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1.
青海湖湖东沙地不同沙丘降雨入渗研究 总被引：2，自引：0，他引：2
降雨入渗对干旱、半干旱区土壤水分的影响很大,降雨量、降雨强度、土壤前期含水量等要素都会影响水分的入渗过程。本文通过监测青海湖湖东沙地3种类型沙丘的土壤水分和降雨情况,对区内降雨特征以及不同要素对沙丘水分入渗的影响进行了分析。结果表明：降雨量只有达到某一临界值才发生下渗,流动沙丘、固定沙丘、经治理（人工植被+麦草方格沙障）的流动沙丘发生下渗的临界降雨量分别为5.6 mm、1.6 mm、0.2 mm。水分累积入渗量随降雨量增大而增加,降雨量相同的情况下,入渗量大小表现为经治理的流动沙丘>固定沙丘>流动沙丘。当降雨量和土壤前期含水量相近时,入渗量随降雨强度的增大而增加,尤其在小降雨事件下,降雨强度是影响入渗的关键因素,大降雨事件下降雨量则成为影响入渗的决定因素。降雨量和降雨强度相近的情况下,入渗量与土壤前期含水量呈负相关关系。随着降雨量增大,入渗水分全部消耗所需要的时间逐渐增加,尤其当降雨量大于10 mm时,入渗水分消耗所需时间将随着降雨量的增大迅速增加。 相似文献
2.
利用数理统计方法分析了石林巴江流域中部近40年（1964-2001年）的气温和降雨量的年、季节和月变化。本区气温的增温速率是0．2℃／10a，与昆明市区增温率相近，低于同期全国增温速率；雨季（夏季）增温幅度大于旱季（冬季）。在过去40年中，年降雨量增加总量约为40mm，雨季降雨量略有降低，而旱季降雨量略有增强，全年第一次降雨强度和全年日最大降雨量也略有增加，但每年连续不降雨天数增加约1．9天。降雨量变化的波动性比气温变化的波动性强。气温、降雨量在1960s、1970s、1980s和1990s表现出不同的变化趋势。 相似文献
3.
根据福州市年降雨量数据资料,采用变异系数、趋势系数和气候趋势率等方法分析不同时间尺度的降雨和降雨侵蚀力的变化趋势。结果表明:(1)福州市年平均降雨侵蚀力和降雨量分别为393.06 MJ·mm·hm~(-2)·h~(-1)和1 394.43 mm。降雨侵蚀力和降雨总量年际波动显著,且年降雨量和降雨侵蚀力年内变化较大,主要集中在5、6、8、9月。(2)总体上夏季、秋季和冬季降雨侵蚀力的倾向率为正,分别为7.57、0.39和1.40 MJ·mm·hm~(-2)·h~(-1)·10 a~(-1),春季降雨侵蚀力倾向率为负值,呈减少趋势。(3)月降雨量和降雨侵蚀力的变化趋势基本一致,1、2、4、7、8、10、11、12月降雨侵蚀力有增加的趋势,3、5、6、9月降雨侵蚀力有减少的趋势。(4)福州雨季的降雨量和降雨侵蚀力分别为990.61 mm和285.90MJ·mm·hm~(-2)·h~(-1),并且其变异系数在全年中最小,均低于0.22;枯季的降雨量和降雨侵蚀力分别为403.82 mm和107.16MJ·mm·hm~(-2)·h~(-1),变异系数在全年中最大,均高于0.40,且福州降雨量和降雨侵蚀力在雨季、枯季及其年际变化均属于中等变异性(0.1≤CV≤1)。研究结果可为福州市的土壤侵蚀评估、预报和水土流失防治提供数据和理论支撑。 相似文献
4.
