摘要:

River runoff and the resulting water resources which provide the needs of mankind for fresh water are subject to variations in space and time mainly depending on the space and time variability of climate characteristics. Thus there are close interrelations between the problems of the provision of fresh water and the problems of both natural and anthropogenic changes in climate. Moreover, these interrelations are characterized by specific features both under natural conditions and during a period of man's intensive impact on water resources. The problem of these interrelations has acquired a particular scientific and practical importance during recent years in which climatologists have attempted to predict global anthropogenic changes in climate for the near future, changes unknown on our plant for millennia. The present paper has been prepared mainly on the basis of research results obtained at the State Hydrological Institute in Leningrad. It describes the global interrelations between climatic characteristics and water resources under natural conditions and in the case of intensive water resources development; up-to-date ideas on the anthropogenic changes of the global climate are given; the possible consequent effects on future water resources are analysed.

ISSN:0262-6667    

DOI:10.1080/02626668909491359

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Water bodies up to 0.9 ha surface area, which are indistinguishable by Landsat Multispectral Scanner (MSS) due to the latter's poor spatial resolution of 80 m, can be identified and mapped reliably and reasonably within ±10% accuracy by Landsat Thematic Mapper (TM) false colour composite because of its higher spectral and spatial resolution of 30 m. Comparative study of Landsat TM and the Survey of India topographical maps revealed reductions in the water surface and drainage basin areas up to 1.8 to 2.4 and 6.0 to 8.0 times, respectively, over a period of 28 years (1958–1986) due to the biotic interference resulting in desertification in the large adjoining areas.

ISSN:0262-6667    

DOI:10.1080/02626668909491360

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

There has been a trend in recent years towards the development and popularity of physically-based deterministic models. However, the application of such models is not without difficulties. This paper investigates the usefulness of a conceptual single-event model for simulating floods from catchments covering a wide variety of climatic and physiographic areas. The model has been calibrated on a group of catchments and the calibrated parameter values related to physical catchment indices. The resulting quantitative relationships are assessed with respect to their value for estimating the parameter values of the model when calibration is not possible. The results indicate that the technique is likely to provide flood estimations for medium sized catchments (5–150 km2) that are more reliable than several flood estimation methods currently in use in South Africa.

ISSN:0262-6667    

DOI:10.1080/02626668909491361

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An attempt is made to incorporate the physical mechanism in a distribution function of low flow in terms of baseflow recession. The derived distribution function contains four parameters of which two are determined from a traditional recession analysis of low flow periods. The other two are derived from a statistical analysis of the maximum length of “dry weather” periods when precipitation is less than an assumed threshold value. The distribution function with the same parameters can be applied to calculate mean low flow for different durations. It is applied and tested for summer low flow in southern and western Norway.

ISSN:0262-6667    

DOI:10.1080/02626668909491362

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In the central part of the Netherlands, a 20 km2drainage basin contains a morainic ridge of Pleistocene sandy deposits and a backswamp area where the sandy subsoil is covered with river clay deposits. Agricultural and “natural” ecosystems are present in both parts. A continuous groundwater flow exists from the ridge to the clay area. A channel network drains the area. For these channels a two-dimensional model for simulating discharge and water quality has been developed. In computations, discharges and concentrations in groundwater, precipitation, and overland flow are treated separately. With a model option for calculating the effects of land use changes, water quality was calculated for base-line conditions. Mean nitrate concentrations were 1/2 to 1/7 of the actual concentrations, mainly caused by manure inputs. Storm events occasionally give very high concentrations, also under base-line conditions. Therefore base-line conditions for ions cannot be described as a single steady value.

ISSN:0262-6667    

DOI:10.1080/02626668909491363

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491364

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491365

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491366

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491367

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491368

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor