Evapotranspiration (ET) plays an important role in integrated water resource planning, developmen... more Evapotranspiration (ET) plays an important role in integrated water resource planning, development and management. This process is particularly relevant in semiarid regions. The aim of this study is, hence, to compare spatial and temporal patterns of actual ET, as well as the temporal trends in two different semiarid forests, Caatinga (Brazil) and Tierra de Pinares (Spain). We used the surface energy balance algorithm for land (SEBAL) to assess actual evapotranspiration (ETa) in both areas. In the Brazilian semiarid forest, Caatinga is the main vegetation, while it is Pinares in Spain. For this purpose, 69 Landsat‐5 and 42 Landsat‐8 images (1995–2019) were used. The Mann–Kendall test was applied to assess the occurrence of trends in precipitation, temperature and potential ET data; and the Temporal Stability Index (TSI) to know which areas have greater seasonal ETa. The annual amplitude of the potential evapotranspiration (ET0) is the same in both areas, however, the Caatinga values are higher. In the Caatinga forest, when ET0 presents its highest values throughout the year, ETa presents the lowest, and vice versa. In the Pinares forest, ETa follows the ET0 dynamics during the year, and the difference between ET0 and ETa is maximum during the summer. The Caatinga forest showed a greater spatial variation of ETa than the Pinares forest as well as a greater extension with lower temporal stability of ETa than the Pinares forest. Both the Caatinga forest and the Pinares forest showed significant positive trends in annual ET0 and ETa. We estimate that the value of ETa increases more rapidly in Pinares than in the Brazilian Caatinga. Taking Caatinga as a hydrological mirror, some consequences are expected to Pinares, such as significant changes in the water balance, increase of biodiversity vulnerability, and reduction of water availability in soil and reservoirs.
As chuvas são tanto a solução quanto o problema para algumas áreas do semiárido nordestino, o pri... more As chuvas são tanto a solução quanto o problema para algumas áreas do semiárido nordestino, o primeiro como solução para crises hídricas e secas severas, e no segundo como agente externo de atuação dos processos erosivos. O presente trabalho tem como objetivo calcular a erosividade da bacia hidrográfica do rio Seridó entre os anos de 1994 a 2015 para que se possa chegar ao entendimento prévio dos processos erosivos atuantes. Através da equação de Lombardi Neto e Moldenhauer foram obtidos os valores de erosividade, e estes foram interpolados através do método da krigagem. Os valores de erosividade dentro da bacia variaram entre 2.208 a 4.802 MJ.mm/(ha.h.ano), ficando assim numa classificação de baixa erosividade anual, em contrapartida, no que se refere a erosividade mensal, o índice sobe para erosividade forte. Portanto, o cálculo da erosividade é um meio para compreender a dinâmica da degradação ambiental, mais especificamente com relação ao solo, através da análise dos processos e...
River networks are among Earth’s most threatened hot-spots of biodiversity and provide key ecosys... more River networks are among Earth’s most threatened hot-spots of biodiversity and provide key ecosystem services (e.g., supply drinking water and food, climate regulation) essential to sustaining human well-being. Climate change and increased human water use are causing more rivers and streams to dry, with devastating impacts on biodiversity and ecosystem services. Currently, more than a half of the global river networks consist of drying channels, and these are expanding dramatically. However, drying river networks (DRNs) have received little attention from scientists and policy makers, and the public is unaware of their importance. Consequently, there is no effective integrated biodiversity conservation or ecosystem management strategy of DRNs. A multidisciplinary team of 25 experts from 11 countries in Europe, South America, China and the USA will build on EU efforts to assess the cascading effects of climate change on biodiversity, ecosystem functions and ecosystem services of DRNs...
Small reservoirs impact on large scale water availability both by supplying water in a distribute... more Small reservoirs impact on large scale water availability both by supplying water in a distributed sense, and by subtracting water from large reservoirs with large scale water supply functions. Water availability from small and large reservoirs is subject to climate change, which has the potential to alter the relation between small and large reservoirs. For a case study area in semi-arid Brazil, water supply from small reservoirs is found to be more sensitive to climate change than water supply from large reservoirs. Changes in evapotranspiration are more consistent amongst models and its’ effects may dominate effects by more uncertain changes in precipitation. The reduction in water availability from large reservoirs by upstream abstractions by small reservoirs is found to be significant and may increase with unfavourable climate changes, even in an absolute sense.
