Analisis Gerakan Tanah akibat Siklon Tropis Seroja dan Dampaknya terhadap Banjir Bandang di Pulau Adonara, Kabupaten Flores Timur, NTT, April 2021: Studi Evaluatif terhadap Strategi Mitigasi Bencana Hidrometeorologi
Analysis of Landslides Caused by Tropical Cyclone Seroja and Their Impact on Flash Floods on Adonara Island, East Flores Regency, NTT, April 2021: An Evaluative Study of Hydrometeorological Disaster Mitigation Strategies
Abstract
Bencana banjir bandang dan tanah longsor yang melanda Pulau Adonara, Kabupaten Flores Timur, Nusa Tenggara Timur (NTT) pada 4 April 2021 merupakan salah satu bencana hidrometeorologi terparah dalam sejarah provinsi tersebut. Dipicu oleh Siklon Tropis Seroja yang oleh BMKG (2021) dikategorikan sebagai siklon paling intensif dalam catatan modern di perairan Flores dengan kecepatan angin mencapai 95 knot peristiwa ini mengakibatkan 72 jiwa meninggal dunia di Kabupaten Flores Timur, 76 orang luka-luka, 1 orang dinyatakan hilang, 27.560 jiwa terdampak, 2.579 jiwa mengungsi, serta terputusnya akses jalan dan lima jembatan utama di Pulau Adonara secara total. Kerugian ekonomi ditaksir mencapai Rp 1,2 triliun berdasarkan estimasi BNPB (2021). Dalam lingkup NTT secara keseluruhan, total korban meninggal dunia akibat Siklon Seroja mencapai 179 jiwa (Wakil Gubernur NTT, 2021). Penelitian ini bertujuan menganalisis mekanisme gerakan tanah yang dipicu Siklon Tropis Seroja, mendokumentasikan dampak banjir bandang terhadap infrastruktur dan masyarakat, serta mengevaluasi efektivitas strategi mitigasi yang ada dan merumuskan rekomendasi perbaikan. Metode yang digunakan adalah kualitatif deskriptif dengan pendekatan library research melalui telaah mendalam terhadap laporan BNPB, PVMBG, BPBD Flores Timur, dokumen kebijakan, hasil penelitian terdahulu, serta pemberitaan media yang terverifikasi. Hasil kajian menunjukkan bahwa faktor utama bencana adalah curah hujan ekstrem (>200 mm/12 jam) yang bertautan dengan kondisi lereng curam (>30°), tanah labil berlapis abu vulkanik Gunung Lewotolo, dan deforestasi kawasan hulu. Mekanisme dam break failure menjadi penguat destruktif yang melipatgandakan energi banjir bandang. Strategi mitigasi yang ada dinilai belum memadai, ditandai oleh ketiadaan sistem peringatan dini yang efektif di tingkat komunitas, lemahnya integrasi peta risiko bencana ke dalam tata ruang kabupaten, dan tingginya kerentanan sosial masyarakat kepulauan. Penelitian ini merekomendasikan pendekatan mitigasi terpadu yang melibatkan: (1) pembangunan EWS berbasis komunitas, (2) reboisasi kawasan hulu DAS, (3) relokasi permukiman rawan secara partisipatif, (4) revisi standar infrastruktur tahan bencana, dan (5) penguatan kapasitas Destana berbasis kearifan lokal.
ABSTRACT
The flash flood and landslide disaster that struck Adonara Island, East Flores Regency, East Nusa Tenggara (NTT) on April 4, 2021, was one of the most devastating hydrometeorological disasters in the province's recorded history. Triggered by Tropical Cyclone Seroja classified by BMKG (2021) as the most intense cyclone in modern records over Flores waters, with wind speeds reaching 95 knots the event resulted in 72 fatalities in East Flores Regency, 76 injured, 1 still missing, 27,560 people directly affected, 2,579 displaced, and the total severance of road access and five major bridges across Adonara Island. Economic losses were estimated at IDR 1.2 trillion by BNPB (2021). Across NTT province as a whole, the total death toll from Cyclone Seroja reached 179 people (Deputy Governor of NTT, 2021). This study aims to analyze the land movement mechanism triggered by Tropical Cyclone Seroja, document the flash flood impact on infrastructure and communities, and evaluate existing mitigation strategies while formulating improvement recommendations. The method employed is descriptive qualitative with a library research approach, through in-depth review of BNPB, PVMBG, BPBD East Flores reports, policy documents, prior research findings, and verified media coverage. Study results indicate that primary drivers were extreme rainfall (>200 mm/12 hours) combined with steep slopes (>30°), unstable volcanic ash-layered soils from Mount Lewotolo, and upstream deforestation. The dam break failure mechanism served as a destructive amplifier that multiplied the flash flood's energy. Existing mitigation strategies are deemed inadequate, marked by the absence of effective community-level early warning systems, weak integration of hazard maps into spatial planning, and high social vulnerability of island communities. This study recommends an integrated mitigation approach encompassing: (1) community-based EWS construction, (2) upstream watershed reforestation, (3) participatory relocation of high-risk settlements, (4) revision of disaster-resilient infrastructure standards, and (5) strengthening Destana capacity based on local wisdom.
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