射阳港近岸海域沉积物特征及冲淤趋势

海岸是陆地与海洋相互接触和影响的地带,通常指受波浪和潮汐等海洋动力作用的沿岸地带,同时也是人类社会经济发展的重要地带,大型人类工程往往会对其短期地貌变化和沉积物特征产生巨大影响。沉积物粒度分析是研究海洋沉积作用及过程的一个基础的、重要的方法,通过射阳港海岸动力地貌调查,研究了射阳港区不同时期的水下沉积物分布特征,将不同历史时期海图的等深线对海床冲淤变化进行对比分析,认为双导堤完工后导堤口区域出现了明显冲刷,导堤两侧出现淤积,沉积物颗粒变细,表明港口工程等局部影响因素会在短期内显著改变水动力地貌。     

未来我国气体能源发展动向研究

"十四五"期间我国能源需求增速将有所放缓,但仍将处于高位,随着经济社会的不断恢复以及环境问题的显现,未来能源安全形势仍然严峻,及早建立清洁、高效、安全、多元化的现代能源体系,调整优化我国能源供给结构迫在眉睫.本文通过判断我国气体能源发展现状,构建气体能源优先发展评价指标体系,运用层次分析法与灰色关联度评价法对各气体能源进行对比分析得出,消耗排放、燃料热值、国际合作、政策扶持、生产成本、资源潜力、生产排放等因素对各气体能源发展影响最大;未来应优先发展致密气、页岩气、煤层气,理性发展煤制气,科学布局可燃冰开发规划;建议加大气体能源勘探投入,提高天然气供能比例,摸清页岩气资源家底,突破核心技术,提升环保监督、安全生产意识,优化统一现有政策.     

石墨、萤石等战略非金属矿产发展趋势研究

战略性新兴产业几乎或多或少都与非金属矿及其制品有关,随着战略性新兴产业的发展,我国战略性矿产资源消费将迎来快速增长期.本文选取石墨、萤石、高纯石英、叶蜡石四种非金属矿产为战略非金属矿产,收集其产量、消费量、贸易情况等资料,对其重要性及用途、供需情况等进行研究,并对其未来需求趋势进行预测.本文认为石墨、高纯石英、萤石、叶蜡石在战略性新兴产业中有重要应用,未来需求将呈快速增长趋势,其中石墨、萤石2030年需求量分别为138.7万t、567.9万t.为国家制定勘查投入及产业发展政策提供参考.     

山东省广饶县地下水位多年动态及其地质环境效应分析

山东省广饶县地下淡水资源丰富,是本区工农业生产和生活用水的重要水源,长期大量开采地下水引发了地下水降落漏斗、咸水入侵、地面沉降等地质环境问题。通过对广饶县地下水多年监测资料的整理和分析,揭示了本区地下水水位的变化规律,预测了地下水水位的变化趋势。分析表明: 在现状开采条件下,浅层地下水降落漏斗已基本稳定,无加重趋势。考虑地面沉降和咸水入侵的发展趋势,提出深层地下水的约束埋深不应大于80 m,甄庙地区咸水入侵临界水位为10 m,这为当地地下水的合理开采与环境地质问题的防治提供了依据。     

1961—2016年我国区域性暴雨过程的客观识别及其气候特征

利用全国2287个气象观测站1961—2016年逐日降水资料,基于对暴雨区进行连续追踪的思路,采用暴雨相邻站点数和暴雨区中心距离确定了中国区域性暴雨过程的客观识别方法;根据区域性暴雨过程的平均强度、持续时间和平均范围构建了区域性暴雨过程的综合强度评估模型。利用该客观方法对1961—2016年中国的区域性暴雨过程进行识别,并分析其气候和气候变化特征。结果显示：我国区域性暴雨过程年均38.5次;区域性暴雨过程一年各月均可出现,但主要出现在4—9月,其中7、8月发生最为频繁,6月区域性暴雨过程持续时间长、范围广、综合强度强,这与长江中下游地区梅雨现象有关。一年中,区域性暴雨过程首次出现日期平均为3月6日,末次出现日期平均为11月14日;1961—2016年,我国年区域性暴雨过程首次出现日期呈明显提前、末次日期呈显著推后、暴雨期呈显著延长的变化趋势;年发生总频次呈微弱增多,较强区域性暴雨过程次数呈明显增加趋势;区域性暴雨过程的覆盖范围和综合强度均呈显著增大趋势。南方型区域暴雨过程变化趋势与全国的基本一致;北方型首次日期呈提前、末次日期呈推后趋势,发生频次有微弱减少趋势,覆盖范围、持续时间、综合强度均无明显变化趋势。     

中国夏季风影响过渡区与其他地区蒸发皿蒸发量趋势相反的原因

夏季风影响过渡区是天气和气候的敏感区,随着全球和区域的变暖,该区域特殊的气候环境响应引起人们重点关注。以南昌、定西、乌鲁木齐作为夏季风影响区、夏季风影响过渡区以及非夏季风影响区的代表站,通过对比中国夏季风影响过渡区和其他地区50年来温度、日照时数、相对湿度、降水量、低云量、风速的变化趋势,以及分析各气象因子单独变化对蒸发皿蒸发量的影响,发现在夏季风影响过渡区各个气象因子的变化均使蒸发皿蒸发量增加,而在其他地区,只有温度变化会使蒸发皿蒸发量增加,其他各因子的变化均会造成蒸发皿蒸发量的下降。贡献度更直观的反映各气象因子对不同地区蒸发皿蒸发的作用。结果表明温度变化对夏季风影响过渡区蒸发皿蒸发变率的贡献最大,贡献度为48.93%。风速变化对夏季风影响区蒸发皿蒸发变率的贡献最大,贡献度为51.54%。降水变化对非夏季风影响区蒸发皿蒸发变率的贡献最大,贡献度为58.57%。此外,低云量的变化对夏季风影响过渡区、夏季风影响区和非夏季风影响区的贡献均达到20%以上。因此,不同地区影响蒸发皿蒸发的最主要的因子是不同的,但低云量对任何地区蒸发皿蒸发的影响都非常重要。     

