Geomatics based approach for assessing Qaroun Lake pollution

Abstract

Discharge of polluted water into Qaroun Lake creates a severe pressure on aquatic life and stimulates proliferation of the invading dangerous parasites. Present study aims to assess pollution, its sources, impacts and proposed solutions in Qaroun Lake using field survey, lab analyses and geospatial techniques. A total number of 24 well distributed sites was sampled (water and sediment) during November 2017 and analyzed for quality characteristics, nutrients, organic content (OM) and toxic heavy metals. EPA standards, contamination factor (CF), degree of contamination (DC) and ecological risk index (Er) were used for assessing water and sediment pollution. Landsat OLI and Sentinel-2 imagery were processed to assess the land uses surrounding the lake. Geospatial analyses in ArcGIS were utilized for mapping purposes. Qaroun Lake is surrounded by variable interrupting land uses (i.e. urban, agricultural and industrial), amounting 32% of the total area. A remarkable fluctuation is observed in most of the studied water and sediment characteristics. Levels of phosphate and nitrate showed a mild (7–8.7 ppm) to a great fluctuation (0.2–46.6 ppm). Ammonia, Pb and Ni levels in water exceeded EPA standards. CF showed that the majority of the Lake is highly contaminated by Cd and Pb. OM was concentrated in the bottom sediments in association with heavy metals. DC and Er showed an increase in pollution and risk in front of El-Bats and El-Wadi drains. Further, metals are impacted and positively correlated with the Lake salinity. It can be concluded that wastewater discharge into Qaroun Lake increased levels of various pollutants to serious grades. To reduce pollution and accelerate Qaroun Lake recovery, two integrated wastewater treatment plants must be established on El-Bats and El-Wadi drains. Keywords: Pollution, Qaroun Lake, Remote sensing, GIS, Drainage water