Daerah Bahaya Banjir Di Sub Daerah Aliran Sungai Sepauk Dan Tempunak, Kabupaten Sintang, Provinsi Kalimantan Barat (Flood Hazard in Sepauk and Tempunak Sub Watersheds, Sintang Regency, West Kalimantan Province)

Flood-prone areas mapping is often constrained by limited data availability at the site level. A quick assessment of sub watershed degradation method can be used to identify the degradation level of a sub watershed includes the flood hazard areas. This method is very easy to be applied at a site level using Geographic Information System (GIS), although it has minimum data. The aim of this study was to analyze the level of flood hazard in Sepauk and Tempunak Sub Watersheds, Sintang Regency, West Kalimantan Province. The required data were DEM/ SRTM (Digital Elevation Model/ Shuttle Radar Topography Mission), daily rainfall, and land cover. Quick assessment of sub watershed degradation method was applied to classify the flood-prone level of the study areas. The results showed that most of the study areas were categorized as high level of flood hazard (78% for Sepauk and 56% for Tempunak). The land covers of those areas were dominated by mixed dryland agriculture, bare land, and settlements. In addition, high level of flood hazard areas in Sepauk Sub Watershed was also affected by the existence of mining and dryland agriculture areas. Since the land cover change is a dynamic process, the flood hazard areas mapping should also be adjusted continuously to minimize the flood impact

Perbandingan Prediksi Hasil Sedimen Menggunakan Pendekatan Model Universal Soil Loss Equation Dengan Pengukuran Langsung (Comparison of Sediment Yield From Prediction Using Universal Soil Loss Equation with Direct Measurement)

Low level of sedimentation is a success indicator of watershed management. Measurement of sedimentation can be conducted directly or through erosion prediction approach. This research aimed to compare sediment yield from prediction by USLE erosion approach using three types formulations of rainfall erosivity with direct measurement. The field data were collected during 2015 in Lowereng Sub Watershed, Sempor District of Kebumen Regency. The slope steepness was derived from ASTER Global Digital Elevation Model and land cover was obtained from World View 2012. Three methods for estimating rainfall erosivity were Utomo and Mahmud, Bols, and Lenvain equations. The USLE applied for every land unit. By considering Sediment Delivery Ratio (SDR), the predicted soil erosion from USLE was converted into sediment yield. The direct measurement of sediment yield was conducted by taking suspended sediment in the outlet of sub watershed. This research indicates that the predicted sediment yield calculated using USLE approach was higher than the direct measurement. The predicted sediment yield using Lenvain's equation was 3.49 ton/ha (196%), which was the closest to the direct measurement (1.18 ton/ha)

Pendugaan Model Pertumbuhan Dan Penyebaran Spasial Populasi Rusa Timor (Cervus Timorensis De Blainville, 1822) Di Taman Nasional Alas Purwo Jawa Timur

Timor deer is ruminant mammals' species with high adaptability which enable them to be introduced easily in to new habitat. The animal was experiencing population decrease which put them in the rare status. The research was aimed at the estimation of demographic parameter, population growth model, and the determination of spatial distribution pattern of the timor deer population in Alas Purwo National Park (APNP). Animal inventory was conducted using strip transect method with sample unit of 1.5 km length and 100 m width strips. Analyses were conducted on demography parameter (size and density, sex ratio, birth rate/natality and mortality), spatial distribution pattern, and population growth model estimation. The result showed that timor deer in APNP has population size of 8157 ± 1224 individuals with population density of 0,20 ± 0,03 individuals/ha. Population size in general was 1 – 8 individuals/group. The age structure of the population was progressive population with reproductive sex ratio of 1 : 2.3. Rough birth rate/natality was 0.19, while juvenile and fawn mortality was 0.13 and 0.31. The population was spatially distributed in group. Growth model of Timor deer was logistic model, with population growth rate of 0.22 in 38,844 individuals/year habitat carrying capacity

Temporal Distribution of Sediment Yield From Catchments Covered by Different Pine Plantation Areas

Soil erosion and sedimentation are environmental problems faced by tropical countries. Many researches on soil erosion-sedimentation have been conducted with various results. Quantifying soil erosion-sedimentation and its temporal distribution are important for watershed management. Therefore, a study with the objective to quantify the amount of suspended sediment from catchments under various pine plantation areas was conducted. The research was undertaken during 2010 to 2017 in seven catchments with various percentage of pine coverage in Kebumen Regency, Central Java Province. The rainfall data were collected from two rainfall stations. A tide gauge was installed at the outlet of each catchment to monitor stream water level. The water samples for every stream water level increment were analyzed to obtain sediment concentration. The results showed that monthly suspended sediment of the catchments was high in January to April and October to December, and low in May to September. The annual suspended sediment fluctuated during the study period. Non-linear correlations were observed between suspended sediment and rainfall as well as suspended sediment and percentage pine areas. The line trend between suspended sediment and percentage of pine areas showed that the increase in pine areas decreased suspended sediment, with the slope of the graph is sharp at the percentage of pine areas from 8% to 40%, then is gentle for pine plantation areas more than 40%

Pola Hujan Di Bagian Hulu Daerah Aliran Sungai Bengawan Solo Dalam Perencanaan Pemanfaatan Sumber Daya Air (Rainfall Pattern for Water Resources Utilization Planning in the Upperstream of Bengawan Solo Watershed)

Informasi mengenai fluktuasi hujan sangat penting terutama bagi masyarakat lokal yang masih bergantung pada sumberdaya alam. Tujuan penelitian ini adalah untuk menganalisis pola hujan di bagian hulu Daerah Aliran Sungai (DAS) Bengawan Solo. Informasi ini dapat digunakan sebagai dasar dalam perencanaan pemanfaatan sumberdaya air. Data curah hujan tahun 1990-2016 dari 14 stasiun penakar hujan dianalisis secara deskriptif untuk mengetahui fluktuasi hujan dan pergeseran musim. Curah hujan tahunan di hulu DAS Bengawan Solo bervariasi antara 1.433,5 mm hingga 3.231,2 mm dengan rerata mencapai 2.224,6 mm. Tidak terjadi Perubahan awal musim hujan maupun musim kemarau, namun demikian durasi musim hujan mengalami peningkatan dari 7 bulan (Oktober-April) pada periode 1990-1998 dan 1999-2007, bertambah menjadi 8 bulan (Oktober-Mei) pada periode 2008-2016. Sebesar 90% curah hujan terkonsentrasi pada musim hujan. Pemanenan air hujan dapat dilakukan untuk mengurangi runoff di musim hujan sekaligus sebagai upaya penyediaan sumberdaya air di musim kemarau