Kajian alokasi air di Daerah ALiran Sungai Opak

IMANANTA, Rudy Teguh, Dr.Ir. Bambang Yulistiyanto

2005 | Tesis | S2 Teknik Sipil

Permasalahan yang timbul dalam DAS Opak yaitu perubahan tataguna lahan mengakibatkan perubahan perilaku hidrologi. Perubahan perilaku hidrologi ditunjukkan dengan terjadi banjir di musim penghujan dan kekeringan di musim kemarau. Banyak studi telah dilakukan untuk menjawab permasalahan ketidakseimbangan ketersediaan dan kebutuhan air, namun belum diungkapkan mengenai pengalokasian air dengan pendekatan analisis lahan. Pengalokasian sumberdaya air yaitu dengan pembuatan Daerah Pelayanan. Ketersediaan air dalam Daerah Pelayanan tersebut dipakai sendiri dalam wilayah tersebut dan sisanya di alokasikan ke DP di bawahnya. Dalam pengalokasian air di DAS Opak ini dilakukan dengan bantuan perangkat lunak yaitu RIBASIM untuk mempermudah serta mengoptimalkan alokasi air. Hasil penelitian ini menunjukkan analisis neraca air sebagian besar DP yang terdapat dalam DAS Opak mengalami surplus air di musim penghujan dan kekeringan di musim kemarau. Pemenuhan kebutuhan air irigasi defisit pada masa tanam ke 2 dan ke 3, kecuali DP Kretek dan Pesing. Pemenuhan kebutuhan RKI tercukupi 100% kecuali DP Bedog, Kotagede, Kretek, dan Winongo defisit di bulan Januari. Pemenuhan kebutuhan perikanan tercukupi 100%. Pengembangan tahun 2010, pemenuhan kebutuhan RKI defisit pada DP di Selatan Saluran Mataram.

Land use change in Opak River Basin causes hydrologic behavior change. It is shown by flooding events that occur during rainy season and lack of water during the dry season. Many studies have be done to cope with the problems of unbalanced water supply and water demand, but water allocation by land analysis approach has never been revealed. Water resource allocation efforts are taken by dividing the area into several Water District. Water supply in a Water District will be used for it’s area only, and the excess will be allocated to the Water Districts in a lower elevation. To allocate water in Opak River Basin, it is supported by the RIBASIM Software in order to obtain a simpler and optimal water allocation. Water balance analysis show that most the Water District in Opak River Basin is surplus during the rainy season and deficit during the dry season. Supply-demand ratio for irrigation was deficit in the second and third cultivation period, except Kretek and Pesing Water District. Supply-demand ratio for DMI is available 100%, except Bedog, Kotegede, Kretek, and Winongo Water District is deficit in January. Supply-demand ratio for fish pond is available 100%. Developing in 2010, supply-demand ratio for DMI is deficit in Water District in South of Mataram Channel.

Kata Kunci : Daerah Aliran Sungai,Alokasi Air,water supply, water demand, water allocation