This project supports a collaborative study by Drs. H.J. Simpson and J.W.C. White of the Geochemistry Division of Lamont-Doherty Geological Observatory, Columbia University and Dr. M.S. Hamza of the Atomic Energy Establishment in Cairo, Egypt. The objective of the study is to obtain indications of the ratio of irrigation water losses through the two important mechanisms of transpiration and evaporation by observation of heavy isotopes (deuteruim and oxygen-18) in residual water. Samples will be taken in Egypt in the Eastern Delta of the Nile River from two separate areas, one where the net groundwater flow is from shallow soils into deeper groundwaters and the second where the net vertical flow is the opposite. The study is hoped to develop a practical empirical approach to estimating evaporation losses from large irrigation networks, independent of estimates of evaporation plus transpiration based on discharge gaging data. The study is expected also to help understand atmospheric water budgets in arid zones with extensive irrigation networks. Scope: The collaboration in this project is beneficial to the U.S. and to Egypt. The project links Egyptian and U.S. scientists of varied experiences that mesh well to provide the necessary skills and knowledge for its success. The information gained through this research could be useful to many countries in arid or semi-arid regions with large irrigation systems.
