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Improvement And Application Of The Soil And Water Assessment Tool

Posted on:2017-01-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:D J ZhaFull Text:PDF
GTID:1310330512962364Subject:Physical geography
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Distributed hydrological models not only incorporate the physical, chemical and biological processes in water cycle, but also full consider the spatial heterogeneity of these processes caused by the difference of underlying land cover/use, soil type and driving forces such as precipitation, temperature and so on. Thus they are extensively used to understand, analyze, model and predict the temporal and spatial variations of water availability and quality under changing environment. Soil and Water Assessment Tool (SWAT) model is one of these kinds. It is a continuous basin-scale distributed hydrological model with a strong physical basis, which has been applied to various watersheds throughout the world to evaluate the effects of landuse and climate change, and management practices on water availability/quality, sediment and nutrients variation. However, it also suffers from some inadequacies in delineating hydrological processes and practical use. It has significant implication in understanding the laws of water cycle, improving performance of runoff, sediment and nutrients simulation abilities, and extending application fields, to overcome these inadequacies. Therefore, following revisions were conducted to improve the performance and ease of application of SWAT model, including:(1) Proposing a seasonal calibration and simulation method to solve the poor performance problem of SWAT in dry seasons, and testing the revision of SWAT (entitle as SWAT-SC) with the data set of Jinjiang Watershed;(2) Incorporating the dynamics of nitrogen deposition and its transport processes with water flows to fully capture the effects of nitrogen deposition on the nitrogen cycle of a watershed, and evaluating this revision of SWAT (entitle as SWAT-CSenm) with the data set of a typical forested watershed of Canada Shield landscape;(3) Developing a cloud-based calibration and uncertainty analysis tool for SWAT (CUT-SWAT) by coupling GLUE method and cloud computing technology, so as to accelerate the processes of model calibration and uncertainty analysis;(4) Developing a web-based Decision Support System for Watershed Management by integrating an open source Web GIS tool (Geoserver), SWAT model, a cloud computing platform (Hadoop), with the purpose of user-friendly and real-time decision-making supports for scientific watershed management.The results of the study show that:(1) a significant improvement was achieved by using SWAT-SC for simulating runoffs in the dry period, and although not as notably as the dry period, improvements for runoff simulation of the wet and overall periods were observed as well; (2) SWAT-CSenm can reasonably reproduce the processes of nitrate in Harp Lake catchment by considering the dynamics of nitrate deposition and other revisions against the special region features; (3) the newly developed cloud-based calibration and uncertainty analysis tool (CUT-SWAT) can take better advantage of computational power, reliability and scalability of cloud computing, and is an ideal method to solve high computational demand problems in hydrological model calibration and uncertainty analysis; (4) the web-based Decision Support System for Watershed Management developed by seamlessly integrating an open source Web GIS tool Geoserver, a modeling component SWAT, a cloud computing platform Hadoop, can meet the functionalities demand while also provides an user-friendly and real-time decision-making supports for watershed management.
Keywords/Search Tags:Nitrogen deposition, Seasonal calibration method, Dry periods, SWAT, SWAT-SC, SWAT-CSenm, Cloud-CUT, Information system for watershed management, Harp Lake watershed, Jinjiang watershed
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