Airborne Remote Sensing in Grand Canyon

History of Aerial Remote Sensing in Grand Canyon

Similar to 2021, 4-band multispectral imagery and photogrammetrically derived topography data were also previously acquired in 2002, 2005, 2009, and 2013. With each of those previous digital image acquisitions, GCMRC remote sensing staff developed and improved upon a methodology for producing a spatially seamless, spectrally consistent, and nearly cloud- and blemish-free image mosaic (Davis and others, 2012; Durning and others, 2016). That proven methodology will be used to develop an image mosaic from the 2021 acquisition.

An abbreviated history of aerial remote sensing of the Colorado River in Grand Canyon:

• The earliest air photos are black and white prints acquired from an airplane in 1935. 
• The first set of air photos acquired after Glen Canyon Dam was completed are black and white prints from May 1965
• The first color and color-infrared air photos were acquired during flights in the 1980s
• The first digital multispectral images were acquired in the late-1990s
• The first acquisition similar to this year's overflight (high spatial resolution digital multispectral imagery and digital topography) occurred in May 2002, and then again in 2004, 2005, 2009, 2013, 2021

Aerial Remote Sensing Science for the Colorado River in Grand Canyon

GCMRC scientists have leveraged this rich archive of data to relate observations of landcover changes to physical, biological and hydrological processes (Figure 1). This remote sensing science helps to support resource management decisions in the iconic Grand Canyon and Colorado River. One example is a quantitative assessment of riparian vegetation changes that occurred as a function of dam operations and climate during the first five decades of the operations of Glen Canyon Dam. Other examples are mapping tamarisk and tamarisk beetle impacts throughout the Colorado River in Glen Canyon and Grand Canyon. For these tamarisk studies, imagery were incorporated from the Worldview 2 constellation satellite and,  while the satellite imagery were helpful, they were not high resolution enough to replace the airborne multispectral imagery such as will be collected in the 2021 overflight. Changes in campsites area used by river runners and dunefields sourced by windblown river sand, which help to preserve archeological sites, are also evaluated with remote sensing. Using highly detailed vegetation and sand maps and predictive modelling, future riparian landcover changes are forecasted as a function of river flows owing to the planned operations of Glen Canyon Dam through 2036.

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