Stable Isotope Ratios: Hurricane Olivia

The oxygen and hydrogen isotopic compositions of rains from HurricaneOlivia (1994) in the eastern Pacific were measured. The rains werecollected on 24 and 25 September during airplane flights conducted at anelevation of 3 km. Hurricane Olivia peaked in intensity to a category-4storm between the two dates. Isotope ratios of rains from HurricaneOlivia were markedly lower ( ¹⁸O = –13.9to –28.8) than that of rain collected from a thunderstormat an elevation of 2.3 km outside the influence of Olivia (¹⁸O = –3.8). A distinct decrease in isotoperatios from the first day to the next ( ¹⁸O =–18.4 to –21.9) in Hurricane Olivia wasattributed to decreased updraft velocities and outflow aloft. Thisshifted the isotopic water mass balance so that fewer hydrometeors werelifted and more ice descended to flight level. A decrease in the averagedeuterium excess from the first day to the next (d = 15.5 to 7.1)was attributed to an increase in the relative humidity of the watervapor `source' area. We hypothesize that the `source' region for therain was in the boundary layer near the storm center and that becausethe hurricane was at peak intensity prior to the second day the relative humidity was higher.     

西南山地滑坡灾害生态风险评价——以大理白族自治州为例

本文以云南省大理白族自治州为例,综合考量生态风险源、受体、暴露响应过程及生态终点,采用信息量模型评估滑坡灾害危险性,基于景观格局指数表征生态脆弱性,并将生态系统服务纳入风险损失的定量表征,定量评估流域滑坡灾害生态风险。结果表明：① 低于1800 m高程、15°~25°坡度、小于0.31植被覆盖指数等10方面因素构成了诱发大理州滑坡灾害的最佳信息量组合,全州普遍处于滑坡灾害危险性中高水平,且西北低、东南高;② 生态脆弱性高值区主要集中在红河流域南部、金沙江流域东南部、澜沧江流域中部;③ 低生态损失流域的水源涵养、粮食供给服务相对较差,生态损失中等流域的净初级生产、土壤保持服务优势明显,高生态损失流域则具有较强的粮食供给和水源涵养服务;④ 基于高中低3种生态风险等级和“高危险—低脆弱—低损失”等8种风险结构,全州367个小流域可划分出避让监测预警区、生态保护恢复区、避让保护兼顾区、自然适应调控区等4种风险防范类型区。     

An analysis of intra-event precipitation variability for the United States (1980–2010)

Hourly precipitation data were collected from 143 first-order US weather stations during the period from 1980 to 2009 to assess the internal distribution of precipitation events lasting at least three hours. A total of 46,595 individual precipitation events were identified and evaluated using the mean, standard deviation, skewness, kurtosis, and the number of peaks occurring within an event. Mean event duration is longest along the West and Northwest coasts, the Mid-South, the Mid-Atlantic, and the Northeast; while shorter-duration events are more frequent in the Rocky Mountains, the Southwest, and the Great Plains. Mean event precipitation and standard deviation are greatest along the Gulf Coast and decrease inland. Precipitation events are positively skewed, indicating that more precipitation tends to occur earlier in the event. The most positively-skewed events are also located in regions flanking the Gulf of Mexico, while less-skewed events are common in the Northwest and Rocky Mountain regions. Event kurtosis is negative throughout the entire USA, with the highest negative values generally west of the Front Range, where cyclonic development and transition produce more evenly distributed precipitation within storms. Intra-event precipitation maxima were also evaluated, with western Florida and the desert Southwest having the greatest number per event.     

历史时期中国重大自然灾害时空分异特征(英文)

Based on historical documents and records this paper analyzes the characteristics of frequency and distribution of major disasters that took place in the history of China. The findings show that occurrences of different types of disasters varied and spatial pattern at provincial level are significantly different as well. The results also indicate that there is a strong relationship between type of disasters and spatial distribution and that the spatial pattern of losses was not the same as that of the frequency. The reasons are: (1) the hazard-formative environments which, to a large extent, determine the spatial pattern of the disasters are significantly different; (2) the losses caused by natural disasters were closely related to the concentration of economy and population. Number of deaths was usually large in areas where agriculture, culture and business were relatively developed. The spatial pattern of disaster losses is an evitable result of uneven economic development in the history of China.     

