甘肃黑河中下游影响绿洲植被发育的某些因素

黑河下游额济纳绿洲区和中下游沿黑河干流河床附近的潜水位埋深较浅,是维系地表植被生长的重要因素。中游高台附近潜水位存在每年双峰值的变化,较之下游额济纳绿洲潜水位每年单峰值的变化更有利于植被的生长。在包气带剖面中,同一时刻水土势、含水量、含盐量随深度的变化趋势基本相同。采样点包气带土壤中易溶离子含量相对较低,全盐量小于5%,中游采样点土壤中以HCO3-为主,下游以SO42-为主,由SO42-、Cl-和Na+、Ca2+组成的盐类构成了包气带土壤中的主要盐分。土壤中易溶离子含量自地表至潜水面之间随深度总体上呈减小趋势。植被的根系分布对包气带土壤含水量、水土势和易溶离子含量随深度的分布有着重要的影响,在植物根系发育带的土壤中含水量、水土势和易溶离子含量升高。     

广东雷州半岛玄武岩地下水水文地球化学特征及演化模拟

应用水化学分析软件和水-岩作用模拟软件对雷州半岛的水文地球化学进行了分析和路径模拟。沿东、西2个地下水径流方向从一级台地补给区至二级台地、三级台地排泄区的模拟计算结果表明,地下水可能经历了一系列复杂的水-岩作用,包括石膏、高岭石、钙蒙脱石、伊利石、绿泥石、斜辉石(或透辉石)、针铁矿、赤铁矿的溶解或沉淀及CO2气体的溶解或逸出等地球化学反应。针铁矿、赤铁矿和透辉石的溶解或沉淀量在沿东面地下水径流方向上远小于沿西面方向;针铁矿和赤铁矿只在少量水点发生溶解进入地下水,在大多数水点处于饱和状态而从地下水中析出;CO2气体在大多数取样点发生溶解进入地下水中,其溶解量较大,且随着CO2在水中浓度的变大,其饱和指数也增大,达到饱和后从水中逸出。可见水-岩作用模拟结果有助于揭示研究区地下水化学环境的演化机制。     

Trend in Observed and Projected Maximum and Minimum Temperature over N-W Himalayan Basin

Recently, study in past trends of climate variables gained significant consideration because of its contribution in adaptions and mitigation strategies for potential future changes in climate, primarily in the area of water resource management. Future interannual and inter-seasonal variations in maximum and minimum temperature may bring significant changes in hydrological systems and affect regional water resources. The present study has been performed to observe past(1970-2010) as well as future(2011-2100)spatial and temporal variability in temperature(maximum and minimum) over selected stations of Sutlej basin located in North-Western Himalayan region in India. The generation of future time series of temperature data at different stations is done using statistical downscaling technique. The nonparametric test methods, modified Mann-Kendall test and Cumulative Sum chart are used for detecting monotonic trend and sequential shift in time series of maximum and minimum temperature. Sen’s slope estimator test is used to detect the magnitude of change over a period of time on annual and seasonal basis. The cooling experienced in annual TMax and TMin at Kasol in past(1970-2010) would be replaced by warming in future as increasing trends are detected in TMax during 2020 s and 2050 s and in TMin during 2020 s, 2050 s and 2080 s under A1 B and A2 scenarios. Similar results of warming are also predicted at Sunnifor annual TMin in future under both scenarios which witnessed cooling during 1970-2010. The rise in TMin at Rampur is predicted to be continued in future as increasing trends are obtained under both the scenarios. Seasonal trend analysis reveals large variability in trends of TMax and TMin over these stations for the future periods.     

Strategies for managing reservoir sedimentation

Sediment deposition in reservoirs has caused the loss of 66% of the reservoir capacity in China. The main sedimentation control strategies are： 1） storing the clear water and releasing the turbid water; 2） releasing turbidity currents; 3） Draw-down flushing and empty flushing; and 4） dredging, The paper summarizes these strategies with examples. Sediment transport in many Chinese rivers occurs mostly during the 2-4 month flood season, that is, 80-90% of the annual sediment load is transported with 50-60% of the annual runoff. By storing the clear water after the flood season and releasing the turbid water during the flood season, less sediment deposits in the reservoir while the reservoir is still able to store enough water for power generation in the low flow season. The Three Gorges and Sanmenxia reservoirs apply this strategy and control sedimentation effectively. Turbidity currents have become the main sedimentation control strategy for the Xiaolangdi Reservoir. Empty flushing involves reservoir draw-down to temporarily establish riverine flow along the impound reach, flushing the eroded sediment through the outlets. Case studies with the Hengshan Reservoir and Zhuwo Reservoir are presented. Jet dredgers have been used to agitate the reservoir deposit so that the deposit is released from the reservoir with currents. The sediment releasing efficiency is 30-100% for storing the clear and releasing the turbid; 6-40 % for turbidity current; and 2,400-5,500% for empty flushing. Empty flushing causes high ecological stress on the ecosystem to the downstream reaches. Storing the clear and releasing the turbid is the best strategy to control reservoir sedimentation while achieving hydro-power benefit and maintain ecological stability.     

