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DPSIR framework application supported by integrated watershed modeling for irrigation from Alqueva dam (Portugal) on Guadiana river estuary
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Abstract(s)
A aplicação estrutural DPSIR apoiada pelo modelo integrado de bacias hidrográficas foi
utilizado para avaliar as condições de desempenho de irrigação no Alqueva, a pressão que
será exercida sobre a de forma de incorporação de nutrientes devido à aplicação de
fertilizantes inorgânicos e seus potenciais impactos no estuário do rio Guadinia.
A barragem e o sistema de irrigação (aproximadamente 110.000 hectares) está situado no
Alentejo, sul de Portugal. O sistema de agricultura planificada será seguido por uma
agricultura de irrigação intensiva, e, como resultado, tem o potencial para contribuir para a
incorporação de nutrientes no estuário do rio Guadania. O objetivo deste estudo é avaliar as
condições do sistema de agricultura irrigada na estrutura holística Driver-Pressão-Estado-
Impacto-Resposta (DPSIR), com o objectivo global de dotar a administração, com
recomendações para a redução da descarga de nutrientes para o estuário do rio Guadiana e o
conseqüente aparecimento da eutrofização. O modelo Basin Sim. 1 GWLF foi usado para
determinar a quantidade de nutrientes incorporada (N & P) no perímetro de irrigação
desenhado. Com o uso deste modelo, as descargas foram simuladas para um período de 4
anos (2002 - 2006) sob o cenário de referência (normal) e "Agricultura total" (com base nas
condições esperadas). O programa ArcView GIS foi utilizado para extrair os parâmetros de
entrada apartir de várias camadas de dados GIS, incluindo modelo de elevação digital e do
solo.
A avaliação com DPSIR mostra que as alterações climáticas (por exemplo, aridez, secas
periódicas), a crescente exigência económica, o turismo (desenvolvimento de circuitos de
golfe) e da variabilidade da precipitação pluviométricas e do fluxo dos rios são as principais
forças motrizes que controlam a barragem do Alqueva e o sistema de irrigação. Os
resultados modelados mostram também que as fontes no perímetro de irrigação geram
146,54 mil toneladas de nitrogénio total (NT) e 12.21 toneladas de fósforo total (FT), nas
condições de referência e estas descargas aumentam para 161,18 toneladas de NT e 14,75
toneladas de FT no cenário de "agricultura total". As actividades agrícolas, seguidas por
águas subterrâneas são as fontes que contribuem maiores proporções. Em termos de
poluição por nutrientes, os resultados encontrados mostram que o sistema de irrigação
intensiva que foi planeado nesta área é altamente determinante na qualidade da água nas
imediações do rio Guadiana e no estuário à jusante. Portanto, um número de respostas
possíveis (sob a forma de normas e legislação, regulamentação, tecnologia, boas práticas
agrícolas, económicas, científicas, modelos, etc) e soluções administrativas que identificam
as recomendações são sugeridas no presente trabalho.
DPSIR framework application supported by integrated watershed modeling was used to assess the conditions of Alqueva irrigation development, the pressure that will be exerted in the form of nutrient loads due to the application of inorganic fertilizers and its potential impacts on the Guadiana river estuary. Alqueva dam and irrigation development (about 110,000 ha) is located in Alentejo, south of Portugal. The planned agriculture development will follow intensive irrigated agriculture and therefore, has a potential to contribute nutrient loadings to the Guadiana river estuary. The aim of this study is to assess the conditions of Alqueva irrigated agriculture development under the holistic Driver-Pressure-State-Impact-Response (DPSIR) framework, with an overall goal of providing management with recommendations to reduce nutrient discharge in to the Guadiana river estuary and consequently the appearance of eutrophication. Basin Sim.1, GWLF model was used to determine the amount of nutrient loadings (N & P) from the planned irrigation perimeter. Using the model, loadings have been simulated for a period of 4 years (2002 – 2006) under baseline (Current condition) and ¨All agriculture¨ (based on expected condition) Scenarios. Arc View GIS was used to extract input parameters from various GIS data layers including digital elevation model and land cover. The DPSIR assessment shows that, Climate change (Such as Aridity, Periodic droughts); Economic growth demands, Tourism (Golf course development) and Rain fall and river discharge variability are the main driving forces which leads to Alqueva dam and irrigation development. Modeling results also shows, the source areas in the irrigation perimeter generates 146.54 tons of Total Nitrogen (TN) and 12.21 tons of Total Phosphorus(TP) under baseline scenario and this increases to 161.18 t of TN and 14.75 t of TP in ¨All agriculture scenario¨. From this, agricultural runoff contributes the largest amount followed by ground water. In terms of nutrient contamination, this shows the planned intensive irrigated agriculture development is highly determinal to the water quality in nearby Guadiana River and downstream estuary. Therefore, a number of possible responses (in the form of Policy and Legislation, Regulation, Technology, Good agricultural practices, Economic, Scientific, Modeling e.t.c) and management solutions that identify the ¨Decision makers recommended.
DPSIR framework application supported by integrated watershed modeling was used to assess the conditions of Alqueva irrigation development, the pressure that will be exerted in the form of nutrient loads due to the application of inorganic fertilizers and its potential impacts on the Guadiana river estuary. Alqueva dam and irrigation development (about 110,000 ha) is located in Alentejo, south of Portugal. The planned agriculture development will follow intensive irrigated agriculture and therefore, has a potential to contribute nutrient loadings to the Guadiana river estuary. The aim of this study is to assess the conditions of Alqueva irrigated agriculture development under the holistic Driver-Pressure-State-Impact-Response (DPSIR) framework, with an overall goal of providing management with recommendations to reduce nutrient discharge in to the Guadiana river estuary and consequently the appearance of eutrophication. Basin Sim.1, GWLF model was used to determine the amount of nutrient loadings (N & P) from the planned irrigation perimeter. Using the model, loadings have been simulated for a period of 4 years (2002 – 2006) under baseline (Current condition) and ¨All agriculture¨ (based on expected condition) Scenarios. Arc View GIS was used to extract input parameters from various GIS data layers including digital elevation model and land cover. The DPSIR assessment shows that, Climate change (Such as Aridity, Periodic droughts); Economic growth demands, Tourism (Golf course development) and Rain fall and river discharge variability are the main driving forces which leads to Alqueva dam and irrigation development. Modeling results also shows, the source areas in the irrigation perimeter generates 146.54 tons of Total Nitrogen (TN) and 12.21 tons of Total Phosphorus(TP) under baseline scenario and this increases to 161.18 t of TN and 14.75 t of TP in ¨All agriculture scenario¨. From this, agricultural runoff contributes the largest amount followed by ground water. In terms of nutrient contamination, this shows the planned intensive irrigated agriculture development is highly determinal to the water quality in nearby Guadiana River and downstream estuary. Therefore, a number of possible responses (in the form of Policy and Legislation, Regulation, Technology, Good agricultural practices, Economic, Scientific, Modeling e.t.c) and management solutions that identify the ¨Decision makers recommended.
Description
Dissertação de mest., Gestão da Água e da Costa, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2009
Keywords
Águas costeiras Estuários Eutrofização Nutrientes