2021年3月中旬东亚中部沙尘天气地面起尘量及源区贡献率估算

2021年3月中旬,东亚中部包括中国北方大部分地区,爆发了持续性的沙尘天气,引发了人们对于沙尘源区、防风固沙生态建设工程效益的高度关注.提出了一个新的地表起尘量估算方法,使用高精度、大范围的气象数据,计算了这次沙尘天气的地面起沙条件、大风过程中的输沙状况,估算了不同时刻的起尘量,获得了14、15日蒙古和中国北方荒漠地区...     

The effect of storm movement on infiltration,runoff and soil erosion in a semi-arid catchment

Rainfall characteristics are key factors influencing infiltration and runoff generation in catchment hydrology, particularly for arid and semiarid catchments. Although the effect of storm movement on rainfall-runoff processes has been evaluated and emphasized since the 1960s, the effect on the infiltration process has barely been considered. In this study, a physically based distributed hydrological model (InHM) was applied to a typical semi-arid catchment (Shejiagou, 4.26 km²) located in the Loess Plateau, China, to investigate the effect of storm movement on infiltration, runoff and soil erosion at the catchment scale. Simulations of 84 scenarios of storm movement were conducted, including storms moving across the catchment in both the upstream and downstream directions along the main channel, while in each direction considering four storm moving speeds, three rainfall depths and two storm ranges. The simulation results showed that, on both the hillslopes facing downstream (facing south) and in the main channel, the duration of the overland flow process under the upstream-moving storms was longer than that under the downstream-moving storms. Thus, the duration and volume of infiltration under upstream-moving storms were larger in these areas. For the Shejiagou catchment, as there are more hillslopes facing downstream, more infiltration occurred under the upstream-moving storms than the downstream-moving storms. Therefore, downstream-moving storms generated up to 69% larger total runoff and up to 351% more soil loss in the catchment than upstream-moving storms. The difference in infiltration between the storms moving upstream and downstream decreased as the storm moving speed increased. The relative difference in total runoff and sediment yield between the storms moving upstream and downstream decreased with increasing rainfall depth and storm speed. The results of this study revealed that the infiltration differences under moving storms largely influenced the total runoff and sediment yield at the catchment scale, which is of importance in runoff prediction and flood management. The infiltration differences may be a potential factor leading to different groundwater, vegetation cover and ecology conditions for the different sides of the hillslopes.     

新元古代末期高家山生物群的生态多样性

新元古代末期是生命演化的关键转折期,也是以微生物占主导的生态系统向显生宙以后生动物占主导的生态系统的转变期,埃迪卡拉纪大型软躯体生物以固着、底栖、食悬浮为特色,普遍缺乏运动能力。作为这一时期特殊代表的高家山生物群,是目前新元古代唯一一个以黄铁矿化三维保存的管状和锥管状化石为主导,兼有骨骼生物、原生动物、钙化蓝细菌类及遗迹化石的多门类生物组合,是研究埃迪卡拉纪末期生命演化和生态系统演变十分重要的载体。本文通过对高家山生物群古生态学的初步研究,揭示出在前寒武纪—寒武纪之交,生态系统已显示一定的多样性。为适应平底面上(level-bottom)微生物席的发育,高家山生物群的许多生物采取了适应性的生存策略,通过黏附或插入微生物席中,营底栖固着食悬浮(如Cloudina、Conotubus)或化学共生(可能的Shaanxilithes)或平躺(如Gaojiashania和Sinotubulites)食碎屑生活。底内遗迹化石表明存在可能的表栖和半内栖、可自由运动、食碎屑的造迹生物。Conotubus中常见的“回春”或“复苏”现象,Gaojiashania和Sinotubulites的身体扭转或生活姿态调整则是对频繁风暴事件的被动适应。     

娄底地区环境地质灾害问题初探

娄底地区环境地质灾害较严重。主要有地震、地裂、塌陷、滑坡、水土流失和水污染等。这些灾害的形成除受天然状态下的第一地质环境影响外,主要与第二环境即开矿、建厂、修路及兴修水和等人类活动有关。针对各类灾害及其危害性,提出了防治对策与建议。     

对数非线性指函数型暴雨公式的分析研究

对现有暴雨公式进行了分析,并根据暴雨公式应该具有的特性,利用雨深与历时的关系建立了三参数指数型对数非线性暴雨公式,该公式克服了现有公式的一些缺陷,能较好的反映暴雨历时强度的变化规律,精度有所提高。     

青岛近海台风暴潮灾害分析

分析了青岛沿海地区的台风暴潮灾害状况,阐明了潮灾成因,明确指出风暴潮在沿海自然灾害中占有重要的地位。