Novel Early flood Warning and Risk Assessment System

a next generation expert system software for flood warning and risk analysis

OutlineIntroduction of NEWS in ChineseTIGGE Global weather forecast centresFlood forecasting procedureTest application 1: Upper Severn catchment (with results of probabilistic forecasts)Test application 2: Upper Huai catchment(ongoing)NEWS potential market value and endusersNEWS in the public domain (website) *

Summary

*NEWSTIGGE(EU JRC)EFAS EFAS3-10EFASNEWS(1) (2) (3) (4) (flood risk map)NEWS (Severn river) (4062Km2)(150)310 NEWSNEWS(ECMWF) ECMWFFlorian PappenbergerNEWSTIGGETIGGENEWS

Global weather forecast centres*: TIGGEn ()

Centre Code Country/Region Forecast Center Centre Abbr. Ensemble Members ammc Australia Bureau of Meteorology BOM 32+1 babj Canada Meteorological Service of CanadaMSC 14+1 cwao China China Meteorological Administration CMC 20+1 ecmf Europe European Centre for Medium-Range Weather Forecasts ECMWF 50+1 egrr UK UK Met Office UKMO 23+1 kwbc USA National Centre for Environmental Predictions NCEP 20+1 rjtd Japan Japan Meteorological Agency JMA 50+1 sbsjBrazilBrazilian Centro de Previsao de Tempo e Estudos Climatico CPTEC14+1

Flood forecasting procedure*Hydrological/Hydraulics model calibrationInitial status, forecast starting timeModel simulation using calibrated parameter set10in testing modeNumerical Weather Forecast (NWP) modelsEnsemble forecasts (replace conventional deterministic single forecast)Downscale forecasts to the catchment model spatial unit(1001)For testing/quality control purpose, not applicable for operational purposes: ()

Severn Basin - DEM*

Severn Basin meteo domain*

Severn Basin ensemble event hydrographJan 2008*

Severn Basin ensemble area of inundation*

Severn Basin probabilistic inundation estimate*20081

, 100% inundated not inundated

Severn Basin a flood case study*Percentage of ensemble Q above flooding threshold at MontfordJan 2008

NEWS project selected area

Upper Huai Catchment (30672 km2)Upstream of Wangjia Ba reservoir ()Huai River Basin ()*

Huai Basin*

Huai Basin*

Huai Basin*

NEWS market valueMarket value in both business and public sectors Insurance companies: to derive flood risk maps to estimate loss values and calculate premium to be allocated to specific regions;Engineering consulting firms: to provide sound climate-proof design for flood defenses and other hydraulic structures. The system can also be used to provide strategic advice on flood insurance including institutional and cost-recovery mechanisms to assist in the development of resilience to climate change through mitigation;

Research institutions: use tailor made modules from the NEWS system for simulation exercises for research and development purposes;Educational institutions: teaching purposes especially targeted at local government authorities and graduate students at advanced learning institutions including universities;Public authorities: to perform flood risk analysis to inform planning and new investment in real estate especially in low lying areas. The forecasting component can be used to issue flood warning, improve public awareness of flood risk and assist regional level policy formulation and decision making.*

NEWS in the public domain - website*

, .Will you like to have an English summary here?All these ensemble prediction systems are based on n time integrations of a numerical weather prediction model, with one (the control forecast) starting from a central analysis, usually the unperturbed analysis generated by a data-assimilation procedure, and the others (the perturbed forecasts) starting from perturbed initial conditions defined to simulate the effect of initial uncertainties.

