Resposta hidrológica devido às mudanças no uso do solo e cobertura vegetal na bacia hidrográfica do rio Itacaiúnas (BHRI) – Amazônia Oriental

Abstract

This study aimed to analyze how, when and how changes in soil use and vegetation cover influenced the hydrological behavior of the Itacaiúnas river watershed (IRW), Eastern Amazonia, during the last 40 years (1973-2013). The main land use and cover changes in the basin in this period were the significant reductions in native forest, marked increase in pasture area and growth in urban areas. Considering the need to quantify the main inputs (precipitation) and outflows (flow) of the basin's water balance, an estimation of precipitation and average flows for the basin was made, which is Manuscript 1 accepted for publication by the Brazilian Journal of Physical Geography (RBGF). In this paper the relationship between observed precipitation data from seven meteorological stations and those resulting from interpolation performed by the Climate Prediction Center (CPC) in the period 1986-2005 was analyzed. Using the methods of correction by the drainage area and standardization of medium flows, the estimated flows were compared with measured flows (1985-1995). The precipitation results were compatible with the seasonal behavior of the region, whose correlation between observed and interpolated data showed that these represent well the space-time variability of precipitation in the IRW. It was observed a tendency of increase in the precipitation from east to west, whose behavior may be associated with dense forest cover that composes the mosaic of Conservation Units (UC's), combined with high altitudes (600- 800 m) of Serra de Carajás. The analysis of the calculated flows showed results consistent with the seasonal behavior of the flow curves within the hydrological year. Although the methods used presented different results in absolute terms, the calculated flow curves follow the behavior of the measured flow curve. In Manuscript 2, Three decades of reference evapotranspiration estimate for a watershed in the Eastern Amazon, accepted for publication in the Annals of the Brazilian Academy of Sciences (ABC), the reference evapotranspiration rate (ETo) for the basin was estimated and the accuracy of eight empirical equations using monthly data (1980-2013). The Turc and Penman-Monteith methods showed the best results. Solar radiation and average temperature are shown to be the main drivers, while relative humidity and wind speed have a much smaller impact. The temporal and spatial variability presents strong stationarity, increase in the dry period and decrease in the wet period. Statistical analysis indicated that there is no correlation between station waste and that physical parameters explain ETo variations. Finally, the 3rd Manuscript, in the final phase of preparation, presented the water balance response to changes in soil use and cover in the eastern Amazon during the last three decades. In this paper, soil texture maps combined with soil use classes in each decade were estimated, estimating the values of CN (Curve Number), soil water storage (S) and storage variation (ΔS). The behavior of the water balance components {Precipitation (P), Potential Evapotranspiration (Eo), Real Evapotranspiration (E) and ΔS} due to changes in soil use and vegetation cover were analyzed according to the Budyko model, at annual and as a function of seasonal aridity and evaporative indices. Seasonal values were aggregated to quantify the interannual variability of changes in evaporation and storage. The seasonality of rainfall and the seasonal dynamics of storage were directly incorporated into the developed model, which allowed us to understand which are the dominant control factors on the water balance. In the last decade (2013) the remaining forest cover is only 48.91%, in turn, the cover formed by pasture is 50.47%. The capacity of water storage in the soil decreases continually reaching 8.1%. The results show an approximately linear tendency whose points exceed the "water limit" (Eo / P> 1) and execute the "energy limit", representing dry years with higher values of PE / (P - ΔS), in which annual soil storage provides a complementary supply for annual E. Although the IRW does not fit into a situation of low water availability, its pedological and storage capacity characteristics indicate an increasing trend in flow rates (CN> 72) and low capacity to store water.

