Background: Previously in Ethiopia reliable climatic and hydro-meteorological data are not available and not maintained properly but the long-term database is needed for the assessment and planning of resource dynamics. To minimize the lack of reliable database, the Soil Conservation Research Program (SCRP) established observatory model watersheds since 1981. Andit tid watershed is one of these watersheds established for monitoring the long term trends of climatic, hydrologic, sediment loss and crop production system as a representative site for central high land parts of Ethiopia at 1982. This research paper compiles the analysis of spatial and temporal distribution of the rain fall; trends of run off and sediment loss and their relation and the influence of position of terraces on crop production.
Result: From the rainfall trend analysis result the rainfall of the watershed has insignificant spatial (PCI=1.07) and temporal (CV=16.7%) variation. The precipitation coefficient (%) value of the watershed indicates that July and August have big rain with high concentration; September have big rain with moderate concentration and these three months could contribute more than one twelfth of total rainfall amount. The highest runoff and sediment yield were observed in August and July, while sediment concentration was generally high in June. All crops delivered statistically highest yield (P<0.05) immediately above bunds (zone a).
Conclusion: The rainfall spatial and temporal distribution trend analysis results conclude that the watershed is not vulnerable for future drought. The highest sediment concentration occurred in June was because of the reason that the lands are plowed and prepared for crop growth; following this small rainfall can carry much soil and can contribute for high suspended sediment concentration. The highest grain yield obtained from above bunds is because of the trapped and accumulated soil and plant nutrient could contribute for better performance and production of crops. To obtain better crop yield; to minimize sediment loss and improve the stream flow it is better to maintain the existed soil and water conservation structures and apply the new interventions.