Cost-effective Extrapolation of Remote Sensing Data for Assessing Seasonal Wetland Water Requirements
* What minimum spectral resolution is needed to cost-effectively extrapolate segmented remotely sensed imagery for accurate delineation of wetland moist soil plants?
* Can field spectrometer data be used to improve classification results for individual moist soil plants and common moist soil plant associations?
* Can we derive additional benefit from satellite and flown imagery that might assist in mapping the spatial variability of wetland soil salinity?
* Using microtopography survey data, the configuration of wetland inlets and outlets, and the areal extent of moist soil vegetation, can we predict areal patterns of salt accumulation in wetland soils?
* Can we validate a conceptual model of seasonal wetland salt balance using soil salinity surveys using a motorized EM-38 instrument.
* Using shallow water table monitoring, can we determine wetland seepage and vertical ground water flow at sufficient accuracy to provide closure for wetland water balance computations?
Need and Benefit
The Central Valley Project Improvement Act (CVPIA) requires that Reclamation develop criteria for evaluating water conservation plans prepared by San Luis Unit contractors. Reclamation has developed a set of tools based on the concept of water balance to aid agricultural contractors' assessment of the benefits of best management practice (BMP) implementation, and has contracted with irrigation consultants to help farmers implement appropriate BMPs once identified. A comparable program for managed wetlands that receive federal water has not yet been developed because of:
* Fundamental quantitative lack of understanding of seasonal wetland hydrology by both Reclamation and wetland water managers
* A lack of analytical tools with which to quantify the water needs of various moist soil plants within each wetland area
* A reluctance to engage with wildlife agencies who have fought Reclamation for decades to mitigate historic losses of wetland habitat.
An important factor in determining wetland water needs and BMPs is accurate measurement of moist-soil plant evapo-transpiration (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. The remote sensing research sponsored by Reclamation's Science and Technology (S&T) Program during fiscal years (FY) 2005 and 2006 has been directed at addressing regional wetland assessment of ET, primarily by developing new capability in identifying moist soil plant communities and quantifying the areal extent of wetland moist soil plant habitat. The final year of this line of research will compare alternate methods of estimating wetland moist soil plant ET and manuscripts will be finalized for submission to the technical journal _Wetlands_ on the successes to date.
A logical extension of these studies is to develop techniques to extrapolate the findings of the studies to cover the entire 130, 000 acre Grasslands Ecological Area and to examine the cost effectiveness of each technique that has been studied. It is in Reclamation's best interest to identify the most cost-efficient technology, given that the costs of imagery will likely be recurring costs. Remote sensing data provides the capability to generate information on the long-term environmental impact of water conservation practices and drainage management strategies to minimize water quality impacts on the San Joaquin River. The Mid-Pacific Region invested $100, 000 in FY 2006 to help construct and operate continuous flow and water quality monitoring stations on 12 wetlands within the 130, 000 acre wetland complex (on approximately 2 percent of the managed seasonal wetland area). It is self-evident that modeling will need to address much of the need on the remaining 98 percent of the area--given the high capital and operating costs of monitoring stations. This follow-on proposal identifies important research topics that are necessary to take the next step to technology transfer and full implementation.
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This information was last updated on March 31, 2015
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