Abstract:
Infiltration wells have been widely applied in urban areas to control runoff so that flooding can be reduced or even prevented. Rain water falling in the roof or impervious object forms overland flow infiltrate into the infiltration wells. Overland flow contains some sediments and chemicals that may enter into the infiltration wells and deposited in the wells. Therefore, it can reduce the effectiveness of the infiltration wells. This study aims to analyze the characteristics of sediment carried by overland flow and its influence on the effectiveness of infiltration wells in sub-urban area. This research was conducted in Sub-Urban dense with housing. A total of 19 infiltration wells have been observed and sediment in those wells were collected and analyzed to study the sediment characteristics. Grains size of the sediment was analyzed in the laboratory. This study shows that the sediments deposited in the infiltration wells mostly classified as loam to sand. Of the 19 wells which were studied, most of them have been filled with sediment over a third of its depth that occurred during the period of 2010-2016. Based on the grain size characteristics, it could be concluded that sediment originated from the surrounding yard area and some of them as a results of Mt. Merapi eruption in 2010 and Mt. Kelud in 2014. Infiltration wells that collect overland flow from the roof tend to have the finer sediment than those collect overland flow from road and yards. They also have a thicker sediment layer. Therefore, infiltration wells that collect water from the roof is more effective than infiltration wells that collect water from roads.
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