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A Study of Agricultural Watershed Health and Sustainability Using a New Catchment-scale Hydro-biogeochemical Model

Wen, Yipei (2022) A Study of Agricultural Watershed Health and Sustainability Using a New Catchment-scale Hydro-biogeochemical Model. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Rainfall runoff and leaching are the main driving forces that lead the agricultural pollutants into streams, lakes and groundwater, and thereby deteriorate water quality. To make better management plan and achieve sustainable development within a watershed, it is crucial to study nutrient biogeochemical processes and their transport at a watershed scale where impacts of temporal and spatial heterogeneities are properly accounted for. However, current environmental models are unsatisfactory in modeling complex biogeochemical processes like denitrification at watershed scale due to various limitations.
In this study, a new distributed hydro-biogeochemical model, DHSVM-N, is developed based on the widely used fully distributed and physically-based hydrological model DHSVM (Distributed Hydrology Soil and Vegetation Model), and the SWAT model (Soil & Water Assessment Tool). DHSVM-N is then used to investigate longstanding and challenging watershed health issues caused by agricultural nutrient contaminants. Compared to the original DHSVM model, DHSVM-N includes four main features: (1) dynamic vegetation growth, (2) vegetation-soil nutrient cycle, (3) contaminant transport module for nitrogen, and (4) wetland and agricultural management simulation. The construct of DHSVM-N model endows it to incorporate realistic landscape unit connectivity in routing/transport processes for overland flow and channel flow in giving physically-based flow pathways and captures spatial distributions of soil moisture. This new DHSVM-N model is applied to a rural watershed to investigate impacts of different model transport approaches on simulating nitrogen-related process and spatial patterns of denitrification under different scenarios, and to evaluate impacts of agricultural management activities on watershed’s health by considering different placement of treatment facilities and different locations of pollution sources.
Results obtained highlight the importance of hydrological processes in modeling biogeochemical processes and the critical role of pollutant transport method in adequately simulating biogeochemical hot spots. This work also showcases how watershed responds to different placement designs of Best Management Practices (BMPs) where wetland with optimized placement can contribute to reduction in nitrate export for nonpoint source and unidentified point source respectively and increase in system reliability. The result emphasizes the need to properly consider BMPs locations when making field-scale management plans and when conducting the watershed health and sustainability study.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Wen, Yipeiyiw58@pitt.eduyiw58
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairLiang,
Committee MemberNg,
Committee MemberLin,
Committee MemberMao,
Date: 10 June 2022
Date Type: Publication
Defense Date: 24 March 2022
Approval Date: 10 June 2022
Submission Date: 28 March 2022
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 151
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Civil and Environmental Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Modeling; Watershed; DHSVM; Transport; Connectivity; Denitrification; Hot spots; Wetland; Water quality;
Date Deposited: 10 Jun 2022 19:16
Last Modified: 10 Jun 2022 19:16


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