Flood risk assessment using GIS. Study case from Romania

Diana-Alexandra GHEORGHE

UNIVERSITY OF BUCHAREST

GEOGRAPHIC POSITIONFlood risk assessment using GIS. Study case from Romania

GENERAL PRESENTATION OF THE AREA

Flood risk assessment using GIS. Study case from Romania

Physical map

Hydrographic network

Bistriţa River

• Main tributary rivers: Bicaz, Tarcău, Cracău and Trotuş• Mean flow: 35 – 66 m3/s• Upstream of Izvorul Muntelui Lake, ice dams forms

every year (end of winter-spring)• Entire Bistrita channel was completely modified after

building the hydro plant of Stejaru-Bicaz• 8 more hydroplants (dams) build on Bistrita stream• The biggest lake - Izvorul Muntelui Lake:– Build in 1961– Dam hight: 127 m– Volum: 1.230 mil. m3

Human settlements map

METODOLOGYFlood risk assessment using GIS. Study case from Romania

• Topographic map 1:25.000 (1980s)• Ortophotoplans (2005)• CORINNE Land Cover 2000• Topobathymetric data for Izvorul Muntelui Lake• Digital Elevation Model (DEM)• Cross sections extracted from DEM• Hydrological data• ArcGIS 9.3. with HEC GeoRAS add-in• HEC-RAS 4.1. (hydrological modeling)

• Modeled two scenarios of dam failure for Izvorul Muntelui – 25% dam area failure– 50% dam area failure

• Analyzed the worst case scenario (50% dam failure), at the maximum flood extent

• Considered the natural channel of Bistrita, neglecting the secondary manmade channels.

RESULTSFlood risk assessment using GIS. Study case from Romania

• Flood wave gets from upstream (Izvorul Muntelui Dam) to downstream (confluence between Bistrita and Siret) in 36 hours

• The flood wave does not mitigate at the confluence point with Siret

• Water depth varies between 0 and 111 m• Lower values – towards Bistrita Valley slopes• Greater values – lake areas

Water depth map

-Flood extent: 150 m and 1 km -Affected: aprox. 70 localities, from which 4 cities (Bicaz, Piatra-Neamţ, Buhuşi, Bacău)

Flood map – maximum flood level

-Affected: railway between Moldavia and Transylvania; several national and county roads-Isolated areas

Means of communication– maximum flood level

Landuse map – maximum flood level

- Pastures- Forest

Piatra-Neamt City – maximum flood level

CONCLUSIONSFlood risk assessment using GIS. Study case from Romania

• The study area is highly vulnerable to floods• A dam failure at Izvorul Muntelui would have a severe

impact on the area:• Over 50 localities affected, including Piatra-Neamt and

Bacau• Several national roads and railways would be closed,

leaving isolated areas• High moisture in soil for long time

• The study is going to be continued, focusing on quantitative aspects and on measuring the effects of this kind of flood in the area (downstream part of Bistrita stream)

• Thanks to Prof. Daniela Nistoran from Politehnica University – hydrological modeling

Thank you!