Full Issue - Volume 9, Issue 1

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Support for Integrated Ecosystem Assessments of NOAA’s National Estuarine Research Reserves System (NERRS), Volume I: The Impacts of Coastal Development on the Ecology and Human Well-being of Tidal Creek Ecosystems of the US Southeast

A study was conducted, in association with the Sapelo Island and North Carolina National Estuarine Research Reserves (NERRs), to evaluate the impacts of coastal development on sentinel habitats (e.g., tidal creek ecosystems), including potential impacts to human health and well-being. Uplands associated with southeastern tidal creeks and the salt marshes they drain are popular locations for building homes, resorts, and recreational facilities because of the high quality of life and mild climate associated with these environments. Tidal creeks form part of the estuarine ecosystem characterized by high biological productivity, great ecological value, complex environmental gradients, and numerous interconnected processes. This research combined a watershed-level study integrating ecological, public health and human dimension attributes with watershed-level land use data. The approach used for this research was based upon a comparative watershed and ecosystem approach that sampled tidal creek networks draining developed watersheds (e.g., suburban, urban, and industrial) as well as undeveloped sites. The primary objective of this work was to clearly define the relationships between coastal development with its concomitant land use changes and non-point source pollution loading and the ecological and human health and well-being status of tidal creek ecosystems. Nineteen tidal creek systems, located along the southeastern United States coast from southern North Carolina to southern Georgia, were sampled during summer (June-August), 2005 and 2006. Within each system, creeks were divided into two primary segments based upon tidal zoning: intertidal (i.e., shallow, narrow headwater sections) and subtidal (i.e., deeper and wider sections), and watersheds were delineated for each segment. In total, we report findings on 24 intertidal and 19 subtidal creeks. Indicators sampled throughout each creek included water quality (e.g., dissolved oxygen concentration, salinity, nutrients, chlorophyll-a levels), sediment quality (e.g., characteristics, contaminants levels including emerging contaminants), pathogen and viral indicators, and abundance and genetic responses of biological resources (e.g., macrobenthic and nektonic communities, shellfish tissue contaminants, oyster microarray responses). For many indicators, the intertidally-dominated or headwater portions of tidal creeks were found to respond differently than the subtidally-dominated or larger and deeper portions of tidal creeks. Study results indicate that the integrity and productivity of headwater tidal creeks were impaired by land use changes and associated non-point source pollution, suggesting these habitats are valuable early warning sentinels of ensuing ecological impacts and potential public health threats. For these headwater creeks, this research has assisted the validation of a previously developed conceptual model for the southeastern US region. This conceptual model identified adverse changes that generally occurred in the physical and chemical environment (e.g., water quality indicators such as indicator bacteria for sewage pollution or sediment chemical contamination) when impervious cover levels in the watershed reach 10-20%. Ecological characteristics responded and were generally impaired when impervious cover levels exceed 20-30%. Estimates of impervious cover levels defining where human uses are impaired are currently being determined, but it appears that shellfish bed closures and the flooding vulnerability of headwater regions become a concern when impervious cover values exceed 10-30%. This information can be used to forecast the impacts of changing land use patterns on tidal creek environmental quality as well as associated human health and well-being. In addition, this study applied tools and technologies that are adaptable, transferable, and repeatable among the high quality NERRS sites as comparable reference entities to other nearby developed coastal watersheds. The findings herein will be of value in addressing local, regional and national needs for understanding multiple stressor (anthropogenic and human impacts) effects upon estuarine ecosystems and response trends in ecosystem condition with changing coastal impacts (i.e., development, climate change). (PDF contaions 88 pages

Evaluating the Impact of Land Use Changes, Drivers of TMDL Development, and Green Infrastructure on Stream Impairments

Despite the water quality improvements and regulatory advancements over the last 50 years since the enactment of the Clean Water Act, water bodies within the United States are still impaired for a broad range of contaminants from non-point source pollution. Improving watershed management approaches to meet this challenge will require a greater understanding of (1) how changes within a watershed, such as changing land use, impact stream water quality, (2) what influence socioeconomic, spatial and political factors may have on the progress towards meeting water quality goals, such as those set within Total Maximum Daily Loads (TMDLs), and (3) how specific best management practices can be designed to address water body impairments. First, land use within a watershed is known to have a direct impact on downstream water quality; however, temporal dynamics of these relationships are ill-defined. This is an important gap as management approaches are largely compartmentalized among land use types. Additionally, while management plans can span several decades, the impact of land use changes on water quality is often overlooked. Therefore, this dissertation evaluates land-use changes and their relationship to discharge and water quality trends at stream gages across the U.S. Second, the TMDL program is the primary regulatory lever in the U.S. for addressing non-point source pollution, but its implementation has been uneven across states. This could be due to the diverse socioeconomic, spatial, and political factors of each state. This dissertation therefore seeks to define the influence of these factors on indicators of TMDL progress. Finally, at the site level, management actions to meet regulatory permits include the use of green stormwater infrastructure to capture, treat, and infiltrate runoff at the source. One of the largest sources of impairments in the TMDL program is temperature; however, it is unclear the degree to which green stormwater infrastructure in series mitigates runoff temperatures during summer storms. To address this gap, this dissertation analyzes the temperature mitigation potential of interconnected green infrastructure practices through field observations. Altogether, the outcomes of this dissertation help to advance our understanding of how watershed planning, regulatory, and engineering actions affect downstream water quality

