Effect of storm pattern on soil erosion in damaged rangeland;field rainfall simulation approach

Raindrop size,rainfall intensity and runoff discharge affect the detachment and transportation of soil particles.Among these three factors,the rainfall intensity seems to be more important because it can change other two factors.Storm patterns can be determined by changing the rainfall intensity during the storm.Therefore,the objective of this research is to test the influence of storm pattern on runoff,soil erosion and sediment concentration on a rangeland soil slope under field rainfall simulation.Four storm rainfall intensity patterns were selected for examining the effects of variations in storm event characteristics on soil erosion processes.The selected storm patterns were:I(45,55 and 70 mm h-1);II(45,70 and 55 mm h-1);III:(70,55 and 45 mm h-1);and IV(55,45 and 70 mm h1).The last pattern is a new one instead of the uniform pattern which has been sufficiently studied in previous researches.The experiments were conducted in field plots(in Kojour watershed,Mazandaran Province,Iran)with an area of one square meter and an constant slope gradient of 18%,surrounded by galvanised sheets.Following the nonuniform prioritization of the storm patterns for the studied variables,time to runoff(I>II>IV>III),runoff volume(III>IV>II>I),sediment concentration(IV>III>I>II)and soil erosion(III>IV>II>I)),it can be generally inferred that each pattern has specific effect on soil erosion processes during a storm.The results of the general linear model(GLM)test indicated that the effects of storm pattern on time to runoff,total runoff volume,runoff coefficient and soil erosion were significant at a level of 99%.The Duncan test showed that the storm patterns can be divided into three groups of III,IV;II;I(for time to runoff),I,II;IV,III(for runoff coefficient),and I;II;IV,III(for runoff volume and soil erosion).

ANALYSIS OF “BIMODAL PATTERN” STORM ACTIVITY CHARACTERISTICS OF THE BAY OF BENGAL

Storms that occur at the Bay of Bengal(Bo B) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the Bo B are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the Bo B storm activity, and the "bimodal period" of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the"bimodal pattern"storm activity in the Bo B. The analysis on sea surface temperature(SST) shows that the SSTs of all the year around in the Bo B area meet the conditions required for the generation of tropical cyclones(TCs). However,the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a "two-peak"storm activity pattern. The genesis potential index(GPI) quantifies and reflects the environmental conditions for the generation of the Bo B storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms.

产流模式空间分布对城市雨洪过程模拟的影响

通过耦合网格产流计算模型(GRGM)和暴雨洪水管理模型(SWMM)汇流计算模块构建了GRGM-SWMM模型。以贾鲁河中牟水文站控制流域(包括郑州市中心城区)为研究区,基于18场实测暴雨洪水资料探究了产流模式空间分布对洪水过程模拟精度的影响。结果表明:研究区超渗产流模式空间分布面积占比高达72%,城市下垫面仍以超渗产流模式为主;相较于仅考虑超渗产流计算的SWMM,考虑超渗、蓄满和混合等不同产流模式空间分布的GRGM-SWMM模型场次洪水产流量、流量过程模拟精度明显提高,产流量模拟相对误差平均降低33.26%、决定系数平均提高0.089,流量过程模拟均方根误差平均降低5.13 m^(3)/s、纳什效率系数和决定系数分别平均提高0.227、0.207。

