Economic Importance of Different Sealant Materials for Seepage Loss Control of Water Harvesting Pond under Irrigated Condition

Abstract

This study was carried out in order to identify low-cost and efficient sealant materials for water harvesting ponds. An extensive cost comparison study of sealant materials was conducted, taking into account seepage reduction and farm income loss. Four seepage control materials were evaluated in terms of their financial cost. The cost analysis was conducted in terms of farm income loss when three crops' water productivity (kg/m³) were considered potato, onion, and wheat; 1.13, 10.57 and 5.27 kg/m³ of wheat, potato and onion, respectively. The cost of sealant materials includes the capital cost of material and labor for purchase and application in water harvesting ponds. The cost-benefit analysis result of sealant materials (compaction, mortar, ash, and bentonite) were compared for the next ten years and gave a significant farm income. For this study a water harvesting pond having a volume of 4,792 m³ was considered to cultivate (wheat, potato, or onion) for one cropping season under irrigated conditions. A farm pond managed by; bentonite and Ash can save 23 % and 43 % than control treatment respectively. The saved irrigation water used to cultivate wheat, potato, and onion crops in 1 ha of land for one cropping season can bring an additional farm income of about 317,632 ETB with Bentonite and 226,798 ETB with Ash when compared to the compaction alone treatment (control). Analysis of cost and income over ten years productivity period showed that, the maximum cost of sealant materials to cover a volume of 4,709.69 m³ requires at least four years investment period to achieve the breakeven point (189,600 ETB), that corresponds to the point at which the cost of sealant materials equals the resulting farm benefits. Therefore, investing in sealant materials for control seepage lose from water harvesting ponds will give a profit of their investment after four and above project years.

Keywords: Cost Effective, Sealant Material, Water harvesting, Water loss