# Soil Erosion Assessment and Prediction in Urban Landscapes: A New G2 Model Approach
## 4 Discussion  
The intense expansion of urban functions and the need for new space for the growth of cities leads to changes in the structure of land cover, i.e., to the transformation of agricultural, as well as natural and semi-natural elements, into non-porous areas. Such surfaces cause the cessation of natural processes and have a highly negative impact on the land surface and groundwater regime causing the intensification of rapid surface runoff, the frequency of high waters, urban floods, and the intensification of erosion processes [85]. These changes lead to an increased risk for the infrastructure (road network and bridges), residential and commercial zones, sewerage and drainage systems, water supply sources and reservoirs, thus disrupts vital urban functions [11, 86, 87]. On the other hand, soil erosion can presents a vector of negative impacts and lead to endangered public health through sources pollution affecting water supply [88], the loss of fertility of agricultural  
Figure 8: Spatial distribution of soil loss using the G2 model for 2001 (**a**) and 2019 (**b**). Figure 9: Average values of soil loss in relation to land cover. land by nutrient removal [89; 90], as well as to participate in factors that cause climate change, given that eroded areas have increased carbon emissions into the atmosphere [91]  
Based on these facts, there is an increased need for the research of modalities for determining relevant research procedures, methods and techniques that will indicate the spatial and temporal scale of the occurrence and development of erosion processes and the environmental degradation forms. Contemporary cities are a dynamic conglomeration of urban functions that primarily depend on the built infrastructure and facilities, but the quality and safety of life of city dwellers also depends on the stability of natural and semi-natural elements as well as on the productivity of agricultural land. The functionality and safety of life of the inhabitants is related to the quality of the environment, so urban landscapes can be interpreted as an outdoor laboratory that has the potential to contribute to determining the modalities of the degradation processes monitoring. Soil loss estimation using the G2 model was analyzed for two time periods, i.e., for the beginning of the entry into force of the Master Plan of Belgrade (2001) and for the period that is close to the end of its validity (2019). For the first period, the annual soil loss ranged from 0 to 200.86 t\(\cdot\)ha\({}^{-1}\cdot\)y\({}^{-1}\), with an average value 4.11 t\(\cdot\)ha\({}^{-1}\cdot\)y\({}^{-1}\). The analysis of the second period revealed an annual soil loss of which values range from 0 to 193.11 t\(\cdot\)ha\({}^{-1}\cdot\)y\({}^{-1}\), with an average value of 3.63 t\(\cdot\)ha\({}^{-1}\cdot\)y\({}^{-1}\). Comparative analysis identified a slight reduction in soil losses. The total area endangered by soil erosion was reduced from 526.46 to 481.39 km\({}^{2}\), which is a decrease of 8.56%. Despite this, all seven categories are present for both observed periods. In other words, the change is not so pronounced that there is a disappearance of a certain category of loss, but there is a distribution of quantities within categories, as well as a certain change in area categories (Table 6). The share of areas in the category of low medium erosion increased from 2.43% in 2001, to 2.95% in 2019, which represents a growth of 10.95%. In addition to this category, the areas in the category of medium erosion increased from 5.38% to 8.05%, and an increase of 36.78% was recorded for that area. In contrast, the areas of high and very high category of erosion were reduced by 30.02% and 21.92%, respectively, while the categories of high-medium erosion and very low erosion were reduced by 8.04% and 9.49%, respectively. Low-intensity erosion, which is classified in the category of low erosion, has experienced the lowest degree of modification, so that it still plays a dominant role in the dynamics of soil erosion.