36 research outputs found
Prediction of Water Discharge and Sediment in Teak Forested Area Using Artificial Neural Network Model
No full textInformation on the relationship of rainfall with discharge and sediment are required in watershed management.This relationship is known to be highly nonlinear and complex. Although discharge and sediment has been monitored continuously, but sometimes the information is not or less complete. In this condition, modeling is indispensable.The research objective is to create a model to predict the monthly direct runoff and sediment using Artificial Neural Network (ANN).The model was tested using rainfall data at t-3 and t-4 as input, and discharge and sediment at t+3 and t+4 as output. The data used is the data from 2001 to 2014. The results showed that of some models tested there are two models for the prediction of discharge and two models for sediment.The model was chosen because it has the smallest MSE, the largest R2 and satisfying K (0.5 to 0.65).Thus, these models can be used to predict discharge andsediment for a period of t+3 and t+4. Prediction of discharge of t+3 and t+4 may use Q t+3 = 0,64 Q t-3 + 0,05 and Q t+4 = 0,65 Q t-4 + 0,074 res pectively, while for predicting sediment of t+3 and t+4 may use equations QS t+3 = 0,45 QS t-3 + 0,052 and QS t+4 = 0,45 QS t-4 + 0,052. This ANN modeling can be applied to predict the flow and sediment in other locations with an architecture adapted to the conditions of available data
Sebaran Potensi Kekeringan Meteorologis di Daerah Aliran Sungai Bengawan Solo Bagian Hulu dan Upaya Penanggulangannya
No full textVariabilitas hujan menyebabkan setiap wilayah berpotensi mengalami kekeringan. Waduk Gajah Mungkur telah berkontribusi menanggulangi kekeringan di Daerah Aliran Sungai (DAS) Bengawan Solo, namun pengelolaannya menghadapi ancaman pendangkalan akibat erosi. Tujuan penelitian ini untuk mengidentifikasi potensi kekeringan di DAS Bengawan Solo bagian hulu, dan mengidentifikasi penyebab pendangkalan Waduk Gajah Mungkur untuk upaya penanggulangannya. Standardized precipitation index (SPI) dari 93 stasiun hujan menunjukkan nilai bervariasi mulai -2,621 (amat sangat kering) hingga 7,689 (amat sangat basah). Kekeringan meteorologis yang terjadi berdurasi antara 1-7 bulan. Wonogiri merupakan kabupaten yang paling sering terpapar kekeringan. Karena ancaman pendangkalan, pembangunan Waduk Gajah Mungkur menjadi kurang efektif dalam menanggulangi kekeringan yang terjadi. Berdasarkan metode Universal Soil Loss Equation (USLE), erosi yang terjadi di hulu berperan terhadap pengurangan volume waduk. Beberapa upaya yang dapat dilakukan untuk menjaga daya tampung waduk adalah pengerukan secara berkala, revegetasi. dan pengolahan lahan yang tepat. Revegetasi dan pengolahan lahan yang tepat dapat dilakukan terutama di daerah dengan tingkat bahaya erosi berat dan sangat sangat berat. Pencegahan pendangkalan waduk ini diharapkan dapat menjaga kontinuitas ketersediaan sumber daya air. Rainfall variability causes every region to experience drought. Gajah Mungkur Reservoir has contributed to the drought prevention in Bengawan Solo Watershed, but its management faces the threat of siltation for soil erosion. This study were aimed to identify potential droughts in the upstream Bengawan Solo Watershed and to identify the causes of siltation in the Gajah Mungkur Reservoir for its prevention efforts. Standardized precipitation index (SPI) of 93 rainfall stations varies from -2,621 (extremely drought) to 7,689 (extremely wet). The meteorological drought duration was between 1 to 7 month. Wonogiri is the most drought-exposed. For the threat of silting, the Gajah Mungkur Reservoir has become less effective in dealing with the drought. Based on the Universal Soil Loss Equation (USLE) method, soil erosion in the upstream contributes to the reduction in reservoir volume. Some efforts that should be done to maintain reservoir capacity are periodic dredging, revegetation. and proper land management. Revegetation and proper land management can be carried out in areas with severe and very severe erosion hazards. Prevention of silting of reservoirs is expected to maintain water resources availability
IDENTIFIKASI TINGKAT BAHAYA LONGSOR DENGAN SKALA DATA BERBEDA UNTUK PERENCANAAN DAS MIKRO NARUWAN, SUB DAS KEDUANG
