Filsa Bioresita, Cherie Bhekti Pribadi : OPEN SURFACE WATERS CHANGE DETECTION MONITORING USING ALOS PALSAR SAR DATA
(A case study: Rawa Pening Lake)
Filsa Bioresita S.T., M.T.
Cherie Bhekti Pribadi S.T., M.T.
The 1st International Conference of Indonesian Society for Remote Sensing 2015
” Harnessing Earth Information from Space”
open surface waters; Rawa Pening Lake; ALOS PALSAR; threshold; changes detection
One of the irreplaceable strategic resources for human survival and social development is surface waters. It plays a very important role in economics and the functioning ecosystems. Reliable information about the spatial distribution of open surface waters is critically important in various scientific disciplines, such as the assessment of present and future water resources, climate models, agriculture suitability, river dynamics, wetland inventory, watershed analysis, surface water survey and management, flood mapping, and environmental monitoring.
Rawa Pening Lake is a semi-natural lake located in the district of Semarang, Indonesia. It is one of the lakes that the quality and quantity of its water become a major concern. Rawa Pening Lake has several strategic functions that can be used by governments and society as a source of irrigation water, the source of electrical power (hydropower), a place for inland fisheries development, flood control, and water attractions. Yet, Rawa Pening lake water conditions deteriorated due to the increase in organic matter content which stimulate the eutrophication. This process causes water surfaces closing by aquatic plants and leads to the closure of surface waters with trigger floating island, shallowing of the lake due to sedimentation, and accumulation of water hyacinth litter in the bottom.
The recent availability of imagery from the ALOS PALSAR sensors offers a unique and unprecedented opportunity for using SAR imagery to accurately monitor the spatial and temporal dynamics of open surface waters areas. Additionally, the successful use of density slicing with threshold value to delineate water bodies provide an effective approach for surface waters mapping. First, an understanding of the data values characteristics of surface waters and land areas was developed. Second, a threshold analysis to classify surface waters and land was also accomplished. Then the results of each images classification were overlaid to be able to see their spatial changes. Monitoring the results in the period 2007-2011 indicate changes in the different location of Rawa Pening lake. This is due to the spread of aquatic plants that cover the surface of the water, at a different location. Multi-temporal ALOS PALSAR data was found to be useful for mapping and changes detection of open surface waters areas in Rawa Pening Lake. The generated maps will be a valuable asset to conserve the water resources and to mitigate the impacts of human development in the region.