Suchergebnisse

Abstrak Sektor pertanian masih merupakan primadona masyarakat dan dijadikan sebagai pekerjaan dalam menunjang kehidupan, meskipun banyak kawasan pertanian yang beralih fungsi menjadi pemukiman terutama di perkotaan. Hampir setiap tahun, luas panen mengalami penurunan. Untuk mengantisipasi hal tersebut, pemerintah dan pemerintah daerah telah banyak membangun infrastruktur keairan, terutama bendung dan bendungan. Daerah irigasi Citanduy dengan luas layanan 427 hektar merupakan salah satu daerah irigasi di Kota Tasikmalaya, sehingga sangat rentan terhadap alih fungsi lahan persawahan menjadi pemukiman. Ketersediaan air sangat penting dalam pemenuhan areal pertanian. Penelitian ini dilakukan untuk mengetahui debit andalan di DAS Citanduy-Sirnagalih seluas 474,65 km2. Terdapat 2 pos curah hujan yaitu Cigede dan Tejakalapa selama sepuluh tahun dari tahun 2009 hingga 2018. Curah hujan rata-rata bulanan dihitung dengan metode Thiessen dengan proporsi luas pengaruh adalah 0,4 dan 0,6. Evapotranspirasi dihitung menggunakan metode Penman-Monteith, dan pemodelan debit menggunakan metode NRECA. Pos duga air Asta-Cikunir digunakan sebagai acuan dalam menentukan parameter kalibrasi yaitu PSUB, GFW, dan tampungan air tanah awal dengan nilai 0,8, 0,29: 100, serta nilai NSE 0,719. Debit andalan Q80 adalah 17,4 m3/s. Debit andalan adalah ketersediaan air di daerah irigasi Citanduy. Berdasarkan debit andalan ini, musim tanam I dan II masih dapat dilakukan secara bersamaan. Kata kunci: debit andalan, kalibrasi, NSE, sungai Citanduy Abstract The agricultural sector is still the prima donna of the community and is used as a job to support life. However, many agricultural areas have been converted into settlements, especially in urban areas. Almost every year, the harvested area has decreased. To anticipate this, the government and local governments have built a lot of water infrastructure, especially weirs and dams. The Citanduy irrigation area with a service area of 427 hectares is one of the irrigation areas in the City of Tasikmalaya, so it is very vulnerable to the conversion of rice fields into settlements. The availability of water is crucial in fulfilling agricultural areas. This research was conducted to determine the mainstay discharge in the Citanduy-Sirnagalih watershed covering an area of 474.65 km2. There are two rainfall posts, namely Cigede and Tejakalapa, for ten years from 2009 to 2018. The average monthly rainfall is calculated by the Thiessen method, with the proportion of the area of influence being 0.4 and 0.6. Evapotranspiration was calculated using the Penman-Monteith method and discharge modeling using the NRECA method. The Asta-Cikunir water gauge post is used as a reference in determining calibration parameters, namely PSUB, GFW, and initial groundwater reservoirs with values of 0.8, 0.29: 100, and NSE values of 0.719. The Q80's dependable flow is 17.4 m3/s. The mainstay of debit is the availability of water in the Citanduy irrigation area. Based on this reliable discharge, planting seasons I and II can still be carried out simultaneously. Keywords: dependable flow, calibration, NSE, Citanduy river

Currently, there are three sub-districts in Tasikmalaya City that are still vulnerable to clean water, namely Kawalu, Tamansari, and Cibeureum sub-districts. PDAM Tirta Sukapura, owned by the Tasikmalaya Regency Government, has not been able to meet clean water needs, so the Tasikmalaya Municipality Government plans to build a new PDAM as an alternative. The Ciwulan river in Cibeuti Village is a source of water that will be used as a collection point. Rain data was taken from 2 stations, namely Gunung Satria and Cikunten II stations, for ten years. The evapotranspiration value was calculated using the Penman-Monteith method. The calculation of the discharge in the intake area, namely Ciwulan-Cibeuti with a watershed area of 405 km2, used the NRECA method using parameters taken from the calibrated Ciwulan-Sukaraja station. The calibration parameters are PSUB = 0.86; GWF = 0.22, reduction coefficient = 0.80; and NSE = 0.764. The determination of the dependable flow is calculated using the Weibull method. The magnitude of the Q90's dependable flow is 4.3 m3/s. The projected population for the next 15 years is estimated at 307,857 people, so the amount of water needed is around 0.535 m3/s. Opportunities for business entities to participate in building PDAM are wide open, with the certainty of return plus profits or independent management by business entities within a certain period of time. The challenge for the government and business entities is to provide reasonable prices to customers and new networks.