Influence of DEM Elaboration Methods on the USLE Model Topographical Factor Parameter on Steep Slopes

Abstract

Runoff erosion is an important theme in hydrological investigations. Models assessing soil erosion are based on various algorithms that determine the relief coefficient using rasterized digital elevation models (DEMs). For evaluation of soil loss, the most-used model worldwide is the USLE (Universal Soil Loss Equation), where the most essential part is the LS parameter, which is, in turn, generated from two parameters: L (slope length coefficient) and S (slope inclination). The most significant limitation of LS is the difficulty in obtaining the data needed to generate detailed DEMs. We investigated three popular data generation methods: aerial photographs (AP), aerial laser scanning (ALS), and terrestrial laser scanning (TLS) by assessing the quality and effect of DEMs generated from each method over an area of 40 m × 200 m in Silesia, Poland. Additionally, the relationship between particular LSUSLE parameter components was carried out based on its final distribution. Our results show that resolution strongly influences DEMs and the LSUSLE parameters. We found a strong relationship between the degree of height data resolution and the accuracy level of the calculated parameters. Based on our investigations we confirmed the highest influence on the LSUSLE came from the S parameter. Additionally, we concluded that in examinations over large areas, terrestrial laser scanners are not ideal; the benefits of their additional accuracy are outweighed by the additional time and labor consumption; in addition, terrestrial-based scans are sometimes not possible due to ground obstacles the limited scope of most lasers. Aerial photographs or point clouds generated by aerial laser scanners are sufficient for most purposes connected with surface flow, and further developments can be based on the use of these techniques for obtaining ground information for modeling erosion processes.

Digital elevation model cell size effect on erosion‐deposition simulation using the unit stream power erosion and deposition model in the dry‐hot valley region of Southwest China

“…For example, Liu et al (2011) has concluded that DEM cell size significantly influenced the calculation of the L factor in a 0.88 km 2 watershed in the lowlands of northern Germany. Similarly, Li et al (2016) and Kruk et al (2020) have found that the S factor was more sensitive to changes in DEM cell size than the L factor, and the value of the LS factor decreased to 1/6-1/3 of its value when the DEM cell size increased from 30 m to 1000 m. These findings indicated that the DEM cell size can greatly affect the simulation accuracy of the USPED models by influencing the value of topographic factor (LS).…”

Linking Soil Erosion Modeling to Landscape Patterns and Geomorphometry: An Application in Crete, Greece

“…To extract the LS-factor, many algorithms are already built into GIS software programs, such as the System for Automated Geoscientific Analyses SAGA GIS [31]. In fact, SAGA provides numerous combinations of algorithms to derive the topographic data and preprocessing algorithms to fill sinks or for sink removal.…”

Estimativa da erosão hídrica em uma bacia hidrográfica no estado de Goiás (Brasil) por meio de modelagem e inteligência geoespacial

“…A USLE é um modelo empírico utilizado para estimar a perda média anual de solo por erosão laminar, considerando os fatores ambientais e antrópicos (Barbosa et al, 2015), sendo uma das equações mais utilizadas para modelar a erosão do solo, mesmo em larga escala (Kruk et al, 2020). Os componentes da equação são: índice de erosividade da chuva (fator R), índice de erodibilidade do solo (fator K), comprimento da rampa (L) e declividade (S) (fator LS), uso e cobertura da terra (fator C), manejo e práticas conservacionistas do solo (fator P).…”