| Abstrak/Abstract |
Nitrate and Fecal Coliform concentration on shallow groundwater of Yogyakarta area are reported increase dramatically since 1980’s to nowadays, especially in the city and its agglomeration area. Kurahan is a small village in Bantul district, Yogyakarta which located about 15 km south of Yogyakarta City. Nitrate and fecal coliform concentration on shallow groundwater on this village is still not known, groundwater vulnerability of the unsaturated zone is also not yet understand and
most of the population on this area are using on site sanitation system. Therefore, the research has three main objectives, which are (1) to know the nitrate and fecal coliform concentration on the groundwater and and their sources, (2) to understand the vulnerability of groundwater to pollution and (3) to define the relationship between nitrate concentrations on groundwater, groundwater vulnerability and the density of population. Result of groundwater sampling show that nitrate
concentration on groundwater ranges from 0.22 – 134.53 mg/L and fecal coliform content ranges between >1.8 - 1600 MPN/100 ml. Based on the nitrate and chloride ratio analysis, the sources of nitrate comes mainly from fecal source presumably human fecal. By applying Simple Vertical Vulnerability mapping method, the groundwater vulnerability to pollution of this area is classified as moderate to high class of vulnerability due to shallow groundwater condition and sandy soil/sediment as the dominant lithological type in the unsaturated zone. Combination of groundwater vulnerability and the density of population reveals a hazard map of nitrate groundwater pollution. Validation of the the hazard map with nitrate concentration show a significant correlation, but this relationship is not found on the case of fecal coliform content. From this research, there are three conclusion can be resumed. First, high concentration of nitrate and fecal coliform on groundwater in Yogyakarta is not only occur in the city but also village outside the city. Second, the application of non proper on site sanitation system is the main source of contaminant and third, even though there is a strong correlation between source of pollution and nitrate concentration but for fecal coliform content is more affected by groundwater vulnerability and or characteristics of the unsaturated zone.
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