MODEL SIMULASI NERACA AIR DALAM PERSPEKTIF EKONOMI LINGKUNGAN SEBAGAI UPAYA MENJAGA KEBERLANJUTAN SISTEM SUMBERDAYA AIR Studi Kasus DTA Danau Rawapening

PURBOSENO, Sentot and Bambang, Azis Nur and Hadi, Sudharto P. and Suripin, Suripin (2014) MODEL SIMULASI NERACA AIR DALAM PERSPEKTIF EKONOMI LINGKUNGAN SEBAGAI UPAYA MENJAGA KEBERLANJUTAN SISTEM SUMBERDAYA AIR Studi Kasus DTA Danau Rawapening. PhD thesis, Program of Postgraduate.

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Abstract

Meningkatnya alih fungsi lahan di kawasan hulu DAS, menyebabkan DAS tidak mampu menyerap air hujan bahkan menimbulkan erosi dan sedimentasi di sungai atau danau. Degradasi fungsi DAS tersebut tidak terlepas dari lemahnya pengelolaan DAS secara terpadu. Salah satunya adalah DAS Rawapening yang merupakan bagian dari DAS Tuntang, kejadian banjir dan kekeringan semakin sering terjadi, bahkan volume tampungan air Danau Rawapening semakin mengecil karena sedimentasi. Upaya pengelolaan DAS terpadu selain memerlukan koordinasi dan waktu yang cukup lama, diperlukan juga pembiayaan yang sangat besar. Salah satu alternatif pembiayaan pengelolaan DAS adalah melalui pembayaran jasa lingkungan. Konsep pembiayaan pengelolaan DAS dengan pembayaran jasa lingkungan, sampai saat ini realisasinya masih sangat rendah dibandingkan dengan kebutuhan biayanya. Untuk meningkatkan realisasi pembayaran jasa lingkungan tersebut, penelitian ini mengusulkan penggunaan mekanisme investasi dalam pembayaran jasa lingkungan. Metode yang digunakan dalam penelitian ini adalah metode eksperimen dengan simulasi. Untuk dapat melakukan simulasi terhadap kawasan suatu sistem, diperlukan model yang dapat merepresentasikan kondisi sistem tersebut. Langkah penyusunan model dimulai dari: 1) analisis komponen pendukung fungsi hidrologis DTA, 2) analisis ketersediaan dan kebutuhan air DAS Tuntang, 3) analisis kebutuhan air, 4) valuasi ekonomi jasa lingkungan, 5) formulasi model neraca air, dan 6) model simulasi. Hasil analisis menunjukkan bahwa volume infiltrasi semakin mengecil dan potensi erosi semakin membesar, selain itu ketersediaan air pada musim kemarau semakin mengecil sedangkan kebutuhan air semakin meningkat. Kegiatan konservasi yang diusulkan mengacu pada peningkatan volume infiltrasi dan pengurangan aliran permukaan. Alternatif kegiatan konservasi yang diajukan adalah pembuatan sumur resapan, biaya untuk membangun sumur resapan didasarkan dari nilai jasa lingkungan yang harus dibayarkan. Nilai imbal jasa lingkungan PLTA Jelok dan Timo sebesar Rp 41,04/m3, penyediaan air baku oleh PT Sarana Tirta Ungaran Rp 615,75/m3, dan nilai jasa lingkungan untuk air irigasi sebesar Rp 4,31/m3. Nilai kelayakan investasi kegiatan konservasi sumber daya air dengan sumur resapan diperoleh titik impas pada akhir tahun ke duabelas dengan nilai parameter ekonomi IRR 13,39 %, NPV Rp 0,777 M dan B/R Ratio 1,10. Penelitian kuantifikasi manfaat konservasi sumur resapan perlu dilakukan peningkatkan dengan uji lapangan secara langsung, penelitian sejenis untuk kegiatan konservasi lain perlu dilakukan untuk meningkatkan kepastian investasi lingkungan. Selain itu untuk merangsang peningkatan jumlah investasi lingkungan, diperlukan dukungan regulasi penurunan suku bunga pinjaman, sehingga lajunya degradasi lingkungan dapat ditekan. Kata Kunci: model simulasi, DAS, konservasi, investasi lingkungan The reduce of land use in the area upstream of Watershed (DAS) causes it the reduce of infiltration of rain water even to cause soil erosion and sedimentation in the river or lake. The function degradation of watershed cannot be not apart from its integrated poor management. One of the watersheds is Rawapening that is the part of Tuntang watershed. The flood and drought in this watershed is more likely to happen even the volume of the water reservoir in Rawapening Lake is decreasing due to land sedimentation. The effort to manage the integrated watershed needs both coordination and a long time and also a great financing. One of the alternatives in managing the watershed financing is through the payment of environmental services. The implementation of the concept in the payment of the watershed management through the payment of environmental services is still low at the moment compared to its cost. To improve it, this research proposes the use of the investment mechanism in the payment of environmental services. The methodology used in this research is experimental method with simulation. To be able to conduct a simulation toward an area of a system, it needs a model that represents the condition of its system. The steps of drafting the model starts from: 1) the analysis of the supporting components of the hydro watershed function, 2) the analysis of the water availability and need of Tuntang watershed, 3) the analysis for the water demand, 4) the economic valuation of environment services, 5) the formulations of the water balance model, and 6) the model simulation. The result of the analysis shows that the infiltration volume is decreasing and the potential of land erosion is increasing. Besides, the water availability in dry season is decreasing while the need of water is increasing. The conservation activities proposed refer to the increase of the infiltration volume and the reduction of the surface flow. The alternative conservation activities proposed is the building of well absorptions. The cost of building well absorption is based on the environment service value that has to be paid. The value in return of environment services of PLTA of Jelok and Timo is Rp 41,04/m3, the raw water supply of PT Sarana Tirta Ungaran Rp 615,75/m3, and the value of the environment services for water irrigation is Rp 4,31/m3. The value of the eligibility of investment activities of water resources conservation with the absorption well is obtained the breakeven point at the fourth year with the value of economic parameter IRR 13,39 %, NPV Rp 0,777 M and Ratio B/R 1,10. The quantitative research of the conservation benefits of the absorption well needs to be improved through a direct field test, a typical research for other conservation activities that needs to be conducted to improve the certainty of the environment investment. Besides stimulating the enhancement of the amount of environment investment, it is necessary to have a regulation support for the reduction of loan interest rates so that the rate of environment degradation could be suppressed. Keywords: simulation model, watershed (DAS), conservation, investment of environment

Item Type:Thesis (PhD)
Subjects:T Technology > TD Environmental technology. Sanitary engineering
Divisions:School of Postgraduate > Doctor Program in Environmental Science
ID Code:66361
Deposited By:Mrs Ekana Perpus Pasca
Deposited On:12 Nov 2018 10:23
Last Modified:12 Nov 2018 10:23

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