隋唐长安城“八水五渠”水系对生态城市建设的启示

隋唐长安城"八水五渠"的水系除了为城市居民提供富足的用水环境外,还为城市提供了良好的生态环境,该文主要的目的在于从隋唐长安城的水系入手,指出当今生态城市在水资源方面的建设需要注意的几个问题。     

International Rivers as Boundaries

Abstract

International rivers serve a number of purposes, the most obvious are the navigational and non-navigational uses. Less noticed is the fact that international rivers are also used to delimit boundaries between nations. The immediate question that would arise is: Where are such boundaries actually drawn across the river? Boundaries, however, are established by treaties and the answer to this question is often included in the interpretation of treaties delimiting such water boundaries, taking into account the special characteristics of the international river. Indeed, this has been the case regarding the boundaries across the Chobe river between Botswana and Namibia. Determining where such boundaries lie would result in deciding to whom a disputed Island, the Kasikili/Sedudu, belongs. In a praiseworthy step, the two countries agreed to take their dispute over the Island, after failure to resolve it through negotiations, to the International Court of Justice. This paper discusses the uses of international rivers as boundaries, and reviews the dispute between Botswana and Namibia, and the decision of the Court thereon.     

A new ‘momentum method’ for the quantitative and qualitative evaluation of Polish rivers

There is a tendency in water management to identify the resources of surface waters with river discharge expressed by the intensity of the flow. However, such an evaluation is insufficient because of the difficulties in the water-economic balancing of the basin resources, since it does not take into account the volume of water contained in the river channel. With heavy pollution of the water flowing in the river channel, this fact may have a considerable influence on the representativity of the balance.The above reasons have become a basis for the introduction of a new measure for the evaluation of pollution resources of flowing water. The quantity of water in motion in a river channel is expressed by the momentum equation.Evaluation of water resources has been carried out for 83 rivers in the Vistula Basin and 52 rivers in the Odra Basin by means of the stream momentum method.     

弯曲河流三维数值模型

将平面正交曲线坐标系和垂向σ伸缩坐标系相结合,建立适合弯曲河流的三维水流数值模型。采用模式分裂技术将控制方程分解为外、内模式联合求解,方程的离散采用有限差分法。采用嘉陵江广元城区河段5个弯段内7个典型横断面地形、水位和流速资料对本文模型进行验证,模型成功地模拟出了水面横比降和弯道二次流,模拟结果与实测数据吻合较好。     

河道采沙对河流河道演变及人类生产活动影响研究述评

河流采沙活动将引起河流水体水质与河道演变的变化,同时亦将对水生生物与人类的生活环境以及相关人类生产活动造成巨大影响,该问题在近年来越来越引起国内外研究者和学者们的关注和重视。本文对国内外研究者就河流采沙活动对河流河道演变及相关人类生产活动的影响问题开展的研究工作及取得的研究成果作了全面的综合性介绍,并就该问题在今后应进一步开展的研究工作提出了一些看法和建议。     

松辽流域2001年汛期雨水情分析

本文从天气形势、降雨分布、洪水特性、水库蓄水、辽河断流等几方面对松辽流域2001年的雨水情特点进行了分析,并与历史资料进行了对比,指出该年汛期流域内降雨量偏少,江河来水量偏枯,整个松辽流域属偏旱年景。     

嘉兴地区中小河流河道整治工程地质勘察技术探讨

近几年,嘉兴市中小河流整治工作如火如荼地展开。那么,如何提高河道的工程地质勘察技术水平呢？本文概述了嘉兴地区中小河流河道整治工程的现状,对嘉兴市河道整治工程地质勘察过程中的一些技术问题进行了分析和探讨。     

