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The contamination of rivers with nitrate from agricultural diffuse sources is not just a risk for ecosystems and their services, but also a health risk for water users. The Great Lakes (USA and Canada) are suffering from eutrophication problems. The Midwest is one of the richest farming land and one of the most productive areas on the planet. Thus, agriculture is one of the biggest drivers of local economies, accounting for billions of dollars of exports and thousands of jobs. The Midwest encompasses the Corn Belt region, a specialised system in corn production. Many of its agricultural basins drain into the Great Lakes. Corn requires a heavy amount of fertilizer to keep the best-yielding varieties. Some of the soils also require artificial drainage due to their low permeability, and to enable agriculture. The Cedar Creek watershed (CCW) in northeastern Indiana in the Corn Belt region is used as a case study area in this dissertation. Intensive agriculture in the CCW is characterised mainly by corn and soybean production. Tile drains are used, ejecting nitrate directly into the water. To find hotspots of nitrate is, then, crucial to avoid water quality deterioration. Identification of critical source areas of nitrate (CSAs) impairing waters is challenging. There are, mainly, two methodologies to identify hotspots of nitrate for the implementation of Best Management Practices (BMP): the targeting technique and the optimization approach. The targeting technique tends to identify hotspots based on loads of nitrate, omitting geomorphological watershed characteristics, costs for BMP implementation, and their spatial interactions. On the other hand, the parsimonious strategy does contemplate the trade-off of the economic and environmental contribution but requires sophisticated computational resources and it is more data-intense. This research presents a new framework based on the synergistic combination of both methodologies for the identification of CSAs in agricultural watersheds. Changes in watershed response due to alternative BMP applications were assessed using the model Soil and Water Assessment Tool (SWAT). Outputs in SWAT (nitrate export rates and nitrate concentration at the subbasin level) were used to evaluate the changes in water quality for the CCW. The newly developed targeting technique (HosNIT) considers SWAT outputs and intrinsic watershed parameters such as stream order, crop distance to the draining stream, and downstream nitrate enrichment/dilution effects within the river network. HosNIT establishes a workflow, based on a threshold system for the parameters considered, in order to spatially identify priority areas from where nitrate is reaching water. The more precise hotspots of nitrate are identified, the more improved the allocation of limited resources for conservation practices will be. HosNIT allows for a more spatially accurate CSAs identification, which enables a parsimonious optimization for BMP implementation. This parsimonious strategy will test BMP’s performance based on the environmental contribution and cost at the hotspots determined by HosNIT. The optimised solution for the CCW comes from the environmental contribution (decrease percentage of nitrate concentration at outlets) per dollar spent. For this case study means a year average of 3.7% of nitrate reduction with the optimised selection of scenarios for the studied period.

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No description available.

The expansion of Interstate 26 from Erwin, TN to the North Carolina border was a project that potentially adversely impacted South Indian Creek because of the steep landscapes and potential for erosion. Several studies have shown the short-term, negative effects of road construction on the water quality of nearby water bodies. Non-point source pollution is the major source of water pollution in the United States. The primary objective of this research is to evaluate the long-term effects of the construction of Interstate 26 on South Indian Creek to see if there has been any ecological recovery. The Environmental Health Sciences Laboratory of East Tennessee State University was contracted by the Tennessee Department of Transportation to collect data from before construction (1991-1992), during construction (1993-1994), and postconstruction (1995-1996). Comparison of microbial enzyme activities and other parameters to present-day (2012-2013) water quality conditions indicate that South Indian Creek has not fully recovered from the effects of the construction of the interstate.

