CIMMYT高降雨量区小麦种质资源的农艺性状和抗性评价

为选择适应湖北省等高降雨量区小麦新品系或中间育种材料,对引进的16份国际玉米小麦改良中心(CIMMYT)高降雨量区小麦种质资源进行了生育期和简单农艺性状的调查,并对其中的9份种质进行了多抗性鉴定。结果表明,与湖北省大面积主栽品种郑麦9023相比,供试种质的拔节期平均提前4d,抽穗期推迟8d,成熟期推迟1d,成穗率、穗粒重和千粒重较低,株高和穗粒数较高;供试种质对条锈病的抗性最好,其次是赤霉病和白粉病,赤霉病抗侵染性比抗扩展性好。筛选出免疫或高抗条锈病种质7份;4份赤霉病抗侵染种质中有1份高抗侵染、中抗扩展;1份种质高抗白粉病,没有发现纹枯病抗性种质。

高动能降雨条件下植被对土壤侵蚀速率的影响

利用降雨模拟器,通过对比试验分析高动能降雨条件下石门小流域植物对土壤侵蚀速率的影响,为科学治理水土流失问题提供依据。结果显示,土壤孔隙度与根系密度呈正相关关系(p<0.05),土壤容重与根系密度呈负相关关系(p<0.001),植被地上部分对土壤侵蚀速率有较大影响,而植物根系对土壤侵蚀速率影响较小。

高降雨下排水沥青路面功能评价及研究

为提高排水沥青路面设计可靠性,提出一种表征排水沥青路面排水能力的新评价指标,与目前常用的评价指标进行对比研究建立关系;同时,基于广西南宁高降雨的实际情况,利用暴雨强度公式进行排水沥青路面空隙率的预估研究,分析在最不利降雨条件下的空隙率取值。研究表明,新评价指标极限排水强度与常用指标渗透系数呈对数相关关系,且渗透系数越大,极限排水强度随之增大。依托项目路面结构设计的排水层厚度h=40mm,路线设计的道路横坡ih=2%,计算所得南宁市暴雨强度下空隙率可控制在17.5%~21.5%之间,空隙率随设计重现期的增大而增大,随降雨历时的增大而减小;当降雨历时t=5min、设计重现期P=20时为最不利的降雨环境,空隙率最大为21.5%。

局部高强度降雨的地质灾害特征分析

传统地质灾害特征分析方法,以地面综合调查为主,忽视局部高强度降雨条件这一主观因素,使得地质灾害特征分析结果存在较高的片面性。该文提出基于局部高强度降雨的地质灾害特征分析方法,根据降雨强度、灾害持续时间和平均降雨量等指标设立临界组合判别运算雨量阈值,按照雨量阈值判断地质灾害类型,并结合预警判据图分析局部高强降雨的地质灾害分布特征。实验结果表明,所提方法可全面分析出实验地区地质灾害具有滞后性、群发性和同时性特征。

降雨循环条件下高切坡稳定性演化过程及预测方法

为进一步揭示降雨循环条件下基岩型台阶状高切坡的降雨入渗及稳定性演化过程,以乐西高速马边至昭觉段某粉质黏土覆盖层基岩型台阶状高切坡为研究对象,通过室内干湿循环试验建立土体抗剪强度参数劣化数学模型;利用Geo-studio数值模拟软件研究多工况降雨循环下高切坡降雨入渗过程,揭示不同降雨循环工况下及雨后高切坡内部渗流场及稳定性变化规律,建立降雨型高切坡稳定系数逐年劣化方程;结合室内试验及数值模拟结果,建立该类高切坡稳定系数预测方法。研究结果表明:降雨入渗过程中高切坡潜在滑移面形状及位置并不发生明显变化,且表现为高切坡深处圆弧面及基岩积水面的组合型滑面;相同降雨时间内,高切坡降雨入渗深度及稳定性劣化幅度与降雨强度成正相关;单次降雨循环周期内,高切坡稳定性劣化幅度与降雨循环次数成负相关;高切坡降雨入渗深度或入渗总量越大,雨后高切坡稳定系数回升越小;高切坡稳定系数劣化系数采用土体抗剪强度参数劣化系数平均值较为安全合理,所建降雨型高切坡稳定系数预测方法具有较高的精度。

