2nd International Conference on Rain Water Cistern Systems
St Thomas, Virgin Islands - June, 1984

Section C: Some Cistern Cystems

Paper C.3

A Rainwater Catchment System For Agricultural Water Supply

James E. Rakocy, John A. Hargreaves, Ayyappan Nair
College of the Virgin Islands, USA

Abstract

A rainwater catchment system was established to demonstrate the Feasibility of using rainwater catchment to supply high quality water for agricultural use. The catchment consists of a nylon-reinforced polyvinyl Chloride (PVC) tarpaulin that is 24 mils thick, 60.8 m long and 30.4 m wide. The tarpaulin is situated on leveled ground lengthwise along a 3% slope. The edge of the lower quarter of the tarpaulin covers an earthen dike with a maximum height of 0.6 m. All of the edges are buried in the ground to secure the tarpaulin.

Rainwater flows off the tarpaulin by gravity through two outlets at the base of the dike and collects in a 12.5-m3 sump where it is then pumped to a 65-m3 above-ground storage tank equipped with a floating cover to prevent evaporative loss. When the storage tank is full, the sump and catchment Provide 75 m3 of additional storage capacity.

The catchment system, including the storage tank, cost $19,800 to construct in 1983. Based on mean rainfall of 1120 mm, the system should Collect 1,673 m3 of rainwater annually, valued at $13,260. The payback period for the system will be approximately 1.5 years. The tarpaulin, which cost $9,600, has an 8-year guarantee.

PDF of full document available to members (15pp, 290kb)