Design tools and performance evaluation of uncoupled subsurface drainage systems

Anamelechi, Falasy Ebere

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https://hdl.handle.net/2142/127128 Copy

Description

Title

Design tools and performance evaluation of uncoupled subsurface drainage systems

Author(s)

Anamelechi, Falasy Ebere

Issue Date

2024-07-30

Director of Research (if dissertation) or Advisor (if thesis)

Cooke, Richard

Doctoral Committee Chair(s)

Cooke, Richard

Committee Member(s)

• Bhattarai, Rabin
• Kalita, Prasanta
• Brazee, Richard

Department of Study

Engineering Administration

Discipline

Agricultural & Biological Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Uncoupling Drainage Coefficients and Flow rates
• Uncoupled Subsurface Drainage Systems
• Layout of Drainpipes
• Illini Drainage Tools
• Drainage Design Tools, QGIS-Based Drainage Tools
• Topological-Sound Networks
• Installation Design Depths
• Pipe Sizing
• Drainage Intensity (DI)
• Drainage Coefficient (DC)
• Skaggs Inequality

Abstract

Subsurface drainage involves the design and installation of a network of drainpipes aimed at eliminating excess water from the soil profile to create optimal conditions for crop cultivation. Employing subsurface drainage systems typically leads to enhanced yields and increased profitability and studies have themselves shown that drainage systems pay for themselves in four to seven years. Despite the benefits associated with the use of subsurface systems, there is a significant drawback, as research findings indicate that subsurface drainage systems facilitate the rapid transport of nutrients to streams and lakes. Consequently, effective nutrient management in drained agricultural lands has emerged as a significant challenge for researchers, policymakers, farmers, and other stakeholders. Given that the bulk of subsurface drainage in the Midwestern US took place during the late 1800s and early to mid 1900s, there is now a push for the enhancement and optimization of subsurface drainage networks, largely driven by the imperative to replace aging infrastructure. Concurrent with this need is the heightened concern with the water quality implications of subsurface. This issue has prompted the emergence of conservation drainage practices, wherein the impact of drainage on nutrient loads and surface water quality is given equal priority alongside production objectives. One of such conservation drainage practice is a recent development in subsurface drainage theory which proposed that drainage systems can be optimized by uncoupling the flowrate used for determining lateral depth, spacing, and sizing (DI); and the flowrate used for the sizing of sub-mains and mains (DC). This new theory suggests that for an optimal system performance the values should be uncoupled, with the DC being at least as large as the DI, that is DC ≥ DI (herein called the Skaggs Inequality) to prevent a decrease in drainage rates and effectiveness. However, uncoupling the DI and the DC is a new concept; most subsurface drainage systems are typically designed with the DI and the DC set to the same value. Moreover, there is no literature that contains any quantitative assessment of the yield response from uncoupled systems, nor is there any existing software for designing such systems. To address this would require developing new drainage design tools that allow for the uncoupling of DI and DC rate values in a subsurface drainage system, and to investigate the impact of such systems on yield output and water quality. To facilitate the development of such new drainage design tools, a deep understanding of how the current subsurface drainage system is designed and structured is needed, identifying key processes in the design phase that can be improved upon from existing systems. In this research, I aim to improve our knowledge on the impacts of applying varying rates of Drainage Intensity (DI) and Drainage Coefficient (DC) to model the subsurface drainage system for water flow, nutrient transport, and yield response. In the first part of this research, I identified a three stage process for the design of subsurface drainage systems that comprises three major objectives of this study. To enable these objectives, I utilized the Python programming language and the QGIS software, a free and open source platform that does not have the proprietary issues and allows for friendly end user interaction was needed to host the new tools., using this platform, I developed a set of tools, Illini Drainage Tools, that uses LiDAR datasets to facilitate drainage system layout, transforming delineated laterals and mains into a structurally sound drainage network, and ensuring the burying and sizing of the entire tile network distribution. The tools developed streamline the design process and improve the efficiency of subsurface drainage system for implementing the use of varying rates of Drainage Intensity (DI) and Drainage Coefficient (DC). Next, I calibrated a deterministic field scale DRAINMOD 7 model for hydrology and water quality predictions in the two test fields, OCS2 and OCS4. I used four different object functions the Nash Sutcliffe Efficiency (NSE), Root Mean Square Efficiency (RMSE), the Percentage Bias (PBIAS), and the Heteroscedastic Maximum Likelihood Estimator (HMLE) to validate the modeling process. Lastly, I use this validated model to gage the significant difference in the impact of using different uncoupled values of DI and DC to model the subsurface drainage system for water flow, nutrient transport, and yield response, under both past (1990 2017) and future projected (2040 2067) weather scenarios time periods. In conclusion, the research successfully optimized subsurface drainage systems by uncoupling DI and DC, demonstrating significant differences in outcomes based on varying combinations. The sensitivity analysis identified key parameters affecting drainage behavior, while calibration and validation confirmed the robustness of the models. The study highlighted the importance of optimal DI values for managing excess water, improving crop yields, and minimizing environmental impacts. The findings underscored that while increased DI and DC improved yields up to a point, further increases led to diminishing returns. Additionally, the research emphasized the need to balance drainage parameters to minimize nitrate loads and maintain water quality. Future climate scenarios indicated potential impacts on crop productivity and nutrient discharge, necessitating adaptive drainage strategies. Overall, the study provided valuable insights into the interplay between drainage parameters, agricultural productivity, and environmental sustainability, validating theoretical frameworks and offering practical guidance for optimizing subsurface drainage systems in the context of climate change.

Graduation Semester

2024-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/127128

Copyright and License Information

©2024 Anamelechi FALASY

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