Rockfill dams have better stability than homogeneous soil dams. It allows to design the dam more slim with a higher slope. The disadvantage of rockfill dam is in the core zone as an impermeable zone. Zoned vertical core rockfill dam is a combination of various material properties. Geometry and drainage design will affect the seepage and phreatic line properties that occur. Numerical modeling and calculations are used to calculate the seepage profile more accurately. The combination of the parameters of the permeability coefficient (K), reservoir water level (Δh) and the length of the seepage path (L) can be used to determine the relationship between parameters with the same unit. 2D modeling take into account saturated/unsaturated conditions with steady state on each parameter. This study uses the Jatibarang-Indonesia dam as a basic model. The seepage profile at condition K1 (k = 1x10-5cm/sec) is q/k = -0.0018 (h2/L)2 + 1.3496h2/L + 53.241 and the seepage profile K2 (k=1x10-7cm/s) is q/k = -0.1521 (h2/L)2 + 90.402h2/L + 5480.2. This equations can be used to estimate seepage that occurs in a dam of other rock fill zoned vertical core dam based on the permeability coefficient value (K) more practically for all values of Δh and L reviewed.Keywords: Seepage, Rockfill Dam, Permeability, FEM, Numerical Analysis
Population growth is increasing, but it is not accompanied by an increase in food needs impartial. Indonesian swamp land potential of about 33.4 million ha, consisting of tidal swamp 20.1 million ha and 13.3 million ha of lowland swamp. The Government has made the development of swamps into agricultural land, including the Semangga swamp area (4,000 ha) The cropping pattern of rice (100%)-crops (40%)-"bero". The problem faced are; the length is 7-month of dry season and low agricultural production, are therefore likely to swamp irrigation system optimalization. The method used to carry out water balance analysis and performance assessment of irrigation system include; the physical condition of irrigation, the application of the system of planting and water delivery techniques to the use of land for a year, then performed according to the potential land development plan and water resources available. Results of water balance analysis on Semangga Swamp Area existing condition indicate that water deficit occurred during the second growing season crops (May-July) and in December. So do the appropriate development plan defined cropping pattern III, namely rice (100%)-crops (60%)-crops (45%) with the addition of a total area of 1,000 ha through the use Kumbe River and Maro River and other water reservoirs to overcome deficits in the availability of water in the dry season that is equal to 2.5m³/s (April to August and October to December), while 6.5m³/s in September, 72.40% irrigation system performance with good category.
The design of rainwater harvesting is planned for alternative water source in Universitas Diponegoro area and hopefully it can reduce the use of groundwater as the main source water to fill the demand of water in Universitas Diponegoro Tembalang area. The use of groundwater to fill the water demand in Universitas Diponegoro Campus for years 2014/2015 of 2.23 lt/dt it more than the optimum discharge are allowable to take the water wells is equal to 0.2-1 lt/dt. Based on that the planning of the rainwater harvesting building is made of with a volume of 245 m 3 with a dimensions of 7m x 7m x 5m and dimensions of infiltration wells with a diameter of 1.5 and depth of 3m. Planning of the rain water harvesting in the Universitas Diponegoro Tembalang area the cost of Rp 275,465,000,-with the process of work for 29 days.
The Telaga Kenyamukan as a raw source of Kudungga WTP is studied to determine the water availability. Historical data used in hydrological analysis are sometimes incomplete or have a short time period, so the results may not match the conditions in the field. Hydrological analysis in this study used rainfall data from Pit-J and AB Station from 2005 to 2016, and climatology data from the Sepinggan Meteorological Station from 2005 to 2016. The discharge was analyzed by Mock method, then generated up to year of 2038 with the Thomas-Fiering method and obtained the dependable flow with the monthly basic method in a 90% probability, resulting in 467l/sec. The water requirements are calculated by projecting the population for the next 20 years, with the results of the RWC (Regional Water Company) total water demand in 2019 amounting to 259.99 l/sec and increasing up to 2038 to 630.32 l/sec. With a water balance analysis, the water availability in the next 20 years in meeting needs is in a surplus condition, but in RWC water supply systems which depend on Water Treatment Plant capacity, since 2028 the WTP capacity must be increased due to a deficit of -12.57 l/sec.
