Establishing the Water Budget of a Tailwater Recovery System

Investigators: Amanda Nelson

Date: 2021

Project Summary

Introuction

Tailwater recovery (TWR) systems are an important best management practice (BMP) used to address 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 a ditch to capture runoff; sometimes an onfarm storage (OFS) reservoir to store captured water; and 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, will be measured for at least five years. 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 and runoff water quality trends will also be analyzed. These data will later be used to model the system to determine its impacts on aquifer dynamics.

Materials and Methods

The field experiment is being conducted at a TWR in Sunflower County, MS. There are one or two outflow pipes from each of the eight 40 acre fields contributing to the TWR. Each outflow pipe is being 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 runoff events. Management of the fields will be at the farmer’s discretion and will be recorded. Within 24 hours of rainfall or irrigation events, runoff samples will be collected, placed on ice, immediately transported to the National Center for Alluvial Aquifer Research (NCAAR) laboratory, and stored at 4°C until analysis. Variables measured will include runoff, solids, and nutrients and their various species. In addition, a rain gauge will be installed at the site and laser water level loggers will be installed in the TWR ditch. Irrigation and pumping records and agronomic management information will be provided by the cooperator. Soil samples will be collected for soil bulk density, nutrient, and texture.

Current Status

This project is currently in the installation phase. Site selection occurred in spring 2021, then sampling equipment was ordered in May and began to arrive in the fall. Beginning in November, field installation began with the help of staff from C.C. Lynch, Inc. Runoff quantity is currently the only variable being recorded. The final sampling equipment is expected to be installed in January 2022 and water sampling will begin then and continue for a minimum of five years.

Project Photos

• Topic:
• Irrigation Scheduling
• Technologies
• Irrigation