Management of river water for irrigation to mitigate soil salinization on a coastal wetland

Abstract

The change in water chemistry in the Axios River delta wetland is due to the interruption of river discharge in this area during the irrigation period. The impact, which visibly affects the wetland's flora, was verified by measuring water salinity in the delta area during the peak irrigation period. Given that additional water supplies are not available, the only way to remedy this problem is to use the available irrigation water wisely. Most irrigation water losses are attributed to the fact that the constant water delivery rate does not respond to water demand of the irrigation networks. To cope with this problem, a water resources management system, based on the assessment of water requirements, was developed. The system can schedule water supply to the irrigation networks, thus saving enough water to maintain discharges at the delta and to keep water salinity within to acceptable levels. The water resource management system, which was based on fully distributed real time inputs (climate data), was developed using a Geographic Information System (GIS). This system adjusts network irrigation supply through a feedback mechanism. This mechanism responds to the changes that might occur in the exogenous system inputs: effective rainfall (Re) and actual evapotranspiration (ETr), and to the difference between the system's target and calculatedepvalues. In this way irrigation water is used efficiently, thus minimizing the degradation of natural resources. Using the proposed method it was found possible to remedy the environmental impact of agriculture by saving enough fresh water to maintain the biotic and abiotic parameters of the natural ecosystem.