Avay Risal
A Graduate research assistant at Biological Engineering Department, Mississippi State University with current research interest in GIS, Remote Sensing and Hydrologic modelling
Supervisors: Prem Parajuli
Phone: +16623124571
Address: 16 Bellard Street, 39759 MS , USA
Supervisors: Prem Parajuli
Phone: +16623124571
Address: 16 Bellard Street, 39759 MS , USA
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decrease by 1.4 C, and average annual minimum temperature may increase by 0.3 C from 2021 to 2050. Similarly, average monthly streamflow volume could increase by about 65% from March–April,
although it could decrease by about 10% in June. Our results highlight the tight hydrological coupling of surface and groundwater. Farmers making use of surface water for irrigation in upstream subbasins may inadvertently cause a decrease in average water availability in downstream subbasins at approximately 14 %, which may result in increased need to abstract groundwater to compensate for deficits. Well-designed irrigated crop rotations that fully utilize both surface and groundwater conversely may increase groundwater levels by an average of 45 mm from 2022 to 2050, suggesting that in particular subbasins the cultivation of two crops a year may not cause long-term groundwater
depletion. Modelled crop yields for the winter and spring seasons were however lower under future climate change scenarios, even with sufficient irrigation application. Lower yields were associated with shortened growing periods and high-temperature stress. Irrigation intensification appears to be feasible if both surface and groundwater resources are appropriately targeted and rationally used. Conjunctive irrigation planning is required for equitable and year-round irrigation supply as neither the streamflow nor the groundwater can provide full and year-round irrigation for intensified cropping systems without causing the degradation of natural resources.
water. For reduction of nutrient from a watershed, it is needed to be quantified followed by implementation of
appropriate management practices. In this study, major sources of nutrient in Big Sunflower River Watershed
(BSRW) were identified, quantified, and Soil andWater Assessment Tool (SWAT) model was applied for assessment
of flow, sediment and nutrient. SWATwas calibrated and validated for streamflow, sediment, total nitrogen
(TN), and total phosphorus (TP) for three United States Geological Survey (USGS) gauge stations within BSRW.
Moreover, different scenarios, based on agricultural operation and bestmanagement practices, were developed.
Performance of SWATwas evaluated using Nash-Sutcliffe Efficiency (NSE) and coefficient of determination (R2).
The performance was good for streamflow during calibration and validation with R2 and NSE ranging from 0.74
to 0.90 and 0.70 to 0.82 respectively. SWAT performed satisfactorily for sediment, TN and TP except in few extreme
conditions, where animal waste was mixed with farm runoff. This study has provided a suitable crop rotation
and management practice for efficient management of nutrient in BSRW. Manure applied on field
cultivated entirely with soybean was the best practice for reduction of TN with R2 and NSE ranging from 0.70
to 0.90 and 0.58 to 0.76 respectively. Application ofmanure only on existing soybean crop-landwas the best practice
for reduction of TP with R2 and NSE ranging from0.51 to 0.69 and 0.41 to 0.60 respectively. Soybean was effective
in accumulating both nitrogen and phosphorus from soil. This study will be helpful for efficient planning
and management of nutrient through suitable crop rotation and management practice.
decrease by 1.4 C, and average annual minimum temperature may increase by 0.3 C from 2021 to 2050. Similarly, average monthly streamflow volume could increase by about 65% from March–April,
although it could decrease by about 10% in June. Our results highlight the tight hydrological coupling of surface and groundwater. Farmers making use of surface water for irrigation in upstream subbasins may inadvertently cause a decrease in average water availability in downstream subbasins at approximately 14 %, which may result in increased need to abstract groundwater to compensate for deficits. Well-designed irrigated crop rotations that fully utilize both surface and groundwater conversely may increase groundwater levels by an average of 45 mm from 2022 to 2050, suggesting that in particular subbasins the cultivation of two crops a year may not cause long-term groundwater
depletion. Modelled crop yields for the winter and spring seasons were however lower under future climate change scenarios, even with sufficient irrigation application. Lower yields were associated with shortened growing periods and high-temperature stress. Irrigation intensification appears to be feasible if both surface and groundwater resources are appropriately targeted and rationally used. Conjunctive irrigation planning is required for equitable and year-round irrigation supply as neither the streamflow nor the groundwater can provide full and year-round irrigation for intensified cropping systems without causing the degradation of natural resources.
water. For reduction of nutrient from a watershed, it is needed to be quantified followed by implementation of
appropriate management practices. In this study, major sources of nutrient in Big Sunflower River Watershed
(BSRW) were identified, quantified, and Soil andWater Assessment Tool (SWAT) model was applied for assessment
of flow, sediment and nutrient. SWATwas calibrated and validated for streamflow, sediment, total nitrogen
(TN), and total phosphorus (TP) for three United States Geological Survey (USGS) gauge stations within BSRW.
Moreover, different scenarios, based on agricultural operation and bestmanagement practices, were developed.
Performance of SWATwas evaluated using Nash-Sutcliffe Efficiency (NSE) and coefficient of determination (R2).
The performance was good for streamflow during calibration and validation with R2 and NSE ranging from 0.74
to 0.90 and 0.70 to 0.82 respectively. SWAT performed satisfactorily for sediment, TN and TP except in few extreme
conditions, where animal waste was mixed with farm runoff. This study has provided a suitable crop rotation
and management practice for efficient management of nutrient in BSRW. Manure applied on field
cultivated entirely with soybean was the best practice for reduction of TN with R2 and NSE ranging from 0.70
to 0.90 and 0.58 to 0.76 respectively. Application ofmanure only on existing soybean crop-landwas the best practice
for reduction of TP with R2 and NSE ranging from0.51 to 0.69 and 0.41 to 0.60 respectively. Soybean was effective
in accumulating both nitrogen and phosphorus from soil. This study will be helpful for efficient planning
and management of nutrient through suitable crop rotation and management practice.