Programme Poster session 3 abstract 624
Temporal Flow Variations: A Challenge for Surface Water Management in
Tanzania
Author(s): Patrick Valimba
Patrick VALIMBA
Department of Water Resources Engineering,
Faculty of Civil Engineering and the Built Environment, College of Engineering and Technology, University of Dar Es
Salaam, P.O. Box 35131, Dar Es Salaam, Tanzania.
E-mail: pvalimba@hotmail.
Keyword(s): River flows, flow seasonality, multi-year variability, water resources management
Session: Poster session 3
Abstract Monthly river
flows in rivers within selected catchments in two different climatological zones in Northeast Tanzania were
investigated to highlight the changes in distribution of river flows over the years. Decadal average monthly flows were
computed for the 1950s through 1990s and assessed to highlight changes in the distribution of flow volumes within
the year while trend analysis was used to highlight changes of monthly flows over the years. Results indicated
progressive amplification of flow peaking in May, declining and shifted low flows from February to March since the
1970s and progressive declining mean annual flows, although some isolated years of the opposite sign were
observed within the decades. Trends indicated predominantly declining dry season flows and augmenting peak wet
season flows between the 1950s and 1990s. This situation has strong implications to water resources management in
the three river basins (Pangani, Sigi and Umba) in Northeast Tanzania where conflicts related to periodic water
scarcity are increasing. It therefore calls for the need of conservation of abundant wet season flows to cater for
increasing multi-sectoral water requirements during the dry season while addressing issues of water provision for
ecosystem needs.