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Schematic flowchart of the test procedure (Slide 5) The forecast procedure is tested in an iterative way such that the disaggregated precipitation input maps could display satisfactory spatial patterns and produce comparable discharge level as that driven by rain-gauge observation. Once the ensemble of forecasted discharges is obtained, a hydraulic model was coupled to the end of the cascade to forecast flood water depth and inundation extent. The time used in this paper is the UTC time.NEWS key model components:Ensemble weather forecasts (obtained from a medium-range global ensemble system TIGGE - to provide probabilistic forecasts for 6 hours up to 10 days and for the whole globe)Rainfall-runoff model (to produce hydrograph using the ensemble weather forecasts)Hydraulics model (to simulate flood inundation using predicted ensemble hydrograph as input)NEWS immediate output:Downscaled ensemble weather forecasts (in the second project phase, a long-term ensemble weather prediction within a timeframe of 30 to 50 years)Predicted ensemble hydrograph Predicted ensemble flood inundation map [a flood risk map with probabilistic diagnosis - (1) inundation area; (2) likelihood of being inundated; (3) inundation depth]Models selectedTIGGE forecast data are disaggregated from approximately 100100 km to 11 km and spatially corrected before being fed into a rainfall-runoff model.The LISFLOOD-RR model (LFRR) has been used within European Flood Alert System (EFAS) and thus selected for the Upper Severn. LFRR is a fully distributed and semi-physically based rainfall-runoff model. The LISFLOOD-FP model (LFFP) has been selected for simulating flood inundation both in the channel and on the flood plain. LFFP uses the Saint-Venant equations of open channel flow within the channel, and a 2D raster model based on the Manning equation for the floodplain. Already tested area: Severn river basin located in the Midlands region of EnglandThe River Severn collects water from the Welsh mountainous area and its tributaries after passing through many steep sided valleys in Wales. It then flows eastwards and contributes significantly high levels of discharge to Montford (see figure on Slide 6). Between Montford and Buildwas, the river channel meanders through a low-lying flood plain. Elevation on both sides of Buildwas rises above the flood plain forcing the river to cut through and form a gorge behind Buildwas. The river diverts its flow southwards just before passing through Bridgnorth. The drainage area up until Bridgnorth is referred to as the Upper Severn catchment. It is approximately 4062 km2 with urban or sealed areas, forest and agricultural land accounting for 3%, 7.1% and 48.5% of the area respectively. Loosely packed peat soil dominates the Upper Severn catchment. Flow levels are generally high in autumn and winter and low in summer.The Shropshire town of Shrewsbury is situated within the incised meander loop of this reach and vulnerable to floods. The simulation of flood inundation is therefore carried out on the river section between Montford Bridge (UK Ordnance Survey grid reference SJ412144) and Buildwas (SJ644044).

Metrological input domain is overlaid with the Severn catchment boundary to give you an impression of the spatial scale of the TIGGE ensemble weather forecast data as well as that of the Regional Climate Model (RCM) [RCM is considered for the second stage of the project when we will like to have NEWS produce both short/medium-term forecast and long-term prediction, the latter is of special interest for insurance]. As you can see from the figure (Slide 7), the meteorological domain is in rather coarse resolution. Approximately 6 points cover the Upper Severn catchment (4062km2). Downscaling or disaggregation is therefore required to bridge the spatial gap between meteorological input and driving inputs for hydrological and hydraulics models. Ensemble discharge forecasts (Qforecast) in comparison with observed discharge (top); ensemble precipitation forecasts issued on 18/01/08 by ECMWF (bottom)Lines with diamond, squares & stars: Q5, Q50 and Q95Horisontal dashed line: EA warning levelThe light grey lines: the ensemble forecasts

Ensemble area of inundation by using ensemble forecasts from the ECWMF centre Probabilistic area of inundation by using ensemble forecasts from the ECWMF centre (a blow-up of area of figure (c) on Slide 6 between Montford and Buildwas)The inundated area isn't extensive in this case due to the low magnitude of the flood event took place in Jan. 2008. The horisontal bars represent the 7 centres in the same order as in table (Slide 4, not the sbsj centre) plus the Grand Ensemble (all 7 centres together).The use of more than one forecast centre gives the forecaster more information at an earlier stage and potentially increases the ability to detect a flood. The flooding signal is visible in some centres as early as 10 days ahead, although only on the 25%-level. The signal becomes persistent approximately 4 days ahead, which ascertains floods are going to take place.Upper Huai catchment has been selected to replace the originally proposed Luohe catchment due to the abundant data of the Upper Huai catchment. Upper Huai Catchment overlaid with the TIGGE ensemble forecast gridsThe differences between Upper Severn (US) and Upper Huai (UH) are (1) hydrological model LISFLOOD-RR for US, Xinanjiang for UH use existing models to facilitate coupling with meteorological inputs; (2) hydraulics model LISFLOOD-FP for US, 1D flood routing model for UH due to the availability of river cross sections and DEM data.Hohai is now coupling Xinanjiang model with meteorological inputs. Results will be then used to drive the 1D hydraulics model. Preliminary results are anticipated in early April.Significant market value through impact in both business and public sectors.Elaborated on the next slide