Many studies have shown that land use changes in watersheds such as forests that convert to settlements, industrial and estates, have an impact on flooding. So it is important to know the correlation between the various land use changes to the discharge within a watershed. This study is a preliminary study in an attemptto assess the correlation between land cover index and peak discharge, with case studies in the Beringin River Basin.The peak discharge with return period of 2, 5, 10, 20, 50 and 100 dihitung menggunakan program HEC-HMS yang merupakan model pengalihragaman hujan menjadi aliran, yang dikembangkan oleh Hydrologic Engineering Centre (HEC) dari US Army Corps Of Engineers, dan indek tutupan lahan (land covered index , LCI) didefinisikan sebagai jumlah dari indek guna lahan (LUI). Hasil studi kasus yang dilakukan menunjukkan bahwa didapat hubungan yang kuat antara indek tutupan lahan dengan debit puncak dengan persamaan Q 100 = -22,42LCI2 + 214, 62,33LCI 2 + 181,19,30LCI 2 + 145,61,36LCI 2 + 118,29,42LCI 2 + 91,44LCI 2 + 53,5. Kata kunci: Guna lahan, debit puncak, daerah aliran sungai, indek guna lahan indek, tutupan lahan. PendahuluanSeiring dengan berkembangnya jumlah penduduk dan meningkatnya aktivitas atau kegiatan masyarakat, akan memicu pertumbuhan kota dengan berbagai pembangunan di berbagai sektor, dan pembangunan sarana dan prasarana fisik adalah sektor yang cukup pesat perkembangannya. Pertumbuhan kota tersebut sering diiringi oleh pembukaan lahan untuk pemukiman, pemekaran daerah industri dan peruntukan lahan yang lain yang bermuara kepada perubahan tata guna lahan. Interaksi alam dari vegetasi, tanah dan air (hujan) disertai dengan intervensi manusia melalui usaha
A change of the characteristic of a river basin's component could transform the behaviour of the basin as a whole. In some parts of Indonesia, the land-use changes from forest into settlement, industry, and farming increase the risk of flooding. Therefore, it is important to understand the correlation between the changes of various land uses and runoff discharge in a river basin. This study makes an attempt to formulate the relation between the land-use change indexes and run-off discharge, i.e. the correlation between the changes in the index of covered land in a river basin and the change in the peak run-off discharge. The peak discharge is computed with HEC-HMS software, developed by the Hydrologic Engineering Center (HEC) and US Army Corps of Engineers, which computes the run-off discharge from the precipitation. As for the land cover index (LCI), it is defined as the sum of the land-use index (LUI). The result of the case study in the Beringin river basin (Indonesia) shows the strong correlation between the change in the land cover index and the change in the run-off discharge with such a relation: DQ = -4E -05 DLCI 2 + 0.0788 DLCI + 6.6187 or DLCI = 0.25 DQ 2 + 6.24 DQ -47.40. DQ is defined as the change in the run-off discharge and DLCI is the change in the land cover index.
Bendungan urugan batu zonal inti tegak mempunyai geometri yang lebih kompleks dibandingkan dengan bendungan tanah homogen. Banyaknya bentuk geometri dan material yang digunakan menyebabkan prediksi dan perhitungan yang lebih rumit. Pemodelan finite element (FEM) sering digunakan untuk menghitung perilaku rembesan yang terjadi. Tujuan dari penelitian ini adalah untuk mendapatkan model numeris yang dapat digunakan sebagai estimasi debit rembesan sekaligus sebagai validasi pemodelan rembesan pada bendungan urugan batu inti tegak. Evaluasi debit berdasarkan pengukuran instrumen diperlukan untuk validasi pemodelan numeris yang dilakukan. Hukum Darcy dan Casagrande dapat digunakan untuk mengevaluasi pola debit terukur. Debit rembesan berbanding lurus dengan ketinggian muka air waduk dan berbanding terbalik dengan panjang lintasan rembesan. Metode statistik dan regresi digunakan untuk mendapatkan pola rembesan berdasarkan akuisisi data rembesan melalui V-Notch. Estimasi dan pola rembesan ini penting untuk diketahui, sehubungan dengan kinerja electronic instrument yang berpotensi mengalami kerusakan dan sulitnya akses pada gallery karena suatu keadaan. Studi kasus pada paper ini dilakukan pada Bendungan Jatibarang (Semarang), dimana bendungan ini mulai beroperasi penuh pada tahun 2015. Inkonsistensi data debit rembesan terjadi sampai dengan 3 tahun setelah penggenangan bendungan dilakukan. Pola linier hubungan debit rembesan (q) berdasarkan ketinggian muka air waduk (h) yaitu q = 0.5221h - 68.958. Koefisien determinasi pada model tersebut sebesar 78.5%, nilai ini mengindikasikan bahwa model tersebut sudah cukup baik untuk digunakan. Pendekatan ini dapat digunakan sebagai validasi data pada semua jenis pemodelan sesuai dengan tujuan pemodelan tersebut akan dilakukan. Kata Kunci : rembesan; bendungan urugan batu; v-notch ABSTRACTVertical zoned rockfill dam has a more complex geometry compared to a homogeneous earthfill dam. The many geometric shapes and materials used to cause more complex predictions and calculations. Finite element (FEM) modeling is often used to calculate seepage behavior. The purpose of this study is to obtain a numerical model that can be used to estimate of seepage discharge and as validation of seepage modeling on zoned vertical rockfill dam. Seepage evaluation based on instrument measurements is needed for validation of numerical modeling performed. Darcy's and Casagrande's Law can be used to evaluate the measured discharge pattern. The seepage discharge is directly proportional to the height of the reservoir water level and inversely proportional to the length of the seepage path. Statistical and regression methods are used to obtain the seepage pattern based on seepage data acquisition using V-Notch. Estimation and seepage pattern is important to know due to the performance of electronic instruments that have apotential damage and difficult access to the gallery. The case study in this paper was carried out at the Jatibarang Dam (Semarang), where the dam began full operation in 2015. The inconsistency of seepage discharge data occurred up to 3 years after the impounding of the dam. The linear pattern of seepage discharge relationship (q) based on reservoir water level (h) is q = 0.5221h - 68.958. The coefficient of determination in the model is 78.5%, this value indicates that the model is good enough to be used. This approach can be used for data validation on all types of modeling in accordance with the purpose of the modeling will be carried out.
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