热带北缘鹅凰嶂季雨林四种群落特征及成熟度分析

为分析我国热带北缘季雨林的不同演替阶段的群落特征,该研究对广东阳春鹅凰嶂典型季雨林中4种(A、B、C、D)不同植物群落展开调查,对群落的物种组成、多样性和空间结构等进行分析,判断成熟度差异,预测演替方向,并提出优化建议。结果表明:(1)4种群落林层单一,小径级木与下层木占主体地位,具有1~3种明显的优势树种。(2)Shannon-Wiener指数为2.72~3.74,Simpson指数为0.90~0.97,Pielou均匀度指数为0.74~0.89,各群落多样性特征差异显著。(3)4种群落乔木胸径大小比数为0.49~0.51,角尺度为0.56~0.61,混交度为0.54~0.83,林分空间结构指数为60.57~71.44,林分空间结构距离为53.15~68.53。(4)综合群落基本特征、多样性和空间结构特征的分析得出,各群落的成熟度排名为D>A>C>B。综上认为,4种群落都处于演替前期或中期,乔木个体胸径和树高发展空间较大;群落整体处于中庸生长状态,个体均呈轻微聚集分布,树种表现为中度、强度或极强度混交,空间结构与理想林分存在一定距离。随着成熟度的增加,4种群落都继续以阳性树种作为主要优势树种进行演替,并初步具备该区域地带性顶极群落的典型植被特征;季雨林群落物种多样性提高,并向混交度增加、空间结构优化、稳定性增强的趋势演替。该研究结果为群落构建机制和森林结构优化等提供科学依据。未来应对该区域加强监管与保护,同时应对该地区的植被生态学和生物多样性保护展开广泛监测与深入研究。

厂房挡水结构设计与有限元分析

高尾水以及施工期高降雨量是额勒赛上电站厂房的两大特点,厂房挡水结构设计也就成为设计中的难点问题。本文以厂房尾水闸墩及边墙结构设计为例,详细阐述了它们在结构设计方面采取的措施以及有限元分析计算过程,为今后类似工程提供了参考。

Slope Debris Flows in the Wenchuan Earthquake Area

Avalanches and landslides,induced by the Wenchuan Earthquake on May 12,2008,resulted in a lot of disaggregated,solid material on slopes that could be readily mobilized as source material for debris flows.Rainstorms triggered numerous slope debris flows with great damage to highways and rivers over the subsequent two years.Slope debris flows(as opposed to channelized debris flows) are defined as phenomena in which high-concentration mixtures of debris and water flow down slopes for short distances to highways and river banks.Based on field investigations and measurements of 19 slope debris flows,their main characteristics and potential mitigation strategies were studied.High rainfall intensity is the main triggering factor.Critical rainfall intensities for simultaneous occurrence of single,several and numerous slope debris flow events were 20 mm/day,30mm/day,and 90 mm/day,respectively.Field investigations also revealed that slope debris flows consist of high concentrations of cobbles,boulders and gravel.They are two-phase debris flows.The liquid phase plays the role of lubrication instead of transporting medium.Solid particles collide with each other and consume a lot of energy.The velocities of slope debris flows are very low,and their transport distances are only several tens of meters.Slope debris flows may be controlled by construction of drainage systems and by reforestation.

High-Resolution Hindcast of Record-Breaking Rainfall in Beijing and Impact of Topography

In this paper,a hindcast study of the record-breaking rainfall event occurring in Beijing on 21July 2012,is conducted by using the Weather Research and Forecasting(WRF)model forced by National Centers for Environmental Prediction(NCEP)Global Forecasting System(GFS)outputs,paired with an investigation of the impact of topography in this region.The results indicate that WRF can reasonably predict the salient features of orographic precipitation;the 24-h rainfall amount and spatial distribution compare reasonably well with the observations.The hindcast simulation also indicates that rainfall events can be predicted approximately 36 h ahead.When the topography is removed,the spatial distribution of rainfall changes remarkably,suggesting the importance of the topography in determining rainfall structure.These results also indicate that prediction of such city-scale heavy rainfall events would benefit from a high-resolution prediction system.

