EVALUATION OF GROUNDWATER QUALITY FOR IRRIGATION IN CENTRAL SAUDI-ARABIA

Appraisal of groundwater used for irrigation in El-Gassim region of Ce ntral Saudi Arabia was made by chemically analysing 217 representative water samples. Based on previous water criteria guidelines and a modi fication by us, the data obtained were intensively processed and trans formed. Accordingly, water quality and suitability maps were developed under the conditions of this study with special focus on wheat produc tion. The water quality parameters investigated revealed the following : 1) water salinity ranged from 210-8200 ppm with an average of 2375 p pm (i.e. between 16.6 and 83 t ha(-1) of salt deposited in soil per se ason for wheat and alfalfa cultivation); 2) extensive water extraction caused a significant increment in SO4= / Cl- ratio; 3) accumulation o f reactive constituents such as H2S, FeS and SO4= caused corrosion and damaged the pivot pipeline and 4) irrigation water contributed to sol uble potassium which amounted to 475 and 2500 kg K2SO4 ha(-1) season(- 1) for wheat and alfalfa crops, respectively.