Aplikasi Tank Model Untuk Evaluasi.Unjuk Kerja Operasi Sistem irigasi Lahan Rendah

ABSTRACT The accuracy of quantitative information on water cycle in how well the operation of irrigation system performs water allocation and drainage control is a crucial one. If return flow exists, performance of the water operation has to be evaluated by considering reused water factor. A case study on such kind of analysis was conducted using data collected in a low-lying paddy area with creek networks irrigation system, located in the Oide district, Saga plain, Kyushu, Japan. A Complex Tank Model was applied for simulating the daily water cyclic in the system. Results show that the system yields remarkable irrigation water conservation characterized by the high value of ratio of water use (RPA) and ratio between the return flow and irrigation water (RWS). But there is severe impact on water quality that needs to be clarified. To overcome this problem, application of the model can be developed using Load Discharge concept

Model Simulasi Neraca Air Untuk Menyususn Garis Eksploitasi Rawa Pening

Fengaturan air rawa Pening sangat menentukan unjuk hasil pengelolaan air di DES Tuntang. Tampungan alami di bggian hulu DES Tuntangmerupakan pusat pengaturan awal distribusi air untuk berbagai kebutuhan air di hilir, antara lain terdapat dua buah FLTA, yaitu FLTA Jelog dan FLTA Timo, dan bendung Glapan yang\u27 mempunyai areal irigasi lebih dari 18.700 ha. Fanelitian ini bertujuan menyusun garis eksploitasi-rawa Pening yang\u27 dapat memberikan hasil pengaturan air optimal, dalav anti jumlah pelayanan air ke masing-.masing zona pengguna air diusahakan sedekat mungkin dengan fluktuasi kebutuhan. Cara yang ditempuh adalah dengan menerapkan model simulasi neraca air (water balance) berdasarkan data historis ketersediaan air dan data kebutuhan air untuk irigasi dan non-irigasi. Basil penelitian berupa usulan alternatifgaris eksploitasi rawa Pening yang memberikan unjuk hasil lebih balk dari garis eksploitasi yang selama ini digunakan. Nilai rerata faktor k di bendung Glapan dapat di tingka tkan untuk masa tanam I dan II. Kata kunci: simulasi neraca air - rawa penin

Optimasi Parameter Kalibrasi Model Hujan Aliran Menggunakan Algoritme "Gauss-Newton" (Optimization of Rainfall-Runoff Model Calibration Parameter Using Gauss Newton Algorithm)

Model for continuous strearnflow simulation, namely Rainfall-Runoff Model PLN-PPE Release 01 has been developed by Faculty of Engineering Gadjah Mada University, through cooperation with Engineering Service Centre of National Electricity State Owned Enterprise (PLN-PPE). In order to improve efficiency of the use of model, particularly on calibration procedure, catchment parameter values were optimized using "Gauss-Newton" search algorithm. ⢠In this research, optimization was done for both of calibration and verification model, based on the data collected from upstream Serayu catchment area at central ofJava. For the preliminary research, four of ten parameters were optimized using three set of initial values. As result, the accuracy of model output which were measured by annual volume error (VE), correlation coefficient (R), and mean of relative error (RE) between computed and observed discharges could be increased. All of the optimized parameters proved be converge on the same .final optimum values. By such approach, computation tune needed to carry out model calibration can be reduced significantly because the initial values of some calibration parameters are determined automaticall

HIDROGRAF SATUAN: PERMASALAHAN DAN ALTERNATIVE PENYELESAIAN

Unit hydrograph is one of flood design method that commonly used in Indonesia. Problems emerge in the unit hydrograph application including high rairifall variability both time and space, lack of automatic rairifall data needed for unit hydrograph derivation. However, the output of the catchment system called hydrograph that represent all the phenomena in the system is available. So, effect ofrairifall variability on unit hydrograph and the possibility to derive unit hydrograph based on hydrograph data without rainfall data need to be studied. Unit hydrograph derivation is done by using different rainfall input i.e. single station, rairifall catchment and inverse effective rainfall derived based on hydrograph alone. The resulted unit hydrographs are then used for design flood calculation. Results show that the resulted unit hydrographs vary among the diffirent rairifall inputs. The difference in peak relative to unit hydrograph derived based on average rainfallfor Bedog, Code and Winongo catchments could reach -18%, -30% and -11%, respectively. This result indicates that in the catchment studied, the rainfall variability is relatively high. However, the difference In flood peak is quite small, that is up to -12%for all the catchments. There is a trend that the station closest to the catchment centroid gives small1Jias in designflood relative to the designflood computed based on average rainfal

