Nandita Basu - Academia.edu (original) (raw)
Papers by Nandita Basu
Environmental Research Letters, 2017
Environmental Science & Technology, 2014
Proceedings of the National Academy of Sciences of the United States of America, Jan 8, 2016
Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy,... more Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fraction of wetland edges where many functions are enhanced, and form complexes with other water bodies to create spatial and temporal heterogeneity in the timing, flow paths, and magnitude of network connectivity. These attributes signal a critical role for GIWs in sustaining a portfolio of landscape functions, but legal protections remain weak despite preferential loss from many landscapes. GIWs lack persistent surface water connections, but this condition does not imply the absence of hydrological, biogeochemical, and biological exchanges with nearby and downstream waters. Although hydrolo...
Increased nutrient loads delivered from watersheds due to agricultural intensification, industria... more Increased nutrient loads delivered from watersheds due to agricultural intensification, industrialization, and urbanization have contributed to the persistence of large hypoxic zones in inland and coastal waters at a global scale. Watershed management practices to target these non-point source pollutants have reportedly resulted in little or no improvement in water quality, even after extensive implementation of conservation measures or Best Management Practices (BMPs). The lag time between implementation of a conservation measure and resultant water quality benefits has recently been recognized as an important factor in the “apparent” failure of these BMPs. Conservation measures are often implemented without explicit consideration of the lag time and with the expectation that they will lead to immediate benefits; the resulting failure to meet such expectations then discourages vital restoration efforts. In order to address this problem, it is important to quantify the lag times ass...
Limnology and Oceanography, 2019
Science, 2019
Ballard et al. argue that our prediction of a 30-year or longer recovery time for Gulf of Mexico ... more Ballard et al. argue that our prediction of a 30-year or longer recovery time for Gulf of Mexico water quality is highly uncertain, and that much shorter time lags are equally likely. We demonstrate that their argument, based on the use of a two-component regression model, does not sufficiently consider fundamental watershed processes or multiple lines of evidence suggesting the existence of decadal-scale lags.
Nature Precedings, 2009
Nitrogen provides a fundamental building block for life. However, some nitrogen species (e.g., NO... more Nitrogen provides a fundamental building block for life. However, some nitrogen species (e.g., NO~3~) cause water quality degradation and contribute to climatic warming as a greenhouse gas (e.g., N~2~O). Denitrification is a central process in the nitrogen cycle, transforming water-soluble nitrogen to gaseous nitrogen, thereby removing nitrogen from the system. The factors controlling denitrification are known, yet the general quantitative comparison of controls on denitrification remains a rich area of study. Understanding the relative importance of various controls over denitrification is critical given its biological importance, role in the Earth system, and the current perturbation of the global nitrogen cycle by human activity. We demonstrate that the 'effective' denitrification rate constant (first-order constant; k~e~ [T^-1^]) and advective water transport (mean residence time; [tau] [T]) scale inversely across diverse systems, ranging from hillslopes and groundwater ...
Water Resources Research, 2019
Frontiers in Ecology and the Environment, 2017
Hydrology and Earth System Sciences, 2016
Rainwater harvesting (RWH), the small-scale collection and storage of runoff for irrigated agricu... more Rainwater harvesting (RWH), the small-scale collection and storage of runoff for irrigated agriculture, is recognized as a sustainable strategy for ensuring food security, especially in monsoonal landscapes in the developing world. In south India, these strategies have been used for millennia to mitigate problems of water scarcity. However, in the past 100 years many traditional RWH systems have fallen into disrepair due to increasing dependence on groundwater. This dependence has contributed to accelerated decline in groundwater resources, which has in turn led to increased efforts at the state and national levels to revive older RWH systems. Critical to the success of such efforts is an improved understanding of how these ancient systems function in contemporary landscapes with extensive groundwater pumping and shifted climatic regimes. Knowledge is especially lacking regarding the water-exchange dynamics of these RWH tanks at tank and catchment scales, and how these exchanges reg...
