Pengaruh Perubahan Tutupan Lahan TerhadapKetersediaan Air Berdasarkan Metode Thornthwaite–Mather (Studi kasus: Kecamatan Dramaga, Bogor)

Abstract

Perubahan tutupan lahan akibat perkembangan wilayah dapat memengaruhi proses hidrologi melalui perubahan kemampuan infiltrasi, limpasan permukaan, dan ketersediaan air. Kecamatan Dramaga merupakan salah satu wilayah di Kabupaten Bogor yang mengalami perkembangan penggunaan lahan sehingga diperlukan kajian mengenai pengaruh perubahan tutupan lahan terhadap kondisi ketersediaan air. Penelitian ini bertujuan menganalisis pengaruh perubahan tutupan lahan terhadap ketersediaan air di Kecamatan Dramaga menggunakan metode Thornthwaite–Mather, yang didukung oleh analisis limpasan permukaan menggunakan metode Soil Conservation Service-Curve Number (SCS-CN). Data tutupan lahan diperoleh dari citra Sentinel-2A tahun 2015 dan 2025 yang diklasifikasikan menggunakan algoritma Random Forest, sedangkan data curah hujan dan suhu udara menggunakan ERA5-Land yang telah divalidasi dengan data observasi BMKG. Hasil penelitian menunjukkan bahwa selama periode 2015–2025 terjadi peningkatan luas permukiman dan lahan terbuka, disertai penurunan luas vegetasi serta badan air. Analisis ketersediaan air menunjukkan bahwa pola evapotranspirasi aktual, surplus, dan defisit air masih didominasi oleh variasi curah hujan. Sementara itu, analisis SCS-CN menunjukkan peningkatan nilai Curve Number yang mengindikasikan meningkatnya potensi limpasan permukaan akibat berkurangnya kemampuan infiltrasi lahan. Secara keseluruhan, perubahan tutupan lahan di Kecamatan Dramaga memengaruhi kondisi hidrologi wilayah, terutama melalui peningkatan potensi limpasan permukaan, sedangkan kondisi ketersediaan air masih didominasi oleh variasi curah hujan.

Land cover change resulting from regional development can affect hydrological processes by altering infiltration capacity, surface runoff, and water availability. Dramaga District, Bogor Regency, is one of the areas experiencing rapid land cover change, making it necessary to assess its impact on water availability. This study aims to analyze the impact of land cover change on water availability in Dramaga District using the Thornthwaite–Mather method, supported by surface runoff analysis based on the Soil Conservation Service–Curve Number (SCS-CN) method. Land cover data were derived from Sentinel-2A satellite imagery acquired in 2015 and 2025 and classified using the Random Forest algorithm. Rainfall and air temperature data were obtained from the ERA5-Land dataset and validated against observations from the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG). The results indicate that between 2015 and 2025, the area of built-up land and open land increased, while vegetation cover and water bodies decreased. The water availability analysis showed that the patterns of actual evapotranspiration, water surplus, and water deficit were primarily controlled by rainfall variability. Meanwhile, the SCS-CN analysis revealed an increase in the Curve Number, indicating a higher potential for surface runoff due to reduced infiltration capacity. Overall, land cover change in Dramaga District has affected the regional hydrological conditions, mainly by increasing the potential for surface runoff, while water availability remains predominantly influenced by rainfall variability.