Itratip (2011) Studi Penilaian Kondisi DAS dan Implikasinya terhadap Fluktuasi Debit Sungai (Studi Kasus pada Sub DAS Jangkok Pulau Lombok). Magister thesis, Universitas Brawijaya.
Abstract
Dua dekade terakhir telah terjadi perubahan sebagian kawasan hutan menjadi kebun di bagian hulu sub DAS Jangkok. Perubahan tataguna lahan yang terjadi di kawasan tersebut akan berpengaruh terhadap koefesien limpasan, erosi, dan fluktuasi debit sungai. Penelitian ini bertujuan untuk mengetahui kondisi bagian hulu sub DAS Jangkok ditinjau dari perubahan tataguna lahan, erosi, dan limpasan permukaan serta pengaruhnya terhadap fluktuasi debit sungai. Metodelogi yang digunakan adalah model digital AVSWAT 2000 dan analisis statistik pengukuran dispersi deviasi rata-rata (MD). Model AVSWAT 2000 digunakan untuk menganalisis erosi dan limpasan permukaan yang terjadi di daerah tersebut. Sedangkan analisis terhadap fluktuasi debit menggunakan rumus statistik deviasai rata-rata (MD) dan nilai KRS (Qmaks/Qmin). Kondisi hulu sub DAS Jangkok akibat perubahan kawasan hutan menjadi kebun dari tahun 1995-2010 seluas 17.32 % masih dalam kualitas baik. Peniliain ini berdasarkan parameter yaitu; (1) Angka koefisien C = 0.16. Artinya 16% curah hujan menjadi limpasan permukaan dan sebesar 84% akan terinfiltrasi mengisi air tanah. Dan (2) Laju erosi potensial rata-rata rendah sekitar 5.75 ton/ha/tahun. Dengan batas toleransi erosi yang diperbolehkan sebesar 9.6 ton/ha/tahun, maka diperoleh indeks bahaya erosinya = 0.59 1 (kategori rendah). Perubahan tataguna lahan bagian hulu sub DAS Jangkok, secara umum tidak berimplikasi signifikan terhadap fluktuasi debit sungai. Hal ini dapat diketahui dari nilai koefisien regim sungai (KRS) dan deviasi rata-rata (MD) debit sungai tahunan. Pada periode tahun 1992-1996 diperoleh nilia KRS (1.67) dan MD (0.21 m 3 /det). Pada periode tahun 1997-2003 menujukkan nilai KRS (2.47) dan MD (0.35 m 3 /det). Sedangkan tahun 2004-2010 diperoleh nilai KRS (2.0) dan MD (0.25) m 3 /det. Namun demikian, dari data yang ada menunjukkan terjadi penurunan debit sungai sebesar 0.03 m 3 /det pertahunnya, curah hujan sebesar 14.64 mm/tahun dan hari hujan sebanyak 10 hari dalam kurun waktu 10 tahun terakhir.
English Abstract
In last two decade, re has been a dramatically land use changes in sub-catchment area of Jangkok, Lombok, from forest toward agroforestry. land use change will significantly affect run off coefficient, soil erosion as well as river-water recharge fluctuation. study was aimed to evaluate current condition of upper stream of sub-catchment of Jangkok in relation to trend of land use changes, soil erosion, runoff and its influence on river-water recharge fluctuation. study was conducted using a digital software - model of AVSWAT 2000 and statistical analysis of dispersion measurement mean deviation (MD) and River Regime Coefficient (Q max/Q min) were used to calculate river-recharge fluctuation. AVSWAT 2000 model was used to analyze soil erosion and run off in such area while river-water recharge fluctuation. result of study show that 17.32% of upper stream of Sub-Jangkok due to land use changes from 1995 to 2010 has not been degraded or still good quality catchment indicated by following variables: coefficient C = 0.16 and potential soil erosion of 6.0 t ha-1 year-1. C = 0.16 means that was only 16% of rainfall undergo run off and rest of 84% goes to infiltration to enrich ground water. According to natural erosion in region which is about 5.75 t ha-1 year-1, erosion index was 0.59 or less than 1 classified as low incident. Overall, land use changes in upper stream of sub-catchment of Jangkok was not significantly correlated to river-water recharge fluctuation. This was confirmed by RRC (1.67) and MD (0.21 m 3 /sec) resulted from 1992-1996. In next seven years (1997-2003) RRC and MD were 2.47 and 0.35 m 3 /sec respectively. In 2004-2010, RRC and MD were 2.0 and 0.25 m 3 /sec. However, re were slightly decline of river-water recharge (0.03 m 3 /sec/year) as well as rainfall (14.64 mm/year) and daily rainfall much as 10 days within last 10 years.
| Item Type: | Thesis (Magister) |
|---|---|
| Identification Number: | TES/628.1/ITR/s/041200011 |
| Subjects: | 600 Technology (Applied sciences) > 628 Sanitary engineering > 628.1 Water supply |
| Divisions: | S2/S3 > Magister Teknik Elektro, Fakultas Teknik |
| Depositing User: | Endro Setyobudi |
| Date Deposited: | 16 Apr 2012 12:45 |
| Last Modified: | 16 Apr 2012 12:45 |
| URI: | http://repository.ub.ac.id/id/eprint/158861 |
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