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Meadows
are vegetated areas that are saturated with water for at least part of the
year. They are common on valley floors in montane, alpine and sub-alpine
zones in the Sierra Nevada Range. There are several meadows on plateaus
at higher elevation in the Battle Creek watershed. Concern has been expressed
by the Battle Creek Conservancy about potential impacts of suburban development
of meadows and implications to streamflows.
Meadows tend to capture sediment and buffer stream flows by storing water during high flows, such as during snow melt, and release the water later in the season (Dunne 1982). There is generally a bedrock layer or other impermeable sub-surface geology that keeps the water table near the surface. The soils that form in a meadow are a mix of sand and peat. Meadows form at higher elevations where snow and cold temperatures for six months of the year restrict decomposition and promote peat formation. A healthy meadow acts like a sponge and can feed water to streams below them well into summer. The water table is recharged primarily by snow melt but also from groundwater from adjacent upslope areas. Plants begin to deplete the water supply in the meadow as air temperatures and plant respiration rise during summer. As the water table drops, areas near the edge of the meadow dry up first. The last place in a meadow to dry up is the lower portion where the meadow may be more confined. Sometimes streams below meadows may dry up late in summer or during droughts. The water table in a meadow actually begins to recharge before rainfall as plants die back in fall. |
Gully formation can also cause a drop in groundwater in meadows and ultimately to meadow loss. According to Hagberg (1995) the key to meadow protection is to maintain sods intact and unbroken to prevent surface erosion in large floods. Hagberg (1995) found that "cattle trampling and chiseling weakens meadow sods" and that grazing rotations should allow enough rest to promote re-establishment of roots which bind the sods.
References
Dunne, T. 1982. Models of runoff processes and their significance. Pages 19-30 in: Scientific Basis of Water Resources Management. Geophysical Study Committee. National Academy Press, Washington D.C.
Hagberg, T.D. 1995. Relationships between hydrology, vegetation and gullies in montane meadows of the Sierra Nevada. Masters Thesis at Humboldt State University, Arcata, CA. 177 p.