Hui Wing-chi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 127-141). / Abstracts in English and Chinese. / LIST OF TABLES --- p.xi / LIST OF FIGURES --- p.xiii / LIST OF ACRONYMS --- p.xvii / Chapter CHAPTER ONE- --- INTRODUCTION / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Conceptual Framework and Study Objectives --- p.7 / Chapter 1.3 --- Scope of the Research and Study Area --- p.10 / Chapter 1.3.1 --- Location and Climate --- p.10 / Chapter 1.3.2 --- Geology --- p.12 / Chapter 1.3.3 --- Landuse Characteristics and Status of Water Quality --- p.13 / Chapter 1.4 --- Significance of Study --- p.14 / Chapter 1.5 --- Organization of Thesis --- p.16 / Chapter CHAPTER TWO - --- LITERATURE REVIEW / Chapter 2.1 --- Landuse Alteration --- p.17 / Chapter 2.1.1 --- Urbanization and Landuse Changes --- p.17 / Chapter 2.1.2 --- Detecting Landuse Changes in Urbanizing Region --- p.19 / Chapter 2.2 --- Impact of Landuse Alteration on Water Quality --- p.21 / Chapter 2.2.1 --- Point and Nonpoint Sources of Water Pollution --- p.22 / Chapter 2.2.2 --- Nonpoint Source Pollution as a Worldwide Environmental Problem --- p.23 / Chapter 2.2.3 --- Methods of Assessing Nonpoint Source Pollution --- p.24 / Chapter 2.2.4 --- GIS-based Modeling of Nonpoint Source Pollution --- p.26 / Chapter 2.2.5 --- Application of Remote Sensing on Water Quality Study --- p.27 / Chapter 2.3 --- Landuse Changes and Their Water Quality Impacts in the Pearl River Delta --- p.28 / Chapter 2.3.1 --- Economic Reform and Urbanization --- p.29 / Chapter 2.3.2 --- Urban Redevelopment --- p.31 / Chapter 2.3.3 --- Rural Industrialization --- p.33 / Chapter 2.3.4 --- Water Pollution --- p.34 / Chapter CHAPTER THREE - --- METHODOLOGY / Chapter 3.1 --- Introduction --- p.36 / Chapter 3.2 --- Computation of Areal Nonpoint Source Pollution Loading --- p.38 / Chapter 3.2.1 --- Assumptions --- p.38 / Chapter 3.2.2 --- Soil Conservation Service (SCS) Curve Number Method --- p.39 / Chapter 3.2.3 --- Generation of Nonpoint Source Pollutants --- p.42 / Chapter 3.2.4 --- Model Operation --- p.43 / Chapter 3.3 --- Instream Water Quality Modeling --- p.45 / Chapter 3.3.1 --- Description ofWASP5 --- p.46 / Chapter 3.3.2 --- Hydraulic Parameters --- p.47 / Chapter 3.3.3 --- Model Constants --- p.48 / Chapter 3.4 --- Description of Model Input Data --- p.49 / Chapter 3.4.1 --- Watershed Delineation --- p.49 / Chapter 3.4.2 --- Soil Data --- p.51 / Chapter 3.4.3 --- Rainfall Data --- p.52 / Chapter 3.4.4 --- Detection Landuse Changes --- p.53 / Chapter 3.4.4.1 --- Image Preprocessing --- p.54 / Chapter 3.4.4.2 --- Classification and Post-classification Analysis --- p.57 / Chapter 3.4.4.3 --- Assessment of Accuracy --- p.60 / Chapter 3.5 --- Scenario Modeling --- p.61 / Chapter CHAPTER FOUR - --- INTERFACING ARCVIE W GIS WITH WATER QUALITY MODEL / Chapter 4.1 --- Watershed Parameter Generator --- p.64 / Chapter 4.1.1 --- Topographic Analysis and Stream Network Definition --- p.65 / Chapter 4.1.2 --- Vectorization of Basin Geometries --- p.68 / Chapter 4.1.3 --- Computation of Basin Geometric Characteristics --- p.69 / Chapter 4.2 --- Nonpoint Source Pollution Loading Generator --- p.69 / Chapter 4.3 --- Instream Water Quality Calculator --- p.74 / Chapter CHAPTER FIVE- --- LANDUSE AND LAND COVER CHANGES ANALYSIS / Chapter 5.1 --- Framework for Analysis --- p.78 / Chapter 5.2 --- Landuse Changes During the Study Period --- p.82 / Chapter 5.2.1 --- Areal Landuse Changes --- p.82 / Chapter 5.2.2 --- Inter-category Landuse Changes --- p.86 / Chapter 5.2.2.1 --- Rural-to-urban Changes --- p.86 / Chapter 5.2.2.2 --- Rural-to-rural Changes --- p.87 / Chapter 5.2.3 --- Error matrix --- p.88 / Chapter 5.3 --- Spatial Pattern of Landuse and Land cover --- p.91 / Chapter 5.3.1 --- Urban Land --- p.92 / Chapter 5.3.2 --- Rural Areas --- p.94 / Chapter 5.4 --- Scenario Building --- p.96 / Chapter 5.5 --- Limitation of Landuse Classification based on Satellite Image Interpretation --- p.96 / Chapter 5.6 --- Summary --- p.98 / Chapter CHAPTER SIX - --- IMPACTS OF LANDUSE CHANGES ON NONPOINT SOURCE POLLUTION LOADING AND WATER QUALITY / Chapter 6.1 --- Impact of Landuse Changes on NPS Loading --- p.100 / Chapter 6.1.1 --- Identification of Curve Number --- p.100 / Chapter 6.1.2 --- Runoff and Areal Nonpoint Source Pollution Loadings --- p.101 / Chapter 6.1.3 --- Sensitivity of NPS Pollution Loading to Landuse Changes --- p.107 / Chapter 6.2 --- Instream Water Quality Analysis --- p.110 / Chapter 6.2.1 --- Downstream Variation of Water Quality --- p.111 / Chapter 6.2.2 --- Comparison with NWQC II --- p.114 / Chapter 6.3 --- Strategic Landuse Management --- p.117 / Chapter 6.4 --- Limitation of the Study --- p.118 / Chapter CHAPTER SEVEN - --- CONCLUSION / Chapter 7.1 --- Summary of Findings --- p.122 / Chapter 7.1.1 --- Landuse and Land Cover Changes --- p.122 / Chapter 7.1.2 --- GIS-based Water Quality Modeling --- p.123 / Chapter 7.1.3 --- Pollution Loading and Instream Water Quality --- p.124 / Chapter 7.2 --- Future Study --- p.125 / REFERENCES --- p.127

