Rivers traversing subarctic wetlands are fed by numerous small tributary creeks, which carry much of the wetland runoff into the rivers during the snow-free season. The wetlands, being saturated, generate abundant surface flow in the spring melt season. This amount of water cannot be accommodated by the tributary creeks and, together with general flooding of the rivers, there is little distinction between overland flow and channelled flow across the wetland, the feeder tributaries, and the major rivers. After snowmelt, the water level subsides, and most of the overland flow from the wetland is funnelled into the feeder creeks. The feeders can usually respond quickly to rainstorms and recessions are short unless surface flow is sustained by extensive marshy depressions. Along the lower reaches of the major rivers, the small tributary creeks are the main conveyors of wetland runoff to the rivers and therefore strongly modify the runoff characteristics of the rivers.

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