Hydrology and Earth System Sciences Discussions, 2015
Rainwater harvesting (RWH), the small-scale collection and storage of runoff for irrigated agricu... more Rainwater harvesting (RWH), the small-scale collection and storage of runoff for irrigated agriculture, is recognized as a sustainable strategy for ensuring food security, especially in monsoonal landscapes in the developing world. In south India, these strategies have been used for millennia to mitigate problems of water scarcity. However, in the past 100 years many traditional RWH systems have fallen into disrepair due to increasing dependence on groundwater. This dependence has contributed to an accelerated decline in groundwater resources, which has in turn led to increased efforts at the state and national levels to revive older RWH systems. Critical to the success of such efforts is an improved understanding of how these ancient systems function in contemporary landscapes with extensive groundwater pumping and shifted climatic regimes. Knowledge is especially lacking regarding the water-exchange dynamics of these RWH "tanks" at tank and catchment scales, and how thes...
Water Resources Research, 2017
Water Resources Research, 2011
Environmental Research Letters, 2016
Global Biogeochemical Cycles, 2017
Ecological Applications, 2015
PloS one, 2015
Irrigated agriculture can modify the cycling and transport of nitrogen (N), due to associated wat... more Irrigated agriculture can modify the cycling and transport of nitrogen (N), due to associated water diversions, water losses, and changes in transport flow-paths. We investigate dominant processes behind observed long-term changes in dissolved inorganic nitrogen (DIN) concentrations and loads of the extensive (465,000 km2) semi-arid Amu Darya River basin (ADRB) in Central Asia. We specifically considered a 40-year period (1960-2000) of large irrigation expansion, reduced river water flows, increased fertilizer application and net increase of N input into the soil-water system. Results showed that observed decreases in riverine DIN concentration near the Aral Sea outlet of ADRB primarily were due to increased recirculation of irrigation water, which extends the flow-path lengths and enhances N attenuation. The observed DIN concentrations matched a developed analytical relation between concentration attenuation and recirculation ratio, showing that a fourfold increase in basin-scale r...
Environmental Research Letters, 2017
Environmental Science & Technology, 2014
Proceedings of the National Academy of Sciences of the United States of America, Jan 8, 2016
Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy,... more Geographically isolated wetlands (GIWs), those surrounded by uplands, exchange materials, energy, and organisms with other elements in hydrological and habitat networks, contributing to landscape functions, such as flow generation, nutrient and sediment retention, and biodiversity support. GIWs constitute most of the wetlands in many North American landscapes, provide a disproportionately large fraction of wetland edges where many functions are enhanced, and form complexes with other water bodies to create spatial and temporal heterogeneity in the timing, flow paths, and magnitude of network connectivity. These attributes signal a critical role for GIWs in sustaining a portfolio of landscape functions, but legal protections remain weak despite preferential loss from many landscapes. GIWs lack persistent surface water connections, but this condition does not imply the absence of hydrological, biogeochemical, and biological exchanges with nearby and downstream waters. Although hydrolo...
Increased nutrient loads delivered from watersheds due to agricultural intensification, industria... more Increased nutrient loads delivered from watersheds due to agricultural intensification, industrialization, and urbanization have contributed to the persistence of large hypoxic zones in inland and coastal waters at a global scale. Watershed management practices to target these non-point source pollutants have reportedly resulted in little or no improvement in water quality, even after extensive implementation of conservation measures or Best Management Practices (BMPs). The lag time between implementation of a conservation measure and resultant water quality benefits has recently been recognized as an important factor in the “apparent” failure of these BMPs. Conservation measures are often implemented without explicit consideration of the lag time and with the expectation that they will lead to immediate benefits; the resulting failure to meet such expectations then discourages vital restoration efforts. In order to address this problem, it is important to quantify the lag times ass...
Limnology and Oceanography, 2019
Science, 2019
Ballard et al. argue that our prediction of a 30-year or longer recovery time for Gulf of Mexico ... more Ballard et al. argue that our prediction of a 30-year or longer recovery time for Gulf of Mexico water quality is highly uncertain, and that much shorter time lags are equally likely. We demonstrate that their argument, based on the use of a two-component regression model, does not sufficiently consider fundamental watershed processes or multiple lines of evidence suggesting the existence of decadal-scale lags.
