Developments in the Design and Construction of Modern Spate Systems in Tigray, Ethiopia

Abstract

Spate irrigation is an ancient irrigation practice that involves the diversion of flashy spate floods running off from mountainous catchments. Spate irrigation system in Ethiopia is common practice in arid areas in the past decades. Raya valley is one of the areas where spate irrigation is being practiced for long times and many schemes were modernizing since 1998. Individual and group discussion with experts and farmers were held and frequent field visit and observation to both traditional and modernized spate irrigation schemes were undertaken. Hara spate irrigation scheme was the first scheme for modernization and it was followed by Tirke spate scheme.  In 2004, 2006 and 2011 many traditional spate schemes were modernizing by government and non-governmental organizations. The major improvement from the first schemes were changing of closed off take type in to open, enlargement of canal sizes, changing the diversion angle from 90⁰ in to 120⁰ and avoid crossing structures. The community participation was not strong during design and construction. As farmers had their own experience in construction of traditional spate schemes they were not happy for the modernized schemes and had less ownership. Sedimentation in both diversion scheme and canals are the major problem and root causes for failures of modernized schemes. Spate irrigation modernization intervention works should be accomplished through real participation of farmers and initiate them to practically influence the planning, designing and construction processes so that successful modernized projects could be accomplished. Spate irrigation has different characteristics from conventional irrigation system, therefore this needs special attention during design. Especial design criteria should set spate scheme construction.

Keywords: spate irrigation, design development, Raya valley, spate modernization