SIMULATION OF SUSTAINABLE WATER USE MANAGEMENT MODEL IN THE CIKERUH SUB-WATERSHED USING DYNAMIC MODELS

• Main Author: Cecilia Dewi, Riezcy
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/71545
• Institution: Institut Teknologi Bandung

The Cikeruh sub-watershed is one of the tributaries of the Citarum watershed, which is included in critical river conditions and located in three districts, namely Bandung regency, Bandung city, and Sumedang regency. The Cikeruh sub-watershed has the function to support food security, supply irrigation water and raw water, and provide energy for the communities around it. However, the Cikeruh sub-watershed occurred a water deficit in 2020. The high population pressure and economic activity in the Cikeruh sub-watershed will encourage increased exploitation of water resources so there will be a future decrease in water resource reserves. The Cikeruh sub-watershed area has a tropical monsoon climate with an average annual rainfall of 4.000 mm in the upstream area and 1.000 mm in the downstream area. The potential of this water resource is very large, but 33,45% of rainwater has not been utilized and is finally wasted in the sea. If this condition is allowed to continue in the long term, it will threaten a water scarcity crisis. These problems require integrated and efficient management of water use, so that water is still available in sufficient quantities in the future. Therefore, the objectives of this study are (1) to analyze land use changes that occurred in the Cikeruh subwatershed from 2015 to 2021, (2) to calculate the availability and demand for water from 2015 to 2021, (3) to analyze the status sustainable management of water resources in the Cikeruh Sub-watershed based on ecological, economic, social and institutional aspects, and (4) determining the best scenario for water use in the Cikeruh sub-watershed using a dynamic model. Land use analysis was carried out using Google Earth image data interpretation with Arc-GIS software and OSD (On-Screen Digitizing) classification. The availability of water that is calculated is only the availability of river water and ground water. The amount of river water and ground water obtained from the SWAT (Soil and Water Assessment Tool) model. The water demand is calculated using SNI 19-6728.1-2002 concerning the preparation of a spatial water balance sheet. The sustainability of water supply in the Cikeruh sub-watershed is then analyzed to determine the value and status of its sustainability and to identify leverage factors. Sustainability analysis is carried out using the Multi Dimensional Scaling (MDS) approach through Rapid Appraisal-DAS (Rap-DAS), which is a modification of Rapfish. Then, leverage factors from each dimension of sustainability are used as the basis for developing the dynamic model. The results of the analysis show that during the period 2015 to 2021 there have been changes in land use in the Cikeruh sub-watershed. The landuse has increased area are forest by 17,01% (1.992,94 ha), urban by 14,51% (2.553,33 ha), open land by 5,08% (893,64 ha), and water by 0,25% (44,25 ha). Meanwhile, the types of land use that occurred a reduction area are agriculture by 22,19% (2.904,71 ha) and rice by 14,66% (2.579,45 ha). The availability of water in the Cikeruh Sub-DAS has changed from 419.134.194 m3/year in 2015 to 430.746.151 m3/year in 2021 or an increase of 0,56% per year. Meanwhile, water demand has changed from 331.032.094 m3/year in 2015 to 467.822.229 m3/year in 2021 or an increase of 5,95% per year. Thus, there will be a water deficit in the Cikeruh sub-watershed in 2020. The results of the multidimensional analysis of the sustainability of water resources in the Cikeruh sub-watershed are " sufficient sustainable", with an index value of 57,68%. The results of the leverage analysis have identified 9 (nine) sustainability leverage factors that can be studied in making a dynamic model of sustainable water use, namely in the form of: 1) catchment area maintenance; 2) availability of water; 3) water utilization rate from the watershed; 4) investment climate; 5) income per capita; 6) public understanding of the preservation of natural resources; 7) community participation in watershed management; 8) inter-institution coordination; and 9) collaboration between stakeholders. The dynamic model shows that intensification efforts (scenario 3), consisting of efforts such as reallocating industrial water from groundwater to river water, increasing river damming, reduction of industrial growth targets, saving irrigation water for agriculture, and saving water for industry. This scenario is considered good because it can provide water in the long term, improve water use efficiency, and generate reasonable and sustainable economic growth.