Persebaran kualitas airtanah bebas kaitannya dengan tingkat kepadatan penduduk di kota medan propinsi Sumatera Utara = Groundwater Quality of the Unconfined Aquifer and It's Relation to The Population Density in the City

This research was conducted in Medan, the capital city of North Sumatra province, which has been developing rapidly. Objectives of this research are investigating about: (1) influence of the level of population density to the quality of groundwater of unconfined aquifer (2) influence of population activities (such as wastewater disposal method, distance of wastewater disposal site and the physical condition of well) to the quality of groundwater of unconfined aquifer. Parameters, which were studied in this research, consist of the depth of groundwater surface, physical field, temperature, taste and odor of wastewater, pH, turbidity, C1NO2-, NO3-, Fe, SO42-, COD, and BOD. Data was analyzed by graphical method, such as a bar graph, to predict the influence population density to groundwater quality. The analysis of variance was used to examine the difference of groundwater quality among population density level, while multiple regression method was used to examine the influence of the method wastewater disposal (Xi), the distance of wastewater disposal (X2), and the physical condition of well (X3) to the pollution risk. The results of this research showed that the increasing level of population density tends to increase temperature, turbidity, Electric conductivity, pH, Cl, and Fe of groundwater quality. Result of multiple regression showed that the physical condition of well (X3), significantly determined the quality of groundwater of the unconfined aquifer. The parameter of ground water quality such as turbidity, Electric conductivity, pH, Cl-, SO42-, NO3-, NO2-, COD, and BOD were relatively high, however they did not exceed water quality standard for drinking water, except those for Fe. High concentration of iron was found in Siti Rejo, subdistrict of Medan Amplas, which was about 1.08 ppm. Key words : Groundwater quality, unconfined aquifer, population density, wastewater