Torrent flood origin from the mountain, but consequences felt in the downstream sections. River basins are dynamic systems constituted by a complex arrangement of fluxes between the land and water environment. Land use pattern and...
moreTorrent flood origin from the mountain, but consequences felt in the downstream sections. River basins are dynamic systems constituted by a complex arrangement of fluxes between the land and water environment. Land use pattern and planning has a observed influence on pick flow and sediments in small catchments. Case study was carried out on a Sushica and Radoviska Reka floods in December 2008. Damages by torrent Sushica were significant and much higher then Radoviska Reka damages. The aim of this study is to defined impact of geospatial factors on appearance of the flood wave and on the damages. A digital landscape model was developed consist of several layers needed for: analyze of discharge (DEM, slope, soil, geology, land cover/use, erosion, precipitation intensity), layers for analyze of reason for damages (urban plan, position of critical facilities, hydraulic structures in the bed, bridges) and analyze of municipality crises management body operation. Basin of Sushica (18,7km2) is smaller then Radoviska Reka (53,8 km2). All natural factors (slopes, drainage net, altitude difference, soil, geology, basin area..) contribute to the fact that Radoviska Reka is much more dangerous. Land cover favor Sushica (consist of arable land, degraded pastures and transitional woodland) while in the Radoviska Reka basin more then a half of the area is forest. Gavrilovic model was used for quantification of natural factors impact. Erosion coefficient is almost double higher in Sushica (Z=0,65) then in Radoviska Reka (Z=0,35). Precipitation value on critical day was 52,5 mm. Radoviska Reka was trained with various hydraulic structures (longitudinal and cross structure - check-dams for sediment retention etc.) Otherwise, there isn’t any type of structure in Sushica bed. Urban plan in the center of the city (where Radoviska Reka pass) is adequate for flood damages minimizing, because there are two streets along the river bed that enable open corridor.. But the main problem for flooding was closure of the bed profile with sediment and improper built bridges (on the “Ancient Bridge” profile was 40% closed). Flood water didn’t contain significant amount of sediments. Urban structure in the industrial part (where Sushica pass) was not adequate. There are installations closed to the torrent bed and these objects were highly damaged. As a result of, high erodibility of the basin and existence of wild landfill, significant amount of sediments closed the bridges, the first bridge collapsed, sediment was re-transported to the second bridge that was totally closed and water jump over the bridge and damaged infrastructure facilities. Municipality body for crises management operated but after the flood according to the national legislation and principles. Early warning system was not established but because of speed of onset of this hazard, practically there was no time for warning the citizens. It can be concluded that the main reason for flooding of the center by Radoviska Reka was improper bridges, while land cover/use pattern and erosion intensity together with the inadequate set up of industrial object and absence of flood control structures result in flood wave that cause significant damages.