High erosion and runoff rates have been measured on road infrastructure, indicating that unpaved ... more High erosion and runoff rates have been measured on road infrastructure, indicating that unpaved roads might be significant sources of sediment in catchments. In this paper, the production of surface sediments from unpaved rural roads is assessed in Northeastern Brazil, in a semiarid area of the caatinga biome, vulnerable to desertification. Sediment production data from road surface segments were monitored for 2 years (2013–2014) under conditions of natural precipitation. By using hydrosedimentological modeling and a geographical information system (GIS), the sediment budget was calculated at the meso‐scale catchment (aprox. 930 km2), in order to identify the relative contribution of roads to the sediment balance. The universal soil loss equation (USLE) associated with Maner's sediment delivery ratio (SDR) equation, proved to be an adequate approach for predicting sediment yield on the road segment scale. The best results were obtained for the road without traffic, due to the n...
This study assesses the extent to which silting increases water-scarcity risk, considering the te... more This study assesses the extent to which silting increases water-scarcity risk, considering the temporal reduction of water availability and increased demand using land use and water-demand scenarios at the transition of Caatinga and Cerrado biomes of the Bocaina reservoir watershed (103hm4), in the Brazilian dry region. Methodological steps were: reservoir silting measured in-situ 20 years after dam construction; climate variables computed with the aid of a conventional station (2005-2014); soil erodibility assessed using 16 soil samples; and topography and land cover estimated based on 21 years of Landsat imagery. Three land use scenarios were generated (invariability, degradation and preservation) with the climate scenario derived from the semi-arid rainfall temporal variability; whereas two water-demand scenarios (invariability and higher efficiency) were a function of the efficiency of the irrigation systems. Water availability was calculated using the volume-yield elasticity (V...
The Brazilian semiarid region strongly depends on superficial reservoirs (one every 5 km 2 ) and ... more The Brazilian semiarid region strongly depends on superficial reservoirs (one every 5 km 2 ) and hence is subject to the deleterious effects of siltation, which reduces water availability. This research proposed a method, simplified bathymetric surveying using remote sensing, for updating the morphological parameters of reservoirs. The study area was the Pentecoste reservoir (360 hm 3 ) in northeastern Brazil. The results were compared to the conventional bathymetric survey method, which demands more sampling points (235 compared to 1) and was assumed as reference. Siltation assessed through the proposed method was nearly twice as high as that observed through conventional surveys. The morphological parameters derived by both methods were used to assess the long-term water balance of the reservoir. The results show that the outflow diverged 30%, while the evaporated discharge and water availability diverged 10% between the methods. Therefore, in the conditions of the Brazilian semia...
Os sertões nordestinos sofrem as consequências da intensificaçãodos processos morfodinâmicos supe... more Os sertões nordestinos sofrem as consequências da intensificaçãodos processos morfodinâmicos superficiais através da erosão, causada por uso intensivo e inadequado do solo. Tais problemas geram consequências para a relação entre a Sociedade e a Natureza. De fato, a erosão e o assoreamento, causam, entre outros, impactos sócio-ambientais e econômicos, tais como o desgaste do perfil de solo, a diminuição da produtividade agrícola, a redução da capacidade de armazenamento de rios e reservatórios, assim como a diminuição da disponibilidade hídrica. A presente pesquisa buscou estimar a erosão bruta da bacia hidrográfica do Rio Seridó (RN-PB, 10 mil km²) afim de entender como se distribui espacialmente a erosão em toda extensão da bacia. Foram utilizados dados primários e secundários na produção de mapas temáticos, revisão teórico-metodológica do objeto, utilização de imagens (sensoriamento remoto), métodos geoestatísticos, realização de trabalho de campo e modelagem sedimentológica. Para...
