Pemodelan Banjir dan Sedimentasi di Sungai Welang, Pasuruan

Genangan banjir di sungai dapat disebabkan oleh peningkatan ketinggian air sungai karena penambahan debit air baik dari curah hujan dan pasang surut dari laut. Simulasi genangan banjir dapat dilakukan dengan menggunakan model banjir numerik. Di DAS Welang, banjir terjadi setiap tahun dan menyebabkan banyak masalah. Banjir yang terjadi pada 29 April 2019, menyebabkan penutupan jalan nasional dan regional dan banyak rumah yang terendam banjir. Dalam penelitian ini, model banjir dilakukan dengan menggunakan perangkat lunak MIKE FLOOD. Desa Semare dan Desa Tambakrejo adalah titik kritis di mana banjir terjadi. Kedalaman air dari model simulasi terjadi 0,3 m - 2,2 m dibandingkan dengan laporan peta banjir oleh Badan Nasional Penanggulangan Bencana Indonesia yang memperkirakan 0,1 m - 1,5 m. Kondisi perubahan kedalaman dasar sungai didominasi oleh agradasi di sepanjang sungai. Degradasi tertinggi terjadi pada titik 4800 m sebesar -1,59 m, sedangkan agradasi tertinggi terjadi pada titik 6000 m setinggi 1,18 m. ============================================================================================== A flood inundation in a river can be caused by an increase in river water level due to the addition of water discharge from both the rainfall and the tides from the sea. Flood inundation simulation can be done by using a numerical flood model. In the Welang basin, floods occur every year and cause many problems. Floods that occurred on April 29, 2019, caused the closure of national and regional roads and many houses that were flooded. In the present study, flood model was carried out by using MIKE FLOOD software. Semare Village and Tambakrejo Village are critical points where floods occur. The depth of the water from the simulation model occurs 0.3 m - 2.2 m compared to the flood map report by the Indonesian National Disaster Management Agency which estimates it at 0.1 m - 1.5 m. The condition of bed level change of the river is dominated by agradation along the river. The highest degradation occurred at the point of 4800 m at -1.59 m, while the highest agradation occurred at the point of 6000 m as high as 1.18 m