EVALUATION OF THE PERFORMANCE OF ROOF WATER HARVESTING SYSTEMS (THE CASE OF BEREHET WOREDA, NORTH SHOWA ZONE, ETHIOPIA)

Abstract

Evaluation of the performance of existing domestic roof water harvesting schemes in terms of social, economical and health aspects enables to measure the appropriateness of the technology and improve the level of water supply sanitation and hygiene coverage.In Berehet Woreda, Recent ly realizing the multidimensional benefit s of roof water harvesting for various stakeholder have made efforts on the distribut ion and ut ilizat ion of the RWH systems to improve safe water supply coverage of the Woreda. The study was conducted on all of the domestic roof water harvesting schemes implemented by water, sanitation and hygiene in the woreda. Site observation, interviews, questionnaires and analytical formulas were employed to probe more information at the grass root level. The commonly adopted roof water harvesting system in Berehet Woreda is from roof catchments, thus the rainwater-harvesting structures are not efficient to satisfy user’s need due to inadequate capacity of structures and shortage of rainfall to be harvested. The gutters adopted also supply to RWH structures only from one side of the roof. Gutters also faced with narrow cross-sectional area and gentle slope resulted in water wastage before reaching the storage tank. Results showed that the water demand were higher than harvested roof water. Moreover, the assessment revealed there are many problems of domestic roof water harvesting in terms of physical water quality, and other performance parameters. The major water quality problems were entry of dust particles and bird dropping which accounts to 50% of the schemes. Demeko plastic tanker and Wesile roof water harvesting schemes has showed a good runoff harvested and system efficiency(greter than 85%) Most of the schemes have showed a benefit cost ratio greater than one which implied roof water harvesting schemes gave good benefit (except for Wesile, Begu and Wansie which have B-C ratio less than 1). In general,the study reveals that lack of awareness and policy about rain water harvesting, poor system operation and maintenance lack of regular monitoring, low storage capacity and poor quality of schemes are among the main findings on the promotion and implementation of the technology.