Soil is an important water compartment into a watershed scale, mainly due to its role in providin... more Soil is an important water compartment into a watershed scale, mainly due to its role in providing water to plants and to the influence of antecedent moisture on the runoff initiation. The aim of this research is to assess the permanence of water effectiveness in the soil under preserved-vegetation constraints in the Caatinga biome, in the semiarid northeastern Brazil. For this purpose, hourly soil moisture measurements were collected with TDR and analyzed between 2003 and 2010 for three soil-vegetation associations in the Aiuaba Experimental Basin. The results showed that in nine months per year soil moisture was below wilting point for two associations, whose soils are Chromic Luvisol and Haplic Lixisol (Abruptic). In the third association, where the shallow soil Lithic Leptosol prevails, water was found non-effective four months per year. A possible reason for the high water permanence in the shallowest soil is the percolation process, generating sub-surface flow, which barely oc...
Esse trabalho apresenta uma ferramenta de análise da vulnerabilidade de reservatórios à eutrofiza... more Esse trabalho apresenta uma ferramenta de análise da vulnerabilidade de reservatórios à eutrofização, visando subsidiar ações de controle e remediação desse processo. Foram analisadas três subbacias de açudes - Araras, Edson Queiroz e Jaibaras, da bacia do Acaraú, CE, Brasil. A análise multiatributo usada na definição de indicadores ambientais de vulnerabilidade dos açudes à eutrofização, considerou sua sensibilidade e fatores de pressão nas suas sub-bacias que acarretam o transporte de sedimentos e nutrientes para os reservatórios. Foi utilizado um Sistema de Informações Geográficas (SIG) com a ferramenta álgebra de mapas para manipular dados de uso e ocupação do solo, declividade do terreno e erodibilidade do solo. Foi identificada alta vulnerabilidade à eutrofização nos três açudes pelas susceptibilidades à erosão, alta carga poluidora principalmente pela pecuária extensiva na região e baixa profundidade relativa dos reservatórios.
Available in: http://www.redalyc.org/src/inicio/ArtPdfRed.jsp?iCve=195318233002 ... Redalyc Scien... more Available in: http://www.redalyc.org/src/inicio/ArtPdfRed.jsp?iCve=195318233002 ... Redalyc Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and ... Augusto Medeiros, Pedro Henrique; Araújo, José Carlos de; ...
Evapotranspiration (ET) plays an important role in integrated water resource planning, developmen... more Evapotranspiration (ET) plays an important role in integrated water resource planning, development and management. This process is particularly relevant in semiarid regions. The aim of this study is, hence, to compare spatial and temporal patterns of actual ET, as well as the temporal trends in two different semiarid forests, Caatinga (Brazil) and Tierra de Pinares (Spain). We used the surface energy balance algorithm for land (SEBAL) to assess actual evapotranspiration (ETa) in both areas. In the Brazilian semiarid forest, Caatinga is the main vegetation, while it is Pinares in Spain. For this purpose, 69 Landsat‐5 and 42 Landsat‐8 images (1995–2019) were used. The Mann–Kendall test was applied to assess the occurrence of trends in precipitation, temperature and potential ET data; and the Temporal Stability Index (TSI) to know which areas have greater seasonal ETa. The annual amplitude of the potential evapotranspiration (ET0) is the same in both areas, however, the Caatinga values are higher. In the Caatinga forest, when ET0 presents its highest values throughout the year, ETa presents the lowest, and vice versa. In the Pinares forest, ETa follows the ET0 dynamics during the year, and the difference between ET0 and ETa is maximum during the summer. The Caatinga forest showed a greater spatial variation of ETa than the Pinares forest as well as a greater extension with lower temporal stability of ETa than the Pinares forest. Both the Caatinga forest and the Pinares forest showed significant positive trends in annual ET0 and ETa. We estimate that the value of ETa increases more rapidly in Pinares than in the Brazilian Caatinga. Taking Caatinga as a hydrological mirror, some consequences are expected to Pinares, such as significant changes in the water balance, increase of biodiversity vulnerability, and reduction of water availability in soil and reservoirs.
