黄河下游的河性

本文探讨了黄河一般特性的综合关系,讨论了河道演变中均衡与非均衡的问题、滩槽冲淤的利与害和主与从的问题,同时讨论了河道冲淤演变特性、与水沙条件的关系、河槽淤积率和淤积比等。     

Geochemistry of arsenic in the Huanghe (Yellow River) and its delta region — A review of available data

Water and suspended sediment samples from the Huanghe and its delta region were analyzed to determine arsenic concentrations. Comparison with the data of previous studies and other world pristine and less disturbed rivers reveals high levels of both dissolved and particulate As in this high turbidity river. Relatively stable distribution along the river course and in delta sediment cores shows that antrhopogenic activities have not altered As concentrations by any significant magnitude since the 1940s. Therefore, high levels of As in the Huanghe should be controlled by natural weathering and lithology. In the estuary, biological removal/regeneration and abiotic events (e.g. remobilization) have been identified to cause the active (non-conservative) As distributions. With the limited data set of the present study, the abiotic and biological contributions cannot be assessed accurately, however.     

Geochemical mass balances of major chemical constituents in the watershed of the Changhuajian River in China

Based on the geological background, R-mode factor statistics, and the analysis of the stability diagram for the corresponding system, five weathering reactions controlling the surface-water chemical composition in the watershed of the Changhuajiang River are deduced. In the mass balance model, the precipitation accounts for some solute input, since the rainwater is dilute without pollution. Most of the Ca²⁺ and HCO ₃ ^– ions are from the dissolution of calcite, K⁺, Na⁺, H₄SiO₄ and some of the Mg²⁺ and HCO ₃ ^– come from albite and biotite weathering to kaolinite. The dissolution of dolomite and gypsum controls the mass balances of Mg²⁺ and SO ₄ ^2– . The dissolution of calcite is the dominant chemical weathering reaction in the watershed because of its reactivity and high concentration. In the watershed in 1986, the chemical weathering rate was 0.073 (kg/m² a), and the mechanical denudation rate is 0.093 (kg/m² a). The chemical weathering mass output proportion of carbonate rocks to silicate rocks was about three to one.     

Heavy Metal Load of Sediments of the River Gurk (Carinthia/Austria) — Merits and Limitations of Sequential Leaching Schwermetallbelastung des Sediments der Gurk in Kärnten — Vorzüge und Einschränkungen sequentieller Löseverfahren

By means of the analysis of sediments cored in the small river Gurk (Carinthia/Austria), the input of Ag, Cd, Ce, Cr, Hg, La, Mo, Ni, V, and W from a chemical industrial plant could be detected. To estimate the actual load, and to obtain data for comparison with other sites, both unsieved fine sediments and sediments sieved to 20 μm were investigated from the same cores. Environmental mobilities of toxic heavy metals (Co, Cr, Cu, Ni, Zn) have been shown by sequential leaching following Tessier/Förstner. In the last step, HNO₃ leaches a purely geogenic fraction, which is fairly constant along the investigated river. Whereas the additional Cr from the input of the chemical plant is mainly found in the oxalate-leachable fraction, short-time-load to unpolluted sediments in the laboratory is found mainly in hydroxylamine/acetic acid. Both is due to the high affinity of Cr to Fe- and Mn-oxides. Adsorption/desorption experiments reveal that the low carbonate content of the Gurk sediments increases the importance of Fe/Mn-oxides for the sorption of Cr compared to other samples containing carbonate. The Ni-load was primarily found in weak-acid-leachable and oxalate-leachable fractions. Similarly, the oxalate-leachable fraction is dominant for adsorption of other metals and phosphorus. Other interelement relationships among the amounts leached, which are attributable partly to carbonate-, silicate-, organic or coating phases, have been found by means of factor analyses together with marker fractions for each type.     

四边形法绘制水下河床等深线图

根据水下河床水深点测量采样的既有规则格网法又有三角形法二者优点的四边形法绘制河床等深线图,该法数据结构简单,编程方便,速度快。文 图表对水下对河床水深点的数据数据结构,四边形的构万能主等深线的追踪作了详细的讨论。     

A two-stage time series model for monthly hydrological projections under climate change in the Lim River basin (southeast Europe)

ABSTRACT

Climate change projections of precipitation and temperature suggest that Serbia could be one of the most affected regions in southeastern Europe. To prepare adaptation measures, the impact of climate changes on water resources needs to be assessed. Pilot research is carried out for the Lim River basin, in southeastern Europe, to predict monthly flows under different climate scenarios. For estimation of future water availability, an alternative approach of developing a deterministic-stochastic time series model is chosen. The proposed two-stage time series model consists of several components: trend, long-term periodicity, seasonality and the stochastic component. The latter is based on a transfer function model with two input variables, precipitation and temperature, as climatic drivers. The Nash-Sutcliffe model efficiency for the observed period 1950–2012 is 0.829. The model is applied for the long-term hydrological prediction under the representative concentration pathway (RCP) emissions scenarios for the future time frame 2013–2070.     

Impacts of droughts on low flows and water quality near power stations

ABSTRACT

Power plants often use river waters for cooling purposes and can be sensitive to droughts and low flows. Water quality is also a concern, due to algal blooms and sediment loads that might clog filters. We assessed the impacts of droughts on river flow and water quality from the point of view of power plant operation. The INCA (INtegrated CAtchment) water quality model was coupled with a climate model to create a dataset of flow and water quality time series, using the River Trent (UK) as a case study. The result hints to a significant decrease in flows and an increase in phosphorus concentrations, potentially enhancing algal production. Power plants should expect more stress in the future based on the results of this study, due to reduced cooling water availability and decreasing upstream water quality. This issue might have serious consequences also on the whole national power network.     

Comparing performance indicators to characterize the water supply to the demands of the Guadiana River basin (Spain)

ABSTRACT

Water indicators and indices are useful tools to assess river basin performance, that is, to measure whether the basin operates satisfactorily under a wide range of possible future demands and hydrological conditions. Spanish regulations assess the performance of water demands by using reliability indicators (RIs), established by law in 2008. This article raises the possibility of updating RIs by comparing them with sustainability indicators (SIs). SIs are widely used for the assessment of river basin performance and several policy scenarios. We applied a water allocation model to the Guadiana River basin in Spain to compare indicators under three scenarios. The study was framed within the science of socio-hydrology, combining the physical environment of a water system with its influence on social aspects. SIs gave better results than RIs when comparing future scenarios. We also propose the introduction of a vulnerability indicator into Spanish regulations.