PENERAPAN METODE STANDARDIZED PRECIPITATION INDEX (SPI) DAN EFFECTIVE DROUGHT INDEX (EDI) UNTUK MENGESTIMASI KEKERINGAN DI DAS REJOSO KABUPATEN PASURUAN

Abstract

Terdapat 19 desa di 5 (lima) kecamatan yang termasuk daerah rawan kekeringan di Kabupaten Pasuruan pada tahun 2018. Perlu adanya pemetaan sebaran kekeringan guna mengetahui wilayah mana saja yang menjadi prioritas dalam penanganan mitigasi dan adaptasi bencana kekeringan untuk instansi terkait. Kekeringan dianalisis dengan indeks kekeringan meteorologi metode Standardized Precipitation Index (SPI) dan Effective Drought Index (EDI). Hasil indeks kekeringan meteorologi dibandingkan dengan indeks kekeringan hidrologi utuk mengatahui hubungan kesesuaian terkuat di antara indeks SPI dan EDI. Kejadian kering terparah menggunakan metode SPI terjadi sebanyak 141 kejadian dan bulan terjadinya kekeringan terparah adalah bulan Januari dan April. Kejadian kering terparah menggunakan metode EDI terjadi sebanyak 237 kejadian dan bulan terjadinya kekeringan terparah adalah bulan Januari dan Februari.  Setelah dilakukan analisis hubungan kesesuaian indeks SPI dan EDI terhadap indeks kekeringan hidrologi, ditemukan korelasi negatif dan persentase kesesuaian bersifat lemah. Kemudian, diambil opsi membandingkan indeks SPI dan EDI terhadap data curah hujan bulanan. Indeks EDI memiliki hubungan terkuat terhadap data curah hujannya, yaitu sebesar 65,69%. Hasil sebaran kekeringan di DAS Rejoso Kabupaten Pasuruan menggunakan metode interpolasi spasial IDW dengan kategori Amat Sangat Kering terjadi di 30 desa.

There are 19 villages in 5 (five) sub districts that are classified as drought prone areas at Pasuruan Regency in 2018. A drought mapping is needed to understand which areas are priority in handling drought mitigation and adaptation for related institution. Drought is analyzed by the meteorological drought index methods which are Standardized Precipitation Index (SPI) and Effective Drought Index (EDI). The results of the meteorological drought indexes are compared with the hydrological drought indexes to find out the strongest correspondence relationship between the SPI and EDI. A total of 141 cases of worst drought using SPI were occurred and the worst drought cases were happened in January and April. A total of 237 cases of worst drought using EDI were occurred and the worst drought cases were happened in January and Februari. After analyzing the relationship between the suitability of the SPI index and EDI to the hydrological drought indexes, it was found a negative correlation and the percentage of suitability was weak. And then, it is needed to take another option for comparing the SPI and EDI by using monthly rainfall data. The EDI index has the strongest correspondence relationship with rainfall data which is 65.69%. The result of the spatial drought distribution in the Rejoso Watershed Pasuruan Regency using IDW interpolation method with Extremly Dry category is occurred in 30 villages.