Abstract
Slope wetlands generally occur at breaks in slope where discharging ground water maintains moist soil conditions. They often are found on the perimeter of highly permeable alluvial fans, but there have been no detailed hydrologic studies of these particular wetlands. We combined stream and spring flow measurements with five years of water-level and piezometric data to understand the hydrology of a 1.6 ha slope wetland at the base of a 5.2 ha alluvial fan in the central Rocky Mountains of Colorado. Step changes in streamflow inputs resulting from an upstream water diversion helped confirm the linkages inferred from the hydrometric data. Nearly 30% of the streamflow along a 180-m reach on the alluvial fan was lost to seepage. Discharge from two springs at the toe of the alluvial fan was eliminated and the piezometric head in the toe of the fan decreased by more than 80 cm within 1–2 days after the stream was diverted, indicating that stream seepage is the primary source of ground-water recharge for the alluvial fan. Streamflow and ground water discharging at the base of the alluvial fan were the primary wetland inflows, with summer precipitation playing a relatively minor role. Consequently, wetland water levels declined by up to 75 cm after the diversion began operating. The largest declines were in the lower part of the wetland, where surface sheet flow from the stream was the main water source. Continuing ground-water discharge into the upper part of the wetland limited the water level declines to less than 40 cm. The importance of streamflow as a water source distinguishes slope wetlands adjacent to alluvial fans from those found in other settings and makes them particularly vulnerable to upstream water diversions.
Similar content being viewed by others
Literature Cited
Bachmann, S. A. 1994. Hydrology of a subalpine wetland complex in Rocky Mountain National Park, Colorado. MS Thesis. Colorado State University, Fort Collins, CO, USA.
Bernaldez, F. G., J. M. Rey Benayes, and A. Martinez. 1993. Ecological impact of groundwater extraction on wetlands (Douro Basin, Spain). Journal of Hydrology 141: 219–238.
Brinson, M. 1993. A hydrogeomorphic classification for wetlands. U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi, USA. Technical Report WRP-DE-4.
Branfireun, B. A. and N. T. Roulet. 1998. The baseflow and storm flow hydrology of a Precambrian Shield headwater peatland. Hydrological Processes 12: 57–72.
Chimner, R. A. and D. J. Cooper. 2002. Modeling carbon accumulation in Rocky mountain fens. Wetlands 22: 100–110.
Cole, C. A., R. P. Brooks, and D. H. Wardrop. 1997. Wetland hydrology as a function of hydrogeomorphic (HGM) subclass. Wetlands 17: 456–464.
Cooper, D. J. 1990. Ecology of wetlands in Big Meadows, Rocky Mountain National Park, Colorado. U.S. Fish and Wildlife Service, Washington DC, USA. Biological Report 90(15).
Devito, K. J., A. R. Hill, and N. Roulet. 1996. Groundwater—surface water interactions in headwater forested wetlands of the Canadian Shield. Journal of Hydrology 181: 127–147.
Drexler, J. Z., B. L. Bedford, A. T. DeGaetano, and D. I. Siegel. 1999. Quantification of the water budget and nutrient loading in a small peatland. Journal of the American Water Resources Association 35: 753–769.
Dunne, T. and L. B. Leopold. 1978. Water in Environmental Planning. W. H. Freeman and Company. New York NY, USA.
Fahey, B., W. B. Bowden, J. Smith, and D. L. Murray. 1998. Hillslope-wetland hydrological linkages in the headwaters of a tussock grassland catchment at Glendhu, South Island, New Zealand. p. 157–164. In K. Kovar, U. Tappeiner, N. E. Peters and R. G. Craig (eds.) Hydrology, Water Resources and Ecology in Headwaters. International Association of Hydrological Sciences. Publication No. 248.
Fitzgerald, D. F., J. S. Price, and J. J. Gibson. 2003. Hillslope— swamp interactions and flow pathways in a hypermaritime rainforest, British Columbia. Hydrological Processes 17: 3005–3022.
Harris, R. R., C. A. Fox, and R. Risser. 1987. Impacts of hydroelectric development on riparian vegetation in the Sierra Nevada region, California, USA. Environmental Management 11: 519–527.
Hauer, F. R., J. S. Baron, D. H. Campbell, K. D. Fausch, S. W. Hostetler, G. H. Leavesley, P. R. Leavitt, D. M. McKnight, and J. A. Stanford. 1997. Assessment of climate change and freshwater ecosystems of the Rocky Mountains, USA and Canada. Hydrological Processes 11: 903–924.
Herron, N. and C. Wilson. 2001. A water balance approach to assessing the hydrologic buffering potential of an alluvial fan. Water Resources Research 37: 341–351.
