Constructed Wetland to Remove Nitrate: Wetland Design Hydrology

By: Cibin Raj

IntroductionProblem?.• Constructed wetland : a solution for nitrate removal• Design of wetland- location identification• Evaluation of effectiveness of constructed wetland

Depth of water? Residence time?

Objectives• To determine monthly average depth of water in wetland• To find out the area extend of wetland (monthly)• Estimate residence time

Study area

• Middle Wabash- Little Vermillion• HUC 05120108

• Data required for location identification

Data Required

Data layer Source dataset How the layer was used in the analysisStreams National Hydrography Dataset (NHD), high

resolution streams, downloaded June 2009Used to eliminate streams as suitable locations for placing wetlands, and to approximate the location where closed drains empty into open drains

Elevation National Elevation Dataset (NED), with one-third arc second resolution

Used to find watersheds, describe how water flows through the landscape, and create contours for wetland design

Roads TIGER 2008 Census data, “edges” Used to break up separate crop fields and also for locating different wetland sites

Cropland National Land Cover Dataset (NLCD), selecting the field “cultivated crops”

Used for locating suitable sites for wetland placement and also to approximate tile-drained land in the landscape

Tile drained land (estimate)

From SSURGO soils and Cropland (poorly, very poorly, and somewhat poorly drained cropland)

Used to locate sites that drain a large watershed of tile-drained land

Hydric soils Soil Survey Geographic (SSURGO) Database To give a general idea of areas that were formerly wetlandOrthophotos Indiana Framework Data, streamed by

University of IndianaUsed for visualization of sites and determination of locations where closed drains empty into open ones

• Data required to find out the depth• Ditch flow to the wetland• Wetland Characteristics- size, normal pool depth• Watershed Characteristics- area, percentage tile drained• Evapotranspiration from wetland

• Begin with available ditch flow data and dam characteristics

• Model the wetland inflow and outflow (possibly HEC)

• Obtain monthly depth of water in wetland• Try to estimate the ditch flow data- as a

function of watershed characteristics, rainfall etc.

Methodology

Thank you