Non-Vegetated Playa Morphodynamics Using Multi-Temporal Landsat Imagery in a Semi-Arid Endorheic Basin: Salar de Uyuni, Bolivia

Abstract

Playas in endorheic basins are of environmental value and highly scientific because of their natural habitats of a wide variety of species and indicators for climatic changes and tectonic activities within continents. Remote sensing, due to its capability of acquiring repetitive data with synoptic coverage, provides a unique tool to monitor and collect spatial information about playas. Most studies have concentrated on evaporite mineral distribution using remote sensing techniques but research about grain size distribution and geomorphologic changes in playas has been rarely reported. We analysed playa morphodynamics using Landsat time series data in a semi-arid endorheic basin, Salar de Uyuni in Bolivia. The spectral libraries explaining the relationship between surface reflectance and surficial materials are extracted from the Landsat image on 11 November 2012, the collected samples in the area and the precipitation data. Such spectral libraries are then applied to the classification of the other Landsat images from 1985-2011 using maximum likelihood classifier. Four types of surficial materials on the playa are identified: salty surface, silt-rich surface, clay-rich surface and pure salt. The silt-rich surface is related to crevasse splays and river banks while the clay-rich surface is associated with floodplain and channel depressions. The classification results show that the silt-rich surface tends to have a positive relationship with annual precipitation, whereas the

A survival guide to Landsat preprocessing

“…Furthermore, some studies have performed relative correction of atmospherically corrected imagery to account for residual differences between images arising from imperfect preprocessing when surface reflectance is desired (Li et al. ). We suggest this approach only if both comparability between images and surface reflectance units are needed for a particular application.…”

Dryland anabranching river morphodynamics: Río Capilla, Salar de Uyuni, Bolivia

“…Because of data availability, we selected two sets of satellite images for detailed bank accretion and erosion in the study area (Table 1). The observation period between the two sets of high-resolution satellite images is representative because longer observation periods using relatively long-term time-series satellite data (e.g., Landsat imagery from 1980 to 2011) have shown that changes in channel morphology are ongoing in the study area (Li et al, 2014b). The QuickBird-02 and Worldview-02 images have been projected to Universal Transverse Mercator (UTM).…”

Cascades of sub‐decadal, channel‐floodplain changes in low‐gradient, non‐vegetated reaches near a dryland river terminus: Salar de Uyuni, Bolivia

“…Although there are no flow gauging records, small to moderate (sub‐bankfull) river flow events occur one or more times in most years, with larger events (bankfull or above) occurring at least once every few years. According to local accounts, following heavy rainfall and significant flow in the Río Colorado and other local rivers, water depths in Salar de Uyuni can reach up to 10 m, but analysis of Landsat time‐series satellite imagery (1985–2011) indicates that the lake typically dries out in the intervening winter months (Li et al, ). Field data on sediment loads are limited, but grain‐size analyses indicate that the lower Río Colorado system is dominated by silt and clay with subordinate very fine sand.…”

“…Salar de Uyuni is the world's largest salt lake, and is periodically supplied with water and sediment by low‐gradient, ephemeral rivers such as the Río Colorado. This river has been the focus of extensive previous studies that have shown, inter alia , how high‐resolution satellite imagery can be useful for quantifying channel‐floodplain morphology and dynamics in this poorly or non‐vegetated dryland setting, including meander bend dynamics, the development of crevasse splays, and avulsions (Donselaar et al, ; Torres Carranza, ; Li, , in press; Li et al, , b, , b, ; Li and Bristow, ; Sandén, ). Erosion cells have been noted in the upstream parts of the Río Colorado catchment (Li et al, ) and are also prominent features farther downvalley but have not been investigated in any detail.…”