Study On The “public Security Space Units” In Urban Area Of The Three Gorges Reservoir Area

The Three Gorges Dam is the world's largest hydropower station in terms of installed capacity, as well as a complex system for sustainable development of the living environment in the reservoir area. However, the peculiar natural environment of mountains and social environment of migration have exposed the urban public security of the reservoir area to great danger. In the reservoir area, wide distribution, diversity and strong association of and between disasters have resulted in frequent occurrence of disaster chains, which plus insufficient disaster-relief facilities and low efficiency pose remarkable consequential threats to the urban public security. Under such background, the present study is conducted in the following four aspects, taking the urban public security of the Three Gorges reservoir area as the study object:(1) Presenting a solution to the core problemTo solve the core problem by using regular public security planning methods(such as “broad” control for plain cities or cities in non-reservoir areas) against frequent occurrence of disaster chains endangering the urban public security(direct threat) and insufficient disaster-relief facilities and low efficiency(indirect threat), this study, based on relevant studies in the field of public security and following the thought of “refined unit control”, has presented the concept of “public security space unit” from the perspective of disaster chains, and first defined “public security space unit” as “a space unit determined in general consideration of control elements at disaster-causing, disaster-affected and disaster-relief stages, following the guidance of proper refined control and based on assessment of specific disaster chain threats”, intending to explore a new approach to solve complex and volatile urban public security problems in the Three Gorges reservoir area.(2) Determination of the focus and conducting specific research“Public security space units” determined based on disaster chains comprise a complex system, in which “disaster-causing, disaster-affected and disaster-relief” elements cannot be generally and systematically coordinated by using regular public security planning methods(for single-disaster control). In consideration of the foregoing, the present study presents a thought of “cross-discipline integration”, and proposes a concept of “disaster tolerance” derived from “fault tolerance” of computer network systems in the system complexity theory, while determining the research focus, i.e. “to enhance the stability of the overall urban public security system by promoting the disaster tolerance of public security space units”.Then “disaster-tolerating mechanism(theory)” of urban public security units and “planning intervention(technique)” are studied.1) Disaster-tolerating mechanisma. Environmental constraint-“what disaster to tolerate”, for identifying the type ofa disaster chain threatening public security space units;b. System nesting-“how many disasters can be tolerated”, for determining thescale of public security space units;c. Structural robustness-“how to tolerate a disaster”, for constructing a systematic structure of public security space units;d. Dynamic evolution-“how to sustain disaster tolerance”, for maintaining the sustainability of public security space units.2) Planning interventiona. Scope determination-“identification and extraction” of public security space units;b. Chain-breaking and disaster-relieving-breaking the “disaster-causing chain” for public security space units(to reduce direct threat);c. Relief against formed chains-constructing a “disaster-relieving chain” for public security space units(reducing indirect threat).(3) Conducting research on differentiated practice and drawing conclusionsCentering on the core urban public security problem of the Three Gorges reservoir area, research on differentiated practices in representative shanty areas, resettlement areas and water front areas selected was conducted. Based on results of the research, the following conclusions are drawn:1) Practical constructionIn reconstruction of shanty areas, prime consideration shall be given to public security problems resulted from “creeping corrosion chain” and “bursting and spillage chain”, while in improvement of resettlement areas and treatment of water front areas, prime consideration shall be given to those resulted from “bursting and spillage chain” and “trunk and branch basin chain”.Unit control of intermediate level is added to the current urban public security planning system, so that the stability of the overall urban public security system can be enhanced by improving the “disaster tolerance” of “public security space units”(of a specific disaster chain); “territories” of public security space units are determined based on multi-scale; “chain-breaking and disaster-relieving” for public security space units are conducted based on evaluation of multiple emergency plans(to reduce direct threat); “relief against a formed disaster chain” among public security space units is analyzed from multiple perspectives(to reduce indirect threat).(4) Collating research content and summarizing key innovations1) Theoretical system-oriented by “refined unit control and cross-discipline integration”, the study has presented the concept of “public security space units” against practical urban public security problems in the Three Gorges reservoir area, and constructed a theoretical research system centering on the “disaster tolerance” of public security space units.2) Technical methods-based on the “disaster tolerance” of public security space units, the study has also discussed “disaster-tolerating mechanism” and “planning intervention”, in which there are three key techniques, i.e. “unit definition, chain-breaking and disaster-relieving and relief against a formed disaster chain”.3) Application in practice-three typical areas with projecting core public security problems are selected in the Three Gorges reservoir area to study differentiated planning of “public security space units”, which has produced some enlightenments in aspects of construction practice and theoretical methods, and indicated the feasibility of planning differentiation.