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Now showing items 1 - 3 of 3

  • Scale-dependent impacts of urban and agricultural land use on nutrients,sediment,and runoff

    Lacher, Iara L.   Ahmadisharaf, Ebrahim   Fergus, Craig   Akre, Thomas   Mcshea, William J.   Benham, Brian L.   Kline, Karen S.  

    We coupled a spatially-explicit land use/land cover (LULC) change model, Dinamica EGO, (Environment for Geoprocessing Objects), with the Chesapeake Bay Watershed Model (CBWM) to project the impact of future LULC change on loading of total nitrogen (TN), total phosphorous (TP) and total suspended solids (TSS) as well as runoff volume in the watersheds surrounding Virginia's Shenandoah National Park in the eastern United States. We allowed for the dynamic transition of four LULC classes, Developed, Forest, Grasses (including both pasture and hayfields) and Crops. Using 2011 as a baseline scenario and observed differences in LULC between 2001 and 2011, we estimated the temporal and spatial patterns of LULC change as influenced by physiographic and socio-economic drivers 50 years in the future (2061). Between transitions of the four LULC classes, the greatest absolute change occurred between the gain in total Developed land and loss in total Forest. New Developed land was driven primarily by distance to existing Developed land and population density. Major findings on the effect of LULC change on watershed model outputs were that: the impact of LULC change on pollutant loading and runoff volume is more pronounced at finer spatial scales; increases in the area of Grasses produced the greatest increase in TP loading, while loss of Forest increased TN, TSS, and runoff volume the most; and land-river segments with a greater proportion of Developed or a smaller proportion of Forest in the 2011 scenario experienced a greater change in runoff than other land-river segments. Results of this study illustrate the potential impact of projected LULC change on nutrient and sediment loads which can adversely impact water quality. Studies like this contribute to a broader understanding of how ecosystem services such as freshwater respond to LULC change, information relevant to those in planning and watershed management. (C) 2018 Published by Elsevier B.V.
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  • Projecting land use change impacts on nutrients,sediment and runoff in multiple spatial scales:Business-as-usual vs. stakeholder-informed scenarios

    Ahmadisharaf, Ebrahim   Lacher, Iara L.   Fergus, Craig   Benham, Brian L.   Akre, Thomas   Kline, Karen S.  

    While the impact of land use/land cover (LULC) change on watersheds has been extensively studied, little attention has been given to the variability of this impact with respect to the projected LULC scenarios at a range of spatial scales. Here, a spatial LULC change model was coupled with the Chesapeake Bay Watershed Model to investigate LULC change impact on nutrients (nitrogen and phosphorous) and sediment loads and runoff volume in northwestern Virginia, U.S. Using 2011 as the baseline scenario, we examined four stakeholder-informed future (50 years hence) LULC scenarios, which differed in projection of population growth and planning strategy, along with a 'business-as-usual' (BAU) scenario, which projected historical LULC trends into the future. Four LULCs-Developed, Forest, Grasses and Crops-were dynamically transitioned. The difference in projected nutrient and sediment loads and runoff volume between the LULC scenarios was greater at finer spatial scales, where planning decisions are most commonly made. The LULC change scenario with reactive planning and high population growth resulted in the largest increase in runoff volume, while the scenario with reactive planning and low population growth showed the largest increase in modeled nutrient and sediment loads. These results suggested that planning strategy plays a more critical role than population growth in watershed management. (C) 2020 Elsevier Ltd. All rights reserved.
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  • Vaccination contre l\"hépatite B ou lacher la proie pour l\"ombre

    D. Sicard  

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