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As cheias na bacia hidrográfica do rio Vez durante os Séculos XX e XXI e a sustentabilidade
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Abstract(s)
Este estudo investiga os registos históricos das cheias na bacia hidrográfica do rio Vez (BHRVez) entre 1900 a 2015. As principais fontes de informação utilizadas foram: os dados dos Censos, do Instituto Nacional de Estatística; os valores diários do caudal médido na estação hidrométrica de Pontilhão de Celeiros e de precipitação da estação udográfica de Casal Soeiro, para o período compreendido entre 1959 e 1990, ambas localizadas na BHRVez; a imprensa periódica regional, especificamente da região de Arcos de Valdevez; cartografia militar do Centro de Informações Geoespaciais do Exército foi usada para georreferenciar "pontos de cheia". O concelho de Arcos de Valdevez ocupa 247,16 km2 de um total de 262,03 km2 da BHRVez, que inclui também os municípios de Paredes de Coura, Ponte de Lima, Ponte da Barca, Monção e Melgaço. Este estudo levou em conta o histórico de cheias no BHRVez. Os registos foram construídos com informações da imprensa periódica regional e validados com os dados de fluxo (Q) e precipitação (P) (método percentual P 90 e P 95). O valor do Q mínimo calculado segundo o método P 90 do mês de maior fluxo (fevereiro), Q = 43,5 m3/s, foi considerado ligeiramente superior ao P 95 de toda a série de valores (40 m3/s). O valor da precipitação, P ≥ 38,6 𝑚𝑚 (maior que P 90), foi considerada como o menor valor para eventos de cheia. Estes valores foram validados contra a imprensa periódica. Foram aplicados 67 questionários correspondentes a 3 % da população de áreas urbanas de oito paróquias. A probabilidade de cheia / ano para a BHRVez foi determinada pela distribuição de Poisson. A mesma distribuição foi aplicada a um dis locais críticos, a Valeta. Desenvolvera-se três modelos para obter indicadores hidrológicos de cheia determinados por regressão linear e validados pelo teste Qui-quadrado: o modelo de alerta de cheia baseado nos dados do limiar de fluxo (Q ≥ 43,5m3/s); o modelo de suscetibilidade física simplificada a cheias, baseado na ordem hierárquica de Strahler (1951) e na ordem de magnitude Shreve (1966); e o modelo de sustentabilidade hidrológica. Verificou-se que as Freguesias/União de Freguesias mais próximas do canal principal do rio Vez foram mais afetadas de acordo com a suscetibilidade às cheias e menos sustentáveis. As Freguesias/União de Freguesias montanhosas mostraram-se mais sustentáveis. Os indicadores de alerta de cheia, suscetibilidade e sustentabilidade, bem como a base de dados de eventos de cheia (eBd), são considerados ferramentas cruciais para a tomada de decisões.
The frequency and magnitude of river basin floods are critical to the study of hydrological threats; consequently, it is fundamental for sustainable land use. It is common practice for researchers to use rainfall, runoff, and flood event references gathered from journals to reconstruct local history in a watercourse and river basin. This study investigates the historical records of floods in the River Vez basin (BHRVez) between 1900 and 2015. The main sources of information were: data from the Census of the National Statistics Institute; the daily values of the flow measured at the Celeiros Pontilhão hydrometric station, and the precipitation of the Casal Soeiro rain station for the period from 1959 to 1990, both located at BHRVez; the regional periodic press, specifically the journals from the region of Arcos de Valdevez; cartography from the Army Geospatial Information Center for geo-referencing "flood points". The municipality of Arcos de Valdevez occupies 247,16 km2 of a total of 262,03 km2 of BHRVez (the remaining area belongs to municipalities of Paredes de Coura, Ponte de Lima, Ponte da Barca, Monção and Melgago). This study took in account the flood history in the BHRVez. The records were built with information from the regional periodical press and they were validated against the flow (Q) and precipitation (P) data (percentile method P 90 and P 95). The value of the minimum Q calculated according to the P 90 method of the month of greatest flow (February), Q = 43,5 m3/s, was considered to be slightly higher than the P 95 of the whole series of values (40 m3 /s). Precipitation 𝑃 ≥ 38,6 𝑚𝑚 (higher than P 90) was considered as the lowest precipitation value for flooding events. These values were validated against the periodic press. It was applied 67 questionnaires corresponding to 3 % of the population of urban areas of eight parishes. The probability of floods/year for the BHRVez was determined by the Poisson distribution. The same distribution was applied for the urban area of Valeta, the most basin flooded area. Three models were developed to obtain hydrological flooding indicators determined by linear regression and valued by the Chi-square: the flood alert model based on the flow threshold data (Q ≥ 43,5 m3/s); the model of simplified flood physical susceptibility based on the hierarchical order of Strahler (1951) and the order of magnitude Shreve (1966); the model for determining the danger to floods; and the model of hydrological sustainability. It was found that parishes closer to the main channel of the Vez River were more affected according to the simplified susceptibility to floods and less sustainable. The mountain parishes showed the highest value. Flood alert, susceptibility, hazard and sustainability indicators, as well as the flood event database (eBd) are seen as crucial tools for decision-making.