《山地学报》2019,(6)
在全球气候变暖背景下,极端性降水导致滑坡泥石流等自然灾害频发,关于降水与地质灾害之间的关系引起公众广泛的关注。本研究在对降水过程进行定量化划分的基础上研究滑坡发生与降水之间的关系,基于全国气象台站的地面降水观测资料,对2658例滑坡事件中的前期降水量、本场激发降水量、极端性降水量等不同时间尺度的降水特征进行了系统性的统计分析。结果表明:绝大部分的滑坡事件都属于前期有效降水主导型;前期降雨在导致滑坡的各个因素中占主导性地位;滑坡灾害发生前10 d特别是前5 d的降雨是导致滑坡发生的关键因素,而且降水产生时间与滑坡事件发生时间相隔越长,其在诱发滑坡事件发生的过程中的作用也越小;本场激发降雨是诱发滑坡事件发生重要的影响因素,持续时间大多集中在6 h之内,且以强度大、时间集中为特点的短时降水为主;极端性降水也是导致滑坡事件的关键诱发因素,大部分滑坡事件中的前15 d有效降水量和当日本场降水量在历史同期降水序列中均超过第90百分位数,具有明显的极端性特征。本研究从全国的视角来系统性地分析研究滑坡与降雨之间的关系,将为全国范围内的滑坡地质灾害预警提供参考。 相似文献
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陕西省降雨侵蚀力时空分布特征 总被引：2，自引：0，他引：2
根据陕西省全省96个数据序列较完整的气象站点逐日降水资料,利用章文波提出的基于日降雨侵蚀力模型估算陕西省的降雨侵蚀力,并采用反距离权重空间插值方法,借助GIS工具绘制全省侵蚀性降雨量以及侵蚀性降雨量空间分布图,分析其全年和四季空间分布特征,并分析了年内变化特征。结果表明:(1)陕西省降雨侵蚀力的空间分布与侵蚀性降雨量的空间分布基本一致,均呈由南向西北递减态势,降雨侵蚀力与降雨量、侵蚀性降雨量均达极显著相关水平;(2)降雨侵蚀力年内集中度高,夏秋季降雨侵蚀力较大,冬春季降雨侵蚀力较小,陕北地区和关中发生水土流失的时期主要集中在7~9月份,而陕南地区5~10月份均可能发生较大的水土流失,侵蚀潜在危险性由北向南递增;(3)陕西省降雨侵蚀力的年际变化也较为明显,年际变率CV在33.1%~77.3%,不同地区的年降雨侵蚀力差异及波动程度都比较大,北部地区降雨侵蚀力的年际变化大于南部地区。 相似文献
6.
通过统计红河州46年降雨资料,研究分析旬、月、季、年降雨量空间分布特征,结果表明:红河州5月降雨量、5～10月降雨量、年降雨量及11～4月降雨量的空间分布都存在从西南到东北呈多雨区、中雨区、少雨区的阶梯式分布待征。雨季前由西南到东北存在旬雨量从3月中旬至5月中旬逐渐增多的分布特征。这种有规律的、呈阶梯式降雨的分布特征和由西南到东北旬雨量从3月中旬至5月中旬逐渐增多的分布特征对指导短期气候预测有十分重要的意义。 相似文献
7.
基于GIS的区域群发性降雨型滑坡时空预报研究 总被引：2，自引：0，他引：2
以滑坡灾害突出的雅安市雨城区为例,综合考虑降雨强度、前期降雨量及下垫面(地形、岩性、植被覆盖等)构建了基于GIS分析获取的易发指数+BP型神经网络时空预报模型。首先通过试验确定了模型的网络参数和网络结构,然后通过危险性区划图获取降雨型滑坡易发指数,并利用GIS的空间插值功能和雨量站数据获取相应降雨型滑坡的雨量数据,将量化后下垫面的易发指数和降雨数据作为神经元输入层数据。将模型应用于研究区,其中46个降雨型滑坡数据作为训练样本,10个降雨型滑坡数据作为检验样本,预测精度达到90%,显示该模型对于降雨型滑坡的时空预报精度较高。 相似文献
8.
单立山李毅段桂芳张正中张荣种培芳 《干旱区地理》2016,(6):1267-1274
为了探讨西北干旱区两种典型荒漠植物1 a生幼苗生长和生物量分配对降雨格局变化的响应,在野外设置了双因素总降雨量和降雨间隔时间控制试验,测定了不同生长季节幼苗的生长及生物量分配情况。结果表明:(1)总降雨量增加30%对两种荒漠植物地下根系生长无显著影响(P>0.05),但促进了地上部分的生长,其中红砂株高、基径分别增加了25%、29%,白刺分别增加了10%、48%,在降雨间隔时间延长的情况下其效果更显著(P<0.05);总降雨量减少30%虽对两种荒漠植物株高和基径无显著影响(P>0.05),但促进了两种荒漠植物地下垂直根系的生长,红砂和白刺主根垂直深度平均分别增加了21%、40%,且降雨间隔延长其效果更显著(P<0.05)。(2)在总降雨量增加30%和降雨间隔时间延长的情况下,两种荒漠植物地上生物量和地下生物量达到最大值;而总降雨量减少30%,降雨间隔时间较短的情况下,两种荒漠植物倾向于将更多的生物量分配到地下,根冠比达到最大值,分别为0.64、0.78。(3)总降雨量增加降雨间隔时间延长的大降雨事件将有利于两种荒漠植物幼苗生长,然而这种促进效应依赖降雨间隔时间;降雨量适当减少虽抑制了两种荒漠植物幼苗地上生长,但增大了根冠比,改变生物量分配模式是其适应干旱胁迫的重要策略。 相似文献
9.
