Storm Flow Generation in Artificially Drained Landscapes of the US Midwest: Matrix Flow, Macropore Flow, or Overland Flow
Vidon P1*, Hubbard H2, Cuadra PE2, Hennessy M2
1The State University of New York College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY, 13210
2Indiana University-Purdue University Indianapolis, 723 W. Michigan St., Indianapolis, IN, 46202
*Correspondence E-mail: [email protected]
Key Words: sub-surface drainage, watershed, flowpath, hydrograph separation, precipitation events, solutes
Received April 24th, 2012; Accepted December 10th, 2012; Published December 18th, 2012;
Available online Januray 5th, 2013
Summary
This study investigates the relative importance of macropore flow (MPF), matrix flow (MTF), and overland flow (OLF) in stream and tile drain flow (MPF and MTF only) in an artificially drained watershed for storms ranging from 1.02-4.45 cm in bulk precipitation. OLF occurrence was primarily associated with wet antecedent conditions, but not necessarily with high precipitation amounts. In the stream, MPF and OLF contributions to flow ranged from 0-40% and 0-58%, respectively; while MTF accounted for 42-100% of flow (mean = 72%). In tile drains, MTF contributions ranged from 32-63% of total flow (mean = 49%). Overall higher MTF contributions to flow in the stream than in tile drains (by 23%) suggest that even in tile drain dominated systems, a significant amount of water (primarily MTF) may be reaching the stream via upwelling or direct lateral seepage to the stream. Higher SO42- and K+ concentrations in the stream than in tile drains confirmed these results. On an individual storm basis, K+, Mg2+, and SO42- dynamics nevertheless remained highly variable, suggesting that these solute concentration patterns are most useful to infer flowpaths at the watershed scale when used along with other techniques (e.g. hydrograph separation). As strategies are implemented to reduce N loading to streams via tile drains, our results stress the need to also include stream/riparian restoration as a strategy to reduce N loading in tile drain dominated systems, as a significant amount of water likely reaches streams via groundwater upwelling or lateral seepage in these systems.