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Intermediate-frequency debris flows has the characteristics of high danger and long outbreak period. Human activities can trigger its occurrence and aggravate its disaster severity. When the channel cannot meet the capacity for drainage and water transport, it will cause blockage and endanger the safety of both sides of the strait and even the main river channel. Due to the lack of analysis on the danger of intermediate-frequency debris flows, this paper takes the intermediate-frequency debris flow in Hada Gully, Yunnan Province as an example to explore its characteristics and the danger of its recurrence and channel blockage caused by debris flows and proposes prevention and control suggestions. The results show that the debris flow has a density of 1.62 t/m³, a flow velocity of 4.794 m/s at the outlet of the channel, a peak flow rate of 54.43 m³/s at the channel outlet and a total discharge of 11072.03 m³ for a single occurrence based on the 10% burst frequency. A culvert was constructed in the downstream channel, with a flow capacity of 16.5 m³/s, which is less than the flow rate of a debris flow once in 20 years. Once a large debris flow occurs, there is a risk of blockage. The study found that the hazard level of intermediate-frequency debris flows in Hada gully is highly dangerous, and the history of blockage indicates the possibility of its recurrence and the risk of debris flow blocking the Lapu River. [ABSTRACT FROM AUTHOR]

Utilization of urban underground space resources (UUSR) is one of the most effective approaches to expand urban space, optimize urban structure, solve city problems, improve city management and achieve high-quality development. The comprehensive evaluation of underground space resources is the premise of ensuring the safety utilization of underground space. This paper systematically analyzes the resource attribute and evaluation status of UUSR, and sorts out the major evaluation methods of UUSR and the application progress in different cities. It shows that the current evaluation of UUSR mainly adopts analytic hierarchy process and expert scoring method to assign value to the evaluation indexes, and to evaluate the exploitation and utilization of suitability, resource capacity, quality, value and development potential of UUSR, which is characterized by various evaluation purposes, extensive content and distinctive indexes selection. However, there are also some problems, such as strong subjectivity of weight assignment, and imperfect evaluation model, etc. Based on the analysis of urban underground space resources evaluation, the trend of UUSR evaluation is analyzed from the perspectives of collaborative evaluation of various underground resources, three-dimensional evaluation of whole space, and response evaluation of geological environment, which could provide valuable reference for the UUSR evaluation and utilization. [ABSTRACT FROM AUTHOR]