银武高速公路同心至固原段边坡面蚀试验分析 总被引：1，自引：0，他引：1
为研究高速公路边坡面蚀,选择银武高速公路同心至固原段固原立交2.5 km范围作为研究区段,根据不同公路边坡类型和防治措施设置6个观测小区,采用插钎法测定坡面的面蚀量,同时由虹吸式自记雨量计记录降雨量。分别测定和计算了降雨量、降雨历时、平均降雨强度、前期降雨量4个因子。分析结果表明,降雨对坡面面蚀的制约关系十分明显。影响面蚀量的主要降雨因子是降雨量和平均降雨强度,面蚀量与降雨量和平均降雨强度呈现极显著和显著的正相关关系,面蚀量与降雨因子中的前期降雨量呈现一定的负相关关系。采用强迫引入法,建立了面蚀量与降雨因子主成分的回归方程。 相似文献
10.
基于地形高程的云南省降雨量空间插值方法研究 总被引：1，自引：0，他引：1
以云南省1961-2010年多年平均降雨量和云南省数字高程模型为基础数据源,通过对降雨数据的分析,将数字高程模型作为影响降雨强度的主要因素,引入到降雨量空间预测的多元地理统计中,并利用协同克里格算法构建降雨强度与地形高程之间的数学关系模型,对云南省年平均降雨数据进行空间插值模拟。插值结果与距离权重法、一阶局部多项式法、二阶局部多项式法、样条函数法、普通克里格法等其他5种空间数据插值方法进行对比与分析,并通过分析各个交叉检验统计量来验证评估数据的误差,从而选取出最优的空间插值方法。结果显示,普通克里格法和协同克里格法对降雨量空间插值的效果和精度高于反距离法、局部多项式法和样条函数法,而协同克里格法由于考虑了地形高程对降雨量的影响,具有更好的插值效果,因而更适合山地降雨数据的空间插值。 相似文献
11.
Antecedent rainfall and short-term intense rainfall both contribute to the temporal occurrence of landslides in British Columbia. These two quantities can be extracted from the precipitation regimes simulated by climate models. This makes such models an attractive tool for use in the investigation of the effect of global warming on landslide frequencies.In order to provide some measure of the reliability of models used to address the landslide question, the present-day simulation of the antecedent precipitation and short-term rainfall using the daily data from the Canadian Centre for Climate Modelling and Analysis model (CGCM) is compared to observations along the south coast of British Columbia. This evaluation showed that the model was reasonably successful in simulating statistics of the antecedent rainfall but was less successful in simulating the short-term rainfall.The monthly mean precipitation data from an ensemble of 19 of the world's global climate models were available to study potential changes in landslide frequencies with global warming. Most of the models were used to produce simulations with three scenarios with different levels of prescribed greenhouse gas concentrations during the twenty-first century. The changes in the antecedent precipitation were computed from the resulting monthly and seasonal means. In order to deal with models' suspected difficulties in simulating the short-term precipitation and lack of daily data, a statistical procedure was used to relate the short-term precipitation to the monthly means.The qualitative model results agree reasonably well, and when averaged over all models and the three scenarios, the change in the antecedent precipitation is predicted to be about 10% and the change in the short-term precipitation about 6%. Because the antecedent precipitation and the short-term precipitation contribute to the occurrence of landslides, the results of this study support the prediction of increased landslide frequency along the British Columbia south coast during the twenty-first century. 相似文献
12.
Representative rainfall thresholds for landslides in the Nepal Himalaya 总被引：14，自引：0，他引：14
Measuring some 2400 km in length, the Himalaya accommodate millions of people in northern India and Pakistan, Nepal, Bhutan, and parts of other Asian nations. Every year, especially during monsoon rains, landslides and related natural events in these mountains cause tremendous damage to lives, property, infrastructure, and environment. In the context of the Himalaya, however, the rainfall thresholds for landslide initiation are not well understood. This paper describes regional aspects of rainfall thresholds for landslides in the Himalaya. Some 677 landslides occurring from 1951 to 2006 were studied to analyze rainfall thresholds. Out of the 677 landslides, however, only 193 associated with rainfall data were analyzed to yield a threshold relationship between rainfall intensity, rainfall duration, and landslide initiation. The threshold relationship fitted to the lower boundary of the field defined by landslide-triggering rainfall events is I = 73.90D− 0.79 (I = rainfall intensity in mm h− 1 and D = duration in hours), revealing that when the daily precipitation exceeds 144 mm, the risk of landslides on Himalayan mountain slopes is high. Normalized rainfall intensity–duration relationships and landslide initiation thresholds were established from the data after normalizing rainfall-intensity data with respect to mean annual precipitation (MAP) as an index in which NI = 1.10D− 0.59 (NI = normalized intensity in h− 1). Finally, the role of antecedent rainfall in causing landslides was also investigated by considering daily rainfall during failure and the cumulative rainfall to discover at what point antecedent rainfall plays an important role in Himalayan landslide processes. Rainfall thresholds presented in this paper are generalized so they can be used in landslide warning systems in the Nepal Himalaya. 相似文献
13.
