自然灾害风险区划是对自然灾害风险区域分异规律的一种具体的量化体现，包括单灾种风险区划和多灾种风险区划。目前单一致灾因子的风险研究比较常见，但不能够反映一个地区受多种致灾因子影响的真实风险，因此，有必要展开自然灾害综合风险区划研究。同时，自然灾害风险区划也被认为是灾害风险管理的理论基础，是开展预防性研究、防灾减灾、灾害风险管理与决策的可靠依据。综上所述，自然灾害综合风险区划研究十分必要，完善自然灾害综合风险区划理论与方法的研究不仅被认为是自然灾害综合风险研究的重要内容,相关成果还将更好地帮助我国各级地方人民政府制订防灾和减灾措施。
本文旨在提出舟曲县以洪涝、旱灾、地质灾害为主要致灾因子的自然灾害综合风险区划方案。具体地，基于R(Risk)= H(Hazard)×V(Vulnerability)风险评估模型，从自然灾害风险识别的角度构建致灾因子危险性评估指标体系，基于承灾体暴露程度、易损性等特征构建承灾体脆弱性指标体系，运用风险要素综合法，对致灾因子和承灾体进行分别评估后再综合，得到多灾种的自然灾害综合风险评估结果，并依据风险评估结果实现自然灾害综合风险区划。得到以下研究成果：
（1）从致灾因子危险性上看，高危险性地区有两类，一类为地形狭窄、地势极低的河谷地区，包括白龙江河谷和拱坝河下游河谷，这类地区的高危险性来自洪涝灾害、河谷两侧易发的地质灾害和河谷内部的干旱灾害。另一类为地势高、地形起伏大、沟谷发育的高山地区，这类地区的高危险性来自洪涝灾害，高山地区降水丰富，在高低起伏的地形作用下，更容易产流、汇流，形成山洪。
（2）从承灾体脆弱性上看，高脆弱性地区主要是人口集中分布的河谷地区，而由于南部乡镇老年人口占比大，人口结构指数更高，因此拱坝河下游河谷地区的脆弱性高于白龙江河谷的人口集中区，南部乡镇脆弱性也整体高于北部乡镇。
（3）从风险分布规律来看，舟曲县自然灾害高风险地区分布在拱坝河下游地区和白龙江流域的人口集中区，其他地区由于人口分布少，承灾体脆弱性偏低，因此自然灾害综合风险也偏低。
研究结果表明，舟曲县的人口过于集中于河谷地区，而河谷地区又受到来自洪涝灾害、干旱灾害、地质灾害的多重威胁，属于致灾因子高危险性地区。同时高强度人口活动带来的水土流失、植被破坏等问题，会使山洪、泥石流、滑坡等灾害频繁发生，给舟曲带来巨大损失。因此，舟曲县要做好对地质灾害隐患点的排查工作，同时做好气象预警工作，提高紧急疏散能力和救援能力。

Natural hazard risk zoning is a specific quantitative representation of the regional differentiation pattern of natural hazard risk, including single-hazard risk zoning and multi-hazard risk zoning. At present, risk studies of single hazard-causing factors are more common, but they cannot reflect the real risk of an area affected by multiple hazard-causing factors, therefore, it is necessary to conduct comprehensive risk zoning studies of natural hazards. At the same time, natural hazard risk zoning is also considered as a theoretical basis for disaster risk management and a reliable basis for preventive research, disaster prevention and mitigation, and disaster risk management and decision-making. In summary, the study of comprehensive natural hazard risk zoning is necessary, and the research on improving the theory and methodology of comprehensive natural hazard risk zoning is not only considered as an important element of comprehensive natural hazard risk research, but also the related results will better help local people's governments at all levels to formulate disaster prevention and mitigation measures in China.
The purpose of this paper is to propose a comprehensive risk zoning scheme for natural disasters in Zhouqu County with floods, droughts and geological hazards as the main causative factors. Specifically, based on the risk assessment model of R(Risk) = H(Hazard) × V(Vulnerability), a hazard assessment index system is constructed from the perspective of natural disaster risk identification for the hazard-causing factors, and a vulnerability index system is constructed for the hazard-bearing bodies based on the exposure and vulnerability of the hazard-bearing bodies. The risk assessment results of multi-hazard natural disasters are obtained, and the comprehensive risk zoning of natural disasters is realized based on the risk assessment results. The following research results were obtained：
(1) In terms of the risk of disaster-causing factors, There are two types of high-risk areas, one is the valley areas with narrow and very low terrain, including the valley of the Bailong River and the lower valley of the Gongba River, and the high risk of these areas comes from flood, the geological hazards that are prone to occur on both sides of the river valley and the drought hazards inside the valley. The other category is high terrain, undulating terrain, valley development of high mountain areas, the high risk of such areas from flooding, high mountain areas rich precipitation, in the role of high and low undulating terrain, more likely to produce flow, confluence, the formation of flash floods.
(2) In terms of vulnerability of disaster-bearing bodies, The high-vulnerability areas are mainly the valley areas where the population is concentrated, and the vulnerability of the lower valley of the Gongba River is higher than the population concentration areas in the valley of the Bailong River due to the large proportion of elderly population and higher demographic index in the southern townships, while the vulnerability of the southern townships is also higher than that of the northern townships overall.
(3) In terms of risk distribution pattern, The high-risk areas for natural disasters in Zhouqu County are located in the downstream area of Gongba River and the population concentration area in the Bailong River basin. Other areas have low population distribution and low vulnerability of disaster-bearing bodies, so the overall risk of natural disasters is also low.
The research results show that the population of Zhouqu County is overly concentrated in the river valley area, which is subject to multiple threats from floods, droughts, and geological hazards, and is a high-risk area for disaster-causing factors. At the same time, high intensity population activities bring about soil erosion and vegetation destruction, which can cause frequent disasters such as flash floods, mudslides and landslides, causing significant damage to Zhouqu. Therefore,, Zhouqu County should do a good job of checking the hidden spots of geological disasters, and also do a good job of weather warning to improve the emergency evacuation and rescue ability.