The environmental impact of agricultural activities on water quality was studied on two sub-watersheds of the L'Assomption river in Quebec, over a 3 year period. The sub-watersheds studied were the Saint Esprit (26.1 km 2) and Desrochers (17.9 km2). Development of a methodology and associated tools for targeting conservation activities and assessing the potential impacts of conservation practices was one of the study's components. A goal of this research was the development of a tool using NPS modelling capability and GIS tools. The ANSWERS 2000 model and SPANS GIS software were selected for integration. / Using the advanced SPANS operation and EASI script language, the ANSWERS 2000 model was integrated into the latest version of SPANS GIS (Explorer ver. 7). Integration of these two software packages provided assistance in creating and handling the extensive input and output data for models, evaluating of model output, and delineating of critical areas. A sensitivity analysis of the ANSWERS model was performed on thirteen parameters to determine their effects on runoff ANSWERS 2000 was found to be most sensitive to depth of soil horizon, silt and clay contents of soil texture, and solar radiation. Four years of runoff predictions by the model were analysed using observed data. Overall, the model was in good agreement with observed runoff in the Saint Esprit watershed, particularly in the years with above the average precipitation. The coefficient of (CP'A) between predicted and observed runoff values was 0.5 and 1.5 for 1994 and 1995, respectively. The model predictions of total cumulative runoff were 66.6% in 1994, 54.9% in 1995, 71.7% in 1996, and 42.4% in 1997, of measured cumulative runoff values.

