Groundwater quality distribution by geostatistical investigation (GIS), Nile Delta, Northern Egypt

The Nile Delta represents two-thirds of agricultural output with low precipitation and population growth that depletes the groundwater. The Quaternary aquifer is consisted of Holocene (aquitard) underlain by Pleistocene (aquifer), and groundwater flows from south to north, northwest, and northeast directions. The total dissolved solids (TDS) concentration increases toward the western and northeastern part in 1997 by seawater intrusion and irrigation practices. The TDS concentration anomalies were in the north and east, and are attributed to pumping within 2003, 2010, and 2013 periods. There is a good match between hydrogeochemistry (TDS content) and hydrogeology (groundwater flow) with the TDS concentration change found to decline mainly in the southwestern and northeastern part within 1997, 2003, and 2013 periods. The TDS concentration change declines toward the northern part of the eastern Nile Delta by increase in potentiometric surface from the River Nile in 2010. The geostatistical application (GIS) is used to determine the groundwater quality and hydrogeochemical parameters distribution, which is accomplished by ordinary kriging. The first produced map is the default options, while the next map (2nd) incorporated more of the spatial relationships constructed. When the latter is estimated, the exploratory spatial data investigation (ESDA) techniques check parameters extent. Trends were deleted and spatial autocorrelation was modeled. The ESDA and geostatistical techniques were used and the surfaces of the major ions were found more accurate. The third surface showed critical probability that TDS concentration threshold point increase drinking and irrigation purposes in the northeastern part and decrease in the southwestern parts of the Nile Delta. The default kriging is the best for mapping the hydrogeochemical parameters. Key words: Total dissolved solids (TDS) change, major ions, geostatistical tools, GIS, Nile Delta.