This study aimed to analyze how, when and how changes in soil use and vegetation cover influenced the hydrological behavior of the Itacaiúnas river watershed (IRW), Eastern Amazonia, during the last 40 years (1973-2013). The main land use and cover changes in the basin in this period were the significant reductions in native forest, marked increase in pasture area and growth in urban areas. Considering the need to quantify the main inputs (precipitation) and outflows (flow) of the basin's water balance, an estimation of precipitation and average flows for the basin was made, which is Manuscript 1 accepted for publication by the Brazilian Journal of Physical Geography (RBGF). In this paper the relationship between observed precipitation data from seven meteorological stations and those resulting from interpolation performed by the Climate Prediction Center (CPC) in the period 1986-2005 was analyzed. Using the methods of correction by the drainage area and standardization of medium flows, the estimated flows were compared with measured flows (1985-1995). The precipitation results were compatible with the seasonal behavior of the region, whose correlation between observed and interpolated data showed that these represent well the space-time variability of precipitation in the IRW. It was observed a tendency of increase in the precipitation from east to west, whose behavior may be associated with dense forest cover that composes the mosaic of Conservation Units (UC's), combined with high altitudes (600- 800 m) of Serra de Carajás. The analysis of the calculated flows showed results consistent with the seasonal behavior of the flow curves within the hydrological year. Although the methods used presented different results in absolute terms, the calculated flow curves follow the behavior of the measured flow curve. In Manuscript 2, Three decades of reference evapotranspiration estimate for a watershed in the Eastern Amazon, accepted for publication in the Annals of the Brazilian Academy of Sciences (ABC), the reference evapotranspiration rate (ETo) for the basin was estimated and the accuracy of eight empirical equations using monthly data (1980-2013). The Turc and Penman-Monteith methods showed the best results. Solar radiation and average temperature are shown to be the main drivers, while relative humidity and wind speed have a much smaller impact. The temporal and spatial variability presents strong stationarity, increase in the dry period and decrease in the wet period. Statistical analysis indicated that there is no correlation between station waste and that physical parameters explain ETo variations. Finally, the 3rd Manuscript, in the final phase of preparation, presented the water balance response to changes in soil use and cover in the eastern Amazon during the last three decades. In this paper, soil texture maps combined with soil use classes in each decade were estimated, estimating the values of CN (Curve Number), soil water storage (S) and storage variation (ΔS). The behavior of the water balance components {Precipitation (P), Potential Evapotranspiration (Eo), Real Evapotranspiration (E) and ΔS} due to changes in soil use and vegetation cover were analyzed according to the Budyko model, at annual and as a function of seasonal aridity and evaporative indices. Seasonal values were aggregated to quantify the interannual variability of changes in evaporation and storage. The seasonality of rainfall and the seasonal dynamics of storage were directly incorporated into the developed model, which allowed us to understand which are the dominant control factors on the water balance. In the last decade (2013) the remaining forest cover is only 48.91%, in turn, the cover formed by pasture is 50.47%. The capacity of water storage in the soil decreases continually reaching 8.1%. The results show an approximately linear tendency whose points exceed the "water limit" (Eo / P> 1) and execute the "energy limit", representing dry years with higher values of PE / (P - ΔS), in which annual soil storage provides a complementary supply for annual E. Although the IRW does not fit into a situation of low water availability, its pedological and storage capacity characteristics indicate an increasing trend in flow rates (CN> 72) and low capacity to store water.

This study aimed to analyze how, when and how changes in soil use and vegetation cover influenced the hydrological behavior of the Itacaiúnas river watershed (IRW), Eastern Amazonia, during the last 40 years (1973-2013). The main land use and cover changes in the basin in this period were the significant reductions in native forest, marked increase in pasture area and growth in urban areas. Considering the need to quantify the main inputs (precipitation) and outflows (flow) of the basin's water balance, an estimation of precipitation and average flows for the basin was made, which is Manuscript 1 accepted for publication by the Brazilian Journal of Physical Geography (RBGF). In this paper the relationship between observed precipitation data from seven meteorological stations and those resulting from interpolation performed by the Climate Prediction Center (CPC) in the period 1986-2005 was analyzed. Using the methods of correction by the drainage area and standardization of medium flows, the estimated flows were compared with measured flows (1985-1995). The precipitation results were compatible with the seasonal behavior of the region, whose correlation between observed and interpolated data showed that these represent well the space-time variability of precipitation in the IRW. It was observed a tendency of increase in the precipitation from east to west, whose behavior may be associated with dense forest cover that composes the mosaic of Conservation Units (UC's), combined with high altitudes (600- 800 m) of Serra de Carajás. The analysis of the calculated flows showed results consistent with the seasonal behavior of the flow curves within the hydrological year. Although the methods used presented different results in absolute terms, the calculated flow curves follow the behavior of the measured flow curve. In Manuscript 2, Three decades of reference evapotranspiration estimate for a watershed in the Eastern Amazon, accepted for publication in the Annals of the Brazilian Academy of Sciences (ABC), the reference evapotranspiration rate (ETo) for the basin was estimated and the accuracy of eight empirical equations using monthly data (1980-2013). The Turc and Penman-Monteith methods showed the best results. Solar radiation and average temperature are shown to be the main drivers, while relative humidity and wind speed have a much smaller impact. The temporal and spatial variability presents strong stationarity, increase in the dry period and decrease in the wet period. Statistical analysis indicated that there is no correlation between station waste and that physical parameters explain ETo variations. Finally, the 3rd Manuscript, in the final phase of preparation, presented the water balance response to changes in soil use and cover in the eastern Amazon during the last three decades. In this paper, soil texture maps combined with soil use classes in each decade were estimated, estimating the values of CN (Curve Number), soil water storage (S) and storage variation (ΔS). The behavior of the water balance components {Precipitation (P), Potential Evapotranspiration (Eo), Real Evapotranspiration (E) and ΔS} due to changes in soil use and vegetation cover were analyzed according to the Budyko model, at annual and as a function of seasonal aridity and evaporative indices. Seasonal values were aggregated to quantify the interannual variability of changes in evaporation and storage. The seasonality of rainfall and the seasonal dynamics of storage were directly incorporated into the developed model, which allowed us to understand which are the dominant control factors on the water balance. In the last decade (2013) the remaining forest cover is only 48.91%, in turn, the cover formed by pasture is 50.47%. The capacity of water storage in the soil decreases continually reaching 8.1%. The results show an approximately linear tendency whose points exceed the "water limit" (Eo / P> 1) and execute the "energy limit", representing dry years with higher values of PE / (P - ΔS), in which annual soil storage provides a complementary supply for annual E. Although the IRW does not fit into a situation of low water availability, its pedological and storage capacity characteristics indicate an increasing trend in flow rates (CN> 72) and low capacity to store water.

