RIVER RESTORATION IN DKI JAKARTA, INDONESIA. A CASE STUDY OF CILIWUNG RIVER

摘要

In the last three decades the rapid economic development of Indonesia and the growing population required excessive conversions of agricultural land and land reclamation mainly for industrial and urban development. Expansion of large cities takes place at a very high speed, especially Jakarta, Semarang and Surabaya. In these large cities, all the main drainage systems receive excessive uncontrolled drainage water including solid waste from catchment areas. As a consequence the water quality of the main drainage systems is poor and this may affect human health and unpleasant views of the surrounding area. The main problems of the drainage systems in Jakarta area can be defined as: 1. Poor water quality and excessive solid waste in the urban drainage systems; 2. Uncontrolled pollutant discharges, mainly from small industry and housing areas; 3. Flood and inundation problems in urban lowland areas during rainy season. One of the options to improve the water quality in the main drainage systems is by flushing. This option is complicated and influenced by many aspects. This research focuses on the improvement of water quality in the main drainage systems in Jakarta. The research work starts with the field survey and data collection. Based on the geometrical and hydraulic data of the system, a mathematical model is developed to check the effect of the flushing options to the river restoration program. By considering the objective of the research (to find out a proper option to improve the main drainage water quality), several options are derived and evaluated in term of hydraulic performances. A case study of Ciliwung River system is selected. A pilot scheme with more detail and systematic research plan related to Ciliwung River is proposed after discussion and consultation with DKI Jakarta as the most important stakeholder. The pilot project will consider segment by segment of the Ciliwung River and in this case an example of a segment between Kelapa Dua and Manggarai was selected. Four options have been checked, i.e. Option1: Flushing by supplying better quality water, Option2: Diluting by rainfall water periodically, Option3: Piping of polluted water and transferred to the water treatment plant before discharged to the sea and Option4: Reducing pollutant concentration. By evaluating these four options, it is concluded that Option 3 and Option 4 will give almost the same result related to the duration which will be needed to improve BOD concentration from 30 mg/l to 10 mg/l within 40 days. It is recommended that based on the simulation results, economic analysis should also be done in order to select the most acceptable option to do the river restoration in Ciliwung River. This research will support directly the 'Clean River Program of Indonesia' where Ciliwung River is one of the rivers which have to be restored.