THE MAGNITUDE OF EVAPORATION LOSSES IN INCREASING SALINITY OF DRAINAGE WATER

Document Type : Original Article

Authors

1 Drainage Research Institute, Water Research Centre, Cairo, Egypt

2 Soils and Water Research Institute, Agricultural Research Centre, Giza, Egypt

Abstract

The severe and increasing shortage of water resources in Egypt becomes imperative to consider re-use of drainage water, which salinity in the drainage water is often difficult to quantify with confidence. A preliminary study has been carried out to estimate the evapo‌ration losses in the rice field, as well as, the effect of this loss on in‌creasing salt concentration of the residual water, where the proportion of water lost to the atmosphere by evaporation rather than transpiration should be greater for this crop than for any other major crop in the Del‌ta. For this study, water samples were collected during June 1988 from El-Roda (conventional drainage system) and Nashart (modified drainage system) rice fields and analyzed for a stable isotope and some major elements. The main finding is that the extent of heavy stable isotope en‌richment in the rice field samples due to evaporation is quite large. From this we can estimate the amount of water lost by evaporation and de‌termine the increasing in salt concentration due to loss in water. This finding can be quite helpful in establishing the sources of salts in the drainage water.