Study of major causes of decresed flow to Nyumba ya Mungu reservoir.

This study was carried out aiming at investigating the major decreased flows to Nyumba ya Mungu reservoir based mainly on the irrigation demand upstream of the reservoir. The amount of water that could be flowing into the reservoir without irrigation diversion was estimated using Linear Perturbation model. Linear trend analysis was done by student's t-test model. Irrigation water requirement of the existing crops in the area was estimated using CROPWAT model. The trend of increased crops pattern in the catchment was calculated and observed that it will take 5 years for 3% increase of acreage. Catchrnent Iddl is the one which does not show a significant decrease, We can plan for the future irrigation. Comparison was made between the entire upstream irrigation water demand for up to 2022 year of irrigation. Abstraction was taking place at this period of time. At the end of this time, the demand was less than the estimated total inflow to Nyumba ya Mungu reservoir. The reservoir alone was receiving minimum flow from September, October and November, for the annual mean discharge. If measures will not be taken to control the situation for increasing crops pattern acreage compromise further with power generation downstream should be met. Therefore implementation of the recommendations proposed, which are promoting use of ground water for irrigation and construction of small dams to store water during raining season is plan for the future important in alleviating the probable water conflicts in Pangani River.