The Evaluation of the Rainfall-Runoff Effects to the Variation of Hydrology of Migina Catchment in Rwanda
The basic implementation of agricultural development and crop production increase in marshland of Migina catchment (ca: 257.4 km2) requires strong and technical analysis of the effect and change of hydro-meteorological aspects from rainfall-runoff parameters. This paper focuses on the effect of rainfall and runoff in Migina catchment and describes in details the study of rainfall and runoff availability in Migina catchment. The study was limited to the analysis of hydrological aspects of the catchment including the water balance. Specifically the paper specifies the seasonally hydrologic variation, evaluates the performance of the catchment area on the environmental activities and studies the rainfall-runoff effect on the variation of hydrology of the catchment. The required data were collected from the thirteen (13) meteorological stations located in the catchment (Meteo-Rwanda, 2008) and historical data from other institutions like: Center of GIS of the University of Rwanda, Ministry of Agriculture (MINAGRI), Ministry of Environment and Ministry of Infrastructure (MININFRA). Arithmetic mean method was used for the determination of annual rainfall. The annual evapotranspiration has been calculated through evaporation pan at Rwasave and Gisunzu stations for data recorded from 2010 to 2012. Annual discharge was determined using rating curve method at Munyazi, Mukura and Cyihene rivers for discharge data of 2010 to 2012. Simple formulas were used in calculations, and the adjusted crop coefficient was found to be 0.66, and the annual rainfall varies with respect to weather or Climate events like Temperature increase.
This can have major effects on society, economy and the environment and was found to be 1569.5mm. The results show that the Migina catchment land use is dominated by the agricultural at 70% (rice, maize and beans) and livestock activities. It is recommended to contribute to the amelioration of Agricultural activities to increase the Rwandan primary sector production and sensitize the population on Rwanda seasonal changes and good governmental catchment protection plan.
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