No full text<p class="JudulABSInd"><strong>ABSTRAK</strong></p><p class="abstrak">Dalam rangka mendukung perencanaan pengelolaan, DAS Mikro Naruwan yang termasuk pada Sub DAS Keduang, DAS Solo, dilakukan identifikasi tingkat potensi bahaya tanah longsor. Penggunaan skala yang berbeda mempengaruhi tingkat kedetilan data. Analisis dilakukan dengan menggunakan <em>software </em>ArcMap 10.2 dengan data spasial yang terdiri dari intensitas hujan, kemiringan lahan, tipe batuan, keberadaan sesar, kedalaman regolit, penggunaan lahan, infrastruktur dan kepadatan pemukiman. Hasil analisis menunjukkan bahwa apabila menggunakan data penutup lahan skala 1:250.000, 86,4% lokasi penelitian merupakan lahan tidak rentan longsor dan 13,6% sedikit rentan. Namun demikian, bila mengunakan data skala 1:5.000 kategori kerentanan tersebut mengalami penurunan tingkat, yaitu kategori tidak rentan berubah menjadi agak rentan 64,2% dan 35,8% sedikit rentan, sedangkan kategori tidak rentan mengalami penurunan menjadi agak rentan dan sedikit rentan. Hal ini menunjukkan bahwa penggunaan skala detil diperlukan dalam perencanaan pengelolaan DAS mikro dan menentukan skala prioritas penanganan. Longsor pada kategori agak rentan paling luas berada di Desa Bubakan (36%), disusul Wonokeling (19,0%) dan Wonorejo (8,6%). Secara fisik, prioritas penanggulangan bencana longsor secara berurutan lebih banyak di lakukan di Desa Bubakan, kemudian di Wonokeling dan Wonorejo.</p><p><strong>Kata kunci</strong>: mikro, DAS, longsor, skala, detil</p><p class="judulABS"><strong><em>ABSTRACT</em></strong></p><p class="Abstrakeng"><em>To support watershed management planning of Naruwan Microcatchment, Keduang Sub Watershed, Solo Watershe. Identification of potential landslide vulnerability was conducted to support. Using the different scale is expected to influence the detail data. Analyses were performed using ArcMap 10.2 software with spatial data that consists of rainfall intensity, slope, rock type, fault, regolith depth, landuse, infrastructure and population density. The results showed that when using land cover data of 1: 250.000 scale, 86,4% of the area are not susceptible to landslides and 13,6% moderately low susceptible. However, when using the data of 1: 5.000 scale, landslide category has decreased its susceptibility level. Not susceptible category turned into moderately susceptible 64,2% and 35,8% moderately low susceptible, while the category declined not susceptible to be moderately susceptible and moderately low susceptible. This fact shows that the use of detailed scale is needed in the micro watershed management planning and it will determine the priority handling. Moderately susceptible landslide is mostly located in Bubakan village (36%), Wonokeling (19,0%) and Wonorejo (8,6%). Physically, the landslide disaster management priorities sequentially should be in the Bubakan village, then Wonokeling and Wonorejo.</em></p><p class="katakunci"><em><strong>Keywords</strong>: micro, watershed, landslide, scale, detail</em></p></jats:p
Degraded Land Analyses of Brantas River Basin to Support Land Rehabilitation
No full textLand degradation in the Brantas River Basin occurs very massively as reflected by high erosion and sedimentation. Information related to soil erosion is important since it is one of the basic information in determining the degraded land in a watershed. The purpose of this study was to analyze and identify the distribution of degraded land in the Brantas river basin as an effort to mitigate land degradation through forests and land rehabilitation in suitable locations. Erosion analysis was carried out spatially on a watershed scale using the USLE (Universal Soil Lost Equation) method. Analyses showed that weighted soil erosion values in the Brantas river basin were448.73 tons/ha/year which was classified as high erosion level. The area of 408,818 ha (41.74%) of Brantas river basinneeds erosion handling because 22.51% was identified in the high erosion value category and 19.23% was included in very high erosion values. Those areas were identified as protected forests, production forests, dry land, and mixed gardens. The type of soil and the erodible of soilare part of the determinants of the high value of erosion, but these factors are difficult to manage while land cover types and land management which are the causes of erosion are relatively manageable. The approach to rehabilitate forests and land can be used as an effort to prevent and reduce erosion by taking into account the selection of related types of habitus (form and stratification) and economic value
CARBON STOCK ASSESSMENT IN PINE FOREST OF KEDUNG BULUS SUB-WATERSHED (GOMBONG DISTRICT) USING REMOTE SENSING AND FOREST INVENTORY DATA
