A qualitative assessment of a hydrometric network for monitoring an integrated hydropower and water supply system

Abstract

Timely access to accurate hydro-meteorological information is required for an efficient management of any water project. It is for this reason that water projects have hydro metric networks incorporated in their design. The Thika Dam–Ng’ethu Water Treatment Plant System is an integrated water supply and hydro power project forming part of the water works of the City of Nairobi. It is an inter-basin water collection and transfer system comprising a reservoir and tunnels interlinking four rivers that serve simultaneously as water sources and transmission channels. The hydro metric installations for monitoring the system include water level and flow measuring structures. The main objective of this study was to assess the network for fitness against the stated project objectives and expectations of integrated water resources management (IWRM). The analysis was performed based on operation rules and field observations. The results show that five out of eleven (45%) of the installed flow monitoring stations were in an unsatisfactory condition: three were non-operational for want of maintenance while two did not seem to conform to theoretical principles of flow measurement. Further, it was found that seven out of fifteen (47%) inflow/outflow elements of the system were left out of the monitoring scheme. It was concluded that lack of maintenance and shortcomings in design make the entire network ineffectual and incapable of supporting management based on IWRM. It is recommended that the network be upgraded and installation of an intelligent water allocation and management system be considered.