LAND USE EFFECTS ON WATER QUALITY: BUILDING A FRAMEWORK FOR CHICAGO RIVER WATERSHED
MAHDI, NAILA GHIDEY ISMAIL
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The purpose of this study is to introduce a framework that enables a holistic watershed approach that models the dynamics of water quality and landuse in a highly urbanized watershed. The landuse-water quality relationship is a complex relationship and has not been adequately addressed for highly urbanized watersheds. Factors such as inadequate urban planning, increase of impervious areas and dynamics of population growth are some of the reasons for the complex relationship. Also point sources are always easy to be identified and controlled unlike nonpoint sources such as urban storm runoff. Both quantities and transport pathways of pollutant inputs are impacted by land use in the watershed. So, examining the factors that govern the relationship between different land uses and water quality within a watershed can give insights and important information about existing and potential sources of contamination. The two backbone concepts in this study are the holistic watershed perspective and the role of historical data records as part of assessment, modeling and integration tools of the watershed framework. Analysis of the records will explain watershed conditions identifying the major problem areas and justify the modeling and post analysis procedures. Data sources are often important but data availability, heterogeneity and conformity are the main challenges in integrating these sources. This research presents an approach to integrate the watershed data in a single repository and methodologies for analyzing and assessing the watershed using data warehouse and data mining technologies. A multi-dimensional model that supports complex querying of watershed data and discovery of trends and patterns in data by incorporating 40 years worth of watershed data from different source agencies in a central repository is introduced. Also, the discipline of data driven modeling was introduced in this thesis using the developed central repository. Several regression and classification algorithms were presented and assessed for their appropriateness for predicting total nitrates using few watershed attributes. The results show acceptable prediction accuracy. Five years of water quality simulation using the multi-purpose environmental analysis system BASINS coupled with the comprehensive, conceptual, and continuous simulation watershed scale model HSPF resulted in export coefficients for level (III), detailed land use for the Chicago River watershed. The water quality simulation approach utilized in this research to generate the coefficients constitutes a new contribution to the Chicago River watershed and other highly urbanized watersheds. The continuous calibrated and validated model can be used in the investigation and analysis of different scenarios and possible future conditions, thus providing a planning tool for regulatory environmental agencies. The data driven models developed can be used as operation tool to maintain the water quality parameters especially if TMDL and WQS are developed for Chicago River Watershed. So the framework proposed for this study can be considered robust with the proposed integration, planning and operating techniques and tools. Furthermore, an optimization tool is introduced in the future work section.