As chuvas são tanto a solução quanto o problema para algumas áreas do semiárido nordestino, o pri... more As chuvas são tanto a solução quanto o problema para algumas áreas do semiárido nordestino, o primeiro como solução para crises hídricas e secas severas, e no segundo como agente externo de atuação dos processos erosivos. O presente trabalho tem como objetivo calcular a erosividade da bacia hidrográfica do rio Seridó entre os anos de 1994 a 2015 para que se possa chegar ao entendimento prévio dos processos erosivos atuantes. Através da equação de Lombardi Neto e Moldenhauer foram obtidos os valores de erosividade, e estes foram interpolados através do método da krigagem. Os valores de erosividade dentro da bacia variaram entre 2.208 a 4.802 MJ.mm/(ha.h.ano), ficando assim numa classificação de baixa erosividade anual, em contrapartida, no que se refere a erosividade mensal, o índice sobe para erosividade forte. Portanto, o cálculo da erosividade é um meio para compreender a dinâmica da degradação ambiental, mais especificamente com relação ao solo, através da análise dos processos e...
River networks are among Earth’s most threatened hot-spots of biodiversity and provide key ecosys... more River networks are among Earth’s most threatened hot-spots of biodiversity and provide key ecosystem services (e.g., supply drinking water and food, climate regulation) essential to sustaining human well-being. Climate change and increased human water use are causing more rivers and streams to dry, with devastating impacts on biodiversity and ecosystem services. Currently, more than a half of the global river networks consist of drying channels, and these are expanding dramatically. However, drying river networks (DRNs) have received little attention from scientists and policy makers, and the public is unaware of their importance. Consequently, there is no effective integrated biodiversity conservation or ecosystem management strategy of DRNs. A multidisciplinary team of 25 experts from 11 countries in Europe, South America, China and the USA will build on EU efforts to assess the cascading effects of climate change on biodiversity, ecosystem functions and ecosystem services of DRNs...
Small reservoirs impact on large scale water availability both by supplying water in a distribute... more Small reservoirs impact on large scale water availability both by supplying water in a distributed sense, and by subtracting water from large reservoirs with large scale water supply functions. Water availability from small and large reservoirs is subject to climate change, which has the potential to alter the relation between small and large reservoirs. For a case study area in semi-arid Brazil, water supply from small reservoirs is found to be more sensitive to climate change than water supply from large reservoirs. Changes in evapotranspiration are more consistent amongst models and its’ effects may dominate effects by more uncertain changes in precipitation. The reduction in water availability from large reservoirs by upstream abstractions by small reservoirs is found to be significant and may increase with unfavourable climate changes, even in an absolute sense.
High erosion and runoff rates have been measured on road infrastructure, indicating that unpaved ... more High erosion and runoff rates have been measured on road infrastructure, indicating that unpaved roads might be significant sources of sediment in catchments. In this paper, the production of surface sediments from unpaved rural roads is assessed in Northeastern Brazil, in a semiarid area of the caatinga biome, vulnerable to desertification. Sediment production data from road surface segments were monitored for 2 years (2013–2014) under conditions of natural precipitation. By using hydrosedimentological modeling and a geographical information system (GIS), the sediment budget was calculated at the meso‐scale catchment (aprox. 930 km2), in order to identify the relative contribution of roads to the sediment balance. The universal soil loss equation (USLE) associated with Maner's sediment delivery ratio (SDR) equation, proved to be an adequate approach for predicting sediment yield on the road segment scale. The best results were obtained for the road without traffic, due to the n...
This study assesses the extent to which silting increases water-scarcity risk, considering the te... more This study assesses the extent to which silting increases water-scarcity risk, considering the temporal reduction of water availability and increased demand using land use and water-demand scenarios at the transition of Caatinga and Cerrado biomes of the Bocaina reservoir watershed (103hm4), in the Brazilian dry region. Methodological steps were: reservoir silting measured in-situ 20 years after dam construction; climate variables computed with the aid of a conventional station (2005-2014); soil erodibility assessed using 16 soil samples; and topography and land cover estimated based on 21 years of Landsat imagery. Three land use scenarios were generated (invariability, degradation and preservation) with the climate scenario derived from the semi-arid rainfall temporal variability; whereas two water-demand scenarios (invariability and higher efficiency) were a function of the efficiency of the irrigation systems. Water availability was calculated using the volume-yield elasticity (V...
