ANALISIS KERENTANAN DAN RESIKO BANJIR DAERAH BOJONEGORO-TUBAN-LAMONGAN, JAWA TIMUR MENGGUNAKAN TEKNIK PENGINDERAAN JAUH (Flood Susceptibility and Risk Analysis on Bojonegoro-Tuban¬Lamongan Area, East Java Using Remote Se

ABSTRACT The objectives of this research are (1) to study some flood indicators which can be identified on aerial photograph and Lnadsat TM image to determine flood susceptibility level at the research area, (2) to enhance of digital image using Tasseled-cap transformation to differentiate between flood prone areas and not flood areas, and (3) to evaluate the sum of flood detriment potential for each flood risk level. The method used for this research consisted of several steps. First, interpretation of landform units using digital Landsat TM data and black-white panchromatic aerial photograph image, and Second, Landsat TM data was then used to make land cover and landuse classification map. Third, a flood susceptibility map was then produced using digital Landsat TM data. For this purpose, digital data has been enhanced with Tasseled-cap Transformation, to obtain indices of brightness, greenness and wetness. Brightness and wetness indices were used to distinguish between moist and dry soil. Based on the soil moisture level, flood susceptibility map can be made. Fourth, flood susceptibility map was then overlaid with landuse map, to produce flood hazard map. This map was overlaid with land productivity and population density maps to result flood risk map. Two table dimension of Boolean logic was also used in this overlay analysis. The results of this research show that: (1) number of landform units in research area is 24 details landform unit. (2) flood susceptible landform units encompass Alluvial Plain (F1), Meander Cut-off (F3), Backswamp (F7) and Flood Basin (F8). (3) the spectral values of Tasseled-cap transformation_ image (especially Wetness Indices) varies, i.e. >22 (highly susceptible to flooding), 17 - 22 (susceptible to flooding), 11 - 16 (moderately), 5-10 (low), and 9.5 meter, and inundation duration of 90¬120 day. Description for the other susceptibility level can be seen on Flood Susceptibility Map attached. Flood risk map as the final result of this research shows that high risk is associated with high chance of loss. Level of loss at high risk class for every 25 Ha at landuse type of irrigated paddy field, dryland, and fresh water fish pond are 1507,50 Kw, 1382,75 Kw, and 391,50 Kw, respectively. Based on these losses, the class of flood risk can be be used to determine priority scale in mitigating flood in a region having limited budget. Key Words: landform, landuse, susceptibility, ris