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Geology topics

P.R. Leavitt

Publications and source records attributed to P.R. Leavitt.

2 recordsLinked to original sources

Historical changes in the Columbia River estuary based on sediment cores: feasibility studies

The importance of the Columbia River estuary to salmon, other fishes, migratory birds, and other species is fairly well established. Relatively little is known, however, about long-term, historic variations in biological processes and conditions within the estuary. For example, have conditions varied greatly with climatic regime shifts and how has dam construction on the Columbia River influenced biological communities over time? We conducted a feasibility study to see if sediment cores from the estuary could be aged and whether biological or contaminant indicators could be identified. Such information could be useful in understanding long-term environmental variation and in restoration studies.

Oregon, Washington

Assessment of climate change and freshwater ecosystems of the Rocky Mountains, USA and Canada

The Rocky Mountains in the USA and Canada encompass the interior cordillera of western North America, from the southern Yukon to northern New Mexico. Annual weather patterns are cold in winter and mild in summer. Precipitation has high seasonal and interannual variation and may differ by an order of magnitude between geographically close locales, depending on slope, aspect and local climatic and orographic conditions. The region's hydrology is characterized by the accumulation of winter snow, spring snowmelt and autumnal baseflows. During the 2–3-month ‘spring runoff’ period, rivers frequently discharge > 70% of their annual water budget and have instantaneous discharges 10–100 times mean low flow.

Hydrological Processes