DISTRIBUSI SPASIAL DAN TEMPORAL CURAH HUJAN DI DAS CERUCUK, PULAU BELITUNG

Abstract

Spatial and temporal distribution of rainfall was studied to obtain  a basic information on water resources management in the cerucuk watershed. The data used in this study are rainfall data of five rainfall stations in the study area. Spatial distribution of rainfall was prepared using isohyets methods. Temporal variability of rainfall were analyzed by statistical methods. Identification of rainfall variability index have determined and analyzed by statistical methods. The results showed that the spatial and temporal distribution of rainfall of Cerucuk watershed influenced by the topography. The annual cycle of rainfall have indicated equatorial type, where the peak rainfall occurs twice a year, in April and December. The monthly rainfall of Cerucuk watershed ranges from 160 mm to 600 mm with average annual rainfall was about 3320 mm. The spatial and temporal distribution of rainfall of Cerucuk watershed influenced by seasonal winds (monsoon), the ITCZ, topography and landuse changes. The annual rainfall, monthly rainfall intensity and monthly maximum rainfall of Buluh Tumbang rainfall station show a downward trend, while in Pilang station show a constant value. The tendency of temporal variation of rainfall, maximum rainfall and rainfall intensity of the stations are associated with land cover changes.

Distribusi spasial dan temporal curah hujan dipelajari untuk memberikan informasi dasar dalam pengelolaan sumber daya air DAS Cerucuk. Dengan menggunakan data dari 5 stasiun curah hujan yang tersebar di daerah kajian, distribusi hujan spasial disusun menggunakan metode isohyet dan distribusi temporal dipelajari dengan metoda statistik. Identifikasi Indeks Variabilitas Hujan ditentukan dan dianalisis dengan metode statistik. Hasil penelitian menunjukan bahwa distribusi curah hujan spasial bulanan dan tahunan di DAS Cerucuk dipengaruhi oleh topografi. Siklus curah hujan menunjukkan tipe ekuatorial, dimana puncak curah hujan terjadi dua kali dalam setahun yaitu pada bulan April dan Desember. Curah hujan rata-rata wilayah bulanan berkisar 160 mm - 600 mm, curah hujan tahunan wilayah rata-ratanya berkisar 3320 mm. Variasi temporal curah hujan DAS Cerucuk dipengaruhi oleh angin musim, ITCZ, dan topografi, dan perubahan tutupan lahan. Curah hujan rata-rata tahunan, intensitas hujan harian dan hujan maksimum harian rata-rata di Stasiun Buluh Tumbang menunjukkan kecenderungan turun, sementara di Stasiun Pilang menunjukkan nilai yang cenderung konstan. Kecenderungan variasi temporal dari curah hujan, hujan maksimum harian rata-rata dan intensitas hujan harian di kedua stasiun ini berhubungan dengan perubahan tutupan lahan.