THE USE OF GIS TECHNIQUES FOR OBTAINING POTENTIALLY FLOODABLE SURFACES IN THE JIJIA FLOODPLAINE

Abstract

The density of the hydrographical network in Romania is high; hence, many settlements are situated in the major floodplain, which is often subjected to floods. The elaboration of hydrological risk maps for the major hydrographical arteries is extremely useful for the development plans of human settlements within plateaus and plains. The Jijia River is the main tributary within the northern sector of the Prut River. It dredges the Moldavian Plain from the NW towards the SE. The modelling of floods in the floodplain of the Jijia River involved three stages. In the first stage, the data necessary for simulating floods were collected (i.e. maximum flows from the hydrometric stations and the LIDAR data). In the second stage, the data obtained were processed (theoretical flows with assurances of 0.1%, 1%, 3% and 5% were calculated using the Pearson III formula and the LIDAR data were processed). In the third stage, the floodable stripes were obtained using the software programs Arc-GIS, HEC-GeoRAS and HEC-RAS. Finally, maps with potential floodable areas were generated. The floodable surface on the Jijia River is 119.078 km for the assurance of 0.1%, 102.06 km for the assurance of 1%, 84.99 km for the assurance of 3% and 71.45 km for the assurance of 5%. Along with the potentially floodable surface, the level of flooding was obtained: it reached a peak value of 6.83 m in case of the assurance of 0.1%. Using the existing data, an analysis was conducted regarding the potential risks in case of major floods. The purpose of the study is to prevent floods and to mitigate their effects on the human settlements within the floodplain of the Jijia River.