广东龙卷时空分布及其母体风暴雷达观测特征

基于《中国气象灾害大典》广东卷(1959—2000年)、广东省防灾减灾年鉴(2002—2022年)和近年来广东龙卷现场灾调记录等历史数据、常规观测、ERA5高分辨率再分析资料以及广东多普勒天气雷达(2006—2022年)等资料,分析1961—2022年广东龙卷的时空分布、天气背景和2006以来的龙卷对流风暴形态等气候统计特征。结果表明:近62年广东共有225个龙卷记录。其中,在多源观测资料较齐备的2006年以来,龙卷年均发生约6个,近50%发生在热带气旋影响天气背景下,40%为西风带系统龙卷,还有约10%为热带扰动龙卷,但龙卷数量逐年波动很大,最高达17个(2008年),部分年份仅1个或无记录。广东龙卷主要发生在4—9月,4—6月主要为西风带系统龙卷,7—9月主要为热带气旋和热带扰动龙卷;约85%的龙卷发生于06—20时,14—18时为最高发时段(占比近40%)。龙卷最频发于珠三角、雷州半岛和潮汕平原一带,北部山区极少。其中,佛山、湛江和广州是广东龙卷最高发的3个城市。广东产生龙卷的对流形态中,约54%带状对流系统,为热带气旋和热带扰动龙卷母体风暴,其风暴结构呈现出低质心的特点;约36%多单体风暴系统,多数为西风带龙卷母体风暴;与美国龙卷易产生于孤立单体和准线状对流系统不同,广东产生龙卷的孤立对流单体和准线性对流系统相对频率很低,均仅约为5%,主要为西风带龙卷母体风暴,其风暴结构往往呈现出高质心的特点。超过90%的龙卷中尺度母体风暴具有低层中气旋,但仅约47%伴随低层龙卷涡旋特征(TVS)。强龙卷通常伴随着旋转速度超过20 m·s^(-1)的低层中气旋、超过40 m·s^(-1)的TVS速度差。

不同暴雨情景下的城市内涝响应特征分析

针对近年来频发的城市暴雨内涝灾害问题,以广州长湴地区为例,构建了基于SWMM和LISFLOOD-FP的内涝耦合模型,结合历史暴雨事件提出一种新的短历时暴雨过程设计方法,在此基础上设计了114种暴雨情景,探讨了不同暴雨雨型和集中度条件下的城市内涝响应特征。结果表明:单峰雨型下的溢流和淹没情况比双峰和均匀型要高;在单峰雨型中,峰后型暴雨的溢流峰值最高,峰中和峰后型暴雨的溢流总量较大,峰后型暴雨导致的整体淹没情况较严重;重现期小于50 a时芝加哥型(r=0.7)暴雨导致的淹没情况最严重,而重现期大于50 a时单峰Ⅱ型(峰后型)暴雨的淹没情况最严重;重现期为100 a时单峰Ⅱ型的淹没范围及水深比芝加哥型(r=0.7)暴雨分别高8%和64%;暴雨集中度每上升一个等级,溢流及淹没情况明显加重;目前常用的芝加哥雨型在一定情况下存在低估内涝的风险,建议在内涝分析时进一步考虑更危险的雨型以及暴雨的集中度。

INFLUENCE ON NORTHERN PACIFIC STORM TRACK OF EQUATO-RIAL CENTRAL AND EASTERN PACIFIC SSTA DURING WINTER

Singular value decomposition (SVD) is conducted of 15 winter tropical Pacific SST with 500 hPa filtered potential height variance over the northern Pacific storm track. It is shown that the first coupled mode obtained depicts the effect on the track of SSTA over equatorial central and eastern Pacific. Further com-posite analysis indicates that the SSTA over there during winter can give rise to or invigorate PNA teleconnec-tion response pattern in 500 hPa height field which, in turn, exerts crucial influence on the interannual variabil-ity in vigor and east-west displacement of the Pacific storm track, especially over its central and eastern part.

Salt Desert and Saline-Ackaline Mixed Dust Storms:An Ignored Issure for Global Climate Change

Salt desert,saline-alkaline dust storm and saline-alkaline mixed dust storm are significant but ignored problems for a long time.After many years of observations and researches,the author believes that salt desert,saline-alkaline dust

Implementation of Sample Graphic Patterns on Derived Scientific/Technologic Documentary Figures

The presenting work deals with implementation of sample graphic patterns derived from published scientific/technologic documentation figures on numeric simulation of multiphase flow and FEM analysis of thin walled mechanical structures. First, geometric plane patterns in rectangular/circular form were demonstrated in contrast to gradual change style in color and graphic configuration. Next, selected artistic/graphic sample patterns were implemented in logo conceptual design and visual innovation storming. The way in editing the above original figures is 2D symmetry, rectangular array geometrically, and converting them in inverse color in software like PS. The objective of this work is to cultivate, explore and discipline trainees＇ visual ability in artistic/aesthetic appreciation, graphic communication and industrial design and application, thus laying ties closely among comprehensive university students from different majors on science, engineering, arts and humanity.

