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Synopsis: This study analyzed the effects of vegetation change on hydrological fluctuations in the Columbia River basin over the last century using two land cover scenarios. The first scenario was a reconstruction of historical land cover vegetation, c. 1900. The second scenario was more recent land cover as estimated from remote sensing data for 1990. The results show that, hydrologically, the most important vegetation-related change has been a general tendency towards decreased vegetation maturity in the forested areas of the basin. This general trend represents a balance between the effects of logging and fire suppression. In those areas where forest maturity has been reduced as a result of logging, wintertime...
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:Document serves as a guide to consistent reporting for Alberta’s State of the Watershed Reports. It outlines a framework for reporting watershed conditions by providing specific criteria and direction to guide consistency in reporting. Framework includes major indicators of watershed health, including section on land cover and pattern indicators which provide critical thresholds for road density impacts to wildlifeThresholds/Learnings:Road density thresholds: grizzly bears- 0.4 km/km2; elk- 0.62 km/km2; black bears- 1.25 km/km2. Road densities for bull trout: 0.0-0.1 km/km2 = low risk; 0.1-0.2 km/km2 = moderate risk; 0.2-0.6 km/km2 = high risk; 0.6-1.0 km/km2 = very high risk; >1.0 km/km2 = extripation....
Conclusions:Presents condition and pressure indicators for land, water quantity, water quality, and aquatic and riparian systems, as a series of categorized indicators of environmental quality. These broadly include: land quality condition indicators, land use pressure indicators, water quantity pressure indicators, water quality pressure indicators, and indicators of aquatic and riparian ecosystem health.Thresholds/Learnings:
    map background search result map search result map Effects of land cover change on streamflow in the interior Columbia River Basin (USA and Canada). Effects of land cover change on streamflow in the interior Columbia River Basin (USA and Canada).