Estimasi Limpasan Permukaan Akibat Siklon Tropis Senyar dan Dampak Ekonomi Banjir Bandang di Kota Padang

Abstract

Siklon Tropis Senyar pada November 2025 memicu hujan ekstrem yang menyebabkan banjir bandang dan menimbulkan dampak ekonomi di Kota Padang. Penelitian ini bertujuan menganalisis distribusi spasial curah hujan ekstrem, mengestimasi distribusi spasial limpasan permukaan, serta menganalisis pengaruh luas kawasan terbangun dan estimasi limpasan permukaan terhadap dampak ekonomi banjir bandang di Kota Padang. Data curah hujan CHIRPS dikoreksi menggunakan metode ratio-based bias correction berdasarkan data observasi, sedangkan estimasi limpasan permukaan dihitung menggunakan metode Soil Conservation Service-Curve Number (SCS-CN) berbasis Sistem Informasi Geografis. Hasil penelitian menunjukkan bahwa curah hujan ekstrem selama periode 21–28 November 2025 terkonsentrasi di wilayah utara hingga barat laut Kota Padang, sedangkan estimasi limpasan permukaan tertinggi berada pada kawasan pesisir dan perkotaan yang didominasi lahan terbangun. Analisis regresi linear berganda menunjukkan bahwa luas kawasan terbangun dan estimasi limpasan permukaan berpengaruh signifikan terhadap total kehilangan (R² = 0,782), kerusakan bangunan (R² = 0,518), dan kerugian non-bangunan (R² = 0,770). Temuan ini menunjukkan bahwa kombinasi karakteristik penggunaan lahan dan respons hidrologi berperan penting dalam menentukan besarnya dampak ekonomi banjir bandang serta dapat menjadi dasar dalam pengembangan strategi mitigasi banjir bandang di Kota Padang.

Tropical Cyclone Senyar in November 2025 triggered extreme rainfall that caused flash floods and economic losses in Padang City, Indonesia. This study aimed to analyze the spatial distribution of extreme rainfall, estimate the spatial distribution of surface runoff, and examine the influence of built-up area and estimated surface runoff on the economic impacts of flash floods. CHIRPS rainfall data were corrected using the ratio-based bias correction method based on observed rainfall data, while surface runoff was estimated using the Soil Conservation Service-Curve Number (SCS-CN) method within a Geographic Information System framework. The results showed that extreme rainfall during 21–28 November 2025 was concentrated in the northern and northwestern parts of Padang City, whereas the highest estimated surface runoff occurred in coastal and urban areas dominated by built-up land. Multiple linear regression analysis indicated that built-up area and estimated surface runoff significantly affected total loss (R² = 0.782), building damage (R² = 0.518), and non-building losses (R² = 0.770). These findings demonstrate that the combined effects of land-use characteristics and hydrological response play an important role in determining the economic impacts of flash floods and provide a scientific basis for improving flash flood mitigation strategies in Padang City.