The document summarizes a study of rainwater harvesting practices in Otukpa community, Benue State, Nigeria. Every household practices some form of rainwater harvesting from rooftops to supplement limited water sources. However, existing systems harvest a low proportion of rainfall and storage is prone to contamination. The researchers designed an improved 450,000 liter elevated rainwater harvesting system using local materials to sustainably provide water for about 250 people during dry months at a cost of 3 million naira. This is more affordable than other water sources and could help address the community's water needs if implemented.

1. RAINWATER HARVESTING PRACTICES AND DESIGN OF RAINWATER HARVESTING SYSTEM FOR OTUKPA COMMUNITY, BENUE STATE, NIGERIA 1OnojaS.B;2Ocheja I.E and 3Isikwue M.O 1,3 Department of Agricultural and Environmental Engineering, University of Agriculture, Makurdi2Lower Benue River Basin Development Authority, Makurdisamomyonoja@yahoo.com

2. IntoductionSources of water for general human utilization include surface water, groundwater and lately rainwater harvestingRainwater harvesting is the interception of precipitation for human use close to where it falls before it sinks into the ground (Thomas, 2000).Domestic Rainwater harvesting (DRWH), a sub-set of rainwater harvesting is usually manifest as roof run-off harvesting because ground run-off is too dirty for safe human consumption (Thomas, 2000)DRWH is motivated by exhaustion of surface supplies and the falling levels of aquifers In Otukpa community, both surface water supplies and groundwater are not availableEvery household in the community practices rainwater harvesting

3. ObjectivesTo study the rainwater harvesting practices in Otukpa communityTo design a rainwater harvesting system that utilizes similar material resourcesMethodologyNumber of villages in otukpa community were identified and total population of the community was estimated for 2015, bearing in mind MDG for water supplyReconnaissance survey was carried out to identify the rainwater practices in the communityLimited laboratory analysis were carried out to determine the quality of harvested rainwater in storageStandard procedures were followed to design a rainwater harvesting system using the same local materials

4. ResultsEvery building in the community had a roof-top rainwater harvesting system in one form or the other, using corrugated iron sheets (Plates 1-3)The harvesting was done using gutters and downpipes (made of local wood, bamboo, folded galvanized iron sheets or PVC pipes), and led it to storage containers that range from simple pots to large ferrocement tanks that are either on the surface or underground or partly on the surface and partly underground.Efforts were made by the community to cover the storage reservoirs in different ways. These covers were however not good enough to protect against contamination from the environment The rainwater harvesting system of the community can be classified as partial as not all the rain that fell on the whole surface area of the rooftops were harvested by the available structures. The proportion of what was harvested to potential yield ranged from 5.06% to 23.05%.Results of the bacteriological study indicate that some of the storage points were contaminated while the samples collected directly from rainfall without passing through the rooftops and storage were consistently free from bacteriological presence.Based on the relationship W = 0.8 x A x R, an elevated rainwater harvesting system including harvesting surface and storage was designed for 450,000 litres to cater for about 250 people to last the critical months of March, April and May of the yearThe cost of the developing this system was found to be about N 3,000,000.00 (Three million naira only). This is very reasonable when compared with the sum of about N9,000,000.00 (Nine million naira only), the cost of drilling a motorized borehole in a basement formation and about N10,000,000.00 ( Ten million naira only), the cost of drilling a motorized borehole in a sedimentary formation

5. Rainwater harvesting practicesPlate 1Plate 2Plate 3

6. Designed elevated rainwater harvesting systemFig 1: Pictorial view of the designed elevated rainwater harvesting system

7. PlanFig 2: Plan of the rainwater harvesting system

8. SectionsFig 3:Sections of the elevated rainwater harvesting system

9. ConclusionsRooftop rainwater harvesting is a practice of every household in Otukpa communityThis supply is however unable to sustain them through the dry period of the yearAn elevated rainwater harvesting system with capacity of 450,000 litres, for about 250 people with a unit cost of about N 3,000,000.00 was designed for OtukpaGovernments, non-governmental Organisations (NGOs), International and Intergovernmental Organisations and Agencies are hereby called upon to fund these projects as a sustainable development for the community