Remote sensing and mapping of floating aquatic vegetation in the Sacramento-San Joaquin River Delta

Authors: BUBENHEIM, DAVID - National Aeronautics And Space Administration (NASA); GENOVESE, VANESSA - California State University; Madsen, John; HARD, EDWARD - California Department Of Boating And Waterways

Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2020
Publication Date: 8/31/2021
Citation: Bubenheim, D., Genovese, V., Madsen, J.D., Hard, E. 2021. Remote sensing and mapping of floating aquatic vegetation in the Sacramento-San Joaquin River Delta. Journal of Aquatic Plant Management. 59s:46-54.

Interpretive Summary: Natural resource agencies managing aquatic weeds in the Sacramento-San Joaquin River Delta have been using LandSAT or Sentinel satellite imagery and a data tool developed by NASA to monitor the floating weeds in the Delta at short time intervals (1 to 3 weeks) at relatively low cost. While less precise than other remote sensing tools, the widely used imagery is available at greater frequency and a reasonable cost.

Technical Abstract: The California Sacramento-San Joaquin River Delta is the hub for California’s water supply to Northern and Southern California communities and agricultural production and supports ecosystem services in the San Francisco Bay/California Delta complex. Expansion of invasive aquatic plants and impacts of changing climate and land use, long-term drought, and fluctuations in water flow and quality are detrimental to water management and the Delta ecosystem. The Delta covers 340,200 ha (840,000 acres, 1312.5 miles2) land and water area in a web of sloughs, levees, rivers channels, marsh, and wetlands. The California Division of Boating and Waterways (DBW) has management responsibility for invasive aquatic plants and has partnered with NASA Ames Research Center, USDA-Agricultural Research Service, and University of California Davis in the Delta Region Areawide Aquatic Weed Project (DRAAWP) to develop science-based, adaptive-management strategies. Satellite-based, remote sensing methods have been developed to provide, for the first time, a comprehensive view of floating aquatic vegetation (FAV) population dynamics on a landscape scale and support operations, assessment and strategic planning/adaptive management. An initial mapping tool utilized Landsat acquisitions, available at 14-day intervals with 30 m pixel size, and NDVI processing to map FAV. The Landsat-based tool confirmed the value of using remote sensing to inform both Delta wide and local operations and assessment, however, significant deficiencies in spatial and temporal resolution and variability were problematic. A second mapping tool using Sentinel-2 satellites acquisitions and processing with the Acolite program provided improved performance in all areas. Enhanced mapping performance enhances the value of information applied to resource managers and Delta stakeholders. This effort supports operational decision making, enables assessment of management practices effectiveness, and provides new tools for planning, verification, and adaptive management. A first-ever, comprehensive, quantitative view of floating aquatic plant populations in the California Delta and linkage with operational decision making and enhanced assessment capabilities increases the efficiency of resource management efforts in the region.