Judul: The Effect of Land Cover Change on River  Flow Discharge in Antokan Sub-watershed, West Sumatra
Abstrak: DAS Antokan merupakan satu dari lima DAS kritis di Sumatera Barat yang memiliki peranan penting. Pada wilayah Sub DAS ini terdapat Danau Maninjau sebagai sumber ekonomi dan energi wilayah Kabupaten Agam. Akibat adanya alih fungsi lahan mengakibatkan kondisi Sub DAS Antokan dalam kondisi kritis. Penelitian ini bertujuan mengetahui pengaruh perubahan tutupan lahan terhadap debit aliran sungai di Sub DAS Antokan, Sumatera Barat. Perubahan tutupan lahan diidentifikasi menggunakan teknik overlay, analisis hubungan curah hujan dengan debit aliran sungai melalui koefisien korelasi, dan analisis hubungan tutupan lahan dengan debit aliran sungai menggunakan koefisien rezim aliran dan koefisien aliran tahunan. Luas tutupan lahan Sub DAS Antokan tahun 2009-2019 yang mengalami peningkatan terbesar yaitu hutan lahan kering sekunder seluas 1503 ha sedangkan luas tutupan lahan yang mengalami penurunan terbesar yaitu pertanian lahan kering campuran seluas 784 ha. Peningkatan tutupan lahan terbesar pada tutupan lahan hutan lahan kering sekunder dari 4090 ha menjadi 5593 ha. Adapun pengurangan tutupan lahan terbesar adalah pertanian lahan kering campuran dari 4048 ha menjadi 3264 ha. Hasil analisis korelasi curah hujan dengan debit aliran sungai tergolong rendah sampai sangat rendah. Nilai KRA pada tahun 2009 dan 2019 menyatakan bahwa kondisi Sub DAS dalam keadaan sangat buruk. Nilai KAT Sub DAS Antokan dari tahun 2009-2019 termasuk dalam kategori sangat rendah. Aliran sungai Sub DAS Antokan dikendalikan oleh PLTA sehingga mempengaruhi sifat aliran permukaan di daerah hilirnya., Antokan watershed is one of five critical watersheds in West Sumatra that have an important role. There is Maninjau Lake in the Antokan Sub-watershed which functions as an economic and energy source for the Agam Regency area. Rapid and extensive land use changes in the area lead the Antokan sub watershed to critical condition. The purpose of the study was to determine the effect of land cover change on river discharge in the Antokan Sub-watershed, West Sumatra. Land cover changes were identified using the overlay technique, analysis of the relationship between rainfall and river flow by means of correlation coefficient, and analysis of the relationship between land cover and river discharge by means of using discharge regime coefficients and annual discharge coefficients. The land cover area of the Antokan Sub-watershed in 2009-2019 which experienced the largest increase was secondary dryland forest covering an area of 1503 ha, while the land cover area that experienced the largest decrease was mixed dryland agriculture covering an area of 784 ha. The largest increase in land cover was in secondary dry land forest land cover from 4090 ha to 5593 ha. The largest land cover reduction was mixed dry land agriculture from 4048 ha to 3264 ha. The results of the analysis of the correlation between rainfall and river flow are classified as low to very low. The KRA value in 2009 and 2019 states that the condition of the Sub-watershed is in a very bad. The KAT value of the Antokan Sub-watershed from 2009-2019 is in the very low category. The discharge of the Antokan sub-watershed is controlled by hydropower construction which affects the discharge properties of the downstream area.
Keyword: Annual flow coefficient, discharge, land cover change, river regime  coefficient, watershed