Deriving reservoir operating rules considering ecological demands of multiple stations

Reservoirs play important roles in hydropower generation, flood control, water supply, and navigation. However, the regulation of reservoirs is challenged due to their adverse influences on river ecosystems. This study uses ecoflow as an ecological indicator for reservoir operation to indicate the extent of natural flow alteration. Three reservoir optimization models are established to derive ecological operating rule curves. Model 1 only considers the maximization of average annual hydropower generation and the assurance rate of hydropower generation. Model 2 incorporates ecological objectives and constraints. Model 3 not only considers the hydropower objectives but also simulates the runoff and calculates the ecological indicator values of multiple downstream stations. The three models are optimized by a simulation-optimization framework. The reservoir ecological operating rule curves are derived for the case study of China's Three Gorges Reservoir. The results represent feasible schemes for reservoir operation by considering both hydropower and ecological demands. The average annual power generation and assurance rate of a preferred optimized scheme for Model 3 are increased by 1.06% and 2.50%, respectively. Furthermore, ecological benefits of the three hydrologic stations are also improved. In summary, the ecological indicator ecoflow and optimization models could be helpful for reservoir ecological operations.

SIMULASI POLA OPERASI EMBUNG SERBAGUNA TAMBAKSARI KABUPATEN CILACAP DENGAN METODE STANDARD OPERATING RULE (SOR)

Human survival depends on water availability as water is a basic needs. As population increases, water becomes more limited. One of the ways to prevent draught is collecting water in retention basin. Tambaksari Multipurpose Retention Basin serves to provide basic water demand and irrigation water for the local community. Water availability and water demand should be equal, so a simulation of the operating patter of the retention basin is necessary to distribute water equally and determining the failure level of the retention basin in performing its task. In the present study, the retention basin operating pattern was simulated using Standard Operating Rule (SOR) method. The present study used secondary data, including population data, rainfall data, climatological data and technical data of the retention basin. The size of DAS Tambaksari is 0.41 km² while the size of the irrigated land is 12 Ha. The rainfall data was from 2008-2018 obtained from two rain stations, population data of Tambaksari Village was from 2008-2019, and the climatological data was from 2014-2019. The simulation result of the retention basin operating pattern using SOR method showed that the final collection wasn’t under minimum collection and failure happened in the operation of the retention basin for one year. . The optimal ability of the target release is 70.83% for the reliability of irrigation needs and the level of reliability for raw water needs of 58.33%. Population projection analysis to determine the population in 20 years showed that the future population of 4044 required 3.861 l/person/s of water. Irrigation demands for rice-rice-palawija planting pattern showed that irrigation intake was 11.89 l/s. Water balance determined the balance between inflow and outflow. The value for average water availability was 0.021 m³/s while total average water demand was 0.016 m³/s. therefore, the water availability in partial intake wasn’t able to meet the irrigation and basic water demands. Keywords: discharge, retention basin operation simulation, SOR

POTENSI PEMANFAATAN SUMBER DAYA AIR KULONG BEKAS PENAMBANGAN TIMAH UNTUK MENUNJANG IMBANGAN AIR DI KABUPATEN BANGKA TENGAH

Sumber daya air kulong bekas penambangan timah mempunyai potensi yang cukup besar untuk dimanfaatkan. Pemanfaatan sumber air tersebut belum didasari pada prinsip nilai keandalan kulong itu sendiri. Penelitian ini bertujuan untuk mengetahui berapa besar potensi keandalan kulong dalam pemanfaatnya. Penelitian ini dilakukan pada 7 (tujuh) lokasi kulong bekas penambangan timah dengan karakterikstik luas dan kedalaman kulong yang bervariasi. Karakterikstik luasan dan kedalaman Kulong diukur menggunakan Ecosounder remote sensing. Estimasi aliran yang masuk ke dalam badan kulong diperoleh dengan melakukan analisis ketersedian air menggunakan model NRECA. Simulasi keandalan kulong untuk masa 21 tahun ke depan (2017-2037) dilakukan dengan metode Standard Operating Rule (SOR) dengan memasukan debit sintesis hasil bangkitan data model Markov untuk musim ganda. Hasil penelitian menunjukan potensi ketersediaan debit rerata (Q) untuk Kulong Krasak, Q =7,24 ltr/s dengan keandalan 50% , Kulong Air PL, Q =11,77 ltr/s dengan keandalan 85%, Kulong Kebintik, Q = 66,45 ltr/s dengan Keandalan 97%, Kulong Baja, Q = 63,02 ltr/s dengan keandalan 0%, Kulong Jongkong Ali, Q = 65,05 ltr/s dengan Keandalan 100%, Kulong Rumbiah, Q = 30,93 ltr/s dengan Keandalan 70%, Kulong Ijo, Q = 37,71 ltr/s dengan Keandalan 96%. Status imbangan air yaitu kebutuhan air total sebesar 297,98 ltr/s, sedangkan ketersediaan air di 7 Kulong dengan total debit sebesar 219,16 ltr/s antara ketersediaan air dari 7 Kulong dengan kebutuhan air dari 6 Kecamatan mengalami defisit air sebesar 78,82 ltr/s, sehingga pemanfaatan 7 Kulong bekas tambang Timah ini cukup sigfinikan untuk menunjang imbangan air di Kabupaten Bangka Tengah.

