Determinação da evapotranspiração com aplicação do algoritmo SAFER em imagens LANDSAT na escala de microbacia
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Data
2017-01-27
Autores
Coaguila Nuñez, Daniel Noe [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Em cenários de mudanças climáticas e de uso e ocupação do solo, a bacia do córrego Cabeceira Comprida, localizada em Santa Fé do Sul - SP, se apresenta degradada com talvegues assoreados, ausência de matas ciliares e nascentes desprotegidas levando à incapacidade de gerar e armazenar água para atender a demanda atual (população, agricultura e saneamento) e em períodos de seca, agravando-se em prolongadas estiagens, como em 2004, 2013 e 2014 agravando o problema do abastecimento de água à população. Sendo assim, torna-se importante avaliar os fluxos hídricos da água acima do solo na bacia com o uso combinado de imagens de satélites Landsat 5 (TM) e Landsat-8 (OLI e TIRS) no período de 2000 - 2011 e 2013 - 2015 e informações provenientes de estações agrometeorológicas. Para tanto, utilizou-se o modelo Simple Algorithm for Evapotranspiration Retrieving (SAFER) para estimativa da evapotranspiração atual (ETa), resultando em uma média da bacia no período avaliado de 0,70 mm dia-1, 0,85 mm dia-1 das espécies invasoras (EI), 1,20 mm dia-1 da mata remanescente (MR), 0,70 mm dia-1 da pastagem (Pa), 0,65 mm dia-1 das culturas anuais (CA) e 0,72 mm dia-1 das culturas perenes (CP). O ano de 2003 registrou a menor média de ETa da bacia com 0,42 mm dia-1, enquanto o ano de 2015 apresentou a maior média anual do período estudado, com 1,03 mm dia-1. Destaca-se que os valores da ETa das EI equivale ao consumo de 25% da população de Santa Fé do Sul, o que traz consequências na época seca quando o recurso hídrico é mais escasso. Estes cenários exigem ações imediatas para a produção e armazenamento de água na bacia, que tem morfometria alongada, evidenciando menor risco de cheias em condições normais de pluviosidade anual. A declividade média de 5,4% caracteriza o relevo como suave-ondulado, com drenagem deficiente (1,054 km km-2). Com essas características morfométricas associadas à precipitação anual média de 1.271 mm e padrão de drenagem caracterizado como do tipo dendrítico, com baixo grau de ramificação (Ordem 3), a disponibilidade de água não deveria ser um problema, mas o é, pelo fato de que a bacia se encontra degradada com apenas 4,5% de MR, os serviços ecossistêmicos fornecidos pela vegetação natural são mínimos e insuficientes para atender a demanda de água por parte dos usuários. São necessárias a adoção de medidas de mitigação, incluindo intervenção e implementação ações como por exemplo, o pagamento por serviços ambientais, sendo uma medida urgente a preservação ou recomposição da mata ciliar.
In a scenario of climate change and land use and occupation, the watershed of Cabeceira Comprida stream, located in Santa Fé do Sul - São Paulo State, presents as degraded with thalwegs sedimented, absence of riparian forests and unprotected springs leading to the inability to generate and store water to meet current demand (population, agriculture and sanitation) in periods of drought, aggravating in prolonged droughts, such as those of 2004, 2013 and 2014 exacerbating the problem of water supply to the population. Being necessary to evaluate the behavior of above-ground water in the watershed with combined use of Landsat 5 (TM) and Landsat - 8 images (OLI and TIRS) in the period of 2000 - 2011 and 2013 - 2015 and information from agrometeorological stations. Therefore, we used the Simple Algorithm for Retrieving Evapotranspiration (SAFER) to estimate actual evapotranspiration, resulting in average basin during the study period of 0.70 mm dia-1, 0.85 mm dia-1 of invasive species (EI), 1.20 mm dia-1 of the remaining forest (MR), 0.70 mm dia-1 of pasture (Pa), 0.65 mm dia-1 of annual crops (CA) e 0.72 mm dia-1 of perennial crop (CP). The year 2003 recorded the lowest average evapotranspiration of the basin with 0.42 mm dia-1, while the year 2015 had the highest annual average in the study period with 1.03 mm dia-1. It is worth noting that the evapotranspiration of the IE corresponds to the consumption of 25% of the population of Santa Fé do Sul, which has consequences in the dry season when the water resource is scarcer, requiring immediate actions for the production and storage of water in the watershed, which has an elongated morphometry, showing a lower risk of flooding under normal annual rainfall conditions. The mean slope of 5.4% is characterized by a smooth-wavy relief with poor drainage (1.054 km km-2). With these morphometric characteristics associated to the average annual precipitation of 1,271 mm and drainage pattern characterized as dendritic type, with low degree of branching (Order 3), the availability of water should not be a problem, but it is due to the fact that the watershed is degraded with only 4.5% of remaining forest, the ecosystem services provided by natural vegetation are minimal and insufficient to meet users' water demand. It is necessary to adopt mitigation actions, including intervention and implementation actions such as payment for environmental services, being an urgent measure the preservation or restoration of the riparian forest.
In a scenario of climate change and land use and occupation, the watershed of Cabeceira Comprida stream, located in Santa Fé do Sul - São Paulo State, presents as degraded with thalwegs sedimented, absence of riparian forests and unprotected springs leading to the inability to generate and store water to meet current demand (population, agriculture and sanitation) in periods of drought, aggravating in prolonged droughts, such as those of 2004, 2013 and 2014 exacerbating the problem of water supply to the population. Being necessary to evaluate the behavior of above-ground water in the watershed with combined use of Landsat 5 (TM) and Landsat - 8 images (OLI and TIRS) in the period of 2000 - 2011 and 2013 - 2015 and information from agrometeorological stations. Therefore, we used the Simple Algorithm for Retrieving Evapotranspiration (SAFER) to estimate actual evapotranspiration, resulting in average basin during the study period of 0.70 mm dia-1, 0.85 mm dia-1 of invasive species (EI), 1.20 mm dia-1 of the remaining forest (MR), 0.70 mm dia-1 of pasture (Pa), 0.65 mm dia-1 of annual crops (CA) e 0.72 mm dia-1 of perennial crop (CP). The year 2003 recorded the lowest average evapotranspiration of the basin with 0.42 mm dia-1, while the year 2015 had the highest annual average in the study period with 1.03 mm dia-1. It is worth noting that the evapotranspiration of the IE corresponds to the consumption of 25% of the population of Santa Fé do Sul, which has consequences in the dry season when the water resource is scarcer, requiring immediate actions for the production and storage of water in the watershed, which has an elongated morphometry, showing a lower risk of flooding under normal annual rainfall conditions. The mean slope of 5.4% is characterized by a smooth-wavy relief with poor drainage (1.054 km km-2). With these morphometric characteristics associated to the average annual precipitation of 1,271 mm and drainage pattern characterized as dendritic type, with low degree of branching (Order 3), the availability of water should not be a problem, but it is due to the fact that the watershed is degraded with only 4.5% of remaining forest, the ecosystem services provided by natural vegetation are minimal and insufficient to meet users' water demand. It is necessary to adopt mitigation actions, including intervention and implementation actions such as payment for environmental services, being an urgent measure the preservation or restoration of the riparian forest.
Descrição
Palavras-chave
Bacia hidrográfica, Estações agrometeorológicas, Simple algorithm for evapotranspiration retrieving, Sensoriamento remoto, Typha sp., Actual evapotranspiration, Agrometeorological stations, Remote sensing, Watershed