Soni Pradhanang | University of Rhode Island (original) (raw)
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Papers by Soni Pradhanang
Water Resources Research, 2016
Agriculture, 2015
This paper describes Nepal's national livestock policies and considers how they can be improved t... more This paper describes Nepal's national livestock policies and considers how they can be improved to help meet the pressing national challenges of economic development, equity, poverty alleviation, gender mainstreaming, inclusion of marginalized and underprivileged communities, and climate vulnerability. Nepal is in the process of transforming its government from a unitary system to a federal democratic structure through the new constitution expected by 2015, offering the opportunity to bring a new set of priorities and stakeholders to policymaking. Nepal's livestock subsector comes most directly within the purview of the National Agricultural Policy 2004, Agro-Business Policy, 2006 and Agricultural Sectoral Operating Policies of the Approach Paper to 13th Plan,
Climate, 2015
Landslides, floods, and droughts are recurring natural disasters in Nepal related to too much or ... more Landslides, floods, and droughts are recurring natural disasters in Nepal related to too much or too little water. The summer monsoon contributes more than 80% of annual rainfall, and rainfall spatial and inter-annual variation is very high. The Gandaki River, one of the three major rivers of Nepal and one of the major tributaries of the Ganges River, covers all agro-ecological zones in the central part of Nepal. Time series tests were applied for different agro-ecological zones of the Gandaki River Basin (GRB) for rainfall trends of four seasons (pre-monsoon, monsoon, post-monsoon and winter) from 1981 to 2012.
Hydrology, 2014
Hydrological simulation, based on weather inputs and the physical characterization of the watersh... more Hydrological simulation, based on weather inputs and the physical characterization of the watershed, is a suitable approach to predict the corresponding streamflow. This work, carried out on four different watersheds, analyzed the impacts of using three different meteorological data inputs in the same model to compare the model's accuracy when simulated and observed streamflow are compared. Meteorological data from the Daily Global Historical Climatology Network (GHCN-D), National Land Data Assimilation Systems (NLDAS) and the National Operation Hydrological Remote Sensing Center's Interactive Snow Information (NOHRSC-ISI) were used as an input into the Soil and Water Assessment Tool (SWAT) hydrological model and compared as three different scenarios on each watershed. The results showed that meteorological data from an assimilation system like NLDAS achieved better results than simulations performed with ground-based meteorological data, such as GHCN-D. However, further work needs to be done to improve both the datasets and model capabilities, in order to better predict streamflow.
Remote Sensing, 2013
Precipitation in mountain regions is often highly variable and poorly observed, limiting abilitie... more Precipitation in mountain regions is often highly variable and poorly observed, limiting abilities to manage water resource challenges. Here, we evaluate remote sensing and ground station-based gridded precipitation products over Nepal against weather station precipitation observations on a monthly timescale. We find that the Tropical Rainfall Measuring Mission (TRMM) 3B-43 precipitation product exhibits little mean bias and reasonable skill in giving precipitation over Nepal. Compared to station observations, the TRMM precipitation product showed an overall Nash-Sutcliffe efficiency of 0.
Hydrological Processes, 2011
This study focuses on the effect of projected changes in rainfall, snow accumulation and snowmelt... more This study focuses on the effect of projected changes in rainfall, snow accumulation and snowmelt, and consequent changes in the timing of runoff on NYC water supply system storage and operation as simulated by the NYC reservoir system Operational Analysis and Simulation of Integrated Systems (OASIS) model. The Generalized Watershed Loading Functions-Variable Source Area (GWLF-VSA)-watershed model is used with future climate scenarios derived from different General Circulation Models (GCMs) to simulate future inflows to reservoirs that are part of the New York City Water Supply System (NYCWSS). Future scenarios that use current system operation rules and demands, but changed reservoir inflows, suggest that changes in precipitation and snowmelt will affect regional water availability on a seasonal basis. The combined effect of projected increases in winter air temperatures, increased winter rain, and earlier snowmelt may result in more runoff during winter. This will cause reservoir storage levels, water releases and spills to increase during the winter and earlier reservoir refill in the spring. An overall increase in precipitation will result in a reduction in number of days the system is under drought conditions, despite increased evapotranspiration later in the year.
