Geodetic and UAV Monitoring in the Sustainable Management of Shallow Landslides and Erosion of a Susceptible Urban Environment

Paul Sestras,Sanda Roșca,Ștefan Bilașco,Branislav Dudic,Artan Hysa,Velibor Spalević

doi:10.3390/rs13030385

Abstract

Landslides are a worldwide occurring hazard that can produce economic impact and even fatalities. The collection and monitoring of data regarding active landslides are important for predicting future landslides in that region, and is critical to minimize the losses caused. In the expanding metropolitan area of Cluj-Napoca, Romania, drastic changes of land use and increasement of construction zones represent a current evolution issue. The urban sprawl phenomenon imposed the expansion of the city limits and outside the old built-up area, and due to the hilly terrain and geomorphology, natural hazards such as landslides and erosion processes are susceptible to appearance or reactivation. The study incorporates interdisciplinary research composed of evaluation of a landslide susceptible hotspot located in an area of interest to the municipality by means of geodetic and topographic precise measurements, combined with the use of unmanned aerial vehicles (UAV) monitoring of surface movement and GIS spatial analysis. The data obtained in a span of over two years reveal that the investigated slope is subjected to a shallow active landslide of a few centimeters per year, and based on the 64 individual placed landmarks the highest displacement value was 67 mm. Through geomatic tools the exchange rate of the slope surface was evaluated with comprehensive volume calculations, such as displacement, erosion, and accumulation that illustrate a volume of material displaced of 107.2 m3 and the accumulated one of 55.7 m3. The results provide valuable insight into the complex landslide and erosion dynamics that are crucial when predicting future movements and prevention measures.

Highlights

The results obtained are presented for each directional alignment, with the values of landmark displacements calculated as linear displacement, obtained as a distance composed of dX, dY, dZ and expressed in millimeters (Figure 12)
The linear displacements on the directional alignments have the maximum values in the upper part of the slope, after which these values decrease toward the lower part, where they register a slight increase, due to the tendency of accumulation of the sliding mass
This fact was found by visual observations on the ground, as at the bottom of the slope the landmarks had a discordant shape with the slope of the land, the stakes being oriented toward the hill, because of the accumulation of displaced land

Summary

Introduction

In the constant expanding and increasingly populated Cluj-Napoca metropolitan area (Transylvania, Romania), the evolution imposed by the changes of land use and increasement of construction zones represents a current issue [1,2,3]. With a general move toward urbanization, land is becoming an increasingly difficult resource to obtain and the construction market is a desideratum. The unprecedented urban sprawl phenomenon imposed the expansion of the city limits and the transformation of adjacent villages from Cluj-Napoca into unprepared suburbs [4,5]. Given the hilly terrain and geomorphology, natural hazards such as landslides and erosion processes are susceptible to appearance or reactivation

Methods

Results

Discussion

Conclusion