This study aimed to analyze how, when and how changes in soil use and vegetation cover influenced the hydrological behavior of the Itacaiúnas river watershed (IRW), Eastern Amazonia, during the last 40 years (1973-2013). The main land use and cover changes in the basin in this period were the significant reductions in native forest, marked increase in pasture area and growth in urban areas. Considering the need to quantify the main inputs (precipitation) and outflows (flow) of the basin's water balance, an estimation of precipitation and average flows for the basin was made, which is Manuscript 1 accepted for publication by the Brazilian Journal of Physical Geography (RBGF). In this paper the relationship between observed precipitation data from seven meteorological stations and those resulting from interpolation performed by the Climate Prediction Center (CPC) in the period 1986-2005 was analyzed. Using the methods of correction by the drainage area and standardization of medium flows, the estimated flows were compared with measured flows (1985-1995). The precipitation results were compatible with the seasonal behavior of the region, whose correlation between observed and interpolated data showed that these represent well the space-time variability of precipitation in the IRW. It was observed a tendency of increase in the precipitation from east to west, whose behavior may be associated with dense forest cover that composes the mosaic of Conservation Units (UC's), combined with high altitudes (600- 800 m) of Serra de Carajás. The analysis of the calculated flows showed results consistent with the seasonal behavior of the flow curves within the hydrological year. Although the methods used presented different results in absolute terms, the calculated flow curves follow the behavior of the measured flow curve. In Manuscript 2, Three decades of reference evapotranspiration estimate for a watershed in the Eastern Amazon, accepted for publication in the Annals of the Brazilian Academy of Sciences (ABC), the reference evapotranspiration rate (ETo) for the basin was estimated and the accuracy of eight empirical equations using monthly data (1980-2013). The Turc and Penman-Monteith methods showed the best results. Solar radiation and average temperature are shown to be the main drivers, while relative humidity and wind speed have a much smaller impact. The temporal and spatial variability presents strong stationarity, increase in the dry period and decrease in the wet period. Statistical analysis indicated that there is no correlation between station waste and that physical parameters explain ETo variations. Finally, the 3rd Manuscript, in the final phase of preparation, presented the water balance response to changes in soil use and cover in the eastern Amazon during the last three decades. In this paper, soil texture maps combined with soil use classes in each decade were estimated, estimating the values of CN (Curve Number), soil water storage (S) and storage variation (ΔS). The behavior of the water balance components {Precipitation (P), Potential Evapotranspiration (Eo), Real Evapotranspiration (E) and ΔS} due to changes in soil use and vegetation cover were analyzed according to the Budyko model, at annual and as a function of seasonal aridity and evaporative indices. Seasonal values were aggregated to quantify the interannual variability of changes in evaporation and storage. The seasonality of rainfall and the seasonal dynamics of storage were directly incorporated into the developed model, which allowed us to understand which are the dominant control factors on the water balance. In the last decade (2013) the remaining forest cover is only 48.91%, in turn, the cover formed by pasture is 50.47%. The capacity of water storage in the soil decreases continually reaching 8.1%. The results show an approximately linear tendency whose points exceed the "water limit" (Eo / P> 1) and execute the "energy limit", representing dry years with higher values of PE / (P - ΔS), in which annual soil storage provides a complementary supply for annual E. Although the IRW does not fit into a situation of low water availability, its pedological and storage capacity characteristics indicate an increasing trend in flow rates (CN> 72) and low capacity to store water.