云南降雨型滑坡县级预警雨量阈值分析

根据云南省华坪县滑坡灾害历史数据和同期气象站实测小时降雨资料,以滇西北的华坪县为例动态地计算了每次滑坡灾害的有效降雨天数和对应前期的有效降雨量;并应用主成分分析法对44场降雨型滑坡进行分析,结果表明间接前期雨量、发生雨量和激发雨量对诱发滑坡都有重要影响,得出诱发滑坡的降水有短时强降雨和长时低强度降雨两种类型。由此建立了含有两类降雨特点的华坪县I〖CD*2〗D（降雨强度〖CD*2〗历时）阈值曲线,并在此过程中提出了确定降雨历时D结束时刻的方法和有待进一步研究的问题。通过对华坪县滑坡预警雨量研究,为其他县级滑坡灾害预警雨量阈值的确定提供一种方法。     

大降雨型滑坡临界雨量及潜势预报模型研究

通过对湖北省1975～2002年发生的194次滑坡个例进行分析发现：滑坡时间主要发生在5-8月,占全年总次数的80％左右,与多年月平均雨量分布比较一致;滑坡区域主要位于湖北西部山地,高频中心在三峡库区;滑坡与前期降雨尤其是大降雨关系非常密切,大降雨型滑坡占滑坡总次数的63．1％。利用实效雨量计算方法,确定了大降雨型滑坡临界雨量,以此为依据建立了潜势预报模型。     

植被覆盖对暴雨型滑坡影响的初步分析

根据遥感资料、地形数据和历史观测资料等,以江西省为例,分析了森林植被覆盖率、森林生物量和暴雨型滑坡的空间分布,以及森林植被类型对大气降水的截留作用。分析结果初步揭示了植被覆盖对滑坡的影响,认为植被覆盖程度高、生物量多和植被覆盖差、生物量低的中低山区,都可能发生滑坡灾害。不同林冠对降水的截留作用,减缓了降水对斜坡的冲刷,但当降水强度达到或超过暴雨强度时,森林对降水的截留率减小。同等地质环境条件下,植被覆盖率低,滑坡较易发生,但当降水强度较大时,特别是达到诱发滑坡灾害发生的临界值时,植被对滑坡体的重力作用则更加重了滑坡的发生。植被覆盖对滑坡的影响主要取决于降水强度。高森林覆盖区发生滑坡的雨量临界值大于森林覆盖率差的区域。     

暴雨型滑坡灾害因素分析及预测试验研究

针对暴雨型滑坡灾害预报预警服务的需要, 以江西为研究区域, 从暴雨型滑坡灾害形成机理及预测理论入手, 通过8个滑坡灾害易发点的监测试验, 系统地研究了大气降水对地下水位、孔隙水压力、滑坡土体应力及滑坡稳定性的影响, 探讨了植被覆盖与滑坡的关系。结果表明:滑坡稳定系数与降水量有较好的负相关关系, 当降水量增大时, 滑坡稳定系数减小, 且略滞后于降水量的峰值; 在其他因素一定的条件下, 地下水位升高, 滑坡稳定系数直线下降。经计算得到8个试验点促使滑坡复活的临界指标是24 h降水量为60~203 mm, 值域的变化与滑坡体的土壤结构、力学性质、植被覆盖程度和降水强度的时空分布等因素有关。     

铜仁地区滑坡临界雨量研究

利用铜仁地区2010—2014年以来61起滑坡事件对应的区域气象站以及气象台站逐小时降水资料,采用统计分析的方法分析了滑坡发生前后的降水类型,建立了不同时效的有效雨量和激发雨量组合的预报模型。结果表明:滑坡前期3天累积雨量与滑坡暴发当日3h最大雨量组合预报模型的准确率最大,空报率最小,滑坡暴发当日24h雨量与滑坡暴发当日3h最大雨量组合预报模型的准确率次之,并分别得到这两种情况下判断滑坡是否发生的判别曲线,根据判别曲线和24h及3h降水预报,可以制作铜仁地区的滑坡预报。     

降水与滑坡稳定性临界值试验研究

针对暴雨型滑坡灾害预报预警服务的需要,以江西为研究区域,建立了8个滑坡灾害监测点.通过监测试验,较系统地研究了大气降水对地下水位、孔隙水压力、滑坡土体应力及滑坡稳定性的影响;进行了大气降水、地下水位和滑坡稳定性的模拟,初步确定了江西省8个代表点促使滑坡复活的临界降水量指标,初步划分出江西省滑坡灾害预警降水量临界值.     

暴雨型滑坡灾害形成机理及预测方法研究思路

暴雨型滑坡灾害形成机理和预测方法研究,在国内外仍是个难题和热点。本研究的总体思路是：以江西为研究区域,从暴雨型滑坡灾害形成机理及预测理论入手。通过8个滑坡灾害易发点的监测试验,系统地研究大气降水对地下水位、孔隙水压力、滑坡土体应力及滑坡稳定性的影响,探讨植被覆盖与滑坡的关系;根据历史资料,进行滑坡风险区划和暴雨型滑坡的时空分布特征分析;应用统计学和试验研究相结合的方法,提出滑坡体发生滑动的临界雨量指标;开发基于Web—GIS的暴雨型滑坡灾害预报预警业务系统,并进行业务试验。     

A Probabilistic Prediction Model for Heavy Rain-Caused Landslides in the Chongqing Region

Landslide (or rockslide) is a geological disaster that is mainly induced by strong precipitation, among a number of other natural inducing factors. Based on 1615 landslide cases, a statistical analysis is performed to find the relationship among the landslide occurrence time, rainfall 0-10 days ahead, and probability of landslides over the Chongqing region. The results show that 1) strong rainfall-caused landslides occur mainly on the day it rains or 1-2 days after the heavy rain, and as time goes on, the likelihood of the disaster reduces rapidly; 2) the heavier the rainfall, the closer the landslide time is to the precipitation time.A concept of "effective precipitation" is thus developed, and a categorical prediction model for heavy rain-caused landslides is established. Tests show that for categories III, IV, and V landslides, the model forecast accuracy arrives at 29.9%, 75%, and 100%, respectively. This indicates that the categorized probabilistic prediction can serve as a warning for the landslide prevention and mitigation.     

机器学习分类算法在降雨型滑坡预报中的应用

针对气象灾害预警业务中客观描述降雨型滑坡发生不确定性的实际需求,利用2014—2020年全国滑坡数据以及多源融合降水实况分析数据,通过样本构建、模型训练、参数优化以及预报输出等关键步骤构建基于机器学习分类算法的区域降雨诱发滑坡概率预报模型,探究不同类型机器学习分类算法识别诱发滑坡的降雨过程的可行性。结果表明:在算法评估中,线性判别分析算法准确率最高且泛化能力最好,其次为逻辑回归算法,再次为最邻近算法。在预报试验中,线性判别分析、逻辑回归以及最邻近等算法能够提取并学习降雨诱发滑坡的条件特征,对诱发滑坡的降雨过程有一定识别能力,最邻近算法和逻辑回归算法的概率预报高值区范围相对较大,易造成虚警结果,线性判别分析算法对局地降雨信息的提炼较好,但线性判别分析算法在非降雨中心区域输出低值概率预报的面积偏大。     

滑坡泥石流大尺度统计预报模型的实时检验

利用滑坡敏感性分布和降雨阈值公式建立了一个滑坡泥石流统计模型,该模型可以用于中国大尺度范围内的滑坡泥石流预警。使用CMORPH卫星降水驱动该统计模型,对2016—2017年的106起滑坡泥石流事件进行了验证分析。结果表明,该模型能较好地预警大多数滑坡泥石流事件,其中对72. 1%的雨季滑坡泥石流事件能较好预警,但对非雨季的事件只有35%能较好预警,对雨季的预警效果明显优于非雨季。由于滑坡泥石流主要发生在雨季,因此该模型总体上具有较好的效能。该模型对于强降雨引发的快速滑坡事件具有较好的预警能力,但对于由强度较小、持续时间较长的降雨引发的慢过程滑坡事件的预警效果有待提升。利用该统计模型以及CMORPH实时卫星降水产品,可以建立滑坡泥石流大尺度实时预警系统,对滑坡泥石流减灾防灾具有一定意义。     

