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UNESCO-IHE Institute for Water Education, Delft (2012)

Optimization of farm water management and agronomic practices under spate irrigation in Gash Agricultural Scheme – Sudan

Avelino, J.C.

Titre : Optimization of farm water management and agronomic practices under spate irrigation in Gash Agricultural Scheme – Sudan

Auteur : Avelino, J.C.

Université de soutenance : UNESCO-IHE Institute for Water Education, Delft

Grade : Master of Science (MS) 2012

Résumé partiel
Spate irrigation, the oldest irrigation system dating back 70 centuries, has been used until today as an important source to support the livelihood for the most marginal communities in Sudan and several other developing countries. On the other hand, it has received little attention from investors, development agencies and researchers. It is only in the past two decades that spate irrigation has increasingly been recognized as an imperative contributor for food security in Sudan. That said, most investment was focused on improvement of spate flow diversion and little focus was given to field water management, and this research aims to fill this gap. The study analysed water distribution at the tertiary canal and field level. In addition, three flood events were determined based on historical water levels at the intake, being 1.0 m s-1, 1.6 m s-1and 2.4 m s-1 for the small, medium and high floods respectively. The water distribution performance analysis was made by using the hydraulic model DUFLOW. The results showed that by narrowing the canal cross-sections from 4.5 m to 2.5 m bottom width at the upstream and from 2.0 m to 1.5 m at the downstream, increased the water depth to the desired 1.0 m at the canal upstream, allowing a proper diversion for the five bank breached off-takes. However, the maximum total irrigable land (340 ha) from the Kasir Rabakasa misga canal contribution to the misga Rabakasa 1 remains the same for the all proposed scenarios, and the remaining area (210 ha) has to be supplied by another canal (the Rabakasa 1 misga canal) considering the high flood event. Using WinSRFR, effectiveness of water distribution within the misga/field was analysed with regard to infiltration water depth and uniformity of application. Under the existing conditions 210 ha (800 m x 2625 m), with 25 days of water application approximately 80 ha were not being irrigated. Improvement by dividing the misga horizontally into 2 plots irrigated for 10 days each gave the best result, where the entire misga is irrigated, at a minimum distribution uniformity of 65%, average infiltration depth of 82 cm and 52 cm at the tail end of the field, based on the small flood event (the frequent event). For the medium and high flood events, the same result could be obtained at 7 and 5 days respectively.

Sujets  : spate irrigation water management agronomy irrigation schemes

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Page publiée le 13 février 2020