Water consumption and environmental behavior of the residents in Lake Toba water catchment area, North Sumatra, Indonesia

One of seventeen points of Sustainable Development Goals (SDGs) is to provide clean water for at least 80% of the global population in 2025. Rural populations living surrounding Lake Toba water catchment area still utilize the lake water for daily use regardless of the susceptible decreasing water quality. This paper describes anthropogenic aspects affecting the water quality of Lake Toba that is consumed as the drinking water source by surrounding residents. The research used a quantitative approach by interviewing 130 household representatives from 3 regencies around the lake to calculate the water consumption and evaluate the water quality in 2018. In addition, this research also assessed the residents' behavior in managing household waste and wastewater. The result showed that the average water consumption is 86,93L/person/day. The majority of the respondents barely treat the water and feel satisfied with the water quality based on its color, turbidity, taste, and odor. On the contrary, the respondents have not adequately treated their domestic waste and household wastewater before being released to the lake, contributing to water pollution. Although most respondents are satisfied with the water quality, it is still needed to perform proper water treatment because the water quality of Lake Toba is reported as slightly up to heavily polluted by the Ministry of Environment and Forestry in 2019.

Evaluasi Pengaruh Rehabilitasi Lahan Dan Hutan Terhadap Koefisien Aliran Tahunan Di Sub Das Krueng Meuleusong

Abstrak. Penelitian ini bertujuan untuk mengetahui pengaruh rehabilitasi lahan dan hutan (RHL) terhadap nilai koefisien aliran tahunan (KAT) di sub-DAS Krueng Meulesong. Pelaksanaan RHL di Desa Riting Kecamatan Indrapuri Kabupaten Aceh Besar yang termasuk dalam DAS Krueng Meuleusong dikategorikan tidak berhasil berdasarkan citra satelit perubahan tata guna lahan tahun 2009, 2014, 2017 dan 2019. Hasil interpretasi citra satelit menunjukkan penurunan luasan hutan sekunder, namun luas perdu dan sabana meningkat. Berdasarkan hasil uji korelasi menunjukkan bahwa pelaksanaan kegiatan RHL tidak berpengaruh terhadap perubahan penggunaan lahan menjadi hutan sekunder dan kegiatan RHL tidak berpengaruh terhadap nilai koefisien aliran tahunan (KAT) di Sub-DAS Krueng Meuleusong.Evaluation Of The Effect Of Land And Forest Rehabilitation On Annual Flow Coefficient In Krueng Meuleusong Sub-WatershedAbstract. This study aims to determine the effect of land and forest rehabilitation (RHL) on the value of the annual flow coefficient (KAT) in the Krueng Meulesong sub-watershed. The implementation of RHL in Riting Village, Indrapuri District, Aceh Besar District which is included in the water catchment area of the Krueng Meuleusong sub-watershed is categorized as unsuccessful based on satellite imagery of 2009, 2014, 2017 and, 2019 of land-use change. The results of satellite imagery interpretation showed a decrease in the area of secondary forest, but shrubs and savanna area had increased. Based on the results of the correlation test, shows that the implementation of RHL activities has no effect on changes in land use to secondary forests and RHL activities have no effect on the value of annual flow coefficient (KAT) in the Krueng Krueng Meuleusong sub-watershed.

Accuracy of The Level of Critical Water Catchment Area for Flood Mitigation Around Bengkulu City, Indonesia

Disaster mitigation activities require the availability of a potentially flooded area (PFA) map. One of the causes of flooding is the criticality of water catchment areas; the higher the criticality level, the higher the flooding potential. This study aims to determine the accuracy of the model for determining the PFA around Bengkulu City, which was derived from the Level of Critical Water Catchment Area (LCWCA) model developed by the Ministry of Forestry. After obtaining the LCWCA Map, another analysis was performed in order to obtain the PFA Map. Furthermore, the overlaying was carried out with the Existing Flood Map in such a way that the level of accuracy is known. The threshold values from Justice are used to justify the level of accuracy in three categories, namely Good (> 85%), Moderate (70 - 85%), and Poor (<70%). The results showed that in the eight sub-watersheds around the city of Bengkulu, there were two sub-watersheds with reasonable accuracy (> 85%), which means that there was > 85% overlap between areas on the Potentially Flooded Area Map as a result of the analysis of The LCWCA with the area on the Existing Flood Map. There are three sub-watersheds with Moderate accuracy (70 - 85%) and three sub-watersheds with Poor accuracy (<70%)