The frequency and magnitude of river basin floods are critical to the study of hydrological threats; consequently, it is fundamental for sustainable land use. It is common practice for researchers to use rainfall, runoff, and flood event references gathered from journals to reconstruct local history in a watercourse and river basin. This study investigates the historical records of floods in the River Vez basin (BHRVez) between 1900 and 2015. The main sources of information were: data from the Census of the National Statistics Institute; the daily values of the flow measured at the Celeiros Pontilhão hydrometric station, and the precipitation of the Casal Soeiro rain station for the period from 1959 to 1990, both located at BHRVez; the regional periodic press, specifically the journals from the region of Arcos de Valdevez; cartography from the Army Geospatial Information Center for geo-referencing "flood points". The municipality of Arcos de Valdevez occupies 247,16 km2 of a total of 262,03 km2 of BHRVez (the remaining area belongs to municipalities of Paredes de Coura, Ponte de Lima, Ponte da Barca, Monção and Melgago). This study took in account the flood history in the BHRVez. The records were built with information from the regional periodical press and they were validated against the flow (Q) and precipitation (P) data (percentile method P 90 and P 95). The value of the minimum Q calculated according to the P 90 method of the month of greatest flow (February), Q = 43,5 m3/s, was considered to be slightly higher than the P 95 of the whole series of values (40 m3 /s). Precipitation 𝑃 ≥ 38,6 𝑚𝑚 (higher than P 90) was considered as the lowest precipitation value for flooding events. These values were validated against the periodic press. It was applied 67 questionnaires corresponding to 3 % of the population of urban areas of eight parishes. The probability of floods/year for the BHRVez was determined by the Poisson distribution. The same distribution was applied for the urban area of Valeta, the most basin flooded area. Three models were developed to obtain hydrological flooding indicators determined by linear regression and valued by the Chi-square: the flood alert model based on the flow threshold data (Q ≥ 43,5 m3/s); the model of simplified flood physical susceptibility based on the hierarchical order of Strahler (1951) and the order of magnitude Shreve (1966); the model for determining the danger to floods; and the model of hydrological sustainability. It was found that parishes closer to the main channel of the Vez River were more affected according to the simplified susceptibility to floods and less sustainable. The mountain parishes showed the highest value. Flood alert, susceptibility, hazard and sustainability indicators, as well as the flood event database (eBd) are seen as crucial tools for decision-making.
Description
Keywords
Cheias Alertas Bacias hidrográficas Rio Vez Sustentabilidade Periódicos Dados 1900-2015 Flood BHRVez Periodic press Alert Susceptibility Danger Sustainability
Citation
Gonçalves, Maria da Glória Salgado - As cheias na bacia hidrográfica do rio Vez durante os Séculos XX e XXI e a sustentabilidade [Em linha]. [S.l.]: [s.n.], 2018. 418 p.