Modeling the Impact of Land Cover Change on Non-point Source Nitrogen Inputs to Streams at a Watershed Level PDF Download
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Author: Diana Mitsova-Boneva
Publisher:
ISBN:
Category :
Languages : en
Pages : 262
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Book Description
The objective of this research is to assess the impact of future land cover changes on nutrient enrichment of streams. It applies cellular automata (CA) Markov chain model to simulate future land cover change and a GIS-based distributed cell-based model to predict non-point source nitrogen loadings to streams. The integration of the two models provides site-specific information on how the spatial location and extent of urban development can affect nitrogen pollution under dry, normal and wet conditions. Two scenarios of land cover change, in particular, were examined. The baseline scenario (Scenario 1) involved only minor protection of environmentally sensitive areas. The open space conservation network scenario (Scenario 2) incorporated the principles of "green" infrastructure as outlined by the relevant literature. Scenario 2 was based on protection of riparian areas, floodplains, wetlands, urban open space, and areas with exceedingly shallow depth to seasonally high water table and bedrock. Increased setbacks, where appropriate, were considered. The impact of the projected land cover change under different development scenarios was then examined in terms of nitrogen delivery ratios, total loads and contributing areas. A spatial hydrological model of the watershed was developed under dry, normal and wet conditions. A non-linear regression model was applied to estimate nitrogen trapping efficiencies and delivery ratios based on field characteristics such as slope, saturated hydraulic conductivity, soil mean particle diameter, Manning's roughness coefficient and length of flow. An attenuation factor taking into account cost distance to streams and decay constant was also incorporated into the model to account for transmission losses. Contributing areas of nitrogen delivery to streams were delineated based on the model results.
Author: Diana Mitsova-Boneva
Publisher:
ISBN:
Category :
Languages : en
Pages : 262
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Book Description
The objective of this research is to assess the impact of future land cover changes on nutrient enrichment of streams. It applies cellular automata (CA) Markov chain model to simulate future land cover change and a GIS-based distributed cell-based model to predict non-point source nitrogen loadings to streams. The integration of the two models provides site-specific information on how the spatial location and extent of urban development can affect nitrogen pollution under dry, normal and wet conditions. Two scenarios of land cover change, in particular, were examined. The baseline scenario (Scenario 1) involved only minor protection of environmentally sensitive areas. The open space conservation network scenario (Scenario 2) incorporated the principles of "green" infrastructure as outlined by the relevant literature. Scenario 2 was based on protection of riparian areas, floodplains, wetlands, urban open space, and areas with exceedingly shallow depth to seasonally high water table and bedrock. Increased setbacks, where appropriate, were considered. The impact of the projected land cover change under different development scenarios was then examined in terms of nitrogen delivery ratios, total loads and contributing areas. A spatial hydrological model of the watershed was developed under dry, normal and wet conditions. A non-linear regression model was applied to estimate nitrogen trapping efficiencies and delivery ratios based on field characteristics such as slope, saturated hydraulic conductivity, soil mean particle diameter, Manning's roughness coefficient and length of flow. An attenuation factor taking into account cost distance to streams and decay constant was also incorporated into the model to account for transmission losses. Contributing areas of nitrogen delivery to streams were delineated based on the model results.
Author: Larry J. Puckett
Publisher:
ISBN:
Category : Nonpoint source pollution
Languages : en
Pages : 18
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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309172683
Category : Nature
Languages : en
Pages : 569
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Book Description
In 1997, New York City adopted a mammoth watershed agreement to protect its drinking water and avoid filtration of its large upstate surface water supply. Shortly thereafter, the NRC began an analysis of the agreement's scientific validity. The resulting book finds New York City's watershed agreement to be a good template for proactive watershed management that, if properly implemented, will maintain high water quality. However, it cautions that the agreement is not a guarantee of permanent filtration avoidance because of changing regulations, uncertainties regarding pollution sources, advances in treatment technologies, and natural variations in watershed conditions. The book recommends that New York City place its highest priority on pathogenic microorganisms in the watershed and direct its resources toward improving methods for detecting pathogens, understanding pathogen transport and fate, and demonstrating that best management practices will remove pathogens. Other recommendations, which are broadly applicable to surface water supplies across the country, target buffer zones, stormwater management, water quality monitoring, and effluent trading.