Determining landslide susceptibility in Central Taiwan from rainfall and six site factors using the analytical hierarchy process method 总被引：6，自引：0，他引：6
This work provides a landslide susceptibility assessment model for rainfall-induced landslides in Central Taiwan based on the analytical hierarchy process method. The model considers rainfall and six site factors, including slope, geology, vegetation, soil moisture, road development and historical landslides. The rainfall factor consists of 10-day antecedent rainfall and total rainfall during a rainfall event. Landslide susceptibility values are calculated for both before and after the beginning of a rainfall event. The 175 landslide cases with detailed field surveys are used to determine a landslide-susceptibility threshold value of 9.0. When a landslide susceptibility assessment value exceeds the threshold value, slope failure is likely to occur. Three zones with different landslide susceptibility levels (below, slightly above, and far above the threshold) are identified. The 9149 landslides caused by Typhoon Toraji in Central Taiwan are utilized to validate the study's result. Approximately, 0.2%, 0.4% and 15.3% of the typhoon-caused landslides are located in the three landslide susceptibility zones, respectively. Three villages with 6.6%, 0.4% and 4.9% of the landslides respectively are used to validate the accuracy of the landslide susceptibility map and analyze the main causes of landslides. The landslide susceptibility assessment model can be used to evaluate susceptibility relative to accumulated rainfall, and is useful as an early warning and landslide monitoring tool. 相似文献
14.
A hydroclimatic threshold for landslide initiation on the North Shore Mountains of Vancouver, British Columbia 总被引：5，自引：0，他引：5
Landslides triggered by rainfall are the cause of thousands of deaths worldwide every year. One possible approach to limit the socioeconomic consequences of such events is the development of climatic thresholds for landslide initiation. In this paper, we propose a method that incorporates antecedent rainfall and streamflow data to develop a landslide initiation threshold for the North Shore Mountains of Vancouver, British Columbia. Hydroclimatic data were gathered for 18 storms that triggered landslides and 18 storms that did not. Discriminant function analysis separated the landslide-triggering storms from those storms that did not trigger landslides and selected the most meaningful variables that allow this separation. Discriminant functions were also developed for the landslide-triggering and nonlandslide-triggering storms. The difference of the discriminant scores, ΔCS, for both groups is a measure of landslide susceptibility during a storm. The variables identified that optimize the separation of the two storm groups are 4-week rainfall prior to a significant storm, 6-h rainfall during a storm, and the number of hours 1 m3/s discharge was exceeded at Mackay Creek during a storm. Three thresholds were identified. The Landslide Warning Threshold (LWT) is reached when ΔCS is −1. The Conditional Landslide Initiation Threshold (CTLI) is reached when ΔCS is zero, and it implies that landslides are likely if 4 mm/h rainfall intensity is exceeded at which point the Imminent Landslide Initiation Threshold (ITLI) is reached. The LWT allows time for the issuance of a landslide advisory and to move personnel out of hazardous areas. The methodology proposed in this paper can be transferred to other regions worldwide where type and quality of data are appropriate for this type of analysis. 相似文献
15.
Dry periods between rainstorms control the soil moisture conditions, and are the antecedent conditions for various geomorphological, hydrological and ecological processes. An annual distribution of dry condition, based on the Dry Days Since Last Rain (DDSLR) approach is presented, showing the duration and timing of dry periods for various daily rainfall thresholds and probabilities.Daily rainfall data from five stations along a climatic transect in Israel, extending from the Judean Mountains, which have a Mediterranean climate, to the Dead Sea arid region were studied. The results show that DDSLR values increased with increasing aridity. At a 0.1 mm rainfall threshold, the DDSLR values were similar along this transect. However, at higher daily thresholds, differences among different locations along the transect, become more noticeable. 相似文献
16.
