater recharge and welfare Implications in Hard Rock Areas of Tiptur, India are studied. Farmers jointly mobilized Rs. One lakh to improve recharge by constructing a tank. Primary data from 35 farmers each from (i) farmers owning irrigation wells in system irrigation tank (GWTI), (ii) farmers owning irrigation wells in canal irrigation (GWCI), and (iii) farmers owning irrigation wells in areas not served by tanks and canals are farmers under sole irrigation (GWSI). About 33% are small farmers (< 5 acres), 50% medium (5-10 acres) and 17% large farmers (>10). More than 70 percent of cropped area is under Coconut /Arecanut, the coping mechanism due to groundwater scarcity. The proportion of well failure in GWSI was 45% followed by GWTI (20%) and GWCI (19%). Externality cost was Rs. 957 in GWTI, Rs 863 in GWCI, and Rs. 3226 in GWSI. Net return per acre, per functioning well and per rupee of irrigation water were Rs. 12210, Rs. 96979, Rs. 18 in GWTI, Rs. 10912, Rs. 77190, Rs. 21 in GWCI, and Rs. 9292, Rs. 57665, Rs. 6 in GWSI. Technology and institutions played a significant role in groundwater recharge. Farmers pooled their resources to invest in an irrigation tank to impound rainwater for recharge. Thus the real cost of groundwater fell from Rs. 32 per acre inch in 1986 to Rs. 15 per acre inch (2008) due to tank. Cost of groundwater (net return) per acre inch in GWTI are Rs. 34 (Rs. 365), in GWCI Rs. 44.46 (Rs. 449) and GWSI 113 (Rs. 547). Surface water recharge from tank reduced economic cost of groundwater and improved net farm income to Rs. 10.73 per acre inch for GWTI, Rs. 10.1 per acre inch for GWCI, Rs. 4.84 per acre inch for GWSI."