Uncertainty of the Linear Trend in the Zonal SST Gradient Across the Equatorial Pacific Since 1881

The change in the zonal sea surface temperature gradient (ZSSTG) across the equatorial Pacific plays an important role in the global climate system. However, there has not yet been a consensual conclusion about the changing ZSSTG at either a short-term (from 20 to 90 years) or a long-term time scale (longer than 90 years) in the literature. In this study, the uncertainty of the trend in ZSSTG for different sub-periods since 1881 was examined using four interpolated datasets and four un-interpolated datasets. It was found that the trend in ZSSTG on the short-term time scale could be significantly influenced by internal variability such as the El Niño–Southern Oscillation and the Pacific Decadal Oscillation. On the long-term time scale, the sign of the ZSSTG trend depends on the dataset used. In particular, it was not possible to draw a uniform conclusion about the secular trends in ZSSTG in recent history, given the high sensitivity of the ZSSTG trends to the period, dataset, and regions used to calculate the trends. Our results imply that it may not be possible to detect the response of ZSSTG to global warming until a longer data record becomes available in the future.     

Flood seasonality across Scandinavia—Evidence of a shifting hydrograph?

Fluvial flood events have substantial impacts on humans, both socially and economically, as well as on ecosystems (e.g., hydroecology and pollutant transport). Concurrent with climate change, the seasonality of flooding in cold environments is expected to shift from a snowmelt‐dominated to a rainfall‐dominated flow regime. This would have profound impacts on water management strategies, that is, flood risk mitigation, drinking water supply, and hydro power. In addition, cold climate hydrological systems exhibit complex interactions with catchment properties and large‐scale climate fluctuations making the manifestation of changes difficult to detect and predict. Understanding a possible change in flood seasonality and defining related key drivers therefore is essential to mitigate risk and to keep management strategies viable under a changing climate. This study explores changes in flood seasonality across near‐natural catchments in Scandinavia using circular statistics and trend tests. Results indicate strong seasonality in flooding for snowmelt‐dominated catchments with a single peak occurring in spring and early summer (March through June), whereas flood peaks are more equally distributed throughout the year for catchments located close to the Atlantic coast and in the south of the study area. Flood seasonality has changed over the past century seen as decreasing trends in summer maximum daily flows and increasing winter and spring maximum daily flows with 5–35% of the catchments showing significant changes at the 5% significance level. Seasonal mean daily flows corroborate those findings with higher percentages (5–60%) of the catchments showing statistically significant changes. Alterations in annual flood occurrence also point towards a shift in flow regime from snowmelt‐dominated to rainfall‐dominated with consistent changes towards earlier timing of the flood peak (significant for 25% of the catchments). Regionally consistent patterns suggest a first‐order climate control as well as a local second‐order catchment control, which causes inter‐seasonal variability in the streamflow response.     

Investigation into the daily precipitation variability in the Yangtze River Delta,China

In this article, by using the daily precipitation data measured at 58 meteorological stations, spatial and temporal variability of daily precipitation including zero rainfall values (called “precipitation”) and without zero rainfall values (called “rain”) and four precipitation extrema (P₀, P₂₀, P₅₀, and P₁₀₀ representing the daily precipitation with the magnitude smaller than 0.1 mm, bigger than 20 mm, 50 mm, and 100 mm per day, respectively) in the Yangtze River Delta (YRD) during 1958–2007 were analyzed, and the effects of urbanization were further investigated. Results indicate that (i) differing from the downward trends in 1958–1985, daily precipitation and rain in 1986–2007 show slowly downward trends in the mid YRD but show upward trends in the northern and southern YRD. (ii) Spatial and temporal variability of the rain is more complex than daily precipitation. Both of them become smaller but show more obvious fluctuations in 1986–2007. (iii) Urbanizations cause not only the urban rainfall island problem but also more obvious fluctuations of rain intensity in the mid YRD, reflecting more uncertainty of daily precipitation variability. (iv) Urbanizations have little effects on the variability of P₀ and P₁₀₀ but cause notable increases of P₂₀ and P₅₀. (v) The spatial variability of daily precipitation and precipitation extrema in 1958–1985 clearly shows a breakpoint at 30°20′N latitude, but the breakpoint disappears afterward because of the effects of urbanization. Copyright © 2012 John Wiley & Sons, Ltd.     

A study of variability of annual river flow of the southern African region

Abstract

Variability of river flow is investigated in 502 river flow gauging stations in nine countries of the southern African region with a view to document the spatial variability of the river flow regimes. Those regions where there is strong evidence of declining or increasing trend in annual runoff have been identified. The study has shown that runoff in the region ranges from over 320 mm year^?1 in the Lower Zambezi and the highlands of Tanzania to less than 10 mm year^?1 in the deserts of Namibia and the Kalahari. There is also evidence of declining runoff in parts of Zambia, Angola, Mozambique and the High Veld in South Africa. The recent decline seems to have started from around 1975.