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Synopsis: This article outlines how wetlands can significantly reduce flooding in the Upper Mississippi watershed. The authors first provide a historical context by estimating the original and lost wetland storage capacities of the Upper Mississippi and Missouri River Basins. Historically, about 10% of the basin would have been classified as wetland in 1780. By 1980, wetland acreage had been reduced to only 4% of the basin, representing about 26 million acres of wetlands eliminated since 1780. The area of wetland restoration required to reduce the risk of future flooding adequately was estimated based on the total amount of excess floodwater beyond bank-full discharge that passed through the City of St. Louis during...
Conclusions:Wetland extent, proximity of wetlands to the sampling station, and the position of a wetland in a watershed (downstream wetlands have greater influence on water quality) influence water quality.Thresholds/Learnings:
Conclusions:Variability in buffer width across a landscape has important effects on landscape discharge. A variable- width buffer retains less material than a uniform-width buffer of equivalent average width.Thresholds/Learnings:
Conclusions:Study found statistically significant relationships among source water quality, percent land cover, and drinking water treatment cost. Increased percent agriculture and urban cover were significantly related to decreased water quality, while decreased forest land cover was significantly related to decreased water quality. High percent land cover by non-forest vegetation was significantly related to low treatment cost.Thresholds/Learnings:
Conclusions:Report synthesizes scientific, planning, and policy-related aspects on the importance of land conservation in areas producing water for potable uses, including watersheds and aquifers. One critical finding indicated that if there is more forest cover in a watershed, water treatment costs are lower.Thresholds/Learnings:For every 10% increase in forest cover in the source area, treatment and chemical costs decreased by about 20%, up to about 60% forest cover. Treatment costs level off when forest cover is between 70-100%.
Conclusions:Wetlands and riparian zones should be strategically placed in watersheds to optimize nitrogen removal, as, for example, in tile-drained farmlands prone to high concentrations of nitrateThresholds/Learnings:Restoring 10 million hectares of riparian zones and wetlands, representing 3.4% of the Mississippi River basin, would reduce nitrogen in the Mississippi River Basin and its tributaries by an average of 40%
Conclusions:Report presents draft outcomes, indicators, and targets for the Red Deer River Basin in three topic areas: wetlands, riparian areas, and land use. Targets established were based on a detailed literature review, combined with Geographic Information Systems (GIS) queries of existing conditions.Thresholds/Learnings:Specific thresholds for the region include: wetland cover should comprise >7.5% of the watershed; peatland cover should comprise > 6.0% in the upper headwaters; 82% of all riparian areas (variable width) in the watershed should have perennial vegetation cover; 97% of all riparian areas (variable width) in the Upper Headwaters should have perennial vegetation cover
Conclusions:Water chemistry parameters sampled in downstream reaches were most closely correlated with riparian land cover adjacent to the smallest (first-order) streams of watersheds or land use in the entire watershed, with riparian zones immediately upstream of sampling sites offering less explanatory power as stream size increased.Thresholds/Learnings:
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Conclusions: Elevation, slope and the percentages of bogs and fens in a landscape influence the degree to which mid-boreal lakes are sensitive to acidic deposition orignating from nearby mining operations. Thresholds/Learnings: Synopsis: This study evaluates the acid sensitivity of lakes in Saskatchewan within ~300km of Fort McMurray. The study area is downwind of atmospheric emissions sources from regional oil sands mining operations and there is concern that the lakes may be threatened by acidification. A helicopter sampling program was implemented in late September 2007 and 2008 to measure 16 chemical variables (e.g., Ca, Mg, Na, pH) and 15 environmental variables (e.g., latitude, elevation, slope, percent bog,...
Synopsis: One recent study examining Eurasian watermilfoil (Myriophyllum spicatum L., hereafter milfoil) invasions using landscape-level variables found that the amount of forest land cover in the catchment is consistently negatively related to milfoil presence (Buchan and Padilla, 2000). These results suggest that further research is needed to examine the relationships between natural and anthropogenic landscape features and macrophyte cover. The ability of lake and landscape features to predict a variety of macrophyte cover metrics using 54 north temperate lakes were examined. Univariate regression analyses demonstrated that these macrophyte cover metrics are predicted by a wide range of predictor variables, most...
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Synopsis: The goal of this study was to examine contaminant loadings associated with stormwater runoff from recently burned areas in urban fringe areas of southern California, to derive regional patterns of runoff and contaminant loadings in this context. Postfire stormwater runoff was sampled from five wildfires that each burned between 115 and 658 km2 of natural open space between 2003 and 2009. The area is characterized by classic Mediterranean climate conditions of relatively mild to cool wet winter and warm to hot dry summers. Between two and five storm events were sampled per site over the first one to two years following the fires for basic constituents, metals, nutrients, total suspended solids, and polycyclic...
