Pereira, Susana

Ramos, Alexandre M.

Trigo, Ricardo

Zêzere, José

English

Universidade de Lisboa: Repositório.UL

CATÁLOGO DE EVENTOS HIDRO-GEOMORFOLÓGICOS EM PORTUGAL CONTINENTAL (1865-2015)S. Pereira1; A.M. Ramos2; L. Rebelo2; R.M.Trigo2; J.L. Zêzere11 CEG, IGOT, Universidade de Lisboa, Portugal (susana-pereira@campus.ul.pt)2 IDL, FCUL, Universidade de Lisboa, Portugal https://www.sciencedirect.com/science/article/pii/S0309170818304056EnvironmentalHazardsandRiskAssessmentandManagementwww.riskam.ul.ptwww.riskam.ul.pt1. OBJECTIVESThis work has the following objectives:(1) to characterize the hydro-geomorphological disaster events documented in theDISASTER database for the period 1865-2015;(2) to classify and analyse the main atmospheric circulation characteristics by means ofweather types associated with the disaster events, including possible presence ofAtmospheric Rivers;(3) to present a national disaster events catalogue and to discuss the role of rainfall asmain driving force of hydro-geomorphological disasters in Portugal.(4) To present disaster events with impacts in the Iberia Peninsula.2www.riskam.ul.pt2. DATA AND METHODS2.1 Disaster database and Disaster events3Flood Disaster cases (a) and landslide Disaster cases (b) (1865-2015).Disaster database registerthose floods and landslidesthat, independently of thenumber of affected people,caused casualties, injuries,evacuated or homelesspeople (Zêzere et al., 2014).Disaster case as a uniquehydro-geomorphologicoccurrence (flood orlandslide), which fulfils theDISASTER database criteriaand is related to a uniquespatial location and a specificperiod of time (Zêzere et al.,2014).www.riskam.ul.pt2. DATA AND METHODS2.1 Disaster database andDisaster eventsDisaster cases are grouped into a set ofdiscrete Disaster events that share the sametrigger mechanism and a specific magnitude intime. Disaster events were selected respectingthe following criteria:i) the disaster event should include at least 3disaster cases;ii) in temporal terms a disaster event endswhen 3 consecutive days without recordeddisaster cases are found; andiii) in spatial terms disaster events must belocated within a relatively continuousspatial pattern devoid of isolated disastercases.4Total 130 disaster eventswww.riskam.ul.pt2. DATA AND METHODS2.2 Reanalysis dataset1) 20th Century Reanalysis (20CR) version 2c (Compo et al., 2011) (NOAA/ERSL PSD)with a resolution of 2º by 2º latitude longitude grid between 1865 and 2014. This datasetprovides a continuous 3-D description of many meteorological fields from 1851 to 2014 andwas already used successfully in others works (Pereira et al., 2016; Trigo et al., 2014).2) We have converted the 3-hourly precipitation rate at surface to daily accumulatedprecipitation in order to have an approximation of the precipitation landfall at the IberiaPeninsula (IP) domain. The precipitation output from the reanalysis precipitation is not theoptimal solution; however, it provides a consistent precipitation data that could becomparable for the entire centennial period.3) Using 6 grid points from the 20CR that are located over Portugal the daily meanaccumulated precipitation was obtained for each day since 1865 till 2015. The dailycumulative precipitation for Portugal was computed for each climatological year, for theperiod 1865-2015.4) The long term climatological year accumulated precipitation 10th, 50th, 90th and 95thpercentile was also computed for the period 1865-2015, highlighting the Disaster eventsand the days with Atmospheric Rivers. 5www.riskam.ul.pt2. DATA AND METHODS2.4 Circulation weather types The atmospheric circulation conditions are determined using physical or geometricalparameters associated to the direction, velocity and vorticity of the geostrophic flow basedon 16 SLP grid points (Trigo and DaCamara, 2000) retrieved from the 20CR.The daily CWTs were computed with the 16 grid points centred in Portugal, for the 1865–2015 period using the same method as Trigo and DaCamara (2000) an adapted version ofthe Lamb weather type).26 different weather types were defined and further re-ordered into 10 types where the 18hybrid (8 for each C or A hybrid) CWT are assigned to their corresponding directional CWT(Ludwig et al., 2016; Rebelo et al., 2018).6www.riskam.ul.pt2. DATA AND METHODS2.4 Circulation weather types Most of the precipitation in Portugal isproduced by Cyclonic (C) and westerlycomponent (SW/W/NW) CWT’s.E, SE and S CWT’s can also produce someprecipitation in Portugal especially in thesouth since they are usually associated tocut off low systems and convectiveprocesses (Ramos et al., 2014a).Anticyclonic (A) and northerly types (NEand N) are predominant in summermonths and usually associated to dryconditions in mainland Portugal.7Percentage of days with Disaster events (1865-2015) and the corresponding CWT.www.riskam.ul.pt2. DATA AND METHODS2.5 Atmospheric Rivers databaseThe AR detection scheme is based on the vertically integrated horizontal water vapourtransport (IVT), following the same approach and domain as (Ramos et al., 2015).The IVT was calculated at a 6-hourly time frame in the 1865-2015 period, between 1000hPaand 300hPa.8The wind vector (m/s) and specific humidity (shaded, g/kg) at 900hPa level for the 22 December 1909 at c) 00UTC and d) 12UTC. Only wind vectors with wind speeds above 12.5 m/s are shown.