No full textCarbon stock in tree biomass can be quantified directly by cutting and weighing trees. It is assumed that 50% of the dry weight of biomass consists of carbon. This direct measurement is the most accurate method, however for large areas it is considered time consuming and costly. Remote sensing has been proven to be an important tool for mapping and monitoring carbon stock from landscape to global scale in order to support forest management and policy practices. The study aimed to (1) develop regression models for estimating carbon stock of pine forests using field measurement and remotely sensed data; and (2) quantify soil carbon stock under pine forests using field measurement. The study was conducted in Kedung Bulus sub-watershed, Gombong - Central Java. The derived data from Satellite Probatoire d'Observation de la Terre (SPOT) included spectral band 1, 2, 3, and 4, Normalized Differences Vegetation Index (NDVI), and Principle Component Analysis (PCA) images. These data were integrated with field measurement to develop models. Soil samples were collected by augering for every 20 cm until a depth of 100 cm. The potential of remote sensing to estimate carbon stock was shown by the strong correlation between multiple bands of SPOT (band 2 , 3; band 1, 2, 3; band 1, 3, 4; and band 1, 2, 3, 4) and carbon stock with r = 0.76, PCA (PC1, PC2, PC3) and carbon stock with r = 0.73. The role of pine forest to reduce CO2 in the atmosphere was demonstrated by the amount of carbon in the tree and the soil. Carbon stock in the tree biomass varied from 26 to 206 Mg C ha-1 and in the soil under pine forest ranged from 85 to 194 Mg C ha-1
APLIKASI SISTEM INFORMASI GEOGRAFIS UNTUK PERHITUNGAN KOEFISIEN ALIRAN PERMUKAAN DI SUB DAS NGUNUT I, JAWA TENGAH
No full textIdentification of the Main Water Quality Parameters for Monitoring and Evaluating Watershed Health
No full textWater quality is one of the crucial parameters in monitoring and evaluating watersheds. A large number of parameters causes the monitoring and evaluation of watershed performance to be less efficient and costly. This study aims to determine the main parameters as a method of simplifying water quality observation parameters by producing equations that can be used to predict the level of pollution of a non-point source pollutant (watershed). A sampling of surface water was carried out by purposive sampling at several outlets located in the Brantas and Upper Solo watersheds. The research parameters analysed were: TSS, TDS, BOD, COD, Phenol, Free Chlorineine, Sulfide, Arsenic, Fe, Pb, Phosphate, Nitrate, Nitrite, Detergent, Turbidity and E. Coli. The results of the analysis of water quality are used to calculate the value of the Pollution Index (PI) according to the Decree of the Minister of Environment No. 115 of 2003 and to determine the class of water quality standards that refer to Class III water quality standards, in Government Regulation No.82 of 2001. The analysis showed that all samples were at mild to moderate pollution levels, and did not meet class III water quality standards. Multiple regression analysis produced two equations, namely: Model 1: PI = 3.952 + 91.668 Phenol and Model 2: PI = 3.086 + 80.167 Phenol + 0.152 BOD, with R squared values of 53% and 69.9% with a confidence level of 0.005. Thus the prediction of pollution levels of similar watershed can be made only by using the two most influential parameters namely phenol and/or BOD alone.
ANALISIS SPASIAL KEMAMPUAN LAHAN DALAM PERENCANAAN PENGELOLAAN DAS MIKRO
No full text<p class="abstrak"><span lang="X-NONE">Untuk mewujudkan kondisi lahan yang produktif sesuai dengan daya dukung DAS diperlukan rencana detil sehingga mudah diterapkan di lapangan. Perencanaan detil perlu didahului dengan penelaahan global untuk mengetahui gambaran umum kondisi lahan aktual, sehingga dapat digunakan untuk menetapkan prioritas-prioritas lokasi yang penting untuk segera ditangani. Dalam paper ini dilakukan analisis kemampuan penggunaan lahan (<em>land use capability analys</em></span><em><span lang="EN-ID">i</span></em><em><span lang="X-NONE">s</span></em><span lang="X-NONE">) skala detil (DAS mikro) berdasar kepada informasi semi detil (sub DAS) dengan menggunakan ArcMap 9.3. </span><span lang="X-NONE">Penelitian dilakukan di DAS Mikro Naruwan yang termasuk dalam Sub DAS Keduang, DAS Solo. DAS Solo merupakan salah satu dari 108 DAS prioritas yang harus dipulihkan. Hasil analisis menunjukkan bahwa 38% lokasi penelitian didominasi tegal, kebun campur 23%, hutan 20% dan sisanya oleh sawah, permukiman dan semak belukar. Meskipun kebun campur dan hutan mendominasi, akan tetapi terdapat 56,24% penggunaan lahan yang tidak sesuai dengan klas kemampuan lahannya. Pada lahan yang tidak sesuai tersebut 33,14% mengalami erosi pada taraf sangat