Conclusions:Report summarizes studies on the impacts of agricultural land use on water quality within Alberta. The impacts of agricultural activities on water quality depend strongly on the amount and distribution of land under cultivation, as well as other measures of agricultural intensity such as fertilizer expenses, chemical expenses and animal unit densities. Generally, streams draining watersheds with more agriculture had higher concentrations of nutrients, bacteria, and pesticides.Thresholds/Learnings:
Conclusions:Report reviews how forests and their management affect the quality and quantity of downstream municipal water supplies in the state of OregonThresholds/Learnings:When >25% of the watershed's forest cover is clearcut in a short period of only a few months, there is a measurable increase in annual streamflows from the watershed.
Conclusions:Within a watershed, about 10% of development is not subject to drainage regulations resulting in cumulative effects from urbanization that significantly degrade watersheds. Instead of regulatory thresholds (e.g. 10% EIA), process controls are required to mitigate the impacts of urbanization on aquatic systems. Without these controls, strict development limits are the only way to limit watershed degradation.Thresholds/Learnings:The study cautions against the use of discrete “thresholds” to predict specific physical and biological effects, but does suggest that thresholds are appropriate indicators for when the perception and tolerance of watershed impacts triggers a regulatory response.
Conclusions:Loss of wetland cover over a 40 year period resulted in increased peak flows, increased sediment, phosphorus and nitrogen flows, and decreased waterfowl populations.Thresholds/Learnings:
Conclusions:Chemical concentrations, turbidity, changes in microclimate, and sediment production were affected to varying degrees by forest harvesting. No significant differences were found between pre-harvest and post-harvest concentrations except for calcium which was 5 times higher and sodium which was 20 times higher in the harvested watersheds. Concentrations declined over the 3 year post-harvest span.Turbidity and suspended sediment increased with road construction but declined rapidly to nearly background levels after 2 years. Air temperature increased after harvesting in all of the smaller watersheds but stream temperature was not affected.Thresholds/Learnings:
Conclusions:Generally, mimimum buffer widths may help maintain natural physical and chemical characteristics of resources whereas greater buffer widths may be required to maintain biological components of many wetlands and streams. Fixed width buffers do not consider site-specific conditions, and therefore may not adequately buffer aquatic resources. Variable width buffers, albeit more site specific and effective, are more expensive and offer less predictability for planning purposes.Thresholds/Learnings:Stream buffers should be a minimum of 15 to 30m in width to be effective in protecting the ecological integrity of wetlands and streams.
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Synopsis: The objective of this study was to examine initial effects of the 2003 Lost Creek wildfire (southwestern Rocky Mountains of Alberta) on concentrations and production (yield and total export) of several nitrogen (N) forms, and to explore initial recovery of these effects within the first 3 years after the fire. During the first postfire year, nitrate (NO3–), dissolved organic nitrogen (DON), and total nitrogen (TN) concentrations in severely burned watershed streams were 6.5, 4.1, and 5.3 times greater, respectively, than those in reference streams. Weaker effects were evident for concentrations of ammonium (NH4+; 1.5 times) and total particulate nitrogen (TPN; 3.0 times). A rapid decline in mean watershed...
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Conclusions: The amount of upstream impervious area affects downstream fish habitat quality, channel stability, and water quality. The use of riparian buffers can reduce the magnitude of urban impacts, however, they cannot fully mitigate the impacts of upstream development in the watershed. Threshold percentages of impervious areas , as well as the percentage of forest cover in a watershed appear to be the most effective indicators of watershed health. Thresholds/Learnings: Impervious areas should be kept at or below 10% of a watershed, and forest cover should be maintained at a minimum of 65% in order to effectively mitigate the impacts of urbanization and development on watersheds. Synopsis: This paper articulates...
Synopsis: Riparian buffers, the vegetated region adjacent to streams and wetlands, are thought to be effective at intercepting and reducing nitrogen loads entering water bodies. Riparian buffer width is thought to be positively related to nitrogen removal effectiveness by influencing nitrogen retention or removal. We surveyed the scientific literature containing data on riparian buffers and nitrogen concentration in streams and groundwater to identify trends between nitrogen removal effectiveness and buffer width, hydrological flow path, and vegetative cover. Nitrogen removal effectiveness varied widely. Wide buffers (.50 m) more consistently removed significant portions of nitrogen entering a riparian zone than...
map background search result map search result map Chemical characteristics and acid sensitivity of boreal headwater lakes in northwest Saskatchewan. Flood reduction through wetand restoration: the Upper Mississippi River Basin as a case history. Urbanization of aquatic systems: degradation thresholds, stormwater detection, and the limits of mitigation. Wildfire Impacts on nitrogen concentration and production from headwater streams in southern Alberta's Rocky Mountains. Stormwater contaminant loading following southern California wildfires Wildfire Impacts on nitrogen concentration and production from headwater streams in southern Alberta's Rocky Mountains. Urbanization of aquatic systems: degradation thresholds, stormwater detection, and the limits of mitigation. Chemical characteristics and acid sensitivity of boreal headwater lakes in northwest Saskatchewan. Stormwater contaminant loading following southern California wildfires Flood reduction through wetand restoration: the Upper Mississippi River Basin as a case history.