The New Island-Wide LS Factors of Taiwan, with Comparison with EU Nations

Abstract

Soil erosion is a global environmental challenge that the United Nations Sustainable Development Goal (UN SDG) #15 wants to address, and the topographic factor, according to the RUSLE (Revised Universal Soil Loss Equation) model, is one of the most critical factors causing soil erosion. In this study, we employed three separate digital elevation models of Taiwan, with horizontal resolution ranging from 20 to 90 m, to compute the LS factors based on the upslope contributing areas and multiple flow directions, utilizing the methodologies used by the European Soil Data Centre. This is the first study to create a map of Taiwan’s island-wide LS factors without using a fixed slope length of 40 m. To compare European Union countries with Taiwan, we also calculated their LS means, standard deviations, and coefficients of variation of LS factors. As a result, Taiwan’s high LS values are readily noticeable as compared to the EU. Taiwan’s LS factor is greater than that of any EU country and the United Kingdom, at 2.69 times the EU average. To put it another way, while all other erosive factors are held equal, Taiwan’s average soil erosion is about 2.69 times that of the EU. With an LS factor of 6.95, Austria has the highest average LS in the EU, yet it is 91 percent of Taiwan’s. The findings demonstrate that Taiwan has a far higher mean LS factor than any EU country or the United Kingdom, which helps to partially explain why soil erosion in Taiwan is substantially higher than in the EU.

Assessing the Impact of Engineering Measures and Vegetation Restoration on Soil Erosion: A Case Study in Osmancık, Türkiye

“…Although the resolution of the digital elevation model (DEM) employed to compute the LS factor within the study region is deemed sufficient at 10 × 10 m, it is worth noting that it could potentially yield elevated values in regions characterized by slopes exceeding 20 degrees [65]. The average value of the LS factor (73.94), calculated for the study area, is approximately ten times higher than Austria, which has the highest average LS factor (6.95) in the European Union [66]. The LS factor is the sole determinant contributing to greater erosion in the study area compared to Europe, irrespective of other influencing factors.…”

Soil Erosion in Taiwan

“…The LS factor for Taiwan is shown in Figure 3c, and it was determined using SAGA GIS and the Desmet and Govers [38] equation, as described in the preceding section. This result was first published by Chen and Nguyen [41]. Eight categories were used to categorize Taiwan's LS factors: 0.1, 0.1-0.5, 0.5-1, 1-2, 2-3, 3-5, 5-10, and >10.…”

“…It is also a significant advance over Lin and Huang's [25] work, which employed a much older digital elevation model with a horizontal resolution of 40 m and assumed a constant L = 40 for each slope in Taiwan. Chen and Nguyen [41] previously published the LS factor distribution for the entire Taiwan island using this approach and compared the results with that of the EU nations.…”