A study was conducted to assess the efficiency of a constructed wetland for sediment and nutrient removal from a riverine source containing non-point source pollution (NPS) in a Nordic climate. The constructed wetland, built near the town of Mystic, Southern Quebec, consists of a sedimentation basin, a sinuous subsurface horizontal flow section and an open water body or pond that continuously receives up to 5% of Walbridge Creek. Flow into and through the system is controlled by gravity. There is a gate on the intake structure, which allows inflow into the wetland to be adjusted, along with three composite weirs; located at the outlet of each section of the wetland. Water samples were analyzed for orthophosphates (PO4), dissolved phosphorus (DP), total phosphorus (TP), ammonium (NH4+) and nitrates (NO3-) The study occurred from May to December 2003 and from May to December 2004. In 2003, there was a 33.6% reduction in TP load from intake to outlet with a retention rate of 2.23 g m-2 year-1. The greatest reduction in TP load during 2003 took place during the summer months (32.2%). In 2004, there was a further reduction of 42.8% in TP load from intake to outlet with a retention rate of 1.56 g m-2 year-1 compared to 2003. The largest reduction in TP load during the operational year of 2004 took place during the summer months (43.7%). Within the wetland, both the submerged flow section and open water basin showed similar and significant reductions of TP load in 2003 and 2004 annually and seasonally. Both annually and seasonally in 2003, NO3- showed no significant decrease in load from intake to outlet or within portions of the wetland. In 2004, there was a 22% annual load reduction from intake to outlet with a retention rate of 43.9 g m-2 year-1. The largest reduction in NO3- load during 2004 took place during the summer months (25.6%). Within the wetland, the submerged flow section showed the greatest reduction in NO3- concentrations annually and during the summer months of 2004. These results confirm the range of treatment efficiencies that can be achieved using a constructed wetland for NPS pollution in a Nordic climate.

The purpose of this study was to determine how much phosphorus could be lost from soils in Quebec. Samples of four soil series and 3 sediment samples from the St. Esprit watershed, Quebec, Canada were treated with KH2PO 4 solutions of 0, 50,100, and 500 mg kg--1 of soil. The relationship between water-extractable phosphorus (soluble phosphorus) and Mehlich III available phosphorus was determined at water: soil ratios 100:1, 200:1, 500:1. Measurements were made on a LACHAT QuickChem AE instrument (based on EPA method 365.3; USEPA, 1983) after 4 hours of shaking. More than 90% of the soluble phosphorus was released after 3 hours of shaking for all the soil samples and the sediment sample. Therefore, the shaking time for release of soluble P was set at 4 hours for all soil groups of the watershed. Mehlich III extractable phosphorus was also determined for each soil and sediment sample. Using a modified form of a well-known equation, it was possible to show that, with appropriate values for the constants, linear relationships exist between the logarithm of soluble phosphorus and the logarithm of Mehlich III extractable phosphorus at different water soil ratios. This was true for all soil groups and the sediment sample. Thus, given the soil type of a particular watershed, and using the linear relationship (isotherm) for that type, it becomes possible to predict the phosphorus yields from agricultural lands with reasonable confidence.

Stream samples were tested at 18 sites in three subwatersheds of the Upper White River for ammonia, nitrate, orthophosphate, atrazine, and diazinon. Nutrient results were tested with a general linear model and in linear regressions with selected landuse characteristics. A critical areas index for surface runoff of pollutants was created using a geographic information system. Comparisons were made between results obtained by Ball State University and by the Muncie Bureau of Water Quality and other outside laboratories. Most mean concentrations of nutrients were likely related to combinations of agricultural and residential landuse factors. Only concentrations of ammonia and orthophosphate were significantly related (a = 0.05) to any landuse characteristics. Atrazine levels were high in the spring, but decreased in the fall. Results suggest that improved or increased best management practices should be implemented in these subwatersheds to control non-point source pollution of the streams. / Department of Natural Resources and Environmental Management