Abstract
Delayed seasonal wetland drawdown is being investigated as one means of improving the scheduling of saline drainage discharge to the San Joaquin River, California, as an application of the principal of basin-scale real-time salinity management. A hybrid rapid vegetation assessment methodology was derived from the California Native Plant Society Rapid Assessment Protocol for classifying the vegetation in these seasonal wetlands. A hybrid remote sensing methodology combining pixel- and object-based components was developed to apply this classification strategy to a 160 km2 region. Twenty-six different plant communities were represented in a total of 20 land cover classes. An overall mapping accuracy ranges from 60% for identification of all 26 plant communities to 100% for identification of a single plant species. Low representation of certain associations for sensor calibration resulted in lower than anticipated mapping success as measured by errors of omission and commission. This image processing methodology provides an important tool, in concert with soil salinity mapping and wetland biology surveys, to assess the long-term impact of adaptive management strategies such as real-time salinity management on the wetland resource.
Highlights
IntroductionHigh-resolution remote sensing imagery has been used successfully in conjunction with image classification software tools for wetland vegetation mapping and wetland vegetation change detection for several decades.[1,2,3] Wetland vegetation in general and seasonal wetland vegetation in particular exhibit high spatial and spectral variability because of steep environmental gradients, which produce short ecotones and often result in sharp borders between vegetated wetland regions.[3,4,5] Spectral reflectance, the property of vegetation that is most often used to discriminate between important plant species of ecological significance, is a function of leaf optical properties that are related to the biochemical and physiological characteristics and health of the plant.[3,6] Adam et al.,[3] in a survey of spectral and multispectral survey techniques, acknowledge the complications with optical remote sensing techniques that perform classification based on spectral reflectance alone, given the similarities of spectral signatures and the potential interference from atmospheric conditions, plant moisture status, and underlying soil and litter characteristics
San Joaquin River assimilative capacity is determined by the salinity water quality objective at a downstream compliance monitoring station (Vernalis) and the ambient salt loading from upstream sources.[11,12,13]
Downloaded From: https://www.spiedigitallibrary.org/journals/Journal-of-Applied-Remote-Sensing on 13 Jan 2022 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use. The results of this mapping endeavor produced the first comprehensive seasonal wetland vegetation maps developed for this region
Summary
High-resolution remote sensing imagery has been used successfully in conjunction with image classification software tools for wetland vegetation mapping and wetland vegetation change detection for several decades.[1,2,3] Wetland vegetation in general and seasonal wetland vegetation in particular exhibit high spatial and spectral variability because of steep environmental gradients, which produce short ecotones and often result in sharp borders between vegetated wetland regions.[3,4,5] Spectral reflectance, the property of vegetation that is most often used to discriminate between important plant species of ecological significance, is a function of leaf optical properties that are related to the biochemical and physiological characteristics and health of the plant.[3,6] Adam et al.,[3] in a survey of spectral and multispectral survey techniques, acknowledge the complications with optical remote sensing techniques that perform classification based on spectral reflectance alone, given the similarities of spectral signatures and the potential interference from atmospheric conditions, plant moisture status, and underlying soil and litter characteristics. The loss of California wetlands since 1850 has been estimated at 91%, and in 1988, the California Department of Parks and Recreation estimated that California had lost 80% of its salt marshes and 90% of its freshwater marshes.[9] The north Grassland Water District and San Luis National Wildlife Refuge (Fig. 1) together comprise 160 km[2] of seasonal wetlands These wetlands lie on the Pacific Flyway and are an important source of food and habitat for migrating and local bird populations. Water management practices include the timing of irrigation and drawdown to maximize desirable food production plants and to minimize undesirable weeds Outflow events, such as wetland drawdown, can affect water quality in the San Joaquin River10—wetland managers could schedule wetland drawdown to match periods of high San Joaquin River assimilative capacity. San Joaquin River assimilative capacity is determined by the salinity water quality objective at a downstream compliance monitoring station (Vernalis) and the ambient salt loading from upstream sources.[11,12,13] The annual wetland salt load contribution to the San Joaquin River ranges from 8% to 11% of the total annual salt loading measured at the Vernalis compliance monitoring station.[11,14]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