Hydrological Processes, 2011
Snow is an important component of the water resources of New York State and the watersheds and re... more Snow is an important component of the water resources of New York State and the watersheds and reservoirs of New York City (NYC) water supply. In many of the NYC water supply watersheds the hydrologic regimes of high-elevation headwaters are linked to streamflow and channel processes in low-elevation stream reaches that serve as inputs to water supply reservoirs. To better simulate this linkage there is a need to understand spatial variations in snowpack and snowmelt. Snowmelt hydrology is an important component of the Soil and Water Assessment Tool (SWAT) model in watersheds where spring runoff is strongly affected by melting snow. This study compares model simulated snowpack and snowmelt at different elevation bands with snow survey data available for the Cannonsville reservoir watershed. Simulations examine the effects of parameterising the SWAT snowmelt sub-model using 1, 3, and 5 elevation bands by comparison with measured snow and streamflow. Comparison between measured and simulated snowpack produced correlation coefficients ranging from 0Ð35 to 0Ð85. Simulations of both daily and seasonal streamflow, improved when using 3 elevation bands with r 2 of 0Ð73 and E NS of 0Ð72. Streamflow simulations showed slightly lower model performance when basin elevation was assumed to be equal to snow survey site elevation, due to the snow survey sites being somewhat biased toward lower elevations. The effect of climate change was also evaluated and showed that under higher air temperatures in future climate change scenarios, SWAT indicated more precipitation falling as rain, increased and earlier snowmelt, and a reduced snowpack leading to a change in the pattern of streamflow, particularly during winter and early spring.
Hydrological Processes, 2011
Snowfall is an important part of the yearly water balance for the Catskill Mountains in New York ... more Snowfall is an important part of the yearly water balance for the Catskill Mountains in New York State, the location of water supply reservoirs for New York City. Recent studies have shown that the effects of climate change on the hydrology of the Catskills will most likely create (1) a decrease in the proportion of precipitation falling as snow, (2) a shift in the timing of snowmelt that will cause snowmelt-supplemented streamflow events to occur earlier in the fall and winter, and (3) a decrease in the magnitude of traditionally high April streamflow. The shift in timing of snowmelt-influenced streamflow events is measured by the winter-early spring centre of volume (WSCV), defined as the Julian Day on which half the total streamflow volume from January to May occurs. Studies of streamflow, precipitation, and temperature trends in the last 50 years have shown that the WSCV is already earlier by about 5-10 days. This study investigates the use of watershed-scale snowpack and snowmelt algorithms that are incorporated in two existing watershed water quality models, Generalized Watershed Loading Functions-Variable Source Area (GWLF-VSA) and Soil and Water Assessment Tool (SWAT), to capture the potential effects of climate change on the timing and magnitude of streamflow during the late fall, winter, and early spring for the Catskill Mountain region. The GWLF-VSA model reasonably simulated the recent shifts in the winter streamflow timing, with simulations over the previous 50-year period yielding shifts in WSCV of 2-15 days. The SWAT model yielded similar results as the GWLF-VSA simulations. Scenarios of potential climate change 100 years in the future showed a similar shift in direction of timing winter streamflow, but at a larger magnitude than observed to date with WSCV occurring 15-20 days earlier.
Hydrological Processes, 2011
In this study, we evaluate the ability of GCMs participating in the Intergovernmental Panel for C... more In this study, we evaluate the ability of GCMs participating in the Intergovernmental Panel for Climate Change's (IPCC) Fourth Assessment Report (AR4) to simulate variability in the snow water equivalent (SWE) in New York City Water Supply watersheds located northwest of NYC in the Catskill Mountains. SWE is estimated using an empirical temperature-based degree day model. Inputs to this model are either measured with historical meteorological data or a GCM model output for the same historical period. The evaluation of the GCMs is based on a skill score developed using probability distribution functions derived from the time series of simulated snowpack. From the skill scores (SS) calculated, the GCMs are ranked based on their ability to simulate the snowpack. These results have implications for selecting a subset of GCM simulations for climate change impact assessments in New York City's water supply.