沂河流域地理特性及人文特点分析

从自然和人文地理角度分析了沂河流域的特性。沂河流域地处降雨高值区,水系呈不对称特征。古老的沂河孕育了丰饶的物产、悠久的历史文化。要坚持人与河流协调发展的原则,使文明成果与自然环境和谐共融,相互促进。

PREDICTION OF SEDIMENT REDUCING BENEFIT UNDER DIFFERENT RAINFALL COND ITIONS AND CONTROL DEGREES ON THE LOESS PLATEAU

Based on the distribution of hydrological stations and zoning of types ofsoil erosion, the Loess Plateau (3 10 x 10~3km^2) is divided into 292 erosion units. And taking theerosion modulus > 5000t/km^2 as a criterion, the emphasis control area (149 x 10~3km^2) of the LoessPlateau is demarked, and is divided into 10 control regions. The controllable area and the locationof control measures are conformed. Level terraces are mainly collocated on the 3° ―15° slopes,woodland and grassland are collocated on the > 15° slopes, and the proportion of woodland tograssland is 8: 2 in the forest belt, 5: 5 in the forest steppe belt, and 2: 8 in the steppe belt.The 9000 combinations of soil-water conservation measures in different rainfall conditions areobtained by the permutation and combination method, according to the 9 rainfall frequencies and thecontrollable areas of level terrace, woodland and grassland at 10% of control progress rate. Thequality standards of level terrace, woodland and grassland are ascertained. The evaluation indexesof soil-water conservation benefits of level terrace, woodland and grassland are establishedrespectively in the condition that rainfall index is higher than that of erosive index of slopingfield. Based on the results above, the sediment reducing benefit and soil erosion modulus in thedifferent rainfall conditions and control degrees are analyzed, which could provide adecision-making basis for soil-water loss control on the Loess Plateau.

Multi-time scale analysis of precipitation variation in Guyuan, China:1957-2005

Morlet wavelet transformation is used in this paper to analyze the multi time scale characteristics of pre cipitation data series from 1957 to 2005 in Guyuan region.The results showed that(1) the annual precipitation evo lution process had obvious multi time scale variation characteristics of 15 25 years,7 12 years and 3 6 years,and different time scales had different oscillation energy densities;(2) the periods at smaller time scales changed more frequently,which often nested in a biggish quasi periodic oscillations,so the concrete time domain should be ana lyzed if necessary;(3) the precipitation had three main periods(22 year,9 year and 4 year) and the 22 year period was especially outstanding,and the analysis of this main period reveals that the precipitation would be in a relative high water period until about 2012.

RELATIONSHIP BETWEEN WEST PACIFIC SUBTROPICAL HIGH AND ENSO AND ITS INFLUENCE ON RAINFALL DISTRIBUTION OF RAINY SEASON IN FUJIAN

Relationship between the variations of West Pacific subtropical high indices in the summer half of the year and preceding SST in North Pacific was examined based on a data set of 1951 2000. The correlation between the subtropical high indices and preceding SST in the equatorial East Pacific was the strongest among the others, and has great persistency from last autumn to spring. It is indicated that ENSO events appeared about six months earlier than the change of the subtropical high activities, and the subtropical high intensities enhanced (weakened) and western ridge point was westward (eastward) in the year of El Nino (La Nina) events. It was also observed that there were similar interdecadal oscillation and abrupt variations between Nino3 SST, subtropical high intensities and rainfall of rainy season in Fujian. Therefore, experiments were made on rainfall distribution of rainy season in Fujian. The results showed that the distribution was directly affected by the subtropical high activities, pronouncedly caused by ENSO effect.

Effect of lake surface temperature on the summer precipitation over the Tibetan Plateau

There are numerous lakes on the Tibetan Plateau(TP),but the role of lake temperature in precipitation over the TP remains unclear.Here the Weather Research and Forecasting(WRF) model was used to detect the impact of lakes on summer rainfall.Three test cases were used to evaluate the effect of lakes surface temperature(LSTs) on precipitation variability.The three cases used different methods to determine initial LSTs,including using sea surface temperature data(SST),the WRF inland water module(avg_tsfc),and a lake model.Results show that when precipitation was stimulated over the TP,LSTs cannot be initialized using SST,which led to large discrepancies of precipitation.Compared with the simulations,the simulated precipitation were improved obviously with LSTs using avg_tsfc,indicating that LSTs have an considerable influence on determining precipitation over the TP.Due to a lack of observational data,the lake scheme does not improve on rainfall simulation,but does effectively simulate precipitation pattern over lakes,such as rainfall over the lakes was dominated by convection during the nighttime.Though the simulated precipitation using SST to initialize LSTs caused largediscrepancies,it suggested that precipitation increase especially convective precipitation with increase in LSTs,which confirmed that the moisture from lakes cannot be neglected over the TP.Generally,it was necessary to monitor the LSTs for accurate weather and climate prediction over the TP.