Author: Sa'D Abdel-Halim Sa'd-Eddin Shannak
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Urban growth contributes to increasing storm water runoff which in turn causes an increase in the frequency and severity of flooding. Moreover, increased storm water runoff contributes to changing the character and volume of energy inputs to the stream. Traditionally, storm water management controls such as detention pond had been extensively studied and evaluated with respect to reducing and controlling peak flows. Nonpoint source pollutants due to urbanization and expanding of agricultural fields have become a big burden on municipalities and states. Low Impact Development practices were developed to negate the negative impacts of urbanization on water resources by reducing the runoff volume and peak flows as well as improving outflow water quality. Though these practices have the capability of reducing runoff volumes and enhancing outflow water quality, they can be costly. Therefore, understanding the impact of installing LID practices on a watershed scale is becoming increasingly important. In this study, field experiment and model study were applied to evaluate the effectiveness of LID practices on a watershed scale in the Blunn Creek Watershed located in Austin, Texas. The three LID practices which were evaluated in this study are permeable pavements, a bioretention area, and a detention pond. The main objective of this study was to investigate the influences of these practices at a watershed scale on: potential reduction on channel bank erosion, potential reduction on flood, and potential impact on aquatic life. This study was one of very few studies that take place in the Blackland clay soil in Texas. A combination of different levels of LID practices such as permeable pavement and bioretention area resulted with achieving the main goal of this study of reducing stream bank erosion, bankfull exceedance, and maintaining acceptable flows for the integrity of aquatic life habitat. All LID practices have shown significant difference with respect to a control treatment at 95% confidence ratio. Performance of the modeled LID practices was validated by showing acceptable agreement in the percentage of reductions in total runoff between field experiments and model data. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152758
Author:
Publisher:
ISBN:
Category : Eutrophication
Languages : en
Pages : 228
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Author: Lev S. Kuchment
Publisher: EOLSS Publications
ISBN: 184826187X
Category :
Languages : en
Pages : 332
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Book Description
Hydrological Systems Modeling is a component of Encyclopedia of Water Sciences, Engineering and Technology Resources in the global Encyclopedia of Life Support Systems (EOLSS), which is an integrated compendium of twenty one Encyclopedias. This 2-volume set contains several chapters, each of size 5000-30000 words, with perspectives, applications and extensive illustrations. It carries state-of-the-art knowledge in the fields of Hydrological Systems Modeling and is aimed, by virtue of the several applications, at the following five major target audiences: University and College Students, Educators, Professional Practitioners, Research Personnel and Policy Analysts, Managers, and Decision Makers and NGOs.
Author: Theodore R. McDowell
Publisher:
ISBN:
Category : Eutrophication
Languages : en
Pages : 31
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Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309679702
Category : Science
Languages : en
Pages : 423
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Book Description
New York City's municipal water supply system provides about 1 billion gallons of drinking water a day to over 8.5 million people in New York City and about 1 million people living in nearby Westchester, Putnam, Ulster, and Orange counties. The combined water supply system includes 19 reservoirs and three controlled lakes with a total storage capacity of approximately 580 billion gallons. The city's Watershed Protection Program is intended to maintain and enhance the high quality of these surface water sources. Review of the New York City Watershed Protection Program assesses the efficacy and future of New York City's watershed management activities. The report identifies program areas that may require future change or action, including continued efforts to address turbidity and responding to changes in reservoir water quality as a result of climate change.
Author: Shanna Williamson
Publisher:
ISBN:
Category : Estuarine ecology
Languages : en
Pages : 76
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Book Description
Freshwater inflow influences numerous physical, chemical, and biological characteristics of estuaries. The influx of freshwater to an estuary typically serves as an important source of allochthonous material from which primary producers derive their energy and transfer this energy to higher trophic levels. Any changes to freshwater flow subsequently impacts nutrient delivery and indirectly impacts organisms across multiple trophic levels. Anthropogenic changes to coastal land use and climate both act to threaten the integrity of estuarine systems by influencing freshwater inflow and dissolved nutrient input. Watershed loading models such as the Regional Nutrient Management (ReNuMa) model offer the ability to estimate freshwater inputs and dissolved nutrient loads to estuaries under current and future conditions. This tracking is important because it allows scientists to better understand how watershed delivery is currently impacted by anthropogenic activities and natural environmental variability, which allows for a better understanding of how watershed delivery is likely to be affected by anthropogenic changes in land use and climate. This research aims to assess how changes in climate and coastal land cover will impact streamflow and loads of total dissolved nitrogen (TDN) and total dissolved phosphorus (TDP) to the New River Estuary (NRE), NC. We applied the ReNuMa model to the NRE watershed to estimate streamflow, TDN, and TDP loads. We used in situ data to calibrate (2009-2011) and validate (2012-2014) modeled streamflow and dissolved nutrient loads within 10 subwatersheds located on Marine Corps Base Camp Lejeune (MCBCL), which surrounds the estuary, and one subwatershed in the off-base portion of the NRE watershed. Following model calibration and validation, model parameters were scaled up from these subwatersheds to estimate loads from the entire NRE watershed. Model results confirm the ability of ReNuMa to capture seasonal variability in streamflow, TDN, and TDP for >50% of the subwatersheds. Under current conditions, most (71-98%) streamflow and dissolved nutrient loads are sourced from the off-base portion of the NRE watershed, while a smaller percentage of loads (2-29%) are sourced from MCBCL. Projected changes in climate revealed that changes in precipitation, even when compounded with changes in temperature, will have the greatest impact on resulting streamflow, TDN, and TDP. Streamflow and dissolved nutrient loads generally increased under anticipated climate projections through the year 2100 and such increases were further amplified under hypothetical increases in land use, especially agricultural land. Watershed delivery patterns for the NRE may therefore be substantially altered under projected changes in climate and land use. The potential impacts of changes in these loads on estuarine physical, chemical, and biological processes highlights the necessity for research assessing the impacts of land use and climate changes on watershed delivery.