暴雨作用下基于滑坡互信息量的白家包滑坡变形响应机制研究

暴雨是诱发滑坡的重要因素之一,但目前对于暴雨作用下滑坡变形响应机制的研究仍不充分。该文以三峡库区白家包滑坡为例,在滑坡详细监测数据的基础上,分析了暴雨作用下白家包滑坡的变形响应特征;采用滑坡互信息量方法揭示了暴雨作用下降雨及库水位变动对白家包滑坡变形的影响规律。结果表明:白家包滑坡变形主要受库水位变动影响,坡表裂缝扩张主要受降雨影响;暴雨是诱发滑坡加速变形及边界处的坡表裂缝快速扩张的主要因素。该文的研究方法可推广到其它多条件联合作用下滑坡响应规律的分析,为类似暴雨作用下水库滑坡防灾减灾提供一定参考。     

Quantitative Analysis of Meso-β-scale Convective Cells and Anvil Clouds over North China

This paper proposes several quantitative characteristics to study convective systems using observations from Doppler weather radars and geostationary satellites. Specifically, in order to measure the convective intensity of each system, a new index, named the ``Convective Intensity Ratio' (CIR), is defined as the ratio between the area of strong radar echoes at the upper level and the size of the convective cell itself. Based on these quantitative characteristics, the evolution of convective cells, surface rainfall intensity, rainfall area and convectively generated anvil clouds can be studied, and the relationships between them can also be analyzed. After testing nine meso-β-scale convective systems over North China during 2006--2007, the results were as follows: (1) the CIR was highly correlated with surface rainfall intensity, and the correlation reached a maximum when the CIR led rainfall intensity by 6--30 mins. The maximum CIR could be at most ～30 mins before the maximum rainfall intensity. (2) Convective systems with larger maximum CIRs usually had colder cloud-tops. (3) The maximum area of anvil cloud appeared 0.5--1.5 h after rainfall intensity began to weaken. The maximum area of anvil cloud and the time lag between maximum rainfall intensity and the maximum area of anvil cloud both increased with the CIR.     

气候变化背景下中国滑坡灾害人口风险评估

中国是世界上滑坡灾害造成人口伤亡较严重的国家.受气候变化影响,极端降水频率与强度的增加会提高滑坡灾害的人口风险.文中将不同RCPs情景多个模式的未来降水数据和SSPs情景下的未来人口数据相结合,构建滑坡灾害人口风险评估模型,评估气候变化背景下的中国滑坡灾害人口风险.研究发现,气候变化下中国滑坡灾害的危险性呈上升趋势,预...     

Rainfall rate distribution in a local scale: The case of Barcelona city

Summary Convective rainfall rate distribution is not very uniform even at a local scale. In order to make an evaluation of it in the urban area of Barcelona, a dense rain gauge network has been stablished in this city. The gauges are of high resolution tilting bucket type. In this paper, preliminary results are presented. The distributions obtained show a strong variation of the rainfall rate for the several parts of the city. The intensity-duration curves for severe storms have been made in the various points of measure together with the areal reduction factors of rainfall. The analysis of raincell movement gives E-W as a predominant direction and a speed in the 3–12 m/s range.With 9 Figures     

气候变化对城市年径流总量控制率分区的影响

城市地区强降水发生频次和强度的增加容易诱发内涝现象,年径流总量控制率作为海绵城市的重要设计参数,更是直接受到降水变化的影响。以江苏省为例,利用全省70个国家级气象观测站1961—2019年最新的日降水量资料评估了气候变化对城市年径流总量控制率分区的影响。研究发现,有效降水的年代际变化十分明显,1991—2019年降水日数、降水量、降水强度均比其他时间段上更多、更强;太湖流域的设计雨量较小,连云港地区的设计雨量较大,南北差异随着控制率的提高而扩大,当控制率为85%时,全省设计雨量平均值为38.1 mm,最大值是最小值的1.7倍;气候变化对年径流总量控制率分区影响明显,江苏的苏南、江淮南部大部分地区的分区变大,导致全省IV区所占面积明显增加。不同等级降水的变化趋势是影响年径流控制率分区的关键因素,大雨以上的雨日、雨量在有效降水中占比增加,则分区变大。     