The Brazilian semiarid region strongly depends on superficial reservoirs (one every 5 km 2 ) and ... more The Brazilian semiarid region strongly depends on superficial reservoirs (one every 5 km 2 ) and hence is subject to the deleterious effects of siltation, which reduces water availability. This research proposed a method, simplified bathymetric surveying using remote sensing, for updating the morphological parameters of reservoirs. The study area was the Pentecoste reservoir (360 hm 3 ) in northeastern Brazil. The results were compared to the conventional bathymetric survey method, which demands more sampling points (235 compared to 1) and was assumed as reference. Siltation assessed through the proposed method was nearly twice as high as that observed through conventional surveys. The morphological parameters derived by both methods were used to assess the long-term water balance of the reservoir. The results show that the outflow diverged 30%, while the evaporated discharge and water availability diverged 10% between the methods. Therefore, in the conditions of the Brazilian semia...
Os sertões nordestinos sofrem as consequências da intensificaçãodos processos morfodinâmicos supe... more Os sertões nordestinos sofrem as consequências da intensificaçãodos processos morfodinâmicos superficiais através da erosão, causada por uso intensivo e inadequado do solo. Tais problemas geram consequências para a relação entre a Sociedade e a Natureza. De fato, a erosão e o assoreamento, causam, entre outros, impactos sócio-ambientais e econômicos, tais como o desgaste do perfil de solo, a diminuição da produtividade agrícola, a redução da capacidade de armazenamento de rios e reservatórios, assim como a diminuição da disponibilidade hídrica. A presente pesquisa buscou estimar a erosão bruta da bacia hidrográfica do Rio Seridó (RN-PB, 10 mil km²) afim de entender como se distribui espacialmente a erosão em toda extensão da bacia. Foram utilizados dados primários e secundários na produção de mapas temáticos, revisão teórico-metodológica do objeto, utilização de imagens (sensoriamento remoto), métodos geoestatísticos, realização de trabalho de campo e modelagem sedimentológica. Para...
Soil is an important water compartment into a watershed scale, mainly due to its role in providin... more Soil is an important water compartment into a watershed scale, mainly due to its role in providing water to plants and to the influence of antecedent moisture on the runoff initiation. The aim of this research is to assess the permanence of water effectiveness in the soil under preserved-vegetation constraints in the Caatinga biome, in the semiarid northeastern Brazil. For this purpose, hourly soil moisture measurements were collected with TDR and analyzed between 2003 and 2010 for three soil-vegetation associations in the Aiuaba Experimental Basin. The results showed that in nine months per year soil moisture was below wilting point for two associations, whose soils are Chromic Luvisol and Haplic Lixisol (Abruptic). In the third association, where the shallow soil Lithic Leptosol prevails, water was found non-effective four months per year. A possible reason for the high water permanence in the shallowest soil is the percolation process, generating sub-surface flow, which barely oc...
Esse trabalho apresenta uma ferramenta de análise da vulnerabilidade de reservatórios à eutrofiza... more Esse trabalho apresenta uma ferramenta de análise da vulnerabilidade de reservatórios à eutrofização, visando subsidiar ações de controle e remediação desse processo. Foram analisadas três subbacias de açudes - Araras, Edson Queiroz e Jaibaras, da bacia do Acaraú, CE, Brasil. A análise multiatributo usada na definição de indicadores ambientais de vulnerabilidade dos açudes à eutrofização, considerou sua sensibilidade e fatores de pressão nas suas sub-bacias que acarretam o transporte de sedimentos e nutrientes para os reservatórios. Foi utilizado um Sistema de Informações Geográficas (SIG) com a ferramenta álgebra de mapas para manipular dados de uso e ocupação do solo, declividade do terreno e erodibilidade do solo. Foi identificada alta vulnerabilidade à eutrofização nos três açudes pelas susceptibilidades à erosão, alta carga poluidora principalmente pela pecuária extensiva na região e baixa profundidade relativa dos reservatórios.
Available in: http://www.redalyc.org/src/inicio/ArtPdfRed.jsp?iCve=195318233002 ... Redalyc Scien... more Available in: http://www.redalyc.org/src/inicio/ArtPdfRed.jsp?iCve=195318233002 ... Redalyc Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and ... Augusto Medeiros, Pedro Henrique; Araújo, José Carlos de; ...
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