Author: Awoke Dagnew Teshager
Publisher:
ISBN:
Category : Agricultural ecology
Languages : en
Pages : 246
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Book Description
Applications of the SWAT model typically involve delineation of a watershed into subwatersheds/subbasins that are then further subdivided into hydrologic response units (HRUs) which are homogeneous areas of aggregated soil, landuse, and slope and are the smallest modeling units used within the tool. In a standard SWAT application, multiple potential HRUs (farm fields) in a subbasin are usually aggregated into a single HRU feature. In other words, the standard version of the model combines multiple potential HRUs (farm fields) with the same landuse/landcover (LULC), soil, and slope, but located in different places within a subbasin (spatially non-unique), and considers them as one HRU. In this study, ArcGIS pre-processing procedures were developed to spatially define a one-to-one match between farm fields and HRUs (spatially unique HRUs) within a subbasin prior to SWAT simulations to facilitate input processing, input/output mapping, and further analysis at the individual farm field level. Model input data such as LULC, soil, crop rotation and other management data were processed through these HRUs. The SWAT model was then calibrated/validated for the Raccoon River watershed in Iowa for 2002 to 2010 and the Big Creek River watershed in Illinois for 2000 to 2003. SWAT was able to replicate annual, monthly and daily streamflow, as well as sediment, nitrate and mineral phosphorous within recommended accuracy in most cases. The one-to-one match between farm fields and HRUs created and used in this study is a first step in performing LULC change, climate change impact, and other analyses in a more spatially explicit manner. The calibrated and validated SWAT model was then used to assess agricultural scenario and climate change impacts on watershed water quantity, quality, and crop yields. Modeling impacts of agricultural scenarios and climate change on surface water quantity and quality provides useful information for planning effective water, environmental, and land use policies. Despite the significant impacts of agriculture on water quantity and quality, limited literature exists modeling the combined impacts of agricultural scenarios and climate change on crop yields and watershed hydrology. Here, SWAT, was used to model the combined impacts of five agricultural scenarios and three climate scenarios downscaled using eight climate models. These scenarios were implemented in a well calibrated SWAT model for the Raccoon River watershed (RRW), IA. We run the scenarios for the historical baseline, early-century, mid-century, and late-century periods. Results indicate that historical and more corn intensive agricultural scenarios with higher CO2 emissions consistently result in more water in the streams and greater water quality problems, especially late in the 21st century. Planting more switchgrass, on the other hand, results in less water in the streams and water quality improvements relative to the baseline. For all given agricultural landscapes simulated, all flow, sediment and nutrient outputs increase from early-to-late century periods for the RCP4.5 and RCP8.5 climate scenarios. We also find that corn and switchgrass yields are negatively impacted under RCP4.5 and RCP8.5 scenarios in the mid and late 21st century. Finally, various agricultural best management practice (BMP) scenarios were evaluated for their efficiency in alleviating watershed water quality problems. The vast majority of the literature on efficiency assessment of BMPs in alleviating water quality problems base their scenarios analysis on identifying subbasin level simulation results. In the this study, we used spatially explicit HRUs, defined using ArcGIS-based pre-processing methodology, to identify Nitrate (NO3) and Total Suspended Solids (TSS) hotspots at the HRU/field level, and evaluate the efficiency of selected BMPs in a large watershed, RRW, using the SWAT model. Accordingly, analysis of fourteen management scenarios were performed based on systematic combinations of five agricultural BMPs (fertilizer/manure management, changing cropland to perennial grass, vegetative filter strips, cover crops and shallower tile drainage systems) aimed to reduce NO3 and TSS yields from targeted hotspot areas in the watershed at field level. Moreover, implications of climate change on management practices, and impacts of management practices on water availability and crop yield and total production were assessed. Results indicated that either implementation of multiple BMPs or conversion of an extensive area into perennial grass may be required to sufficiently reduce nitrate loads to meet the drinking water standard. Moreover, climate change may undermine the effectiveness of management practices, especially late in the 21 st century. The targeted approach used in this study resulted in slight decreases in watershed average crop yields, hence the reduction in total crop production is mainly due to conversion of croplands to perennial grass.