PRODUKTIVITAS PADI SAWAH DEGAN POLA IRIGASI HEMAT AIR

Traditional irrigation system requires around 80% of the available water resources. Huge water applied in paddy rice cultivation is difficult to fullfill in the next future due to increasing demandfbr other non-irrigation needs such as industry and domestic as a result of increasing population. In addition, the water availability tends to decrease especially during dry season. To overcome the conflict among water users in the future, growing paddy rice with less water is urgently needed Number of water saving irrigation (WSI) systems and traditional irrigation (TRI) system are tested in the paddy rice cultivation. Those WSI systems are the alternate wetting and drying (AWD), semi-dry cultivation (SDC), system of rice intensification (SRI) dan modified traditional method (MTR). Results of the WSJ systems in terms of water productivity i.e. ratio between the yield (kg) with total irrigated water (m3) is compared to TRI that currently applied by farmes in paddy rice cultivation. Results show that in terms of agronomic and water aspects, WSJ systems give better yield than traditionil system. Comparing with TRI, under the SDC system productive tillers and the ,yields increased by 9.7% and 125%, respectively, The SDC and AWD systems could save water up to 38.6% and 34% relative to TRI. The highest water productivity is obtained under SDC system (2.68 kg/ m3) followed by AWD (2.55 kg/ m3), MTR (1.27 kg/ m3) and TR1 (0.79 kg/ m3)

PENGEMBANGAN PERANGKAT LUNAK MODEL HUJAN-ALIRAN METODE GIUH

Untuk mengatasi kesulitan dalam perkiraan hidrograf banjir pada DAS tak terukur di DTA Waduk Wonogiri, dilakukan penelitian awal penggunaan hidrograf satuan metode GIUH. Evaluasi ketelitian metode ini menggunakan acuan hidrograf satuan terukur pada empat DAS yang dihitung menggunakan metode Collins, dengan mencermati debit puncak, waktu puncak, dan waktu dasar. Hasil penurunan hidrograf satuan GIUH digunakan untuk hitungan hidrograf banjir menggunakan program aplikasi model hujan-aliran yang dibuat menggunakan compiler Visual Studio. Hasil penelitian menunjukkan bahwa program aplikasi dapat digunakan untuk hitungan hidrograf banjir secara cepat dengan memanfaatkan sistem telemetri data hidrologi real time dan online. Debit puncak hidrograf banjir metode GIUH cenderung underestimated, yaitu antara -9,3% sampai dengan -54,9%. Untuk waktu puncak dan waktu dasar tidak ditemukan pola perbedaan yang spesifik, yaitu antara 11,1% sampai dengan +66,7% dan -6,7% sampai dengan +46,15%. Penelitian lebih lanjut perlu dilakukan dengan mengkaji lebih detil faktor orde sungai tertinggi dan rumus empirik dynamic parameter velocity agar diperoleh hidrograf satuan yang lebih akurat

Hidrograf Satuan: Permasalahan dan Alternative Penyelesaian

Unit hydrograph is one of flood design method that commonly used in Indonesia. Problems emerge in the unit hydrograph application including high rainfall variability both time and space, lack of automatic rainfall data needed for unit hydrograph derivation. However, the output of the catchment system called hydrograph that represent all the phenomena in the system is available. So, effect of rainfall variability on unit hydrograph and the possibility to derive unit hydrograph based on hydrograph data without rainfall data need to be studied. Unit hydrograph derivation is done by using different rainfall input i.e. single station, rainfall catchment and inverse effective rainfall derived based on hydrograph alone. The resulted unit hydrographs are then used for design flood calculation. Results show that the resulted unit hydrographs vary among the different rainfall inputs. The difference in peak relative to unit hydrograph derived based on average rainfall for Bedog, Code and Winongo catchments could reach -18%, -30% and -11%, respectively. This result indicates that in the catchment studied, the rainfall variability is relatively high. However, the difference in flood peak is quite small, that is up to -12% for all the catchments. There is a trend that the station closest to the catchment centroid gives small bias in design flood relative to the design flood computed based on average rainfall

Correcting Radar Rainfall Estimates Based on Ground Elevation Function

X-band radar gives several advantages for quantitative rainfall estimation, involving higher spatial and temporal resolution, also the ability to reduce attenuation effects and hardware calibration errors. However, the estimates error due to attenuation in heavy rainfall condition cannot be avoided. In the mountainous region, the impact of topography is considered to contribute to radar rainfall estimates error. To have more reliable estimated radar rainfall to be used in various applications, a rainfall estimates correction needs to be applied. This paper discusses evaluation and correction techniques for radar rainfall estimates based on ground elevation function. The G/R ratio is used as a primary method in the correction process. The novel approach proposed in this study is the use of correction factor derived from the relationship between Log (G/R) parameter and elevation difference between radar and rain gauge stations. A total of 4590 pairs of rainfall data from X-band MP radar and 15 rain gauge stations in the Mt. Merapi region were used in evaluation and correction process. The results show the correction method based on the elevation function is relatively good in correcting radar rainfall depth with values of Log (G/R) decreased up to 81.1%, particularly for light rainfall (≤ 20 mm/hour) condition. Also, the method is simple to apply in a real-time system