Water Resources Research, 2016
Agriculture, 2015
This paper describes Nepal's national livestock policies and considers how they can be improved t... more This paper describes Nepal's national livestock policies and considers how they can be improved to help meet the pressing national challenges of economic development, equity, poverty alleviation, gender mainstreaming, inclusion of marginalized and underprivileged communities, and climate vulnerability. Nepal is in the process of transforming its government from a unitary system to a federal democratic structure through the new constitution expected by 2015, offering the opportunity to bring a new set of priorities and stakeholders to policymaking. Nepal's livestock subsector comes most directly within the purview of the National Agricultural Policy 2004, Agro-Business Policy, 2006 and Agricultural Sectoral Operating Policies of the Approach Paper to 13th Plan,
Climate, 2015
Landslides, floods, and droughts are recurring natural disasters in Nepal related to too much or ... more Landslides, floods, and droughts are recurring natural disasters in Nepal related to too much or too little water. The summer monsoon contributes more than 80% of annual rainfall, and rainfall spatial and inter-annual variation is very high. The Gandaki River, one of the three major rivers of Nepal and one of the major tributaries of the Ganges River, covers all agro-ecological zones in the central part of Nepal. Time series tests were applied for different agro-ecological zones of the Gandaki River Basin (GRB) for rainfall trends of four seasons (pre-monsoon, monsoon, post-monsoon and winter) from 1981 to 2012.
Hydrology, 2014
Hydrological simulation, based on weather inputs and the physical characterization of the watersh... more Hydrological simulation, based on weather inputs and the physical characterization of the watershed, is a suitable approach to predict the corresponding streamflow. This work, carried out on four different watersheds, analyzed the impacts of using three different meteorological data inputs in the same model to compare the model's accuracy when simulated and observed streamflow are compared. Meteorological data from the Daily Global Historical Climatology Network (GHCN-D), National Land Data Assimilation Systems (NLDAS) and the National Operation Hydrological Remote Sensing Center's Interactive Snow Information (NOHRSC-ISI) were used as an input into the Soil and Water Assessment Tool (SWAT) hydrological model and compared as three different scenarios on each watershed. The results showed that meteorological data from an assimilation system like NLDAS achieved better results than simulations performed with ground-based meteorological data, such as GHCN-D. However, further work needs to be done to improve both the datasets and model capabilities, in order to better predict streamflow.
Remote Sensing, 2013
Precipitation in mountain regions is often highly variable and poorly observed, limiting abilitie... more Precipitation in mountain regions is often highly variable and poorly observed, limiting abilities to manage water resource challenges. Here, we evaluate remote sensing and ground station-based gridded precipitation products over Nepal against weather station precipitation observations on a monthly timescale. We find that the Tropical Rainfall Measuring Mission (TRMM) 3B-43 precipitation product exhibits little mean bias and reasonable skill in giving precipitation over Nepal. Compared to station observations, the TRMM precipitation product showed an overall Nash-Sutcliffe efficiency of 0.
Hydrological Processes, 2011
This study focuses on the effect of projected changes in rainfall, snow accumulation and snowmelt... more This study focuses on the effect of projected changes in rainfall, snow accumulation and snowmelt, and consequent changes in the timing of runoff on NYC water supply system storage and operation as simulated by the NYC reservoir system Operational Analysis and Simulation of Integrated Systems (OASIS) model. The Generalized Watershed Loading Functions-Variable Source Area (GWLF-VSA)-watershed model is used with future climate scenarios derived from different General Circulation Models (GCMs) to simulate future inflows to reservoirs that are part of the New York City Water Supply System (NYCWSS). Future scenarios that use current system operation rules and demands, but changed reservoir inflows, suggest that changes in precipitation and snowmelt will affect regional water availability on a seasonal basis. The combined effect of projected increases in winter air temperatures, increased winter rain, and earlier snowmelt may result in more runoff during winter. This will cause reservoir storage levels, water releases and spills to increase during the winter and earlier reservoir refill in the spring. An overall increase in precipitation will result in a reduction in number of days the system is under drought conditions, despite increased evapotranspiration later in the year.
