ANALISIS DEBIT SUSPENSI PADA DAERAH TANGKAPAN AIR (DTA) PETAK 13 HUTAN PENDIDIKAN WANAGAMA I, KABUPATEN GUNUNGKIDUL, YOGYAKARTA

RAHMAD ISNAWAN, PRASETYO NUGROHO, S.Hut., M.Sc.

2016 | Tugas Akhir | D3 PENGELOLAAN HUTAN SV

Daerah Tangkapan Air (DTA) Petak 13 Hutan Pendidikan Wanagama I, Kabupaten Gunungkidul, Yogyakarta memiliki berbagai jenis tutupan lahan, yaitu sawah, tegalan, tegakan jati lokal, dan tegakan jati mega, selain itu terdapat aktivitas pengolahan lahan yang dilakukan oleh para petani yaitu pembuatan lubang tanam, pendangiran, penggebrusan tanah, penyiangan, pemupukan, dan pencarian rumput untuk pakan ternak. Berdasarkan penelitian Saifudin (2015) pada DTA petak 13 Hutan Wanagama, diperoleh hasil erosi sebesar 0,736 ton/ha/27 hari, hasil tersebut dipengaruhi oleh pengolahan lahan pada DTA tersebut. Oleh karena itu, penelitian ini perlu dilakukan untuk mengetahui debit suspensi dan erosi pada lokasi penelitian, sehingga didapatkan kontinyuitas data. Penelitian ini dilakukan pada Stasiun Pengamat Arus Sungai (SPAS) tipe V-Notch Weir 900 DTA Petak 13. Pengambilan sampel muatan tersuspensi dilakukan menggunakan suspended sampler yang terdapat di mulut weir. Adapun data pendukung lainnya seperti kenampakan tutupan lahan, pengolahan lahan, dan peta DTA petak 13. Perhitungan debit suspensi dengan menggunakan bantuan Software Microsoft Excel dan Sigmaplot. Dari hasil penelitian diperoleh persamaan kurva lengkung suspensi (suspended rating curve) Qs = 3,3375(x)0,8662 dengan koefisien determinasi (R2) = 0,7850. Potensi erosi yang terjadi di DTA Petak 13 selama waktu penelitian yaitu sebesar 1,091 ton/ha/42 hari. Hasil tersebut meningkat cukup banyak dibandingkan dengan penelitian Saifudin (2015) pada DTA petak 13, yang sebelumnya sebesar 0,736 ton/ha/27 hari. Hal tersebut dikarenakan meningkatnya air larian yang terjadi dan juga aktivitas pengolahan lahan yang intensif.

Catchment area Plots 13 Wanagama I Educational Forest, Gunungkidul, Yogyakarta has various types of land cover, which is paddy field, moor/fields, Local teak stands and mega teak stands. In addition there are land management by farmers that is making planting hole, cultivation, groundbreaking, weeding, fertilizing, and search of grass to animal feed. Based on research by Saifuddin (2015) in the catchment area plot 13 of Wanagama forest, the results is debit suspension is amounted to 0.736 tonnes/ha/27 days, the result are influenced by land management in the catchment area. Therefore, this research should be conducted to determine the amount of suspension debit and erosion at the study site, so it obtain continuity of data. The research was conducted on the River Flow Monitoring Station type V-Notch Weir 900 in the catchment area Plot 13. The sampling of load suspended was performed by using suspended sampler that is found in the mouth of the weir. The other supporting data such as the appearance of land cover, land management, and a map of the catchment area plot 13. The calculation of debit suspension using Microsoft Excel Software and Sigmaplot. From the results, suspended rating curve or Qs = 3,3375(x)0.8662 with a coefficient of determination (R2) = 0.7850. Potential erosion in the catchment area Plot 13 during the study period amounted to 1,091 tonnes/ha/42 days. The results increased quite when compared with the results of Saifuddin (2015) in the catchment area plot 13, that is previously amounted to 0.736 tonnes/ha/27 days. It is caused by increased water run-off that is occurring and intensive land cultivation.

Kata Kunci : Wanagama, Catchments Area, Debit Suspension stream.