Houston, J. 2002. Groundwater recharge through an alluvial fan in the Atacama Desert, northern Chile: mechanism, magnitudes and causes. Hydrological Processes 16: 3019–3035.
Hunt, R. J., J. F. Walker, and D. P. Krabbenhoft. 1999. Characterizing hydrology and the importance of ground-water discharge in natural and constructed wetlands. Wetlands 19: 458–472.
Johnson, B. 2001. Documentation of reference conditions in the slope wetlands of the southern Rocky Mountains: reference database, site descriptions and revised functional models. U.S. Environmental Protection Agency, Region 8 and the Colorado Department of Natural Resources, Fort Collins, CO, USA.
Kondolf, G. M., J. W. Webb, M. J. Sale, and T. Felando. 1987. Basic hydrologic studies for assessing impacts of flow diversion on riparian vegetation: examples from streams in the eastern Sierra Nevada, California. Environmental Management 11: 757–769.
Novitzki, R. P. 1979. Hydrologie characteristics of Wisconsin’s wetlands and their influence on floods, stream flows, and sediment. P. 377–388. In P. E. Greeson, J. R. Clark, and J. E. Clark, (eds.) Wetland Functions and Values: the State of our Understanding. AWRA, Minneapolis MN, USA.
Novitzki, R. P. 1982. Hydrology of Wisconsin wetlands. Wisconsin Geological and Natural History Survey Circular 40.
Roulet, N. 1990. Hydrology of a headwater basin wetland: groundwater discharge and wetland maintenance. Hydrological Processes 4: 387–400.
Ruddy, B. C. and R. S. Williams. 1991. Hydrologie relations between streamflow and subalpine wetlands in Grand County. USGS Water Resources Investigations Report 90-4129.
Shaffer, P. W., M. E. Kentula, and S. E. Gwin. 1999. Characterization of wetland hydrology using hydrogeomorphic classification. Wetlands 19: 490–504.
Shimada, J., I. Kayane, Y. Shimano, and M. Taginguchi. 1993. Use of several environmental tracers to detect the surface—subsurface interaction in an alluvial fan. p. 263–274. In Tracers in Hydrology (Proceedings of the Yokohama Symposium, July, 1993). International Association of Hydrological Sciences. Publication No. 215.
Siegel, D. I. 1988. The recharge—discharge function of wetlands near Juneau, Alaska: Part I. Hydrogeological Investigations. Groundwater 26: 427–434.
Smith, S. D., A. B. Wellington, J. L. Nachlinger, and C. A. Fox. 1991. Functional response of riparian vegetation to streamflow in the eastern Sierra Nevada. Ecological Applications 1: 89–97.
Stein, E. D., M. Mattson, A. E. Fetscher, and K. J. Halama. 2004. Influence of geologic setting on slope wetland hydrodynamics. Wetlands 24: 244–260.
Suso, J. and M. R. Llamas. 1993. Influence of groundwater development on the Donana National Park ecosystems. Journal of Hydrology 141: 239–269.
Tóth, J. 1963. A theoretical analysis of groundwater flow in small drainage basins. Journal of Geophysical Research 68: 4795–4812.
Waddington, J. M., N. T. Roulet, and A. R. Hill. 1993. Runoff mechanisms in a forested groundwater discharge wetland. Journal of Hydrology 147: 37–60.
Windell, J. T., B. E. Willard, D. J. Cooper, S. Q. Foster, C. F. Knud-Hansen, L. P. Rink, and G. N. Kiladis. 1986. An ecological characterization of Rocky Mountain montane and subalpine wetlands. US Fish and Wildlife Service, Washington DC, USA. Biological Report 86(11).
Winter, T. C. 1999. Relation of streams, lakes and wetlands to groundwater flow systems. Hydrogeology Journal 7: 28–45.
Winter, T. C. and D. O. Rosenberry. 1995. The interaction of ground water with prairie pothole wetlands in the Cottonwood Lake area, east-central North Dakota, 1979–1990. Wetlands 15: 193–211.
Woods, S. W. 2000. Hydrologie effects of the Grand Ditch on streams and wetlands of Rocky Mountain National Park, Colorado. M.S. Thesis. Colorado State University, Fort Collins, CO, USA.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Woods, S.W., MacDonald, L.H. & Westbrook, C.J. Hydrologic interactions between an alluvial fan and a slope wetland in the central Rocky Mountains, USA. Wetlands 26, 230–243 (2006). https://doi.org/10.1672/0277-5212(2006)26[230:HIBAAF]2.0.CO;2
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1672/0277-5212(2006)26[230:HIBAAF]2.0.CO;2