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A Quantitative Geomorphic Approach to Predicting Productivity of Pink and Chum Salmon Streams in Southeast Alaska (Classic Reprint) - Softcover
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Excerpt from A Quantitative Geomorphic Approach to Predicting Productivity of Pink and Chum Salmon Streams in Southeast Alaska
Thompson and Hunt (1930) stressed the importance of the drainage basin as a whole, not just the stream, in their investigations of the basic nature of stream productivity. Slack (1955) reinforced this concept in his studies of stream productivity factors, demonstrating that the biolog ical productivity of a stream is directly related to the physical environment of the watershed, which controls drainage pattern, flow rates, gravel size and shape, channel gradient, and general stability characteristics. Statistical analysis of quantitative geomorphic parameters of individual watersheds can help identify these factors.
Quantitative geomorphic techniques developed by Horton (1932, 1945) and Strahler (1952, 1953, 1954) provide a convenient method for obtaining numerical data on gross basin character istics, given limited funding and difficulty of access and sampling of test streams. Measurement of physical parame ters based on basin and channel geometry, obtainable from aerial photographs and topographic maps, provides correlation units such as drainage size and shape, stream density, and pattern, number, and length of tribu~ taries. These in turn provide an estimate of stage of water shed development, probable basin discharge, extent of bedrock control of drainage,impact of unstable slopes, and extent of channel suitable for spawning. Such techniques have been used successfully to analyze relationships between erosion, climate, surface properties, and geomorphology (melton 1957, Maxwell 1960, Dissmeyer In 1973, Ziemer used quantitative geomorphic techniques to relate drainage basin and channel configuration to changes in production of pink salmon on Montague Island Prince William Sound, Alaska, after large vertical tectonic adjustments resulting from the Good Friday Earthquake of 1964. Using five drainage system factors, he showed a correlation between drainage system geometry and freshwater production factors for pink salmon, with escapement as his indicator of production. He assumed that (1) the number of spawners using a stream is a sound measure of fish production in that stream, (2) escapement counts were consistently made from year to year and stream to stream, and (3) the impact of the fishery was consistent between stocks and years. He realized the problems involved by making these assumptions, but he had no other tools available.
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A Quantitative Geomorphic Approach to Predicting Productivity of Pink and Chum
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Paperback. Condition: New. Print on Demand. This book presents a practical approach to predicting the productivity of pink and chum salmon streams in southeast Alaska using geomorphic variables. The author developed a discriminant model using 21 quantitative geomorphic variables measured from aerial photographs and topographic and geologic maps of 78 watersheds. Of these, eight variables were found to be significant in differentiating between good and poor producers of pink and chum salmon, including drainage area, mean valley side slope, avalanche index, drainage density, stream gradient, stream length with acceptable spawning gradient, and the presence of lakes in the stream system. The model provides a qualitative estimate of potential salmon production for any southeast Alaska stream, aiding in land management decisions and research on factors affecting salmon productivity. This book is a reproduction of an important historical work, digitally reconstructed using state-of-the-art technology to preserve the original format. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in the book. print-on-demand item. Seller Inventory # 9781390541915_0
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