An official website of the United States government.
The objectives of the project are to integrate research, extension, and education to:<P> 1) Develop a framework for targeting high priority areas on a watershed scale using remote sensing to compute actual crop evapotranspiration and groundwater and surface water information to applied irrigation water. <P> 2) Research on-farm irrigation practices and irrigation system performance in areas identified as high priority and low priority to confirm that irrigation system and operational modifications can demonstrate conservation and improved quality of water resources on a watershed scale.<P> 3) The evaluations are expected to reveal innovative conservation practices already being implemented, behavioral and social constraints limiting implementation of traditional practices, and ways to overcome these constraints to implement new techniques through extension and education. <P> 4) Disseminate procedures and identify future areas of research on innovative water conservation techniques with Cooperative Extension assistance. <P> 5) Educate current and future water resource managers on the targeting procedures and innovative techniques used in agricultural irrigation for water quality and conservation through university-level course material development, professional short courses, and grower field days.
Non-Technical Summary: <BR>On-farm losses (runoff and deep percolation) can be a significant source of non-point source contamination in agricultural, rural, and urbanizing watersheds. In most cases, these losses can be attributed to improper irrigation scheduling and low system distribution uniformity. Since both can have negative impacts on yield, water and energy cost, fertilizer effectiveness, etc., it is likely that growers having one or more of these items may not know where problems exist. The amount of agricultural fields within a watershed can number in the hundreds or thousands. This, combined with limited resources at a watershed manager's disposal, creates the need for a procedure to target areas with high potential for water conservation/quality improvement through irrigation system and management modifications. The framework developed in this proposed project will focus on techniques to determine where on-farm losses are most likely occurring within a watershed. This will allow watershed managers to focus limited resources on high priority areas to achieve watershed-wide water quality and water conservation objectives focusing on irrigation systems and management. We believe that understanding the spatial relationship between applied water and actual evapotranspiration over a watershed is a critical piece of this framework. <P> Approach: <BR> METRICTM (Mapping EvapoTranspiration at High Resolution with Internal Calibration) is an algorithm based on the surface energy balance equation. Evapotranspiration is computed from LandSAT Thematic Mapper (TM). It is expected that 10 to 14 LandSAT 5 images, from Path 41 Row 36, will be evaluated initially for calendar years 2010 and 2011. Evapotranspiration will be interpolated between the images to attain the annual values on a pixel by pixel basis. Local stakeholders maintain pumping records by parcel number. A comparison of pumping volumes to ETc on an annual basis will allow us to evaluate fields that may have low ETc to applied water ratios throughout the watersheds. The basis of this evaluation will be grower surveys. Once the relationship between actual ETc and applied water by farm is established spatially using GIS, individual will be identified targeting high and low ratios of ETc to applied water. Additionally, grower selection will be based on crop type and geographic location (distance away from the ocean). We expect that the surveys will provide some insight into causes of the variability in ETc to applied water ratios. Several issues that we expect to be brought up include: - Utilization of different irrigation methods (sprinkler versus drip). - Using frequent sprinkler irrigation during Santa Ana Wind conditions - Extra water for salinity management - Utilizing frequent sprinkler irrigations for germination/transplanting - Perched water table meeting a portion of the crop water demands The field level evaluations will incorporate a systematic procedure to accurately assess the irrigation system distribution uniformity, operation, and management a portion of the field examined. Standardized procedures will be utilized to accumulate comparative results. 1. Irrigation system distribution uniformity evaluations. 2. Growers will be asked to maintain a log of activities throughout a season detailing when they plant, harvest, cultivate, and conduct specific irrigation management practices. 3. Monitoring of Irrigation Schedule (frequency and duration. 4. Four indices will be developed to assess the source of the loss (irrigation scheduling or distribution uniformity) and for overall framework assessment. Three indices will be computed as the annual loss (loss attributed irrigation scheduling, and loss attributed to distribution uniformity, and combined loss) divided by the evapotranspiration of irrigation water. The fourth index will be computed as the actual ET of irrigation water divided by the potential ET of irrigation water assuming no under irrigation (a soil water balance model output). This index will be used to evaluate whether under-irrigation occurred. In addition, the indices will be incorporated into GIS to evaluate spatial trends and evaluate crop and soil impacts. 5. Develop a matrix of recommendations Having a procedure to target potential areas for water conservation leading to improved water quality is critical since there are often limited resources available to assist in improvements.