Comparing modern and Pleistocene ENSO-like influences in NW Argentina using nonlinear time series analysis methods

Higher variability in rainfall and river discharge could be of major importance in landslide generation in the northwestern Argentine Andes. Annual layered (varved) deposits of a landslide dammed lake in the Santa Maria Basin (26°S, 66°W) with an age of 30,000 ¹⁴C years provide an archive of precipitation variability during this time. The comparison of these data with present-day rainfall observations tests the hypothesis that increased rainfall variability played a major role in landslide generation. A potential cause of such variability is the El Niño/Southern Oscillation (ENSO). The causal link between ENSO and local rainfall is quantified by using a new method of nonlinear data analysis, the quantitative analysis of cross recurrence plots (CRP). This method seeks similarities in the dynamics of two different processes, such as an ocean–atmosphere oscillation and local rainfall. Our analysis reveals significant similarities in the statistics of both modern and palaeo-precipitation data. The similarities in the data suggest that an ENSO-like influence on local rainfall was present at around 30,000 ¹⁴C years ago. Increased rainfall, which was inferred from a lake balance modeling in a previous study, together with ENSO-like cyclicities could help to explain the clustering of landslides at around 30,000 ¹⁴C years ago.     

Anomalous Midsummer Rainfall in Yangtze River-Huaihe River Valleys and Its Association with the East Asia Westerly Jet

In this study, the interannual and interdecadal relationship between midsummer Yangtze River-Huaihe River valley (YHRV) rainfall and the position of the East Asia westerly jet (EAWJ) were investigated. The midsummer YHRV rainfall was found to significantly increase after the 1980s. Moreover, the location of the EAWJ was found abnormally south of the climatic mean during 1980–2008 (ID2) compared to 1951–1979 (ID1). During ID2, associated with the southward movement of the EAWJ, an anomalous upper-level conver-gence occurred over middle-high latitudes (35°–55° N) and divergence occurred over lower latitudes (～30°N) of East Asia. Correspondingly, anomalous descending and ascending motion was observed in middle-high and lower latitudes along 90°–130° E, respectively, favoring more precipitation over YHRV. On an interan-nual time scale, the EAWJ and YHRV rainfall exhibited similar relationships during the two periods. When the EAWJ was centered abnormally southward, rainfall over YHRV tended to increase. However, EAWJ-related circulations were significantly different during the two periods. During ID1, the circulation of the southward-moving EAWJ exhibited alternating positive–negative–positive distributions from low to middle– high latitudes along the East Asian coast; the most significant anomaly appeared west of the Okhotsk Sea. However, during ID2 the EAWJ was more closely correlated with the tropical and subtropical circulations. Significant differences between ID1 and ID2 were also recorded sea surface temperatures (SSTs). During ID1, the EAWJ was influenced by the extratropical SST over the northern Pacific; however, the EAWJ was more significantly affected by the SST of the tropical western Pacific during ID2.     