Hydrological Processes, 2011
Snow is an important component of the water resources of New York State and the watersheds and re... more Snow is an important component of the water resources of New York State and the watersheds and reservoirs of New York City (NYC) water supply. In many of the NYC water supply watersheds the hydrologic regimes of high-elevation headwaters are linked to streamflow and channel processes in low-elevation stream reaches that serve as inputs to water supply reservoirs. To better simulate this linkage there is a need to understand spatial variations in snowpack and snowmelt. Snowmelt hydrology is an important component of the Soil and Water Assessment Tool (SWAT) model in watersheds where spring runoff is strongly affected by melting snow. This study compares model simulated snowpack and snowmelt at different elevation bands with snow survey data available for the Cannonsville reservoir watershed. Simulations examine the effects of parameterising the SWAT snowmelt sub-model using 1, 3, and 5 elevation bands by comparison with measured snow and streamflow. Comparison between measured and simulated snowpack produced correlation coefficients ranging from 0Ð35 to 0Ð85. Simulations of both daily and seasonal streamflow, improved when using 3 elevation bands with r 2 of 0Ð73 and E NS of 0Ð72. Streamflow simulations showed slightly lower model performance when basin elevation was assumed to be equal to snow survey site elevation, due to the snow survey sites being somewhat biased toward lower elevations. The effect of climate change was also evaluated and showed that under higher air temperatures in future climate change scenarios, SWAT indicated more precipitation falling as rain, increased and earlier snowmelt, and a reduced snowpack leading to a change in the pattern of streamflow, particularly during winter and early spring.
Hydrological Processes, 2011
Snowfall is an important part of the yearly water balance for the Catskill Mountains in New York ... more Snowfall is an important part of the yearly water balance for the Catskill Mountains in New York State, the location of water supply reservoirs for New York City. Recent studies have shown that the effects of climate change on the hydrology of the Catskills will most likely create (1) a decrease in the proportion of precipitation falling as snow, (2) a shift in the timing of snowmelt that will cause snowmelt-supplemented streamflow events to occur earlier in the fall and winter, and (3) a decrease in the magnitude of traditionally high April streamflow. The shift in timing of snowmelt-influenced streamflow events is measured by the winter-early spring centre of volume (WSCV), defined as the Julian Day on which half the total streamflow volume from January to May occurs. Studies of streamflow, precipitation, and temperature trends in the last 50 years have shown that the WSCV is already earlier by about 5-10 days. This study investigates the use of watershed-scale snowpack and snowmelt algorithms that are incorporated in two existing watershed water quality models, Generalized Watershed Loading Functions-Variable Source Area (GWLF-VSA) and Soil and Water Assessment Tool (SWAT), to capture the potential effects of climate change on the timing and magnitude of streamflow during the late fall, winter, and early spring for the Catskill Mountain region. The GWLF-VSA model reasonably simulated the recent shifts in the winter streamflow timing, with simulations over the previous 50-year period yielding shifts in WSCV of 2-15 days. The SWAT model yielded similar results as the GWLF-VSA simulations. Scenarios of potential climate change 100 years in the future showed a similar shift in direction of timing winter streamflow, but at a larger magnitude than observed to date with WSCV occurring 15-20 days earlier.
Hydrological Processes, 2011
In this study, we evaluate the ability of GCMs participating in the Intergovernmental Panel for C... more In this study, we evaluate the ability of GCMs participating in the Intergovernmental Panel for Climate Change's (IPCC) Fourth Assessment Report (AR4) to simulate variability in the snow water equivalent (SWE) in New York City Water Supply watersheds located northwest of NYC in the Catskill Mountains. SWE is estimated using an empirical temperature-based degree day model. Inputs to this model are either measured with historical meteorological data or a GCM model output for the same historical period. The evaluation of the GCMs is based on a skill score developed using probability distribution functions derived from the time series of simulated snowpack. From the skill scores (SS) calculated, the GCMs are ranked based on their ability to simulate the snowpack. These results have implications for selecting a subset of GCM simulations for climate change impact assessments in New York City's water supply.