(December 1909 event #8)www.riskam.ul.pt3. RESULTS3.1 Disaster events characteristics9www.riskam.ul.pt3. RESULTS3.1 Disaster events characteristics10Best fit probability distributions and disaster events with 0.01 and 0.05 probabilitiesaccording to the number of disaster cases, days with events, fatalities, and injured,evacuated and displaced people.Min. Max. Best fit probability distributionKolmogorov Smirnov testDisaster events ID with P ≤0.01Disaster events ID with P ≤ 0.05Disaster cases 3 83 Pearson 5 0.1319 - 8; 84;95Days with events 1 12 Gamma 0.1454 95; 101 8; 10; 11; 28; 37; 47; 95; 101; 111Fatalities 0 522 GeneralizedPareto0.2397 84 1; 7; 8; 38; 84; 97Injured 0 330 GeneralizedPareto0.3088 84 10; 13; 60; 82; 84; 107Evacuated people 0 4244 GeneralizedPareto0.0615 95 8; 32; 95; 101; 114Displaced people 0 14322 GeneralizedExtreme Values0.2368 73; 94; 95; 97 35; 59; 73; 82; 84; 88; 94; 95; 97; 101 www.riskam.ul.pt3. RESULTS3.2 Temporal and spatial distribution of the Disaster events11Number of Disaster events and accumulated percentage of fatalities and displaced people (a); totalannual rainfall for Lisbon rain gauge (b). Decadal moving average for Disaster events and total annualrainfall is also represented.www.riskam.ul.pt3. RESULTS3.2 Temporal and spatial distribution of the Disaster events12Number of affected people and percentage of Disaster events per district.www.riskam.ul.pt3. RESULTS3.3 Circulation Weather types13Percentage of Disaster cases, fatalities anddisplaced people according to the CWT of the totalset of Disaster events.Cyclonic CWT is widelyassociated with convectivesystems that can generate flashfloods and urban floods oftenresponsible for fatalities andinjured people.CWTs with a westerlycomponent (NW, W, SW) can beassociated to prolonged wetperiods that can induce floodevents in the main rivers andlandslides in the mountain areas.www.riskam.ul.pt3. RESULTS3.3 Circulation Weather types14Percentage of flood types (a) and landslides types (b) identified in Disaster events, accordingto the CWT. The sum of the percentage of floods, flash floods and urban floods by CWT is100% (a); the sum of the percentage of falls, flows and slides by CWT is 100% (b).www.riskam.ul.pt3. RESULTS3.3 Circulation Weather types15Number of days with Disaster events andpercentage of days per CWT.• In the central and northern PortugalDisaster events are mainly driven bySW, W, NW and C Weather Types;• The CWTs with a southern andeastern component (E, SE and S) arethe main drivers in southernPortugal.www.riskam.ul.pt3. RESULTS3.3 Circulation Weather types16Long term climatological year accumulated rainfall 10th, 50th 90th and 95th percentilecompared with the climatological year 1909/1910 (a); mean daily rainfall (light greybars) along with the correspondent circulation weather type (in colours) (b).www.riskam.ul.pt3. RESULTS3.4 Disaster events catalog1718Largest floods in 200 years in Douro19Flood and landslide DISASTER cases from 20–28 December 1909 event over Iberia.Source: Disaster database for Portugal and Spanish newspapers.Numbers in the map correspond to the affected hydrographic basins: (1) Coruña basins;(2) MinhoBasin; (3) Lima and Cávado basins; (4) Douro Basin; (5) Águeda, Mondego, and West basins; (6)Tagus Basin; (7) Sado Basin.Disaster case 134(130 floods and 5 landslidesTotal affected people: 3876Total fatalities 89 (57 floodsand 32 landslides)www.riskam.ul.pt3. RESULTS3.4 Disaster events catalog2021Damages in the great Roman Bridge in the city ofMérida caused by the rising of Guadiana river. www.riskam.ul.pt4. CONCLUSIONS22• The typology and severity of impacts from climate extreme events depend notonly on the extremes themselves and on the physical constrains of the landscape,but also on exposure and vulnerability of societal system.• The disaster events catalogue is an important historical and meteorological datasource of the damaging floods and landslides that occurred in Portugal in a 150-year period.• This catalogue allows for the ranking of disaster events in the country in terms ofhuman damages and the type of meteorological system that triggered the events.• The catalogue is used to identify those events that generated higher impacts inpopulations and settlements along time and space, contributing to the furtherdetailed study of the events at national and Iberian scale, and to the civilprotection authorities to associate the predicted CWT with the generation ofspecific hydro-geomorphological events and associated types of damage.• The methodology used to build the DISASTER database and the disaster eventscatalogue can be applicable to other study areas where floods and landslides aremostly associated with the atmospheric circulation, as is the case of the NorthAtlantic and the Mediterranean regions.Thank you for your attention!This work was financed by national funds through FCT-Portuguese Foundation forScience and Technology, I.P., under the framework of the project FORLAND—Hydro-geomorphologic risk in Portugal: driving forces and application for land use planning(PTDC/ATPGEO/1660/2014).http://www.ceg.ulisboa.pt/forland/

Catálogo de eventos hidro-geomorfológicos em Portugal Continental (1865-2015)

https://repositorio.ul.pt/bitstream/10451/40850/1/Oral_2018_Pereira_et_al_CIG.pdf

Catálogo de eventos hidro-geomorfológicos em Portugal Continental (1865-2015)

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