Fine sediment carrying capacity of combined wave and current flows

The so-called fine sediment in many coastal areas and estuaries in China is mostly referred to the mixture of cohesive sediment and non-cohesive sediment. To predict the mixed type time sediment transport, sediment carrying capacity formulae combined with the 2-D suspended sediment transport equation and morphologic equation have been widely used in China. In the present study, the sediment carrying capacity formula suggested by Dou et al. （1995） for wave conditions has been improved and implemented for the prediction of sediment transport in nearshore regions where wave activities are significant. The improvement is based on the wave energy dissipation principle inside and outside the surf zone. In the improved formula, sediment in suspension increases with the magnitude of the wave period and this feature complies with general observations. More than 300 laboratory and field measured data sets have been reviewed and 12 of them have been used to verify and determine the major coefficients in the improved formula. The application of the sediment carrying capacity model in combined wave and current situations shows that the model can faithfully reproduce the cross-shore sediment concentration distributions at the southwest coast of Bohai Bay.     

Analysis of the Frequency Domain Water-level Deconvolution Method Based on Reservoir Airgun Source Data

Based on the 2016 airgun experimental data of the Fujian Nanyi reservoir, we adopted the frequency domain water-level deconvolution method and cross-correlation time delay detection technique to study the influence of level scaling factor and the background noise level of the station on deconvolution calculation results, and analyze the effect of deconvolution on eliminating the influence of the source caused by different air-gun pressures. The results show that:(1) When the level scaling factor is smaller, the signal to noise ratio of the waveform after the deconvolution is smaller, and when the level scaling factor is over smaller, the identification error of travel time is greater. (2) When the SNR of the station record is higher, the recognition accuracy of travel time is higher, the influence of SNR on the reference station record is far greater than the far station, when the SNR of the far station record is more than 10, the error of travel time is within 6ms, but when the SNR of the reference station record is 30, the travel time error may reach to 20ms. (3) When the airgun source difference is big, the frequency domain water-level deconvolution method has better effect on eliminating the source influence, but the method error may be introduced when the source difference is small.     

鱼潭水电站地下厂房裂隙层状围岩的变形特征

通过分析鱼潭水电站地下厂房围岩松动圈、块体塌滑,应力变化和收敛位移等特征,揭示了本工程裂隙层状围岩变形破坏的一般规律。     

水文工作回顾与展望

新中国成立５０年来,水文工作经历了迅速发展、曲折前进,改革开放三个发展阶段。新中国的水文工作在水文测验、水文情报预报,水文分析计算和水资源评价,水文科学研究,水文教育,水文国际合作与交流诸方面都取得了前所未有的巨大成就,为社会主义建设作出了巨大贡献。当前,中国水文工作面临着新的挑战和机遇,今后必须有新的发展,以满足新的迫切的社会需求。     

Application of extension theory in risk zoning of debris flow in Beijing

The occurrence of debris flow is affected by many factors. Risk zoning of debris flow plays a vital role in the early-warning and prediction of abrupt geological hazards, and exploration of new method is needed in the early-warning and prediction of geological hazards. The extension theory is a new method to solve contradiction matters. Based on extension theory, AHP and GIS, the risk zoning model of debris flow was established in this paper. The result of this research provides a new way in the risk zoning, early-warning and prediction of debris flow     

在迟家店石榴石二辉橄榄岩的橄榄石中发现自然铁及其意义

通过高分辨电子显微镜研究，发现在山东荣成迟家店石榴石二辉橄榄岩的橄榄石中除钛铁矿和磁铁矿出溶物外。还有一种矩形出溶物，长为20μm、宽为5μm．能量损失X射线分光谱(XEDS)分析矩形物的成分为Fe。选区电子衍射花样计算表明该矿物与和JCPDS中的标准矿物自然铁-α和自然铁-γ衍射数据一致。根据自然铁的化学成份推断橄榄石中自然铁-α和自然铁-γ的形成温度范围为490～900℃，压力不超过8．2GPa，并讨论了自然铁与深源地幔流体作用。