[en] A detailed account of the application of isotope and geochemical techniques in the study of waterlogging and selenization of agricultural lands in Peshawar valley area is presented. Precipitation samples, surface / groundwater samples and aqueous sulphate were analysed for tritium and stable isotope ratios of hydrogen, oxygen and sulphur. The data show that the artesian aquifer is recharged by the precipitation at high mountain whereas local precipitation and irrigation canal waters are mainly responsible for the recharge and waterlogging in the unconfined aquifer. In some parts of the valley, upward leakage from artesian water is found to cause waterlogging. The valley area contains water recharged after 1953. The chemical quality of the shallow groundwater is quite poor as compared to that of deep groundwater. 18 figs. (author)