APPLICATIONS OF REMOTE SENSING FOR DETERMINING DUNE MIGRATION RATES, ALGODONES DUNE FIELD, CA

Dune migration rates can be extremely variable based on seasonal, decadal and multi-decadal climate variations. It order to fully understand the migration rates, dune fields must be examined on multiple time scales ranging from hours (individual events) to years (seasonal cycles) to decades (multi-decadal cycles) and longer. Longer time series data is limited. Multi-decadal relies primarily on historical aerial photos acquired at infrequent intervals while longer investigations apply techniques of sedimentology and chronology. Newly available remote sensing techniques for assessing environmental change have allowed the use of Satellite imagery from Landsat to examine migration rates over the past ~30 years.

California’s Algodones Dune Field is located in the south eastern section of the Salton Trough. Research conducted in the 1980s and 1990s have indicated that the dunes are composed remnant beach sands derived from former Lake Cahuilla (modern-day Salton Sea) shoreline deposits.

We analyzed daily averaged wind velocities between 1948 and 2017 to establish migration thresholds to determine when the field may have been active. The results of the wind analysis was used to examine periods of time between 1987 and 2018 using Landsat imagery. The imagery was analyzed for change using Cosi-Corr. Analysis of migrations rates are spatially limited dune to the 15 m spatial resolution of the Cosi-Corr and Landsat technique as well as temporally limited based on availability of Landsat data.

Previous researchers have reported a migration rate of 1.0 m/yr using a fifteen-year monitoring period between 1973 and 1987. Wind velocity analysis indicate that this time interval was during a period of enhanced windiness. The Cosi-Corr analysis suggest a slightly lower average of 0.6 m/yr over the 1987-2017 time period. The results of this study, when compared with previous research indicate the importance of variability of driving processes (wind velocity and climate) at short temporal scales. As new satellite data products become available with longer time series (e.g. Planet Labs, 3 m resolution), applications of remote sensing will be able to measure migration rates on shorter time scales and develop a better relationship between event, seasonal and multi-decadal variation in climate conditions.