THE ENERGETIC AGGREGATION AND RESLEASE IN THE HEAVY RAIN REGION

Using the new formula of moist available energy (MAE), the value of the MAE’s key terms ofthree heavy rainfall cases in Guangdong province in 1998 was calculated. The energetic aggregation andenergetic discharge are analyzed. It shows that the value of the key terms in the formula appears different featureclearly in the different precipitation period, as well as the function of each term presents in the heavy rain region.

Climate Characters of Summer Drought in Mountain City and the Effect on Flowers and Trees

[Objective] The aim was to provide references for development of industries engaging in flowers and trees in Beipei area in Chongqing. [Method] The occurring trend, intensity trend of summer drought, relationship of intensity with rainfall and extremely highest temperature, occurring trend during initial period of summer drought and the effects in mountain cities were analyzed, based on information on lasting period, rainfall, average temperature, extremely highest temperature of sum- mer drought in Beipei area in mountain cities during 1981-2010 and, growth condi- tion and phenological phenomena of Michelia champaca during 2005-2007. [Result] The occurring probability of summer drought in mountain cities was 57% and the probabilities of light, moderate, heavy and extreme drought were 30%, 10%, 7% and 10%; intensity of summer drought was none of linear relation with rainfall and ex- tremely highest temperature. In summer drought, daily average rainfall was less than 0.9 ram; extremely highest temperature was 35.0-45.0 ℃ with probability at 30%; initial period of summer drought was from later June to middle August and of extreme drought was later June-later July; the ending period was early September. During drought, when the extremely highest temperature （〉35.0 ℃） occurred in three days within a Hou, flowers and trees were affected by the hot drought and when the extreme temperature （〉40.0 ℃） occurred in three days within a Hou, the plants were seriously affected. [Conclusion] Based on characters of summer drought, pre- cautions can be taken to reduce effects of summer drought on flowers and trees with the help of weather forecast.

降雨入渗对不饱和崩积土坡水文特性的影响

中国集水区内有许多崩积土坡,而夏季所带来的高降雨强度,时常会造成大规模崩塌,危害人类生命财产安全。因此,如何避免此类灾害发生,是值得关心及讨论的议题。研究目标旨在探讨降雨入渗对不饱和崩积土坡水文特性的影响。研究崩塌区的不饱和浅层崩积土壤的现地监测结果,包括降雨量、渗透系数。然后,采用Geo Studio中的数值分析软件SEEP/W滑裂面进行渗流分析,以及滑裂面SLOPE/W滑裂面进行边坡稳定分析。

The influence of rainfall and land use patterns on soil erosion in multi-scale watersheds: A case study in the hilly and gully area on the Loess Plateau, China

Soil erosion has become a major global environmental problem and is particularly acute on the Loess Plateau(LP), China. It is therefore highly important to control this process in order to improve ecosystems, protect ecological security, and maintain the harmonious relationship between humans and nature. We compared the effects of rainfall and land use(LU) patterns on soil erosion in different LP watersheds in this study in order to augment and improve soil erosion models. As most research on this theme has so far been focused on individual study areas, limited analyses of rainfall and LU patterns on soil erosion within different-scale watersheds has so far been performed, a discrepancy which might influence the simulation accuracies of soil erosion models. We therefore developed rainfall and LU pattern indices in this study using the soil erosion evaluation index as a reference and applied them to predict the extent of this process in different-scale watersheds, an approach which is likely to play a crucial role in enabling the comprehensive management of this phenomenon as well as the optimized design of LU patterns. The areas considered in this study included the Qingjian, Fenchuan, Yanhe, and Dali river watersheds. Results showed that the rainfall erosivity factor(R) tended to increase in these areas from 2006 to 2012, while the vegetation cover and management factor(C) tended to decrease. Results showed that as watershed area increased, the effect of rainfall pattern on soil erosion gradually decreased while patterns in LU trended in the opposite direction, as the relative proportion of woodland decreased and the different forms of steep slope vegetation cover became more homogenous. As watershed area increased, loose soil and craggy terrain properties led to additional gravitational erosion and enhanced the effects of both soil and topography.