ANALISA EROSI DAN SEDIMENTASI MENGGUNAKAN APLIKASI MODEL AVSWAT 2000 DI DAS BAGEK KEMBAR KABUPATEN LOMBOK BARAT PROVINSI NUSA TENGGARA BARAT

Imam Nashrullah, Ussy Andawayanti, Suwanto Marsudi

Abstract


ABSTRAK : Di muara sungai Bagek Kembar akan dibangun PLTGU Lombok Peaker. Dalamupaya melindungi dan menjaga kelestarian bangunan PLTGU Lombok Peaker serta menjagakelestarian DAS Bagek Kembar, dilakukan analisa untuk memprediksi erosi dan sedimentasi padaDAS Bagek Kembar. Analisa ini akan mengkaji hasil erosi dan sedimentasi di DAS BagekKembar dengan menggunakan aplikasi model AVSWAT (Arc View Soil And Water AssessmentTool) 2000. Hasil perhitungan menggunakan AVSWAT 2000 mulai tahun 2000 sampai dengantahun 2009 didapatkan nilai laju erosi rata-rata pada DAS Bagek kembar adalah sebesar 58.48ton/ha/th dan hasil sedimen rata-rata sebesar 14.96 ton/ha/th atau 1.25 mm/th. Lokasi bangunanpengendali sedimen yang pertama (Check Dam 1) berada pada hilir subdas 12 dengan nilai IndeksBahaya Erosi (IBE) sangat tinggi, sedangkan lokasi bangunan pengendali sedimen yang kedua(Check Dam 2) berada pada hilir subdas 14 dengan nilai IBE sangat tinggi. Volume tampunganCheck Dam 1 adalah sebesar 7783.78 m3 diharapkan dapat mengontrol laju sedimentasi sebesar124% dari potensi laju sedimentasi normal. Sedangkan volume tampungan Check Dam 2 adalahsebesar 17142.86 m3 diharapkan dapat mengontrol laju sedimentasi sebesar 243% dari potensi lajusedimentasi normal.Kata Kunci : AVSWAT 2000, DAS Bagek Kembar, erosi, sedimentasi, Check Dam

ABSTRACT : At the estuary of the Bagek Kembar River will be built PLTGU Lombok peaker. Inan effort to protect and maintain the sustainability of the building of PLTGU lombok peaker aswell as maintaining the conservation Bagek Kembar’s Watershed, an analysis was conducted topredict the erosion and sedimentation in Bagek Kembar’s Watershed. This analysis will examinethe results of erosion and sedimentation in Bagek Kembar’s Watershed by using the application ofthe model AVSWAT (Arc View Soil and Water Assessment Tool) 2000. Calculation using AVSWAT2000 from 2000 to 2009 was conducted to obtain the results of the average erosion rate on BagekKembar’s Watershed is 58,48 tons / ha / yr and the average sediment yield is 14,96 tons / ha / yror 1.25 mm / year. The location of the first Check Dam is located at downstream sub-watershed 10with the value of index of erosion hazard (IBE) very high, whereas the location of the secondCheck Dam is located at downstream sub-watershed 14 with the value of IBE very high. Thevolume of the first Check Dam is 7783.78 m3 and expected to control the sedimentation rate by124% of the potential of normal sedimentation rate. While the volume of second Check Dam is17142.86 m3 and expected to control sedimentation rate by 243% from the potential of normalsedimentation rate.Keywords : AVSWAT 2000, Bagek Kembar’s Watershed, erosion, sedimentation, Check Dam


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