The Orinoco river: A review of hydrobiological research

The Orinoco River is one of the world's longest rivers (2060 km) and in terms of average water discharge (36000 m³ s^?1) it ranks third. Seventy per cent of its basin (1.1 × 10⁶km²) is found in Venezuela and the rest in Colombia. Due to the uneven distribution of the population toward the northern coastal areas (97 per cent of the population inhabits 55 per cent of the country with only 16 per cent of the surface waters) plans have been carried out to develop resources in the Orinoco Basin. So far these programs include mining (mainly iron and bauxite), oil exploration and extraction from the Orinoco Oil Belt, industry, river transport, and hydroelectric exploitation. Development of the latter has involved the construction of two dams on the Caroní River (the most important blackwater tributary of the Orinoco) and two more are planned on this same river. Hydroelectric projects are also being considered for the Orinoco River. Physicochemical and biological characterization has been regarded as of major importance to establish base-line information to detect and quantify possible alterations in this river which is considered to be in a pristine state. Systematic hydrobiological research has recently been carried out in the river, some of its major tributaries, and floodplain lakes, and a fair amount of knowledge has emerged mainly from its lower section. Phytoplankton studies have revealed the presence of over 400 species of algae. Zooplankton research has identified 116 taxa of rotifers and 58 taxa of cladocerans. In general plankton densities negatively correlate with water level. Diatoms were observed to predominate in the Orinoco River while Cyanophyta predominate in the studied floodplain lakes. Seventeen aquatic macrophyte species have been recorded in the lakes of the Orinoco with high densities of Eichhornia crassipes, Oxycarium cubense, and Paspalum repens. Rooted emergent and floating-plant cover tends to increase rapidly during high water. Some 318 species and subspecies of fish have been reported for the Orinoco Basin, even though this number is far from complete. Preliminary data have revealed different species associations among relatively close lakes with biomasses ranging between 30 to 900kg ha^?1 displaying considerable variations in diversity and species richness. Fisheries along the Orinoco are mainly of a multispecific nature and their overall potential has been estimated as being in the order of 45 000t yr^?1. In general, management plans have taken into consideration the multispecific potential of the Orinoco Basin but indicate a lack of sufficient knowledge of the physical, biological, and social aspects involved. Furthermore development plans tend to precede the generation of this basic knowledge, thereby increasing the risks of conflict among the various users of the resources involved.     

The East Kent Chalk Aquifer during the 1988-92 Drought

Groundwater resources of Chalk aquifers may become depleted during drought periods; major causes of this depletion include reductions in the aquifer transmissivity and the interaction between aquifers and rivers. In the East Kent aquifer there are certain catchments where difficulties are encountered in maintaining yields but, in other catchments, drought periods have little effect on the available resources. A mathematical model is developed to help understand the flow processes within the aquifer system, and the model is used to predict the consequences of possible abstraction scenarios.     

Determining loss characteristics of arid zone river waterbodies

Understanding the retention time of water in waterbodies during periods of no surface flow in dryland rivers provides an important context for evaluating the ecological importance of a waterhole to the river system. Time series of water level data were collected from 10 waterbodies spread across three river systems of the Lake Eyre Basin (LBE), Australia. Observed loss rates in the absence of surface flow were compared to modelled evaporation rates in order to determine whether open water evaporation was the main loss process from isolated waterholes and to what extent there is evidence of interaction between the surface water and any shallow groundwater aquifers. The modelled evaporation rates were determined using the Penman combination equation and meteorological data from the closest climate station in the region of the waterbodies. The modelled evaporation data were able to explain only some of the variability in the observed loss data but did highlight periods where other processes (including observation error) need to be invoked. These other possible processes, which include temporary groundwater connection and the effect of heat storage on the evaporation losses, probably contribute as much to the observed data variability as error introduced by the use of regional meteorological data. Assuming evaporation is the dominant process determining water loss in the absence of flow, the persistence of a waterhole is primarily dependent upon its depth when flow ceases. The annual loss shown by most waterbodies lies within the range of the modelled evaporation rate using the Penman combination equation and equates between 1.5 and 2.5 m per annum. The use of water level data in conjunction with the modelled evaporation rates was able to provide important insights into controls on waterbody loss rates and persistence. Copyright © 2007 John Wiley & Sons, Ltd.