Effects of water abstraction on Burguret flows, Kenya

Abstract

The water flows of Burguret River, located on the slopes of Mt. Kenya in Burguret catchment, were assessed along the profile to determine the water abstraction status. Downstream water users are faced with challenges of low river flows or no flows during the dry season which leads to a lot of conflicts arising due to the water allocation in these areas. Methods used for assessment of water abstraction included field survey visit to ascertain abstraction points details, the water users’ interviews in which convenience and random sampling methods were used. Flow duration curves, fdcs were developed from the observed river flow discharge to ascertain the water supply of Burguret River and finally Mike Hydro model was used to predict optimal flows for water allocation within Burguret catchment. Majority of upstream abstractions used gravity pipes and abstracted large amounts, 14,502 m-3day (67%) of water compared to downstream users who mostly used portable pumps and abstracted 2,696 m-3day (16%). The unofficial abstractions took place when abstractors exceed the allocated amounts. Burguret River can supply 21,953 m-3day and 10,800 m-3day during normal flows from the Naturalized and Observed fdcs respectively. The Nash Sutcliffe Efficiency, R2 was found to be 0.71 and 0.61 during calibration and validation periods respectively. This showed that the model performed well and was used to adequately simulate scenarios which yielded results after optimal allocation and the river supply stood at 15,984 m-3day which was good enough to ensure downstream and environmental flows are restored.