Title

Assessment of nutrient sources at watershed scale in agro-ecosystem of Mississippi

Author

Avay Risal

Advisor

Parajuli, Prem B.

Committee Member

Ouyang, Ying

Committee Member

Dash, Padmanava

Committee Member

Linhoss, Anna C.

Date of Degree

12-1-2020

Original embargo terms

Visible to MSU only for 2 years||12/15/2022

Document Type

Dissertation - Open Access

Degree Name

Doctor of Philosophy

Abstract

Excessive nutrient concentrations from a different point and non-point sources are the main cause of water impairment in the United States. Appropriate management practices, according to the source and quantity of pollutions, need to be implemented to control excessive nutrient influx in the water body. Various types of hydrological and water quality models with diverse function, capability and degree of complexity are employed to quantify watershed hydrologic processes and nutrient pollution. Multiple models can be applied to a watershed but the suitable model must be selected based on watershed type and simulation need. Two watershed-scale models, Soil and Water Assessment Tool (SWAT) and Hydrologic Simulation Program-Fortran (HSPF) were chosen for this study to simulate runoff, sediment yield, and nutrient load from the Big Sunflower River Watershed (BSRW) of Mississippi. The objectives of this study are to access the nutrient sources within the watershed, determine the appropriate model to quantify them, develop and evaluate model considering spatial and temporal variations in input data, and evaluate the effectiveness of different Best Management Practices (BMPs) on surface runoff, sediment yield and nutrient load at watershed scale. This study has identified a potential source of nutrients in BSRW and provided a suitable BMP for its management. Similarly, the study found both SWAT and HSPF were efficient in the simulation of streamflow, sediment yield and nutrient load, where SWAT was more efficient during simulation streamflow and sediment yield. Likewise, the study established that both water-quantity and water-quality are sensitive to the change in LULC data layers and thus, seasonal LULC data applied to SWAT will better explain variation in hydrology and water quality as compared to the annual cropland data layer. Moreover, the study showed that well managed vegetative filter strip was very efficient in reducing sediment yield, TN, and TP at both field and watershed scale among different BMPs evaluated at field and watershed scale. This study will be beneficial in developing efficient nutrient management strategy at field and watershed scale, selecting appropriate model and input according to the need and type of watershed, and providing further research opportunities to the scientific community.

URI

https://hdl.handle.net/11668/20838

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