Tools to Assess Seasonal Wetland Best Management Practices for Water Conservation and Salinity Management Using High Resolution Remote Sensing, Direct Evapo-transpiration (ET) Monitoring And Modeling
* Using high quality satellite imagery, can we accurately quantify temporal and spatial coverage of seasonal wetland vegetation?
* Can reliable pattern recognition software be developed in conjunction with ground truthing and hydrologic monitoring to establish relationships between moisture status, temperature, soil salinity and vegetation succession?
* Will new technology in eddy covariance monitoring provide accurate evapotranspiration estimates for wetland moist soil plants?
* With the aid of water and salt mass balance models, can we begin to develop a template for seasonal wetland best management practices to satisfy Central Valley Project Improvement Act (CVPIA) water conservation goals?
Need and Benefit
The CVPIA requires that Reclamation develop criteria for evaluating water conservation plans prepared by contractors for the San Luis Unit, California. The criteria for agricultural and urban water contractors have already been established. However, little progress has been made on developing similar criteria for public wetlands such as the San Luis National Wildlife Refuge and private wetlands such as the Grassland Water District. Much of failure can be attributed to lack of analytical tools with which to quantify the various moist soil plants within each wetland area and to estimate the water needs of these individual plant species within each wetland complex. An important factor in determining wetland water needs and best management practices is accurate measurement of moist-soil plant ET. The published literature (Norman et al. 1993, Boyd 1987, Lafleur 1990, Mitsch and Gosselink, 1986) is inconclusive in estimates of ET rates for the most important moist soil plants commonly found in seasonal wetlands. For example, the crop coefficient (Kc) typically assigned to cattails ranges from 0.8 to 1.2--a potential error of 50 percent.
Hydrologic water balances have not been used to good effect to back-calculate moist soil plant ET because of the failure to quantify wetland plant species. Monitoring of water deliveries and drainage return flows has also been overlooked--further discouraging the use of this simple technique. Where water quality data are available, water balances can be supplemented with salinity balances which can act as a check on wetland direct evaporation and ET estimates. Quantification of seasonal wetland hydrology will be critical in the assessment of the effectiveness of various seasonal wetland practices on the ability to meet San Joaquin River, California, salinity objectives.
The research proposed will take advantage of spectacular recent advances in the availability of high resolution (4 meter) imagery from the IKONOS satellite system and technological advances in signal processing toolboxes such as MATLAB that provide the ability to match spectral signatures to individual moist soil plant species with a high degree of reliability. Work underway at Berkeley National Laboratory has had some early success in moist soil plant identification using this technology in a private duck club in the Grassland Water District.
The research will also dovetail with a CALFED sponsored drainage and water quality monitoring program, which started in the summer of 2003, to develop water and salinity balances for the San Luis National Wildlife Refuge.
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