GRSG Conference 2022: Orbit to Outcrop

Title: LiDAR application for assessing the restoration success by reducing soil erosion of phosphate mines

Author: Shir Fuchs


Mining contributes significantly to economic development at both the local and global levels. However, these contributions are frequently accompanied by extensive environmental damage, such as widespread land degradation, water, air pollution, and other environmental disturbances (Levi, 2021). Stripping, excavation, transportation, and dumping have different effects on soils properties and soil erosion rate. Moreover, the reconstructed landscape produces increased small-scale spatial heterogeneity of mined soils that affect hydrology, soil erosion, and the entire landscape.

Thus, restoration of mining area seeks to return the land to its original function and conditions, thus restoring the ecosystem that was degraded or damaged to its previous state. However, estimating the restoration success based on geomorphic characteristics of soil erosion in mining areas presents a significant challenge (Zou, 2019).

In the current study, I aim to examine the mechanism of phosphate mining restoration in two different restoration methods (rehabilitation and ecological restoration), focusing on the geomorphological aspect of soil erosion and assessing the quality of the restoration success in each technique.
My study will take place over the area of an open-pit phosphate mine in the Negev Desert, Israel. The Zin phosphate mine is the largest in Israel, includes 30.4 km^2 and has been active since the 1970’s. it is one of several mining fields located at the eastern edge of the Negev Highlands. The local climate is hyper-arid with a long-term annual average rainfall of about 50 mm and high potential evapotranspiration rates. Until the 1990’s, minimal efforts were made to rehabilitate the area.

These efforts mainly included redistributing the overburden into the open pit and stabilizing the surface using road rollers to return it to its original topography and were prevalent until the beginning of the 1990’s. However, for the past 20 years, the mining practices have changes towards a more ecological restoration approach that includes topsoil applications. The geomorphological restoration phase is the initial reclamation phase in the new method (topsoil conservation method).

Accordingly, my first objective is to determine whether an area to which the topsoil conservation method was applied resembles the adjacent natural area better in terms of the geomorphological properties, considering the extreme environmental and climatic conditions in this hyper-arid region. My second goal is to evaluate the restoration success over time in both the topsoil conservation method and the traditional method. I wish to assess the geomorphological restoration success using remote sensing technologies, mainly by Light Detection and Ranging (LiDAR) – a remote-sensing method used to examine the earths surface.

LiDAR can be used to create high-resolution 3D- point clouds, reconstruct topography and allow geomorphologists to evaluate the landscape at a level beyond the capabilities of aerial photography, satellite imagery, and topographic maps alone. A critical ability associated with LiDAR data is processing to virtually remove vegetation and other obstructions in order to see the bare earth underneath.

The high resolution (high-density point data) of the LiDAR allows for more detailed analysis at the sub surface scale. Also, repeat LiDAR or comparison of LiDAR with other remote sensing methods such as imaging spectroscopy, can be used to evaluate landscape change over time due to the variety of processes: rivers and streams, landslides, floods and erosion, and in the case of the current study – due to phosphate mines restoration efforts. The restored success will be considered by linking the geomorphological processes and restoring diverse habitats properties, such as soil micro-organisms, and biocrusts.