Irrigation water saving by management of existing subsurface drainage in Egypt

Abstract

Egypt is faced with a water scarcity situation due to increasing demands on a fixed resource which could limit the country's ability to further its overall economic development. There is a danger that farmers in the Nile Valley and Delta may receive less irrigation water and of lower average quality in the future if no actions are taken towards irrigation water saving.In Egypt more than 2 million ha have a subsurface drainage system. These systems have been designed with fixed drain depths and spacings to meet certain strict drainage criteria based on conservative design assumptions regarding crop type and rooting depth. However, over the life of a drainage system under different conditions of crop type, crop growth stages and water availability occur. The original design assumptions only occur for short periods and so for most of the time excessive drainage occurs. Approximately 7.2 BCM of water is drained from areas with subsurface drainage systems in Egypt.A new perspective for managing these systems as a key part of integrated water resources management is needed. For that reason new management concepts for existing subsurface drainage systems have been developed to improve irrigation water use efficiency. The management concepts were to change the effective drain spacing and effective drain depth by applying simple, easily adoptable management measures. These management options were compared with the conventional ''no management'' by applying the DRAINMOD-S model to the Western Delta of Egypt.The results indicate that by using the proposed management concepts it is possible to improve the existing irrigation water use efficiency by 15-20% without any yield reduction. Overall it was found that about 0.4 BCM of irrigation water may be saved in the Western Delta of Egypt alone by application of these management concepts. Copyright En É gypte il y a plus de 2 millions d'hectares qui ont un système de drainage souterrain. Ces systèmes ont été dessinés avec une profondeur et une espace fixée, pour répondre à certains critères d'irrigation basés sur le type d'agriculture et la profondeur des racines des plantes dans la terre. Cependant, durant la vie d'un système de drainage on voit des conditions différentes d'agriculture, de stade de croissance et de disponibilité d'eau. Les assomptions des dessins originaux sont seulement pour des périodes courtes, ainsi pour la plupart du temps il y a

Integrated Irrigation and Drainage Practices to Enhance Water Productivity and Reduce Pollution in a Rice Production System

“…This provides drainage during wet periods, but utilizes control structures to manage the water level in the drainage outlet, making it possible to reduce over‐drainage and increase water use efficiency (Osmond et al ., ). Controlled drainage has also been recognized as the best management practice to reduce the transport and delivery of nitrogen and phosphorus to sensitive surface waters, and many studies have shown that controlled drainage can improve drainage water quality when properly designed and carefully managed (Wesström et al ., ; Ng et al ., ; Dukes et al ., ; Khan et al ., ; Wahba et al ., ; Luo et al ., ).…”

Assessment of Options for the Sustainable Use of Agricultural Drainage Water For Irrigation in Egypt by Simulation Modelling

“…This controlled drainage approach is further described and simulation results provided in Wahba et al . ().…”

“…Crops are grown in Egypt in rotation and the choice of crops for a rotation depends on the soil conditions, crop characteristics, water availability, economic values of crops, current practices and cultural preferences. One of the most common rotations in the Nile Delta is wheat–maize–berseem–cotton (W–M–B–C) (Wahba et al , ). The crop input data required for the DRAINMOD‐S model are the crop planting and harvesting dates, which are shown in Table .…”

The added value of research on drainage in irrigated agriculture

“…To investigate whether controlled drainage can maintain higher groundwater tables without increasing soil salinity the simulation model DRAINMOD-S was applied to the western Nile Delta. The results showed that controlled drainage has the potential to maintain and even increase yields while increasing irrigation water use efficiency by 15-20% (Wahba et al, 2005). The savings can be obtained with low-cost and easily operated devices.…”