Surface Hydrologic Modeling and Analyzing Watershed Hydrologic Response to Landcover Change

Urban flooding is the most frequently occurring disaster in rapidly urbanizing cities. Rapid urbanization in general, is characterized by an increase in the total impervious surface area, which means less soil cover for the stormwater to infiltrate and a greater volume of runoff from the area in case of a storm event. This increased volume of surface runoff, if not drained, results in urban flooding. Urban flooding can cause serious economic and environmental damages by disrupting transportation and spreading pollution. It is therefore, essential to understand the cause, behavior and effects of urban flooding so as to minimize the risks and costs associated with urban floods. Hydrologic models are useful tools for understanding hydrologic processes and for designing urban stormwater drainage infrastructure to reduce the risks of floodings. This research aims to study urban hydrology by estimating surface runoff from an urban area using an event based distributed parameter hydrologic model. In this research, an event-based distributed parameter hydrologic model is developed, which uses Green-Ampt infiltration model to estimate the surface runoff from a given catchment. The developed model is tested on two small catchments. The ‘rainfall-runoff modeling’ part of the developed model is calibrated for the rainfall events of May 22, 2017 and, May 24, 2017 over the Moores Run study area, and, validated for the rainfall event of April 17, 2017. The ‘flood-modeling’ part of the developed model is validated for the rainfall event of Sep 11, 2012 over the Parking-lots area at UNLV. The results of the rainfall-runoff simulation and flood depth and extent estimation for different land-cover change scenarios over the Parking-lots catchment is also provided. The testing on Moores Run study area resulted in calibration at 30-m resolution DEM and a hydraulic conductivity value of 0.19 cm/hr. for soil group D. The error in the model’s estimation of the catchment area is 7.75%. The model over-predicted the runoff volume from the catchment for the first rainfall event while under-predicted the runoff volume from the catchment for the second rainfall event. The average error in estimation of the runoff volume is 1.8%. The model also over-predicts the ‘time-to-peak’ and under-predicts ‘peak runoff’ in both cases. The average of RMSE between the predicted hydrograph and actual hydrograph for the two rainfall events is 0.0071 m3/s in calibration, and, 0.011 m3/s in validation. The testing on UNLV Parking-lots area resulted in calibration at 10-m resolution DEM. For the rainfall event of Sep 11, 2012, the model predicts over predicts the peak flood depth and under-predicts the maximum extent of flooding. The error in flood depth estimation is found be 12.9%. From watershed hydrologic response to landcover change analysis, it is observed that Manning’s roughness coefficient doesn’t affect the total volume of runoff, however, the time to peak is significantly delayed for landcover with higher values of Manning’s roughness co-efficient. This research provides an insight into surface hydrologic modeling. It also provides an overview of calibration against DEM resolution and hydraulic conductivity values. Finally, it provides an understanding of watershed hydrologic response to different landcovers with various Manning’s roughness values

SYSTEM DYNAMICS MODELING AS A QUANTITATIVE-QUALITATIVE FRAMEWORK FOR SUSTAINABLE WATER RESOURCES MANAGEMENT: INSIGHTS FOR WATER QUALITY POLICY IN THE GREAT LAKES REGION

