The use of remotely sensed data to detect channel hydromorphology; River Tummel,Scotland

Colour aerial photography and multi‐spectral imagery acquired from airborne platforms for the River Tummel, Scotland, was used in conjunction with field survey to assess the feasibility of monitoring hydromorphology and human alteration within the river corridor. The study was undertaken to investigate the possibility of remotely sensing the physical status of a nation's rivers at the national scale to comply with the requirement of the European Water Framework Directive. Visual assessment and unsupervised and supervised automated classifications of the imagery were undertaken and compared with field survey data. In the absence of overhanging vegetation canopies most features above the water line of interest were visible on the imagery. Below the water line, morphology and substrate composition together with bank materials on vertically cut banks are less easily detected. The overall accuracy of automated classification procedures, compared to field survey, was 60% for the colour aerial photography and 68% for the multi‐spectral imagery. Supervised classification was superior to unsupervised classification procedures. Sun glint on water surfaces and shadows caused by high banks, trees and buildings were observed as the cause of most misclassification of features. Overall, the study demonstrates that remotely sensed digital imagery has the potential to allow panoptic mapping of river hydromorphology and human impacts. The possibilities and constraints, in light of the findings of this study, are discussed. In the context of new legislation which requires environmental protection agencies to have robust tools for monitoring the physical status, as part of meeting the objective of good ecological status, of rivers across an entire nation, remote sensing appears to provide a way forward. Copyright © 2004 John Wiley & Sons, Ltd.     

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.     

The Potential of Interdisciplinarity for Leisure Research

Abstract

Knowledge about preferences for campsite attributes is needed so that management strategies can be guided by users’ preferences for settings and experiences. However, results of campsite choice studies have shown great variability across settings. Reexamination of this research shows a hierarchical typology of attributes: most important are necessity attributes, which supply basic camping needs, followed by experience attributes, which enhance preferred experience outcomes, and finally amenity attributes, which are relatively minor but can improve site quality. A survey of Whitewater boaters confirmed the predicted order of attribute importance and generally supported the proposed definitions of attribute types. A tentative model of campsite choice is offered in which sites are evaluated first for their ability to provide necessity attributes, then experience attributes, and finally, if more than one potential site remains, amenity attributes. Constraints may cut the evaluation process short anytime after the initial (necessity attribute) stage.     

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.     

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。     

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.     

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.     

河流健康评估的原则和方法

河流健康评估应包括物理-化学评估、生物栖息地质量评估、水文评估和生物群落的评估等内容.评估需要建立生境因子与生物因子的相关关系,需要建立基准点即参照系统,需要明确水文条件、水质条件和栖息地质量三个要素,需要因地制宜地为每一条河流建立健康评估体系及建立生物监测系统和网络.     

新型卷波弧形台阶防浪堤

本文表述既能抗御台风暴潮又能回卷波浪，集海塘、挡潮、交通、旅游多种功能于一体的两级台阶弧形组合防浪堤的设计基本点及其运用特性。