FLOOD MAPPING Menaxhimi i rezikut te permbytjeve Objektivat Gjenerale

General Objectives 1.Protect people and goods 2.Preserve river capacity and flood plants 3.Conserve ecological equilibrium To reach these objectives, a regulation of land use in the floodplain is necessary: –Forbidding new construction in high risk areas, –Controlling urban extension in floodplain, –Limiting embankment to minimum.

Example of flood risk mapping Zone 1 - Little / no risk Zone 2 - Low to Medium risk (light blue) Zone 3 - High risk (dark blue)

Principe of flood risk analysis –Flood hazard assessment: three hydraulic parameters considered 1.Water depth, 2.Flow velocity, 3.Duration of inundation

Flood risks analysis Flood hazard classification Depth Velocity Low velocity (Plain flood) Medium velocity High Velocity (Flash flood) Depth < 0.5 mModerate Moderate to high 0.5m 1.0m ModerateHigh Depth >1.0mHigh

Flood risk assessment Vulnerability classification by distinguishing urban / non urban areas Flood risk mapping Flood plainUrban areas High flood hazardHigh risk Moderate flood hazard Low riskHigh risk  Flood hazard + vulnerability,  Vulnerability mapping

EXAMPLE Land use regulation Nature of time construction Type Non urban Zone Urban Zone Moderation hazard High flood hazard Habitation, Industries, activities NewXPrescriptionsX ReconstructionXXX ExtensionPrescriptions ModificationPrescriptions Public equipment All kindsPrescriptions Camping NewXXX ExtensionXXX Others NewXXX ExtensionXPrescriptionsX ModificationPrescriptions

Where are we now ?

Methodology Flood

Flood Hazard / Flood Risk Different scales –Preliminary flood risk assessment Drini River Basin –Local flood risk map Pilot area : Skenderaj

Preliminary flood risk assessment DATA GATHERING AND PROCESSING Topographical and hydrological data –SRTM 90 DEM –Contour lines (10m) –Historic floods etc. Problems and accuracy –SRTM DEM : 90m x 90m, dZ~10m –Shifting between different maps

DEM from contour lines SRTM DEM

Shifting between different maps

What are we going to do ?

Improving preliminary delineation of flood areas –Send questionnaires for the most sensitive towns –Process with available satellite imagery –For sensitive areas assess flood hazard with simplified hydraulic calculations and fields visits –Georeferencing all data

Remember past flooding events ( )

Skenderaj flooding zone

Local flood risk map Pilot area: Skenderaj  Work completed: Field visits Questionnaire prepared TOR for topographic survey  Next steps Hydraulic modelling Flood risk mapping Discussing about a pilot flood risk management plan

A quick presentation of the technology

Floodplain Mapping Approach Water surface profiles ArcGIS Geometric data Parameters Schematic Flow discharge Hydrology Hydraulic model ArcGIS HydraulicHydrology

Floodplain Mapping Approach ArcGIS Input Data DEM Hydrology Flood discharge Hydraulic Water surface profiles ArcGIS Flood plain maps Flow discharge Geometric data Parameters Schematic ArcGIS HydraulicHydrology

Digital Terrain Model: DTM ArcGIS HydraulicHydrology Observed points and break lines for constructing a triangular irregular network (TIN).

TIN components: - nodes - edges - triangles Triangular Irregular Network : TIN ArcGIS HydraulicHydrology DTM -

3D display of a TIN. DTM – TIN 3 D display of topography ArcGIS HydraulicHydrology

DTM – TIN Display of buildings Embedding Buildings into the TIN. ArcGIS Hydraulic Hydrology

Topographic survey: Cross Sections Stream centerline. Banks. Flow paths. Cross sections. ArcGIS HydraulicHydrology

Hydraulic Modelling stream geometry. Cross-sections extracted from the TIN. ArcGIS HydraulicHydrology

Hydraulic Modelling Water surface elevations. ArcGIS HydraulicHydrology

Floodplain Mapping Floodplain ArcGIS HydraulicHydrology

Floodplain Mapping 2-D floodplain animation. ArcGIS HydraulicHydrology

Floodplain Mapping 3-D floodplain animation.