Analisis Pengaruh Perubahan Penggunaan Lahan terhadap Debit Sungai (Studi Kasus : Sub DAS Cikeas)

Land use change have an impact on infiltration capacity. There is often an annual flood on Kadumanggu District. When the rainfall is high so the river will be overflow. The outlet of Cikeas sub-basin was located on Kadumanggu District. This research aimed to determine the maximum discharge of the Cikeas River and analyze the relation between land use change and discharge of Cikeas River. The research was conducted by delineating the water catchment area, analyzing rainfall, making a land use map and modeling with HEC-HMS. Based on the modeling results, the maximum discharge of the Cikeas River in 2000 was 74.3 m3/s, in 2009 was 84.9 m3/s, and in 2018 was 91.7 m3/s. The catchment area with an extensive use as residential had a higher river discharge compared to the area with a large green area. It meaned that, land use changes greatly affected the river discharge.

Flood Management Based on The Potential Urban Catchments Case Study Padang City

The water catchment area also indirectly impacts on flood control for areas that are lower than it because rainwater does not fall to the lower areas but is absorbed as groundwater. Increased development of Padang City will be inversely proportional to the reduction in water catchment areas and become an area that is impermeable that makes rainwater stagnate on the surface and flood occurs. The development of remote sensing technology and geographic information systems has made it possible to study the spatial patterns of potential water catchment areas in a wide range, including mapping the potential of water catchment areas in Padang City. This study aims to analyze the condition of the availability of water catchment areas for controlling water management and flood disasters in Padang City based on data on spatial parameters such as rainfall data, slope, soil type maps, and land use obtained from Landsat 8 OLI imagery data. This study uses the scoring and overlay method with the Geographical Information System. The results show that the condition of the water catchment area in the western part of Padang City have been critical, reaching 18.29% of the total area of ​​Padang City, this is due to land use that has undergone a change of function. If the water infiltration condition worsens (critical), it gives more opportunities for flooding and inundation. Thus the areas with the potential for water absorption which are categorized as critical and very critical in the research location can be said to be areas that are potentially prone to flooding and inundation, because the ground surface is no longer able to absorb water. Monitoring the potential of water catchment areas is one form of flood mitigation efforts.

Estimasi Volume Sedimentasi Waduk Sermo Menggunakan Metode RUSLE, Batimetri dan Angkutan Sedimen

Sermo Reservoir is a reservoir which was built by Indonesian Government and supported by Asian Development Bank in program Integrated Irrigation Sector Project (IISP) in 1996. Sermo Reservoir functions as a flood control, raw water source and irrigation. Changes that occur to water catchment area of the Sermo Reservoir affects its condition. Especially changes that occur in aspects of water runoff, sediment production and watershed deposition of watershed aspects which are caused by erosion in water catchment area resulting in sedimentation. Long term sedimentation causes a decrease in reservoir capacity. To overcome this problem it is necessary to estimate the sedimentation volume to determine the latest condition of the Sermo Reservoir. In this activity, volume estimation of sedimentation was conducted using RUSLE, bathymetry and sediment transport methods. The data used in this activity are the data in 2016, 2017 and 2018. In this activity, the analysis of the RUSLE method in the Ngrancah Watershed includes the factors of rainfall erosivity, soil erodibility, length and slope and land cover and preservation. In addition to RUSLE, an analysis was carried out using the bathymetry method. This method calculates sedimentation based on reservoir baseline DTM data of 2017 and 2018. From the difference between both DTM epochs, obtained sediment volume and spread of Sermo Reservoir. Besides, analysis of the sediment transport method was conducted using water soil content data of 2016 which is assumed static until 2018. While analyzing with RUSLE, bathymetry and sediment transport methods using ArcGIS Software. The results of volume estimation of sedimentation using RUSLE, sediment transport and bathymetry consecutively yields 184.158,580 m3/year, 163.151,173 m3/year and 149.959,800 m3/year. Thus the estimation results of sediment thickness velocity of Sermo Reservoir using RUSLE, bathymetry and sediment transport are 8,687 mm/year, 7,790 mm/year and 7,074 mm/year. Generated volume from the methods was tested by using precision test yielding RSD 8,407 % thus classified as low accuracy. From the precision test can be concluded that sediment transport was the most precise because it has a percentage difference of -0,766 % of the average sediment volume.