The “science” of erosion control is heavily biased by experiences and technical studies along ocean coasts. Oceans are very different from large inland lakes, because ocean shorelines are subject to daily tidal regimes, enormous waves, a lack of calm waters and ice influences, and waters near ocean shores are often very deep. In addition, average coastal sea levels have been rising over time which in itself increases erosion problems.
In contrast, the large lakes of Manitoba (Lake Winnipeg, Lake Manitoba, etc.) are extremely shallow, contain abundant supplies of sand, and are subject to long term cyclic changes in water levels. Erosion concerns generally arise when sustained high water levels from storm seiches are driven by north winds.
Beach loss will always occur when lake levels are very high even on beaches with no shoreline erosion projects, but most beaches on our shallow lakes are “dynamic”; sand returns and builds dunes along the cliff-banks behind beaches when lake levels recede. Permanent sand loss in front of erosion control structures is not typical unless there have been significant changes to shoreline configuration and/or prevailing near shore water currents. Substantial sediment flow appears characteristic of the south basin of Lake Winnipeg.
We advocate Adaptive Management (AM) principles for any shoreline protection efforts. In a nutshell, AM is learn-by-doing approach that promotes building scientific knowledge based upon actions taken. AM acknowledges both successes and failures in achieving pre-determined objectives. Traditional methods involving long term pre-project studies often take years of study and seldom reduce the level of uncertainty inherent in any habitat manipulation projects – delay also does not protect valuable lakeshore assets from further erosion. AM requires a statement of expectations, monitoring of results, and adjustments to project designs when corrections are deemed necessary. The process requires action and a committment to attaining a planned outcome.
In contrast, the large lakes of Manitoba (Lake Winnipeg, Lake Manitoba, etc.) are extremely shallow, contain abundant supplies of sand, and are subject to long term cyclic changes in water levels. Erosion concerns generally arise when sustained high water levels from storm seiches are driven by north winds.
Beach loss will always occur when lake levels are very high even on beaches with no shoreline erosion projects, but most beaches on our shallow lakes are “dynamic”; sand returns and builds dunes along the cliff-banks behind beaches when lake levels recede. Permanent sand loss in front of erosion control structures is not typical unless there have been significant changes to shoreline configuration and/or prevailing near shore water currents. Substantial sediment flow appears characteristic of the south basin of Lake Winnipeg.
We advocate Adaptive Management (AM) principles for any shoreline protection efforts. In a nutshell, AM is learn-by-doing approach that promotes building scientific knowledge based upon actions taken. AM acknowledges both successes and failures in achieving pre-determined objectives. Traditional methods involving long term pre-project studies often take years of study and seldom reduce the level of uncertainty inherent in any habitat manipulation projects – delay also does not protect valuable lakeshore assets from further erosion. AM requires a statement of expectations, monitoring of results, and adjustments to project designs when corrections are deemed necessary. The process requires action and a committment to attaining a planned outcome.
Science
