Eric Gamble
Geological Research at the IGS

Evaluating tillage practices on near-surface groundwater recharge

Status Start Date End Date Locations
completed Jan 1, 2016 Apr 30, 2017 Boone, Hendricks
Director: Sally Letsinger
Other Researchers: Robert Autio, Shawn Naylor, Eric Gamble Bob Barr, IUPUI-CEES
Funding: Indiana Department of Environmental Management (IDEM)
Issue: A previously funded project (2014-2015) developed an outdoor laboratory in a small subwatershed in Indiana (School Branch watershed, Hendricks County, Indiana), which is being used to collect data sufficient to develop a complete water budget (micrometeorological, soil, subsurface- and surface-water components) and accurately quantify fluxes directed toward the saturated zone as opposed to surface runoff. These sites are located in agricultural settings managed by conservation tillage practices. These sites were added to the Indiana Water Balance Network ( In evaluating the early results of the installed instrumentation, two important questions have arisen that we will address: a. Is the behavior of surface infiltration and near-surface recharge dependent on the management of the land? For the currently installed sites, soil moisture and groundwater fluxes are very responsive to surface boundary conditions. Is that responsive behavior governed by the surficial geology, or do tillage practices play a role? b. Is a trench installation disruptive to the measurement of in situ soil moisture, or is a borehole sensor preferable to observe ambient conditions?
Objective: The goals of this project are to install sensors and monitor the resultant water-balance data in different areas of the small watershed being subjected to different land-management (particularly agricultural) practices. Over time, statistically significant differences in the sites might be able to be linked back to how the land is managed.
Approach: We will partner with the cooperators in the School Branch watershed and identify a plot using conventional tillage; at that location we will install a water-balance monitoring station (micrometeorology, soil moisture, and groundwater). We will monitor the water fluxes and compare them with those from the sites using conservation tillage practices. We will also continue to maintain the current water-balance monitoring sites and will calculate water-balance components (precipitation, potential evapotranspiration) at the network sites. We will install a 4-ft Sentek Drill and Drop soil moisture and temperature probe adjacent to the existing trench installation at the site known as School Branch East on Starkey Farms. We will compare the time-series responses to surface boundary conditions (wetting, drying, crop growth) and determine if one approach is preferable or if they are comparable.
Products: A final project report will be submitted to IDEM that summarizes the data collected during the project period, and interprets (as appropriate) the data in the context of the research questions.
Benefits: At the conclusion of this project, a framework will be in place to monitor the water balance at different locations in an agricultural/suburban watershed on the edge of a major metropolitan area. Over time, the data should yield insights into the linkages between land-management practices and near-surface hydrological processes.

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