Early water resources modeling efforts were aimed mostly at representing hydrologic processes, but the need for interdisciplinary studies has led to increasing complexity and integration of environmental, social, and economic functions. The gradual shift from merely employing engineering-based simulation models to applying more holistic frameworks is an indicator of promising changes in the traditional paradigm for the application of water resources models, supporting more sustainable management decisions. This dissertation contributes to application of a quantitative-qualitative framework for sustainable water resources management using system dynamics simulation, as well as environmental systems analysis techniques to provide insights for water quality management in the Great Lakes basin. The traditional linear thinking paradigm lacks the mental and organizational framework for sustainable development trajectories, and may lead to quick-fix solutions that fail to address key drivers of water resources problems. To facilitate holistic analysis of water resources systems, systems thinking seeks to understand interactions among the subsystems. System dynamics provides a suitable framework for operationalizing systems thinking and its application to water resources problems by offering useful qualitative tools such as causal loop diagrams (CLD), stock-and-flow diagrams (SFD), and system archetypes. The approach provides a high-level quantitative-qualitative modeling framework for big-picture understanding of water resources systems, stakeholder participation, policy analysis, and strategic decision making. While quantitative modeling using extensive computer simulations and optimization is still very important and needed for policy screening, qualitative system dynamics models can improve understanding of general trends and the root causes of problems, and thus promote sustainable water resources decision making. Within the system dynamics framework, a growth and underinvestment (G&U) system archetype governing Lake Allegan\u27s eutrophication problem was hypothesized to explain the system\u27s problematic behavior and identify policy leverage points for mitigation. A system dynamics simulation model was developed to characterize the lake\u27s recovery from its hypereutrophic state and assess a number of proposed total maximum daily load (TMDL) reduction policies, including phosphorus load reductions from point sources (PS) and non-point sources (NPS). It was shown that, for a TMDL plan to be effective, it should be considered a component of a continuous sustainability process, which considers the functionality of dynamic feedback relationships between socio-economic growth, land use change, and environmental conditions. Furthermore, a high-level simulation-optimization framework was developed to guide watershed scale BMP implementation in the Kalamazoo watershed. Agricultural BMPs should be given priority in the watershed in order to facilitate cost-efficient attainment of the Lake Allegan\u27s TP concentration target. However, without adequate support policies, agricultural BMP implementation may adversely affect the agricultural producers. Results from a case study of the Maumee River basin show that coordinated BMP implementation across upstream and downstream watersheds can significantly improve cost efficiency of TP load abatement

Modelling the impacts of land-used and climate change in Skudai river watershed

Predicting the impact of land-use, climate change and Best Management Practices (BMPs) on a watershed is imperative for effective management of aquatic ecosystems, floods, pollutant control and maintenance of water quality standard in a tropical climate. Based on the prediction, unique information can be derived that is critical to the watershed management under dynamic environmental conditions. The study seeks to evaluate how land-use and climate change influences the hydrology, sediments, and water quality of an urbanized tropical watershed in which the land-use is controlled by urban development as observed from historical and projected land covers. Therefore, the response of a tropica l watershed and its river system under climate and land-use changes were evaluated using Skudai River watershed as a case study. Seven land-use scenarios from the year 1989 to 2039 were developed using remote sensing teclmiques, and nine projected climate change scenarios were derived using dynamically downscaled model from the based projection under representative concentration pathways (RCPs) scenarios. These scenarios were integrated into the Hydrological Simulation Program FORTRAN (HSPF) model to determine the impact of land-use , climate change, and pollutants control via best management practices in a tropical watershed system. The model was calibrated and validated from 2002 to 2014, and the performance coefficients showed a good correlation between simulated and observed streamflow, water temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD), ammonia nitrogen (NH3-N), nitrate nitrogen (N03-N), and orthophosphate (P04) concentrations. The output of the validated model under land-use changes showed that the hydrological water balance of the watershed changes with total runoff as the primary source of water loss. For streamflows and in-stream concentrations (NH3-N, N03-N, and P04) , as the streamflow increases, NH3-N and P04 concentrations increase while N03-N concentration showed low response as compared to the other two concentrations. As urban development increased from 18.2% to 49.2%, nutrient influx such as total nitrogen (TN) and total phosphorus (TP) loads increased from 3080 to 4560 kg/yr and from 130 to 270 kg/yr, respectively. Furthermore, TN to TP ratio changed from 8.3:1 to 7:1, an indication that the rivers are receiving excess nutrients flows which might result in eutrophication at the downstream of the watershed . The amount of sediment load produced in the watershed decreased by approximately 17.8% as a result of the changes in land-use derived from urban development. Further analysis ofthe results showed that climate change with high rainfall and increase in air temperature do not affect DO concentration and water temperature in comparison to climate change with low rainfall. Implementation of multiple detention pond BMPs in identified Critical Source Areas (CSAs) reduced pollutant loads by 14% to 27% as compared to watershed without any BMPS, independent ofclimate and landuse changes. Analysis ofBMPs using existing and future land-use is very important to ensure their effectiveness to control and maintain water quality. This study provides a basis to develop water resource management in an urban watershed and be resilient to land-use and climate changes

Land Use Change from Non-urban to Urban Areas

This reprint is related to land-use change and non-urban and urban relationships at all spatiotemporal scales and also focuses on land-use planning and regulatory strategies for a sustainable future. Spatiotemporal dynamics, socioeconomic implication, water supply problems and deforestation land degradation (e.g., increase of imperviousness surfaces) produced by urban expansion and their resource requirements are of particular interest. The Guest Editors expect that this reprint will contribute to sustainable development in non-urban and urban areas