Landslides are one of the most frequent natural disasters that cause significant damage to property in Vietnam, which is characterized by mountainous terrain covering three-quarters of the territory. In 17 northern mountainous provinces of the country, over 500 communes are at a high to very high landslide hazard. The main goal of this study was to establish landslide hazard maps and conduct a comparative evaluation of the efficiency of the methods employed in Tinh Tuc town, Cao Bang province. The landslide hazard assessment was carried out in this study using the combined Fractal-frequency ratio (FFR) and the Frequency ratio (FR) methods. The FR method is based on the actualist principle, which assumes that future landslides may be caused by the same factors that contributed to slope failure in the past and present. The FFR method is based on the determination of the fractal dimension, which serves as a measure of the landslide filling density in the study area. Eight landslide-related factors were considered and presented in cartographic format: elevation, distance to roads, slope, geology, distance to faults, land use, slope aspect, and distance to drainage. Determining the area under the receiver operating characteristic curve (ROC-AUC) and verification index (LRclass) was performed to assess the performance of prediction models and the accuracy of the obtained maps. As a result, five zones were identified for the study area, characterized by very low, low, moderate, high, and very high landslide hazards. The analysis of the reliability of the obtained landslide hazard maps using the AUC and LRclass indices revealed that the FFR model has a higher degree of reliability (AUC = 86 %, LRclass = 86 %) compared to the FR model (AUC = 72 %, LRclass = 73 %); therefore, its use is more effective.
The content of the state monitoring of endogenous geological processes (GMEGP) consists of the results of regular observations of the development of exogenous processes under the influence of natural and anthropogenic factors. All information obtained and analyzed is of two classes: factual and spatial. On the other hand, the information is divided into conditionally constant and changing over time. The use of GIS-technologies makes it possible to proceed to the creation of duty maps in the GMEGP system.
At present the system of monitoring of dangerous exogenous geological processes includes four levels: federal, regional, territorial and local. Data on development of exogenous geological processes are received from 2.1 thousand objects equipped with 24 thousand wells, profiles, benchmarks, etc. Special attention is paid to landslide processes which make up 40% of exogenic processes. Priority areas are: re-engineering geological survey of the territory of Russia, reorganization of structure and composition of observation network, creation of specialized subsystems for development of exogenous geological processes.
