Influence of urban land cover changes and climate change for the exposure of European cities to flooding during high-intensity precipitation

Abstract. The extent and location of impervious surfaces within urban areas due to past and present city development strongly affects the amount and velocity of run-off during high-intensity rainfall and consequently influences the exposure of cities towards flooding. The frequency and intensity of extreme rainfall are expected to increase in many places due to climate change and thus further exacerbate the risk of pluvial flooding. This paper presents a combined hydrological-hydrodynamic modelling and remote sensing approach suitable for examining the susceptibility of European cities to pluvial flooding owing to recent changes in urban land cover, under present and future climatic conditions. Estimated changes in impervious urban surfaces based on Landsat satellite imagery covering the period 1984–2014 are combined with regionally downscaled estimates of current and expected future rainfall extremes to enable 2-D overland flow simulations and flood hazard assessments. The methodology is evaluated for the Danish city of Odense. Results suggest that the past 30 years of urban development alone has increased the city's exposure to pluvial flooding by 6% for 10-year rainfall up to 26% for 100-year rainfall. Corresponding estimates for RCP4.5 and RCP8.5 climate change scenarios (2071–2100) are in the order of 40 and 100%, indicating that land cover changes within cities can play a central role for the cities' exposure to flooding and conversely also for their adaptation to a changed climate.

[1]  P. Linden,et al.  ENSEMBLES: Climate Change and its Impacts - Summary of research and results from the ENSEMBLES project , 2009 .

[2]  C. Arnold,et al.  IMPERVIOUS SURFACE COVERAGE: THE EMERGENCE OF A KEY ENVIRONMENTAL INDICATOR , 1996 .

[3]  Heejun Chang,et al.  Climate Change, Land‐Use Change, and Floods: Toward an Integrated Assessment , 2008 .

[4]  S. Djordjević,et al.  Potential and limitations of 1D modelling of urban flooding , 2004 .

[5]  H. Madsen,et al.  Evaluating adaptation options for urban flooding based on new high-end emission scenario regional climate model simulations , 2015 .

[6]  T. Stocker,et al.  Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. A Special Report of Working Groups I and II of IPCC Intergovernmental Panel on Climate Change , 2012 .

[7]  C. Frei,et al.  Future change of precipitation extremes in Europe: Intercomparison of scenarios from regional climate models , 2006 .

[8]  P. Bates,et al.  Benchmarking 2D hydraulic models for urban flooding , 2008 .

[9]  F. Canters,et al.  Improving Distributed Runoff Prediction in Urbanized Catchments with Remote Sensing based Estimates of Impervious Surface Cover , 2008, Italian National Conference on Sensors.

[10]  Dragan Savic,et al.  Comparison of 1D/1D and 1D/2D Coupled (Sewer/Surface) Hydraulic Models for Urban Flood Simulation , 2009 .

[11]  Henrik Madsen,et al.  Comparison of different statistical downscaling methods to estimate changes in hourly extreme precipitation using RCM projections from ENSEMBLES , 2015 .

[12]  M. Bauer,et al.  Estimating and Mapping Impervious Surface Area by Regression Analysis of Landsat Imagery , 2007 .

[13]  S. Sobolowski,et al.  Background information on the RiskChange simulations by BCCR and DMI , 2014 .

[14]  Rasmus Fensholt,et al.  Using Landsat Vegetation Indices to Estimate Impervious Surface Fractions for European Cities , 2015, Remote. Sens..

[15]  Frank Canters,et al.  Assessing urbanisation effects on rainfall-runoff using a remote sensing supported modelling strategy , 2013, Int. J. Appl. Earth Obs. Geoinformation.

[16]  H. Madsen,et al.  Assessing future climatic changes of rainfall extremes at small spatio-temporal scales , 2013, Climatic Change.

[17]  Judith Klostermann,et al.  Urban adaptation to climate change in Europe: Challenges and opportunities for cities together with supportive national and European policies , 2012 .

[18]  D. B. Jennings,et al.  Changes in anthropogenic impervious surfaces, precipitation and daily streamflow discharge: a historical perspective in a mid-atlantic subwatershed , 2002, Landscape Ecology.

[19]  A. Pathirana,et al.  Impacts of Climate Change on Rainfall Extremes and Urban Drainage Systems , 2012 .

[20]  K. Calvin,et al.  The RCP greenhouse gas concentrations and their extensions from 1765 to 2300 , 2011 .

[21]  G. Hollis.  The Effect of Urbanization on Floods of Different Recurrence Interval , 1975 .

[22]  Dušan Prodanović,et al.  Overland flow and pathway analysis for modelling of urban pluvial flooding , 2009 .