Establishing the Water Budget of a Tailwater Recovery System

Investigators: Amanda Nelson

Date: 2022

Project Summary

Introduction

Tailwater recovery (TWR) systems are an important best management practice for addressing both water quality and quantity issues in the Mississippi Delta. TWRs are systems for capturing surface water runoff to be later used for irrigation. TWRs consist of 1) a ditch to capture runoff; sometimes an on-farm storage (OFS) reservoir to store captured water; and 2) pumps to move surface water from the ditch into the OFS reservoir and to irrigate nearby fields. To determine if TWR systems are an effective way to reduce water use and downstream nutrient loads, water quality and quantity data from a closed ditch TWR system in Sunflower County, MS, is being measured in a long-term evaluation. The objective of this study is to establish a water budget for a closed TWR system, where the TWR is used as the primary irrigation source. Seasonal and rainfall event runoff quantity and quality trends are also being analyzed. These data will later be used to model TWR systems to determine their impacts on aquifer dynamics.

Materials and Methods

The field experiment is being conducted at a TWR system in Sunflower County, MS. There are one or two outflow pipes from each eight, 40 acre fields contributing to the TWR, each equipped with an automatic runoff sampler (ISCO GLS, Teledyne ISCO, Lincoln, Nebraska) and an area velocity flow sensor (ISCO 2150) to collect composite water samples and flow rates for each runoff event. Management of the fields are at the farmer's discretion and are recorded. Within 24 hours of rainfall or irrigation events, runoff samples are collected, placed on ice, immediately transported to NCAAR laboratories, and stored at 4°C until analysis. Variables measured include runoff volume, sediment, and nutrients. In addition, two rain gauges were installed at the site and a laser water level loggers was installed in the TWR ditch. Irrigation and pumping records and agronomic management information are provided by the cooperator.

Current Status

Beginning in November 2021, field installation began with the help of staff from C.C. Lynch, Inc. Installation of this project and was completed in the summer of 2022, with minor adjustments still being made. Runoff quantity was recorded throughout the 2022 growing season, with data and samples collected from nine irrigation events and thirteen rain events in 2022 (Figure 2).

Outcomes

This work is expected to demonstrate that TWR systems are an effective way to reduce water use and downstream nutrient loads from a closed ditch TWR system for the Mississippi Delta. Such results will be useful for minimizing Alluvial Aquifer withdraw.

Project Photos

• Topic:
• Irrigation