Flood risks/Description: Difference between revisions

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|Status=On hold
|Status=On hold
|Reference=Loveland et al., 2000; Van Beek et al., 2011; Wada et al., 2011; Hinkel and Klein, 2009;
|Reference=Loveland et al., 2000; Van Beek et al., 2011; Wada et al., 2011; Hinkel and Klein, 2009;
|Description===The flood model==
|Description===Model core==
The purpose of the [[GLOFRIS model]] ([[Winsemius et al., 2012]]; [[Ward et al., 2013]]) is to estimate the effect of land cover and climate change on flood risks in river catchments and coastal areas on a global level. The global flood risks are expressed in the projected number of people affected, annually, and in GDP value. GLOFRIS uses land-cover input from [[IMAGE land use model|IMAGE]] and climate time series, such as the IPCC GCM projections. These input data drive a global hydrological model ([[PCR-GLOBWB model|PCR-GLOBWB]], the computational core of the module). PCR-GLOBWB calculates where and when flooding events may occur, and calculates the inundation extent and depth needed to estimate flood risks. PCR-GLOBWB has features (daily time steps and proper accounting of  the relationship between non-linear soil moisture and run-off) that make this model appropriate for simulating flooding events. The spatial resolution currently used by the model is 0.5 x 0.5 degrees (and 5 x 5 minute resolution, currently under development). The different model steps of the main GLOFRIS module are shown in the model flow diagram of GLOFRIS on the right.
The purpose of the [[GLOFRIS model]] ([[Winsemius et al., 2012]]; [[Ward et al., 2013]]) is to estimate the effect of land cover and climate change on flood risks in river catchments and coastal areas on a global level. The global flood risks are expressed in the projected number of people affected, annually, and in GDP value. GLOFRIS uses land-cover input from [[IMAGE land use model|IMAGE]] and climate time series, such as the IPCC GCM projections. These input data drive a global hydrological model ([[PCR-GLOBWB model|PCR-GLOBWB]], the computational core of the module). PCR-GLOBWB calculates where and when flooding events may occur, and calculates the inundation extent and depth needed to estimate flood risks. PCR-GLOBWB has features (daily time steps and proper accounting of  the relationship between non-linear soil moisture and run-off) that make this model appropriate for simulating flooding events. The spatial resolution currently used by the model is 0.5 x 0.5 degrees (and 5 x 5 minute resolution, currently under development). The different model steps of the main GLOFRIS module are shown in the model flow diagram of GLOFRIS on the right.


==Land cover.==
==Land cover==
The land-cover map ‘Global Land Cover Characterization’ ([[HasAcronym::GLCC]]) ([[Loveland et al., 2000]]) is the basis of the parameters of the PCR-GLOBWB hydrological model (model flow diagram of GLOFRIS on the right). These parameters express the hydrological characteristics of different land-cover types. IMAGE and PCR-GLOBWB are linked by lookup tables that translate the IMAGE land-cover classification into that of GLCC.  
The land-cover map ‘Global Land Cover Characterization’ ([[HasAcronym::GLCC]]) ([[Loveland et al., 2000]]) is the basis of the parameters of the PCR-GLOBWB hydrological model (model flow diagram of GLOFRIS on the right). These parameters express the hydrological characteristics of different land-cover types. IMAGE and PCR-GLOBWB are linked by lookup tables that translate the IMAGE land-cover classification into that of GLCC.  


==Flood hazard.==
==Flood hazard==
The hydrological model PCR-GLOBWB ([[Van Beek et al., 2011]]; [[Wada et al., 2011]]) requires data on daily precipitation, potential evaporation and temperature that are consistent with the IMAGE scenario. Daily data are required because that reflects intermonthly and interannual climate variability and its effect on flood risk.  
The hydrological model PCR-GLOBWB ([[Van Beek et al., 2011]]; [[Wada et al., 2011]]) requires data on daily precipitation, potential evaporation and temperature that are consistent with the IMAGE scenario. Daily data are required because that reflects intermonthly and interannual climate variability and its effect on flood risk.  
The PCR-GLOBWB model includes a routing component on river flooding that estimates inundation fractions and average inundation depths on a time-step basis. These inundation fractions and depths are used to estimate flood risk. GLOFRIS scenarios typically cover a 30-year or longer climatological model run; from this time series, annual extreme values of the inundated fractions and water depths are derived and summarised in an extreme value probability distribution. This probability distribution is subsequently used for annual projections on the damage of flood risk.   
The PCR-GLOBWB model includes a routing component on river flooding that estimates inundation fractions and average inundation depths on a time-step basis. These inundation fractions and depths are used to estimate flood risk. GLOFRIS scenarios typically cover a 30-year or longer climatological model run; from this time series, annual extreme values of the inundated fractions and water depths are derived and summarised in an extreme value probability distribution. This probability distribution is subsequently used for annual projections on the damage of flood risk.   
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After the high-resolution flood hazard maps have been established, the annual extreme values can be combined to form average annual flood hazard maps and flood risk maps. At this scale, also more local detail can be applied about cropland locations, high-resolution maps on population and GDP or other exposure data of interest to the user. The resulting flood hazard maps can be combined with these high-resolution maps on population and GDP and, if possible, more localised damage models.  
After the high-resolution flood hazard maps have been established, the annual extreme values can be combined to form average annual flood hazard maps and flood risk maps. At this scale, also more local detail can be applied about cropland locations, high-resolution maps on population and GDP or other exposure data of interest to the user. The resulting flood hazard maps can be combined with these high-resolution maps on population and GDP and, if possible, more localised damage models.  


==More information==
More information about GLOFRIS, its underlying models and methods, as well as the downscaling module can be found in Winsemius et al. and Ward et al. ([[Winsemius et al., 2012]];  [[Ward et al., 2013]]).
More information about GLOFRIS, its underlying models and methods, as well as the downscaling module can be found in Winsemius et al. and Ward et al. ([[Winsemius et al., 2012]];  [[Ward et al., 2013]]).
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Revision as of 10:13, 19 December 2013

GLOFRIS, the flood risk model in IMAGE 3.0
Flowchart Flood risks. See also the Input/Output Table on the introduction page.

Model description of Flood risks