Analisis Perkuatan Tebing dan Normalisasi Sungai Wulan Sebagai Pengendali Banjir di Wilayah Kabupaten Kudus 20 31

Abstrak

Kudus Regency frequently experiences flooding due to the overflow of the Wulan River. This problem is caused by the river's inadequate capacity due to high rainfall, sedimentation, and channel narrowing, as well as critical bank conditions prone to landslides. This study aims to analyze integrated river normalization and slope reinforcement as a flood control solution. The methodology includes hydrological analysis to calculate the Q25 design flood discharge and hydraulic analysis to evaluate the existing capacity and the planned normalization. The hydrological analysis used 10 years of rainfall data (2015-2024) from the Jatisari Station. The flood discharge was calculated using the Synthetic Unit Hydrograph (HSS) Nakayasu method based on the Log Pearson Type III rainfall distribution analysis, which was selected after goodness-of-fit testing. Geotechnical analysis was conducted to verify the stability of the planned gabion (bronjong) slope reinforcement using Rankine's theory. The results show the Q25 design flood discharge is 21,327.426 m³/sec. The existing channel capacity (B=80 m, H=7.78 m) is only 16,426.96 m³/sec, making it incapable of accommodating the Q25 flood. The normalization plan (B=80 m, H=10 m, m=3) increases the capacity to 34,169.47 m³/sec, which is deemed safe. The 7-meter high gabion slope reinforcement design was also declared safe against overturning (FS = 15.49 > 2) and sliding (FS = 3.29 > 1.5).