RISIKO BENCANA LONGSORLAHAN PADA LAHAN PERTANIAN DI WILAYAH KOMPLEKS GUNUNGAPI STRATO KUARTER ARJUNO JAWA TIMUR

Nugroho Hari Purnomo, SP.,M.Si., Prof. Dr. Sutikno

2012 | Disertasi | S3 Geografi

Paradigma pengurangan risiko beranggapan bahwa bencana dapat dikurangi dampaknya bila masyarakat memahami karakteristik wilayah rawan bencana, memahami objek yang rentan bahaya, dan memahami kapasitas individu serta masyarakat dalam menghadapi bencana. Permasalahan yang timbul adalah bagaimana konsep risiko bencana longsorlahan pada lahan pertanian semusim di wilayah kompleks gunungapi strato Kuarter Arjuno Jawa Timur. Berdasarkan masalah tersebut maka penelitian ini bertujuan untuk (1) mengkaji karakteristik tingkat bahaya longsorlahan di lahan pertanian tanaman semusim; (2) mengkaji tingkat kerentanan lahan pertanian tanaman semusim dan kapasitas masyarakat petani terhadap longsorlahan; dan (3) menyusun model konseptual risiko bencana longsorlahan pada lahan pertanian tanaman semusim di wilayah gunungapi strato. Satuan lahan hasil dari proses tumpangsusun peta geologi, bentuklahan, lereng, tanah, dan penggunaan lahan dijadikan sebagai kerangka penentuan lokasi pengambilan sampel sekaligus kerangka analisis. Pengambilan sampel faktor lahan dilakukan secara purposif, sementara pengambilan sampel masyarakat petani dilakukan secara aksidental. Analisis dilakukan secara deskriptif, pengujian hipotesis dengan statistik parametrik dan nonparametrik, serta analisis keruangan. Hasil penelitian menunjukkan bahwa bahaya longsorlahan sangat tinggi ada di bentuklahan kerucut gunungapi tertoreh dan lereng gunungapi tertoreh. Tingkat kerentanan ekonomi lahan pertanian tanaman semusim berkisar antara Rp. 8.879.310,-ha/th - Rp. 44.036.061,-ha/th. Sementara karakteristik sosial ekonomi masyarakat petani secara umum adalah bercirikan masyarakat transisi wilayah urbanisasi perdesaan. Risiko bencana longsorlahan tinggi ditentukan oleh bentuk penggunaan lahan sawah pada lahan dengan material lapukan batuan yang tebal, tanahnya berkonsistensi batas lekat rendah, terletak pada lereng dengan kemiringan tinggi, wilayahnya dengan curah hujan tinggi, yang diusakan oleh petani dengan pendidikan rendah, pengetahuan penyebab dan pengetahuan konservasi lahan terkait longsorlahan rendah, serta berusia cenderung tua. Model konseptual risiko bencana longsorlahan di wilayah gunungapi strato dinyatakan bahwa sumberdaya lahan pertanian tanaman semusim dengan tingkat bahaya longsorlahan tinggi dapat diusahakan dengan risiko yang dapat diterima apabila kerentanan komoditas pertaniannya bernilai ekonomi rendah dan kapasitas petani yang mengusahakannya tinggi.

The risk reducing paradigm has as its assumption that the impacts of a disaster can be reduced in case that the people are familiar with the characteristics of the area at risk, the object at risk, and the individual and community capacities in coping with the disaster. The problem arising here is how to understand the concept disaster risk of landslide on the seasonal agricultural land at area of the quartenary strato volcano complex of Arjuno East Java. In view of the problem, this research was designed for the purposes of (1) studying the characteristics of the landslide hazard level at the seasonal plant farmland; (2) studying the vulnerability of the seasonal plant farmland and the people capacity in dealing with the landslide; and (3) developing the conceptual model disaster risk of landslide for the seasonal plant farmland at the stato volcano area. The land unit as a result of intercropping processes of geological map, land shape, slope, soil and land use were used as the framework in determining of the sampling location and analysis model. Sampling of the land factor was carried out in a purposive way and the sampling of the people was carried out accidentally. The analysis was conducted descriptively, the hypothetical test using parametric and non-parametric statistics, and spatial analysis. The findings showed that the extremely high landslide risk occurred at the cone shape of the incised volcano and the slope of the incised volcano. The economic vulnerability of one-seasonal crop farmland was about Rp. 8,879,310,-ha/year – Rp. 44,036,061 ha/year. While, the socio-economic factor of the farmers was generally characterized by a transition into a periurban area. High risk was determined by the model of paddy field use at the land with thick decayed rocks, with the soil being in low sticky limit consistency, located at the slope of high steep, high rain fall area, cultivated by the low educated farmers with perception of the cause and conservation relevant to low landslide, and tend to be old in age. The conceptual model of landslide risk in the areas of strato volcano stated that the resources of seasonal plant farmland with the high risk of landslide can be cultivated with the acceptable risk if the vulnerability of agricultural commodity is low in economic value and the capacity of farmers cultivating it is high.

Kata Kunci : Risiko, Longsorlahan, Lahan Pertanian, Gunungapi Strato