SIMULASI POLA OPERASI EMBUNG SERBAGUNA TAMBAKSARI KABUPATEN CILACAP DENGAN METODE STANDARD OPERATING RULE (SOR)

Human survival depends on water availability as water is a basic needs. As population increases, water becomes more limited. One of the ways to prevent draught is collecting water in retention basin. Tambaksari Multipurpose Retention Basin serves to provide basic water demand and irrigation water for the local community. Water availability and water demand should be equal, so a simulation of the operating patter of the retention basin is necessary to distribute water equally and determining the failure level of the retention basin in performing its task. In the present study, the retention basin operating pattern was simulated using Standard Operating Rule (SOR) method. The present study used secondary data, including population data, rainfall data, climatological data and technical data of the retention basin. The size of DAS Tambaksari is 0.41 km² while the size of the irrigated land is 12 Ha. The rainfall data was from 2008-2018 obtained from two rain stations, population data of Tambaksari Village was from 2008-2019, and the climatological data was from 2014-2019. The simulation result of the retention basin operating pattern using SOR method showed that the final collection wasn’t under minimum collection and failure happened in the operation of the retention basin for one year. . The optimal ability of the target release is 70.83% for the reliability of irrigation needs and the level of reliability for raw water needs of 58.33%. Population projection analysis to determine the population in 20 years showed that the future population of 4044 required 3.861 l/person/s of water. Irrigation demands for rice-rice-palawija planting pattern showed that irrigation intake was 11.89 l/s. Water balance determined the balance between inflow and outflow. The value for average water availability was 0.021 m³/s while total average water demand was 0.016 m³/s. therefore, the water availability in partial intake wasn’t able to meet the irrigation and basic water demands. Keywords: discharge, retention basin operation simulation, SOR

ANALISIS IMBANGAN AIR EMBUNG JONGKONG KABUPATEN BANGKA TENGAH MELALUI KAPASITAS TAMPUNGAN

Sumber daya air embung di Kabupaten Bangka Tengah mempunyai potensi sumber daya air yang cukup besar untuk dimanfaatkan. Embung Jongkong terletak di Kecamatan Koba Kabupaten Bangka Tengah merupakan salah satu embung yang sekarang ini sudah dimanfaatkan untuk keperluan air baku Perusahan Daerah Air Minum (PDAM) di Kecamatan Koba Kabupaten Bangka Tengah Provinsi Bangka Belitung, namun masalah erosi lahan dan sedimentasi pada suatu embung dapat berpengaruh pada perubahan kapasitas tampungan yang dapat mempengaruhi umur operasi embung. Untuk itu perlu dilakukan analisis imbangan air embung antara ketersediaan air dengan kebutuhan air yang digunakan dengan metode Standar Operating Rule (SOR). Optimasi aliran yang masuk ketampungan sebagai ketersediaan air dianalisis menggunakan model NRECA dari tahun 2008-2018 dan menunjukan rerata debit maksimum dan minimum yang masuk ke tampungan dengan model NRECA adalah 0,259 MCM dan 0,016 MCM. Aliran yang masuk ke tampungan dibangkitkan dengan model Markov musim ganda selama 20 tahun (2019-2039) dan didapatkan debit bangkitan yang masuk ketampungan dengan rerata maksimum dan minimum adalah 0,280 MCM dan 0,017 MCM. Selanjutnya data debit yang dibangkitkan digunakan sebagai data aliran masuk ketampungan dalam pengaturan pola operasi standar (SOR) untuk mengetahui keandalan tampungan 20 tahun kedepan (2019-2039) didapatkan debit optimum pengambilan jika keandalan tampungan 100% dengan target pelepasan 80% dengan debit distribusi 21,537 ltr/s Maka dapat disimpulkan bahwa debit optimum tidak mampu memenuhi kebutuhan air domestik dan non domestik masyarakat Kecamatan Koba Kabupaten Bangka Tengah pada tahun 2039 (Qkeb>Qket) atau debit optimum hanya mampu melayani 48% kebutuhan air masyarakat Kecamatan Koba Kabupaten Bangka Tengah pada tahun 2039.