Probabilistic landslide risk analysis considering direct costs in the area north of Lisbon (Portugal) 总被引：7，自引：1，他引：6
The purpose of the present study is the analysis of landslide risk for roads and buildings in a small test site (20 km2) in the area north of Lisbon (Portugal). For this purpose, an evaluation is performed integrating into a GIS information obtained from multiple sources: (i) landslide hazard; (ii) elements at risk; and (iii) vulnerability. Landslide hazard is assessed on a probabilistic basis for three different types of slope movement (shallow translational slides, translational slides and rotational slides), based on some assumptions such as: (i) the likelihood of future landslide occurrence can be measured through statistical relationships between past landslide distribution and specified spatial data sets considered as landslide predisposing factors; and (ii) the rainfall combination (amount–duration) responsible for past slope instability within the test site will produce the same effects (i.e. same type of landslides and similar total affected area), each time they occur in the future. When the return period of rainfall triggering events is known, different scenarios can be modelled, each one ascribed to a specific return period. Therefore, landslide hazard is quantitatively assessed on a raster basis, and is expressed as the probability for each pixel (25 m2) to be affected by a future landslide, considering a rainfall triggering scenario with a specific return period. Elements at risk within the test site include 2561 buildings and roads amounting to 169 km. Values attributed to elements at risk were defined considering reconstruction costs, following the guidelines of the Portuguese Insurance Institute. Vulnerability is considered as the degree of loss to a given element resulting from the occurrence of a landslide of a given magnitude. Vulnerability depends not only on structural properties of exposed elements, but also on the type of process, and its magnitude; i.e., vulnerability cannot be defined in absolute terms, but only with respect to a specific process (e.g. vulnerability to shallow translational slides). Therefore, vulnerability was classified for the three landslide groups considered on hazard assessment, taking into account: (i) landslide magnitude (mean depth, volume, velocity); (ii) damage levels produced by past landslide events in the study area; and (iii) literature. Finally, a landslide risk analysis considering direct costs was made in an automatic way crossing the following three layers: (i) Probabilistic hazard map for a landslide type Z, considering a particular rainfall triggering scenario whose return period is known; (ii) Vulnerability map (values from 0 to 1) of the exposed elements to landslide type Z; and (iii) Value map of the exposed elements, considering reconstruction costs. 相似文献
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19.
站点密度对泥石流当日雨量和前期有效雨量计算的影响 总被引：1，自引：0，他引：1
研究气象站点密度在当日雨量和前期有效雨量因子内插中的影响程度,对提高对这2个因子的内插精度有重要的意义。本文针对我国东南地区87个泥石流灾害点和207个站点的降水资料,建立站点密度在5%~100%间变化的空间采样方案,采用反距离加权法(IDW)计算不同站点密度下泥石流灾害点的当日雨量和前期有效雨量。利用分位数方法对站点密度与当日雨量和前期有效雨量的关系进行分析,结果表明:诱发泥石流灾害的当日雨量和前期有效雨量的内插值,均随着气象站点密度的降低呈减少趋势;前期有效雨量的内插值相对于当日雨量的内插要稳定一些。在站点密度大于5%的情况下内插的前期有效雨量可以保持60%以上的雨量值,而当日雨量只大于30%。 相似文献
20.
Rainfall thresholds for landsliding in the Himalayas of Nepal 总被引：5，自引：0，他引：5
Emmanuel J. Gabet Douglas W. Burbank Jaakko K. Putkonen Beth A. Pratt-Sitaula Tank Ojha 《Geomorphology》2004,63(3-4):131-143
Landsliding of the hillslope regolith is an important source of sediment to the fluvial network in the unglaciated portions of the Himalayas of Nepal. These landslides can produce abrupt increases of up to three orders of magnitude in the fluvial sediment load in less than a day. An analysis of 3 years of daily sediment load and daily rainfall data defines a relationship between monsoonal rainfall and the triggering of landslides in the Annapurna region of Nepal. Two distinct rainfall thresholds, a seasonal accumulation and a daily total, must be overcome before landslides are initiated. To explore the geomorphological controls on these thresholds, we develop a slope stability model, driven by daily rainfall data, which accounts for changes in regolith moisture. The pattern of rainfall thresholds predicted by the model is similar to the field data, including the decrease in the daily rainfall threshold as the seasonal rainfall accumulation increases. Results from the model suggest that, for a given hillslope, regolith thickness determines the seasonal rainfall necessary for failure, whereas slope angle controls the daily rainfall required for failure. 相似文献