Analisis Perubahan Tata Guna Lahan terhadap Laju Sedimen pada DAS Cimuntur

(Studi Kasus DAS Cimuntur Kab. Ciamis)

Abstract

Abstrak: Dampak dari erosi tanah dapat menyebabkan sedimentasi di sungai sehingga dapat mengurangi daya tampung sungai, demikian pula yang terjadi pada DAS (Daerah Aliran Sungai) Cimuntur karena telah banyak mengalami perubahan lingkungan terutama perubahan tataguna lahan di daerah hulu maka erosi dan sedimentasi yang terjadi di sungai Cimuntur cukup besar dan berdampak pada berkurangnya kemampuan sungai Cimuntur dalam menampung aliran air terutama pada saat musim hujan sehingga akan menyebabkan banjir. Jenis tanah di sungai Cimuntur didominasi oleh latosol coklat tua kemerahan dengan karakteristik tanah latosol memiliki kemampuan menyerap air tinggi, dan mudah tererosi. Penggunaan lahan di sungai Cimuntur didominasi oleh perkebunan (56.815%), area pemukiman (12.682%), bangunan (15.088%), hutan (6.469%). Berdasarkan hasil analisa menggunakan USLE (Universal Soil Loss Equation) maka dipilihlah 5 (lima) rangking anak sungai Cimuntur yang memiliki peringkat erosi yang paling besar yaitu: Sub-DAS Pamanyoan = 69.095 Ton/Ha/Tahun,  Sub-DAS Ciderma = 51.903 Ton/Ha/Tahun,  Sub-DAS Cikadondong = 151.303 Ton/Ha/Tahun,  Sub-DAS Cipaderen = 140.001 Ton/Ha/Tahun,  Sub-DAS Citeras = 49.789 Ton/Ha/Tahun. Pada lahan DAS/Sub-DAS Cimuntur dilakukan tindakan konservasi lahan dengan 3 (tiga) skenario yaitu  pada lokasi studi yang memiliki kemiringan ≥ 30 % (Curam) akan dilakukan kegiatan konservasi tanah berupa teras bangku sedang (P = 0.15). Pada lahan perkebunan akan dilakukan konservasi dengan cara penutupan lahan secara rapat (P = 0.1), kombinasi 1 + 2.

Kata Kunci: erosi, sedimentasi, konservasi, penggunaan lahan, DAS

Abstract: The impact of soil erosion can cause sedimentation in the river so that it can reduce the capacity of the river, as well as what happens to the Cimuntur watershed because it has undergone many environmental changes, especially changes in land use in the upstream area, the erosion and sedimentation that occurs in the Cimuntur river is quite large and has an impact on the reduced ability of the Cimuntur river in accommodating water flow, especially during the rainy season so that it will cause flooding. The type of soil in Cimuntur river is dominated by reddish dark brown latosol with latosol soil characteristics having high water absorption ability, and easily eroded. Land use in Cimuntur river is dominated by plantations (56,815%), residential areas (12,682%), buildings (15,088%), forests (6,469%). Based on the results of the analysis using USLE (Universal Soil Loss Equation) then selected 5 (five) ranks of Cimuntur tributaries that have the largest erosion rating, namely: Sub-WATERSHED Pamanyoan = 69,095 Tons / Ha / Year, Sub-watershed Ciderma = 51,903 Tons/Ha/Year, Cikadondong Sub-watershed = 151,303 Tons/Ha/Year, Cipaderen Sub-watershed = 140,001 Tons/Ha/Year, Citeras Sub-Watershed = 49,789 Tons/Ha/Year. On watershed / Sub-watershed Cimuntur conducted land conservation actions with 3 (three) scenarios, namely at the study site that has a slope of ≥ 30% (Steep) will be conducted land conservation activities in the form of a medium bench terrace (P = 0.15). On plantation land will be done conservation through land closure tightly (P = 0.1), a combination of 1 + 2.

Keywords: erosion, sedimentation, conservation, land use, watershed