Assessing Post-Storm Forest Dynamics in the Pyrenees Using High-Resolution LIDAR Data and Aerial Photographs

We evaluated how historical storm events have shaped the current forest landscape in three Pyrenean subalpine forests(NE Spain).For this purpose we related forest damage estimations obtained from multi-temporal aerial photographic comparisons to the current forest typology generated from airborne Li DAR data, and we examined the role of past natural disturbance on the current spatial distribution of forest structural types.We found six forest structural types in the landscape: early regeneration(T1 and T2), young even-aged stands(T3), uneven-aged stands(T4) and adult stands(T5and T6).All of the types were related to the timing and severity of past storms, with early-regeneration structures being found in areas markedly affected in recent times, and adult stands predominating in those areas that had suffered lowest damage levels within the study period.In general, landscapes where high or medium levels of damage were recurrent also presented higher levels of spatial heterogeneity,whereas the opposite pattern was found in the less markedly affected landscape, characterized by thepresence of large regular patches.Our results show the critical role that storm regimes in terms of timing and severity of past storms can play in shaping current forest structure and future dynamics in subalpine forests.The knowledge gained could be used to help define alternative forest management strategies oriented toward the enhancement of landscape heterogeneity as a measure to face future environmental uncertainty.

次降雨时空分布对流域产流产沙的影响

降雨时空变异性对流域产流产沙过程具有重要影响。选取数据完整性较好、分辨率较高的美国俄克拉荷马州柯尔堡(Fort Cobb)流域为研究对象,基于高时空分辨率次降雨空间分布及移动特征的量化分析,探究降雨雨型、降雨强度、时空变异等对流域产流产沙过程的影响。结果表明:依据降雨特征(降雨量、降雨历时,30 min最大降雨强度)可将Fort Cobb流域的雨型划分为4类(A型、B型、C型和D型),其中,降雨量和30 min最大降雨强度较小的A型、B型降雨最为常见;C型降雨的30 min最大降雨强度最大,是造成该流域水土流失的主要类型。对于4种雨型,流域产流量与降雨量,产沙量与次降雨侵蚀力皆呈显著正相关关系(P<0.05);单位降雨量导致的流域产流量表现为C型>A型>D型>B型;相同次降雨侵蚀力条件下,不同雨型导致的流域产沙量则表现为D型>B型>A型>C型。流域降雨量空间分布呈现由东南向西北减少的趋势,集中分布在流域东部的降雨量占总降雨量38.96%。降雨移动特征分析表明,流域内向下游移动和顺时针移动的降雨场次最多,发生频次为51.16%,2类降雨量占总量的57.94%,其导致的流域产流量占总量的81.61%,产沙量占总量的84.84%。降雨过程相似时,次降雨移动特征对流域产流产沙作用存在明显差异。降雨由上游至下游移动,流域水文响应速度慢,流量、含沙量峰值高;而降雨由下游至上游移动,流域水文响应速度快,且流量、含沙量峰值较低。

横琴口岸下穿路雨水泵站设计分析

横琴口岸地处台风频发地区,内部两层下穿路属于市政道路,排水防涝要求高。论文根据实际工程特点,选用合适的暴雨重现期,通过芝加哥雨型生成器得到了设计暴雨曲线;根据分时雨水径流量,动态模拟雨水调蓄池进排水量,得到合理的设计参数,为下穿路雨水提升泵站的设计提供参考。