berat (&gt;480 ton/ha). Lahan yang tidak sesuai tersebut terutama adalah tegal. Karena sebagian besar merupakan lahan milik masyarakat sehingga tidak mudah untuk merubah penggunaannya. Oleh sebab itu perlu dilakukan kompromi untuk mengurangi dampak negatifnya yaitu dengan pengembangan hutan rakyat dengan sistem agroforestri, perbaikan hutan di bantaran sungai, peningkatan persentase penutupan lahan, pembuatan teras gulud, pemberian mulsa, pembuatan rorak, pembangunan dam penahan dan dam pengendali untuk mengendalikan erosi. </span></p><p class="katakunci"><strong><span lang="AF">Kata kunci:</span></strong><span lang="AF"> kemampuan</span> lahan<span lang="AF">, penggunaan lahan</span>, <span lang="AF">erosi, perencanaan, konservasi<strong></strong></span></p><p class="judulABS"><strong><span lang="AF">ABSTRACT</span></strong></p><p class="Abstrakeng"><em><span lang="X-NONE">To create a productive land condition in accordance with the carrying capacity of watershed needs a detailed planning so it is applicable in the field. The detailed planning needs to be preceded by a global assessment to comprehend the actual general description, so it can be used to set priorities that are important to be addressed. In this paper, land use capability analys</span><span lang="EN-ID">i</span><span lang="X-NONE">s were used in the detail planning (micro-catchment) based on the semi-detail (sub-watershed) information by utilizing GIS analys</span><span lang="EN-ID">i</span><span lang="X-NONE">s. The study was conducted in Naruwan micro watershed which is included in Keduang Sub-Watershed of Solo Watershed. Solo Watershed is one of 108 watersheds that should be recovered. Analys</span><span lang="EN-ID">i</span><span lang="X-NONE">s show that 38% of the area is dominated by dryland, 23% mixed garden, 20% production forest, and the rest consisted of paddy field, settlement and shrubs. Although the mixed garden and forest dominate, but there are 56</span><span lang="EN-ID">,</span><span lang="X-NONE">24% of the land use that is suitable to its land capability. The 33</span><span lang="EN-ID">,</span><span lang="X-NONE">4% of the unsuitable land use, have very severe erosion (&gt;480 ton/ha). The unsuitable land use is dry land agriculture. Since most of the land belonging to the community, so it is not easy to change its usage. Therefore it is necessary to compromise the type of land uses which reducing its negative impact namely the development of community forest by applying agroforestry system, improvement of riparian forest, increasing the percentage of permanent land cover, terracing, mulching, manufacture of sediment trap (rorak), building retaining dam and control dam to control erosion.</span></em></p><p class="katakunci"><em><strong><span lang="AF">Keywords: </span></strong>land c<span lang="AF">apability, </span>l<span lang="AF">and</span> u<span lang="AF">se, erosion, planning, conservatio</span><span lang="EN-ID">n</span></em></p></jats:p
THE POTENTIAL OF FOREST BUFFER TO PREVENT STREAM FROM WATER POLLUTANTS:A CASE STUDY IN GROJOKAN SEWU SUB-WATERSHED, KARANGANYAR DISTRICT, CENTRAL JAVA
No full textPopulation growth leads to water scarcity in terms of both quality and quantity. Agricultural and urban watersheds potentially produce more pollutantsthan forested area. It is considered that forested area has potential in storing and protecting water supply in such a way that water distribution and quality can be guaranteed. The objective of the study was to determine the relationship between the percentages of forested area in a watershed with the water quality. Thestudy was conducted in 2010in GrojokanSewu Sub-watershed, Karanganyar District, Central Java. Using GIS (Geographic Information System), this sub-watershedwas divided into four sub-sub-watershedswith different percentages of forested areas. Water samples were collected in each sub-sub-watershedto find out the relationship between the forested area and the total dissolvedsolids, turbidity, sodium, nitrite, nitrate, sulfate and organic matters. The statistical analysis indicates relationships in quadratic form between sodium, nitrite, TDS, sulfate and organic matters with the percentage of forested area (R2=0.99, R2=0.99, R2=0.98, R2=0.95 and R2=0.77, respectively). The relationships are different from those of turbidity and nitrate that have low R2 (R2=0.28 and R2=0.36) values. It implies that the forested area is capable to reduce sodium, nitrite, TDS, sulfate and organic matters, and thus water pollutants can be reduced by forest formation as it can filter water through retention of sediments and nutrients
