HYDROCHEMICAL AND STABLE-ISOTOPE STUDY OF GROUNDWATER IN THE SAINT CATHERINE WADI FEIRAN AREA, SOUTH SINAI, EGYPT

The groundwater of the investigated area resides in both crystalline r ocks and alluvial deposits. The salinity of the collected water sample s is governed by the rock type, air-borne dust and marine aerosols. Th e groundwater in the monzonite is more saline than that in the alluviu m, granite and volcanic rocks. It is characterised by a high sulphate content due to the oxidation of sulphide bearing minerals. The water w as found to be suitable for drinking and agricultural purposes. The gr oundwater samples have an O-18 and deuterium composition similar to th at of precipitation, which is presumably the main source of the ground water recharge in this area. In addition, fossil water (palaeowater) m ay also play a role in the recharge of the investigated water via faul ts, dykes and joints which exist in the area. The deuterium excess val ues observed in some of investigated groundwater samples are much lowe r than that for the Mediterranean area. This is evidence of evaporatio n before infiltration to the aquifer. (C) 1998 Elsevier Science Limite d.