Surface and Groundwater Interactions: Cikapundung Bandung, Kanal Banjir Timur Semarang and Cisadane Tangerang

摘要

In most Asia countries, the riverbank area is mostly inhabited by the low-income population, due to the shortage of formal housing. Most of the settlement areas are not equipped with proper sanitation system. Hence, the water quality gets lower over time with the increasing number of inhabitants around the riverbank. Th water quality gets worse with the close hydrological connection between surface water and the shallow groundwater. We compare the state of water quality based on our three case studies: Cikapundung Bandung, Kanal Banjir Timur Semarang, and Cisadane Tangerang. In each location, we gathered the following data: water level measurements, water flow mapping, and water quality samples. Then we make maps to evaluate existing status. The comparison will be made based on the physical and chemical properties that we get from the field. On all locations, we find very close interactions between surface water and groundwater. The hydrological connections are different in direction from upstream to downstream: gaining stream, combined stream or perched stream, and losing stream. However different river gradient gives a slightly different length of hydrological zonations. All samples show a high bicarbonate from rain water, the dissolution of carbonate minerals from the rocks and soils, and also organic species from microbial activities, which induced by domestic wastes. However, we need to make a carbonate balance calculation to break down the components. All samples also have high nitrate and nitrite concentration which come from domestic waste along the river and fertilizer from the rice fields upstream (only in Cikapundung river). For further research, we suggest chemical modeling to break up the contamination components and possible sources.