Water Management in Arid Irrigated Agriculture

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Project Summary

This research project aims to develop software-based surface-irrigation technologies applicable to on-farm, project, and basin-scale irrigation systems.    On-farm, we plan to expand our current surface-irrigation software development (WinSRFR), and will provide the software with new or enhanced analytical capabilities relative to our legacy applications.  Central to this effort will be the development and validation of methodologies that can be used to evaluate infiltration properties needed for surface irrigation system design and management, based on soil physical principles.  To this end, we will use irrigation evaluation data and pedotransfer functions to determine field-averaged parameters for 1-D and 2-D Green-Ampt infiltration formulations.    We will also develop and validate models for predicting sediment and constituent (phosphorous and nitrogen) transport in the surface irrigation stream.  The models will consider the unsteady nature of surface irrigation flows.  Advection and dispersion processes will be considered in modeling constituent transport.  These models will be incorporated into WinSRFR.  We plan to implement and test our canal control concepts on a large delivery system, in collaboration with an irrigation district in Arizona.  The effort will potentially provide an initial test for a fully automated system, from main canals to laterals.  Finally, we plan to modify current methodology for assessing the potential impacts of proposed on-farm irrigation system improvements (conservation practices).  The products of the research effort, science-based software, packaged for convenient use, made available to our clients, the NRCS, mobile labs, consultants and universities, should provide ample opportunity for enhancing the efficiency of surface irrigation and minimizing its environmental impact.

Objectives

1. Develop management tools to improve the performance of surface irrigation systems at the field scale.
2. Develop model components that can be used to predict irrigation-induced erosion and constituent transport in surface irrigation at the field scale.
3. Develop management tools to improve the operation of irrigation water delivery systems.
4. Develop a strategy and tools for assessing the performance of surface irrigation systems at the water district or watershed scale.

The overall project objectives are to improve the performance of surface irrigation systems, particularly in arid environments and where water is supplied to farms from large distribution networks. Objectives 1 and 2 provide specific tools to help water users improve their irrigation system and its performance at the field scale. These are particularly useful to NRCS personnel. Objective 3 deals with methods to improve the performance of the delivery part of the system, which has implications for the performance of both the water delivery system itself and the farm irrigation system. Under this plan, useful tools will be developed under Objectives 1 and 3. Attempts will be made to determine the effectiveness of these tools in improving irrigation system performance. The long-term goal of Objective 4 encompasses the other three objectives, providing specific tools for NRCS and others to assess the impact of irrigation system improvements at the watershed scale.