基于卫星降水和WRF预报降水的“6.18”门头沟泥石流事件的回报检验研究

2017年6月18日北京门头沟地区突发泥石流,造成6人伤亡。短时强降水是这起事件的主要诱发因素,但常规气象观测并没有很好地观测到此次降水过程,可见降水数据的准确性对于滑坡泥石流的实时预警及预报至关重要。近年来,卫星遥感估算降水发展迅速,WRF（Weather Research and Forecasting Model）模式关于降水的预报技巧也逐渐提高。本文以自动站降水资料为参考,首先利用定性方法和泰勒图、TS（Threat Score）评分等定量的方法比较了CMORPH（CPC MORPHing technique）、GPM（Global Precipitation Measurement）和PERSIANN-CCS（Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System）三种卫星降水资料以及不同起报时间的WRF预报降水对此次降水过程的表现能力,然后利用降水数据驱动滑坡泥石流统计预报模型,对此次事件进行了回报,分析不同降水数据在模型中的实际应用效果,最终为滑坡泥石流实时预警和预报系统的构建提供参考。结果表明,三种卫星降水资料基本上能反映出此次降水过程东北—西南向的带状空间分布形态,其中,CMORPH与自动站资料的空间相关性最好,命中率也最高,但对降水量有一定的高估,GPM对平均降水量的时间变化有较好的反映,体现了卫星降水在观测较少地区的良好利用价值,PERSIANN-CCS的表现则相对差些。WRF模式能预报出此次降水的带状空间分布特征,但降水中心的位置与实际有所偏差;此外,预报的最大降水量的峰值出现时间比实际上晚。由于此次降水的强局地性,只有空间分辨率均匀且质量相对较好的CMORPH卫星降水驱动模型可以回报出此次事件,而自动站点资料由于空间分布不均,则没有回报出此次事件,这表明了卫星降水在滑坡泥石流实时预警系统的构建中具有一定的优势。WRF模式降水驱动模型可以提前做出预警,虽然预报的事件发生时间与实际相比偏晚3~5 h,但WRF可以较好地预报72 h内的降水,因而可以延长灾害的可预见期。WRF模式预报降水的时间和空间精度都需要进一步提高,但是仍具有很好的参考意义。     

基于水土耦合机制的流域滑坡预报研究

降水诱发型滑坡灾害涉及水文与土壤失稳过程,是个非常复杂的预报难题。本研究应用CRESLIDE(Coupled Routing and Excess Storage and Slope-Infiltration-Distributed Equilibrium)模型,研究基于水土耦合机制的流域滑坡预报。模型输入格点降水由基于流域逐小时加密雨量站的反距离权重法插值获取;基于GIS、DEM和遥感技术,提取滑坡流域下垫面信息;采用分布式水文模型CREST模拟预报出滑坡研究区域的流域水文过程,作为中间变量驱动滑坡模型SLIDE,实现降水诱发型滑坡的预报。选择陕南月河流域2012年7月3—5日降水诱发型滑坡过程进行模拟预报,验证模型的适用性。结果表明,基于CRESLIDE模型的流域水土耦合滑坡预报模型在滑坡时空预报上表现稳定;通过ROC曲线分析CRESLIDE模型取得的特异性(87.8%)和敏感性(52.9%)均较好;本研究基于流域水土耦合机制研究滑坡机理预报,耦合了流域水文过程与土力学过程,使得流域水文模拟更为合理,在滑坡的预报与早期预警中表现良好,对同类滑坡预报有一定的借鉴意义。     

暴雨型滑坡灾害预报预警方法研究评述

滑坡灾害对人类和社会经济的影响已成为仅次于地震的第二大自然灾害。暴雨诱发的滑坡占滑坡总数的90％左右。从滑坡预报方法、暴雨型滑坡灾害时空预报预警、降雨和滑坡机制及稳定性、GIS在滑坡预报中的应用等几方面,分析了国内外动态及发展趋势。分析结果认为,现代数理科学新理论在滑坡预报中的综合应用得到了较快发展;“3S”技术作为滑坡监测预报手段,仍存在没有开发出来的较大潜力;从理论上,机理研究与区域统计研究结合程度有待进一步发展和突破;已建立的滑坡灾害预测预报模型具有很大的地域性、分散性以及由于监测资料不足带来的不稳定性,有必要进行更加系统深入的探讨,尤其要着力建立基于滑坡灾害发生机理的宏观区域预警模型;降雨-滑坡关系需有更准确的模型;受降水影响的土体含水量和孔隙水压力的测量方法应更精确、有效;基于Web-GIS平台建立区域滑坡灾害实时预警预报系统十分必要。