Nature Precedings, 2009
Nitrogen provides a fundamental building block for life. However, some nitrogen species (e.g., NO... more Nitrogen provides a fundamental building block for life. However, some nitrogen species (e.g., NO~3~) cause water quality degradation and contribute to climatic warming as a greenhouse gas (e.g., N~2~O). Denitrification is a central process in the nitrogen cycle, transforming water-soluble nitrogen to gaseous nitrogen, thereby removing nitrogen from the system. The factors controlling denitrification are known, yet the general quantitative comparison of controls on denitrification remains a rich area of study. Understanding the relative importance of various controls over denitrification is critical given its biological importance, role in the Earth system, and the current perturbation of the global nitrogen cycle by human activity. We demonstrate that the 'effective' denitrification rate constant (first-order constant; k~e~ [T^-1^]) and advective water transport (mean residence time; [tau] [T]) scale inversely across diverse systems, ranging from hillslopes and groundwater ...
Water Resources Research, 2019
Frontiers in Ecology and the Environment, 2017
Hydrology and Earth System Sciences, 2016
Rainwater harvesting (RWH), the small-scale collection and storage of runoff for irrigated agricu... more Rainwater harvesting (RWH), the small-scale collection and storage of runoff for irrigated agriculture, is recognized as a sustainable strategy for ensuring food security, especially in monsoonal landscapes in the developing world. In south India, these strategies have been used for millennia to mitigate problems of water scarcity. However, in the past 100 years many traditional RWH systems have fallen into disrepair due to increasing dependence on groundwater. This dependence has contributed to accelerated decline in groundwater resources, which has in turn led to increased efforts at the state and national levels to revive older RWH systems. Critical to the success of such efforts is an improved understanding of how these ancient systems function in contemporary landscapes with extensive groundwater pumping and shifted climatic regimes. Knowledge is especially lacking regarding the water-exchange dynamics of these RWH tanks at tank and catchment scales, and how these exchanges reg...
Hydrology and Earth System Sciences Discussions, 2015
Rainwater harvesting (RWH), the small-scale collection and storage of runoff for irrigated agricu... more Rainwater harvesting (RWH), the small-scale collection and storage of runoff for irrigated agriculture, is recognized as a sustainable strategy for ensuring food security, especially in monsoonal landscapes in the developing world. In south India, these strategies have been used for millennia to mitigate problems of water scarcity. However, in the past 100 years many traditional RWH systems have fallen into disrepair due to increasing dependence on groundwater. This dependence has contributed to an accelerated decline in groundwater resources, which has in turn led to increased efforts at the state and national levels to revive older RWH systems. Critical to the success of such efforts is an improved understanding of how these ancient systems function in contemporary landscapes with extensive groundwater pumping and shifted climatic regimes. Knowledge is especially lacking regarding the water-exchange dynamics of these RWH "tanks" at tank and catchment scales, and how thes...
Water Resources Research, 2017
Water Resources Research, 2011
Environmental Research Letters, 2016
Global Biogeochemical Cycles, 2017
Ecological Applications, 2015
PloS one, 2015
Irrigated agriculture can modify the cycling and transport of nitrogen (N), due to associated wat... more Irrigated agriculture can modify the cycling and transport of nitrogen (N), due to associated water diversions, water losses, and changes in transport flow-paths. We investigate dominant processes behind observed long-term changes in dissolved inorganic nitrogen (DIN) concentrations and loads of the extensive (465,000 km2) semi-arid Amu Darya River basin (ADRB) in Central Asia. We specifically considered a 40-year period (1960-2000) of large irrigation expansion, reduced river water flows, increased fertilizer application and net increase of N input into the soil-water system. Results showed that observed decreases in riverine DIN concentration near the Aral Sea outlet of ADRB primarily were due to increased recirculation of irrigation water, which extends the flow-path lengths and enhances N attenuation. The observed DIN concentrations matched a developed analytical relation between concentration attenuation and recirculation ratio, showing that a fourfold increase in basin-scale r...