Optimasi Pemanfaatan Air Waduk Gongseng di Kabupaten Bojonegoro
Optimizing Gongseng Reservoir Water Utilization in Bojonegoro Regency
Waduk Gongseng terletak di Desa Kedungsari, Kecamatan Temayang, Kabupaten Bojonegoro. Waduk ini termasuk Proyek Strategis Nasional (PSN) yang dirancang untuk memenuhi kebutuhan irigasi sawah seluas 6,191 ha, penyediaan air baku 300 liter/detik, konservasi pariwisata, reduksi banjir hingga 133,3 m3/detik serta PLTMH 0,7 megawatt. Berdasarkan hal tersebut, penting untuk dilaksanakan optimasi pemanfaatan air Waduk Gongseng agar sumber daya air dapat dikelola secara optimal berdasarkan ketersediaan air waduk. Dalam studi ini, optimasi dilakukan untuk kebutuhan air irigasi, air baku, dan potensi PLTA. Untuk mengatasi keterbatasan air, kebutuhan air baku dianggap konstan. Kebutuhan air irigasi dihitung dengan beberapa alternatif luas baku sawah yang berbeda untuk dapat dicukupi kebutuhan irigasinya. Setiap alternatif pola operasi waduk dihitung dengan water balance air waduk.
Berdasarkan analisis, diperoleh hasil yaitu tampungan efektif Waduk Gongseng sebesar 14,765 x 106 m3, debit inflow dengan metode FJ. Mock diperoleh debit maksimal 14,369 m3/detik dan debit terendah -1,431 m3/detik, kebutuhan air baku untuk Kecamatan Temayang, Sugihwaras, Kedungadem, dan Sukosewu keadaan normal 0,241 m3/detik, pada Hari Maksimum 0,278 m3/detik dan kebutuhan pada Jam Puncak 0,422 m3/detik, hasil paling optimal untuk solusi pola operasi waduk pada alternatif 3 dengan luas baku sawah yang dapat diairi tanpa mengalami kegagalan tampungan seluas 2500 Ha dan total kebutuhan air irigasi sebesar 58,048 x 106 m3, nilai debit andalan Q25 2,66 m3/detik, Q50 2,14 m3/detik, Q75 1,58 m3/detik, Q80 1,46 m3/detik, Q90 1,22 m3/detik, Q95 0,66 m3/detik, dan potensi PLTA dengan debit andalan Q90 1,22 m3/detik, menghasilkan daya listrik 291,661 kW dan energi listrik yang didapatkan 2554,955 MWH.
Kata kunci : Waduk Gongseng, Optimasi, water balance, air baku, irigasi, PLTA
Gongseng Reservoir is located in Kedungsari Village, Temayang District, Bojonegoro Regency. This reservoir is a National Strategic Project (PSN) which is designed to meet the irrigation needs of 6,191 ha of rice fields, raw water supply of 300 liters/second, tourism conservation, flood reduction of up to 133.3 m3/second and 0.7 megawatt PLTMH. Based on this, it is important to optimize the use of Gongseng Reservoir water so that water resources can be managed optimally based on the availability of reservoir water. In this study, optimization was carried out for irrigation water needs, raw water and hydropower potential. To overcome water limitations, raw water requirements are considered constant. Irrigation water needs are calculated using several different standard rice field area alternatives to meet irrigation needs. Each alternative reservoir operating pattern is calculated using the reservoir water balance.
Based on the analysis, the results obtained are that the effective storage of the Gongseng Reservoir is 14,765 x 106 m3, inflow discharge using the FJ method. Mock obtained a maximum discharge of 14,369 m3/second and the lowest discharge of -1,431 m3/second, the raw water requirement for Temayang, Sugihwaras, Kedungadem and Sukosewu sub-districts is normal 0.241 m3/second, on the maximum day it is 0.278 m3/second and the demand at peak hours is 0.422 m3/second, the most optimal result for the reservoir operation pattern solution in alternative 3 with a standard area of rice fields that can be irrigated without experiencing storage failure of 2500 Ha and a total irrigation water requirement of 58,048 x 106 m3, the mainstay discharge value Q25 is 2.66 m3/second , Q50 2.14 m3/sec, Q75 1.58 m3/sec, Q80 1.46 m3/sec, Q90 1.22 m3/sec, Q95 0.66 m3/sec, and potential for hydroelectric power with a mainstay discharge of Q90 1, 22 m3/second, producing 291,661 kW of electrical power and 2554,955 MWH of electrical energy obtained.
Keywords : Gongseng Reservoir, Optimization, water balance, raw water, irrigation, hydropower