Determining effect of irrigation water use on groundwater quality and drainage.

This work was carried out in Akarsu Irrigation District (AID) of 9 495 hectares. Drainage and groundwater salinity problems developed due to mismanaged irrigation systems, low irrigation efficiency, heavy soil texture, inadequate drainage systems and other likely problems which all cause reduced agricultural production. The undertaken work investigates interrelations between the existing irrigation practice with groundwater depths and salinity, using groundwater observation wells. With additionally installed drainage observation wells, a total of 107 wells were under survey in 2006. The groundwater depths were measured in May and July and samples were collected concurrently for measuring electrical conductivity (EC, dS m-1). The groundwater depths in May showed that there was no drainage problem in the area. However, drainage problem (ground water depth < 1 m) was evident during high irrigation season in July. Mean groundwater salinity in May and July were respectively 4.3±10.1 and 2.8±4.3 dS m-1. The high groundwater salinity observed during the peak irrigation season in July was attributed to wide spread practice of excess irrigation resulting both low field irrigation efficiency and low irrigation water use efficiency