Journal of Hydroinformatics Sample Issue

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© IWA Publishing 2014 Journal of Hydroinformatics

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16.1

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2014

Assessment of GeoEye-1 stereo-pair-generated DEM in flood mapping of an ungauged basin I. K. Tsanis, K. D. Seiradakis, I. N. Daliakopoulos, M. G. Grillakis and A. G. Koutroulis

ABSTRACT A very high resolution (VHR) digital elevation model (DEM) is produced from a GeoEye-1 0.5-mresolution satellite stereo pair and is used for floodplain management and mapping applications such as watershed delineation and river cross-section extraction. For this purpose, a 2 m × 2 m resolution terrain surface is produced from the stereo pair by using the Leica Photogrammetry Suite (LPS) enhanced Automatic Terrain Extraction (eATE) algorithm. DEM accuracy is assessed by comparison with measured individual ground control points (GCPs), stream cross-sections and other landscape features. Results show that the produced DEM is in good agreement with ground truth and superior to products of lower resolution, such as 90 m NASA Shuttle Radar Topography Mission (SRTM) and 1:5,000 topographical maps. One- and two-dimensional hydraulic models are used to simulate

I. K. Tsanis (corresponding author) K. D. Seiradakis I. N. Daliakopoulos M. G. Grillakis A. G. Koutroulis Department of Environmental Engineering, Technical University of Crete, Chania, Greece E-mail: tsanis@hydromech.gr I. K. Tsanis Department of Civil Engineering, McMaster University, Hamilton, Canada

rainfall–runoff characteristics and flood wave kinematics of the flash flood event of 17 October 2006 that occurred in the ungauged basin of Almirida, using the 2 m VHR-DEM as an input. Results show that the hydraulic simulation based on the generated VHR-DEM, calibrated and validated via field data, produces an accurate extent and water level of the flooded area. Remote sensing stereo reconstruction is a promising alternative to traditional survey methods in flood mapping applications. Key words

| digital elevation model, flash flood, flood mapping, satellite stereo pair, very high resolution

INTRODUCTION Floods are among the world’s most costly disasters with the

subject to increasing human activity such as urbanization

estimated cost of flood damage in Europe increasing signifi-

that reduces infiltration leading to the increase of surface

cantly in the past decades (Re ; Barredo ). In 2002

runoff, the shortening of the flood’s travel time and an

only, Europe suffered over 10 billion Euros in damages and

increase in the peak flow. Urbanization can directly affect

dozens of people were killed (Toothill ). Flash floods

the capacity of a stream when infrastructure such as

constitute a great challenge in civil protection as they rep-

bridges are constructed within a stream encroaching the

resent a great destructive force. Within minutes to a few

floodplain, or indirectly causing stream channel enlarge-

hours from the causative storm event, flash flood water

ment as a response to the change in stream flow regime

levels can reach their peak, leaving insufficient warning

accompanying urbanization (Hammer ; Gregory et al.

time to prevent human casualties (Borga et al. ; Collier

; Konrad ). Especially in the case of ungauged

). They occur both in areas with no flooding history

basins, flash floods also pose a great challenge to science

and areas with such frequent floods that flooding is con-

as heterogeneities and the lack of observational data

sidered a local climate component (Llasat et al. ).

enhance uncertainties in providing quantitative assess-

The flooding potential of a hydrological basin is mainly

ments (Sivapalan ).

doi: 10.2166/hydro.2013.197


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