<p>Drainage water recycling (DWR) is the practice of capturing,
storing, and reusing subsurface drained agricultural water to support
supplemental irrigation and has recently been proposed as a practice for
improving the crop production and water quality performance in the tile-drained
landscape of the U.S. Midwest. This study describes the development of a
modeling framework to quantify the potential irrigation and water quality
benefits of DWR systems in tile-drained landscapes and the application of the model
using ten years of measured weather, tile drain flow and nutrient
concentrations, water table, and soil data from two sites in the U.S. Midwest.
From this modeling framework, the development and testing of an open-source
online tool is also presented.</p><p></p><p>A spreadsheet model was developed to track water flows
between a reservoir and drained and irrigated field area at each site. The
amount of tile drain flow and associated nutrient loads that could be captured
from the field and stored in the reservoir was estimated to calculate the
potential water quality benefits of the system. Irrigation benefits were
quantified based on the amount of applied irrigation annually. A reservoir size
representing 6% to 8% of the field area with an average depth of 3.05 m was sufficient
in meeting the annual irrigation requirements during the 10-year period at each
site. At this reservoir size, average annual nitrate-N loads were reduced by
20% to 40% and soluble reactive phosphorus loads by 17% to 41%. Variability in
precipitation within and across years, and differences in soil water
characteristics, resulted in a wide range of potential benefits at the two
sites.</p><p>An online tool was developed from the model, and a
variance-based global sensitivity analysis was conducted to determine
influential and low-sensitivity input parameters. The input parameter, depth of
root zone, was the most influential input parameter suggesting that the
estimation of total available water for the field water balance is a critical
component of the model. Input settings describing the irrigation management and
crop coefficients for the initial establishment and mid-season crop growth
periods were also influential in impacting the field water balance. Reservoir
seepage rate was influential in regard to the reservoir water balance,
particularly at larger reservoir sizes. Sensitivity analysis results were used
to develop a user-interface for the tool, Evaluating Drainage Water Recycling
Decisions (EDWRD).</p><p>This study shows that DWR is capable of providing both irrigation and water quality benefits in the tile-drained landscape of the U.S. Midwest. The developed modeling framework supports future research on the development of strategies to implement and manage DWR systems, and the online tool serves as a resource for users to increase their awareness and understanding of the potential benefits of this novel practice.</p><p></p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/11310323 |
| Date | 03 December 2019 |
| Creators | Benjamin D Reinhart (8071469) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Evaluating_drainage_water_recycling_in_tile-drained_systems/11310323 |
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