In this study, a novel data fusion approach was used to monitor the water-body extent in a tropical wetland (Lake Sentarum, Indonesia). Monitoring is required in the region to support the conservation of water resources and biodiversity. The developed approach, random forest database unmixing (RFDBUX), makes use of pixel-based random forest regression to overcome the limitations of the existing lookup-table-based approach (DBUX). The RFDBUX approach with passive microwave data (AMSR2) and active microwave data (PALSAR-2) was used from 2012 to 2017 in order to obtain PALSAR-2-like images with a 100 m spatial resolution and three-day temporal resolution. In addition, a thresholding approach for the obtained PALSAR-2-like backscatter coefficient images provided water body extent maps. The validation revealed that the spatial patterns of the images predicted by RFDBUX are consistent with the original PALSAR-2 backscatter coefficient images (r = 0.94, RMSE = 1.04 in average), and that the temporal pattern of the predicted water body extent can track the wetland dynamics. The PALSAR-2-like images should be a useful basis for further investigation of the hydrological/climatological features of the site, and the proposed approach appears to have the potential for application in other tropical regions worldwide.

Cimanuk watershed is one of the national priority watersheds for rehabilitation considering its critical condition. In this area, Jatigede Reservoir operates, which is the second largest reservoir in Indonesia, after Jatiluhur Reservoir. The reservoir performs several functions, including flood control, irrigation for 90.000 ha of rice fields, water supply of 3.500 litres per second, and power generation of 110 MW. In 2004 the Jatigede Reservoir catchment area had a critical land area of 40.875 ha (28% of the catchment area). The sedimentation rate in Cimanuk River at Eretan station shows a high rate (5.32 mm/year), which potentially decreases the function of Jatigede Reservoir. Therefore, a strategy of Best Management Practice's (BMP's) is required to mitigate the problem by using SWAT hydrology modelling. The aim of this study is to examine the impact of BMP's on surface runoff and sediment yield in Jatigede Reservoir Catchment Area. Simulations were conducted using land use in 2011. The results of this study suggest that SWAT model is considered as a reasonable modelling of BMP's simulation concerning Nash-Sutcliffe Coefficients (0.71). The simulation is using terraces, silt pit, and dam trenches as BMP's techniques. The BMP's application can reduce surface runoff from 99.7 mm to 75.8 mm, and decrease sediment yield from 61.9 ton/ha/year to 40.8 ton/ha/year.

Appropriate spatial planning can be analysed by looking at its impact on water resources on a watershed scale through a hydrological modelling approach. The objective of this study was to examine the effect of land-use change and the spatial plan of the region in the Cimandiri watershed using Soil Water Analysis Tools (SWAT) hydrological modelling. The Cimandiri watershed (1,830 km²) is situated in West Java Province, Indonesia. This watershed has a strategic position because of its proximity to the Capital City of Jakarta. This study highlights the importance of hydrological response considerations in spatial planning. From 1994 to 2016, there has been a reduction of forest land cover (157.8 ha), paddy fields (688.5 ha) and plantations (216.4 ha). This land-use change affects the hydrological conditions of the Cimandiri Watershed. The results indicated that there was an increase in the surface flow of 8.7 mm/year (186.6 to 195.3 mm/year), from 1994 to 2016 while baseflow decreased from 781.64 to 777.7 mm/year. The verification models were in satisfactory categories (R2 0.62 and NSE 0.51). Therefore, this indicated hydrological conditions in 1994 were relatively better than in 2016. The simulation result on the spatial plan shows the surface runoff, and the base rate was 284.9 mm/year and 684.7 mm/year, respectively. Interestingly, land use proportion based on urban spatial planning generated relatively higher surface runoff and sediment yield compared to existing land use. Hence there should be a review of the existing urban spatial planning of Sukabumi Regency that was resulting in the worst hydrological response based on SWAT model.

Purpose: The over-depletion of natural resources in the Ambang watershed is the recent cause of the flooding in the region. The Ambang watershed, located in the larger Malang region of Indonesia's East Java Province, is the subject of this article because of the importance of this resource to local residents.This study follows the rules set out by Regulation No. P.61/2014 of the Indonesian Ministry of Forestry, which governs the assessment and monitoring of watershed management, in order to determine the Ambang watershed's effectiveness. Finding out how much water the Ambang watershed can hold and how well the regulation works to control floods were the two main goals of this research Method: This study primarily uses data on floods, conservation initiatives, land use, and water value in the Ambang river basin. Data and information on floods, conservation regulations, and the worth of water infrastructure comes from government sources and community discussions. The data on land usage was derived from the analysis of satellite images. Literature reviews and reports from key government agencies (such as the regional agricultural agency, the regional environmental protection agency, and the district government) were used to gather secondary data for the Ambang watershed management study Results and Conclusion: Land cover, as a percentage, can reduce run-off rates and enhance infiltration capacity in a watershed, hence monitoring it is crucial for assessing the state of land carrying capacity. With an area of 86,783.77 ha, the Ambang sub-watershed has 27,311.79 ha of vegetative land cover (PPV), which is classed as poor, falling between 20 and 40%. The result is expressed as a percentage. One way to measure the difference between allowed and actual erosion is via the Erosion Index. Based on the analysis, the Ambang sub-watershed, which covers an area of 86,783.77 ha, experiences heavy erosion on average with 190.8 tons/ha/year. The erosion index is 14.2, and the IE classification is > 2, which is very bad. This is due to factors such as steep to very steep slopes in some areas, poor to moderate soil conservation, and the presence of annual plants on the land, with some exceeding 25%. Research Implications: In order to better educate the public about the conservation and restoration efforts of different stakeholders and to improve the recommendations for potential conservation and restoration actions in each of the Ambang watershed regions, a series of investigations and experimental projects are planned. Laws enacted by the Indonesian government (number 37/2012) and the Ministry of Forestry (number 6061/2014) control the administration of water-related regions in the country. Before receiving any funds from the National State Budget, regional (provincial) governments must develop a management plan that takes into account the watershed's ability to sustain initiatives. Our investigation showed that Regulation 61/2014, issued by the Federal Forestry Minister, does not adequately evaluate the Ambang watershed's harbor capacity. Especially in arid regions, further studies should help Indonesian watersheds better gauge the potential of their water supplies.