Hydrologic Effects of Wetland Location and Size in an Agricultural Landscape 1

D. M. Amatya, G. M. Chescheir, R. W. Skaggs 2

Abstract

The hydrology of agricultural landscape is strongly dependent upon the size and position of the natural wetlands. DRAINMOD based simulations were conducted to study the effects of the area and location of natural wetlands on peak outflow rates and annual outflow from a 7200 ha hypothetical watershed in an agricultural landscape. Results based on one year of simulation indicated the reduction of as much as 38% in peak rates larger than 6 mm/day as well as total annual outflows as the size of the wetland increased. Wetlands located off of the main tributary of the watershed had a much smaller effect on attenuating the peak outflow rates. Based on simulation for one year, a wetland area of 5% of the watershed located at the downstream end was as effective as the one that constitutes 40% of the watershed located at the upstream end. Reduction in annual outflow was due to large surface storage of the wetland as compared to that of agricultural land.

  1. Paper of the Journal Series of the Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC 27695. This work was supported by a grant from USDA CSRS. The authors would like to acknowledge the contribution of Francois Birgand.
  2. D.M. Amatya, Research Associate; G.M. Chescheir, Research Associate; R.W. Skaggs, William Neal Reynolds and Distinguished University Professor, Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, Box 7625, Raleigh, NC 27695-7625.

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