不同设计雨型对雨水管网数值模拟影响研究

为探讨不同设计雨型对雨水管网数值模拟结果的影响,利用Infoworks ICM软件,分别使用暴雨强度公式推求出的特定雨型和芝加哥雨型,模拟相同下垫面条件下雨水管网系统的排水能力。结果表明,芝加哥雨型对雨水管网系统的排水能力要求更高。因此在进行城市雨水管网系统设计时不应忽视降雨时程分配对雨水管网排水能力的影响,应根据当地的降雨情况对设计雨水管网系统进行校核,以达到顺利排出雨水、降低内涝几率的目的。

呼吸道病毒感染导致炎症风暴的研究进展

炎症反应是机体抵抗病原体入侵的重要过程,但是过度的炎症反应会造成炎症因子风暴,加速病毒感染导致后续疾病。本文重点综述炎症因子风暴的成因及炎症因子风暴在呼吸道病毒感染相关疾病中的作用机理,并梳理了临床上通过靶向炎症因子风暴相关通路治疗该类病毒感染相关疾病的方案,以期为该类病毒感染相关疾病的诊疗提供参考。

衡水市某片区雨水径流及暴雨雨型研究

暴雨重现期及雨峰位置参数将显著地影响缺水型城市的雨水径流方式、雨水蓄排设计规划方式及蓄排系统运行预期。基于此,本文运用衡水市不同降雨重现期下的暴雨强度及芝加哥雨型分析方法,对衡水市某片区的暴雨强度及雨型变化进行研究,以分析雨水径流变化。研究结果表明:1)降雨强度随着降雨重现期的增加将得到明显地提高,且随着降雨历时的增加暴雨强度之间的比值稳定于2.99;2)随着雨峰参数(r)的提高,研究区域内的芝加哥雨型在降雨历时内暴雨强度分布发生了明显变化。研究结果为北方典型缺水城市——衡水市的海绵城市规划及片区排水系统工程设计提供基础的理论指导,并对衡水市的雨水蓄排系统的稳定运行提供一定的预期。

中国降雨过程时程分型特征

为研究降雨过程雨强随历时的变化关系,利用中国14个气象站近40年逐分钟降雨资料,采用动态K均值聚类法并根据雨峰在降雨过程中出现的位置,将中国10256次降雨过程分为4种类型,即降雨前期集中型(I型)、降雨中期集中型(II型)、降雨后期集中型(III型)和降雨均匀分布型(IV型)。结果表明:中国I型降雨出现频次最高,占47.1%;II型次之,占21.2%;III型和IV型出现频次相当,分别占15.3%和16.4%。夏季I型降雨发生频次占绝对优势,为夏季总降水过程的52.2%;冬季各类雨型发生频次相差不大。I型多为短历时高强度降雨,而IV型多为长历时低强度降雨,II型和III型居中。历时越短时,I型降雨的比重越大;随着降雨历时的增加,I型降雨的比重明显下降,IV型降雨的比重增加。

城市设计暴雨雨型研究

采用模糊模式识别方法对我国四个雨量站的雨型进行分类和统计，获得了短历时暴雨雨型的分布特性；经过模拟分析和比较，找出了一种较好地满足城市排水设计要求的设计雨型。

连云港温带风暴潮及可能最大温带风暴潮的计算

用 4 6a资料首次对连云港温带风暴潮进行了统计分析 ,计算了不同重现期的温带风暴潮 (增、减水 )值 ,并划分引起温带风暴潮的天气类型 ;进而首次构造引起连云港可能最大温带风暴潮 (增、减水 )的天气系统 ;最后 ,采用经过典型温带风暴潮过程数值模拟检验的风暴潮数学模型 ,计算了连云港可能最大温带风暴潮 ,计算结果已被江苏田湾 (连云港 )

华北平原对流风暴的个例分析

应用较详细的卫星云图、多普勒雷达和探空资料对一次强对流风暴进行了综合分析研究。