摘要:

Snowmelt runoff is a significant component of the hydrological cycle in many regions. Major problems of snowmelt runoff modelling associated with the physiographic and climatic conditions of these regions, and problem solutions being investigated, are reviewed. Problems common to all regions include: (a) definition of the spatial and temporal distribution of model input; (b) measurement or estimation of snow accumulation, snowmelt, and runoff process parameters for a range of applications and scales; and (c) development of accurate short term and long term snowmelt runoff forecasts. Procedures being investigated to solve these problems include: (a) integrating conventional and remote-sensing data to improve estimates of input data; (b) developing snowmelt process algorithms which have parameters that are closely related to measurable basin and climatic characteristics; and (c) updating model parameters and components using measured data or knowledge of past uncertainty. Research needs include development of improved model capabilities and establishment of standardized techniques and measures to evaluate model performance and results.

ISSN:0262-6667    

DOI:10.1080/02626668909491371

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In order to estimate areal evapotranspiration (ET), a system using Landsat MSS and elevation data is developed. After extraction of the study area and its geometric correction, Landsat MSS data are classified into land use categories, which give empirical parameters for calculation of ET. Elevation data, which are originally given at the mesh of 7.5” in latitude by 11.25” in longitude, are interpolated and fitted to each pixel of land use image data. Calculation of ET is executed by using empirical functions in terms of meteorological elements which are linearly regressed with elevation from data at several observatories. The calculated results are represented by the form of not only statistical quantities but also transformed image data. The distribution of ET over mountainous areas, represented as image data, reasonably shows the effect of topography. After comparing with observed data of pan evaporation and with the values estimated by Thornthwaite's method, one can conclude that this system would reliably estimate the actual monthly ET over large areas.

ISSN:0262-6667    

DOI:10.1080/02626668909491372

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The possible impacts of modifications in rainfall patterns due to the greenhouse effect on the function of a sewerage system are studied based on a case study of the city of Lund, Sweden. The Storm Water Management Model is used to simulate changes in the runoff pattern. The paper lists the possible effects of increases in rainfall intensity on the urban water cycle, quantifies changes in the runoff pattern, and discusses the significance of detected changes in terms of economic and environmental consequences and the possibilities to undertake preventative measures. For the purpose of the present study, 10%, 20% and 30% levels of rainfall increase were assumed. In spite of considerable uncertainty regarding the potential future rate of hydrological changes, the examples given of possible impacts of the greenhouse effect on the function of the sewerage system bear witness to the great vulnerability of sewerage systems to the results of climate changes.

ISSN:0262-6667    

DOI:10.1080/02626668909491373

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The chemistry of streamwater, bulk precipitation, throughfall and soil waters has been studied for three years in two plantation forest and two moorland catchments in mid-Wales. Na and CI are the major ions in streamwater reflecting the maritime influence on atmospheric inputs. In all streams, baseflow is characterised by high pH waters enriched in Ca, Mg, Si and HCO3. Differences in baseflow chemistry between streams reflect the varying extent of calcite and base metal sulphide mineralization within the catchments. Except for K, mean stream solute concentrations are higher in the unmineralized and mineralized forest catchments compared with their respective grassland counterparts. In the forest streams, storm flow concentrations of H+are approximately 1.5 times and Al four times higher than in the moorland streams. Annual catchment losses of Na, Cl, SO4, NO3, Al and Si are greatest in the forest streams. In both grassland and forest systems, variations in stream chemistry be explained by mixing waters from different parts of the catchment, although NO3concentrations may additionally be controlled by N transformations occurring between soils and streams. Differences in stream chemistry and solute budgets between forest and moorland catchments are related to greater atmospheric scavenging by the trees and changes in catchment hydrology consequent on afforestation. Mineral veins within the catchment bedrock can significantly modify the stream chemical response to afforestation.

ISSN:0262-6667    

DOI:10.1080/02626668909491374

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The present work describes the development and calibration of a mathematical model for the Tigris River downstream of Sadam Dam. The river stretch studied is 75 km long extending from the Sadam Dam to Mosul city. The field work was conducted during the period from July to September 1986. Water samples were collected bimonthly from specified sampling points. The model simulates river assimilation capacity for a variety of water quality parameters by performing the numerical solution of a set of differential equations representing the aquatic system under steady state conditions. Generally, a noticeable increase in the concentrations of water quality parameters arising from water impoundment was observed. A good agreement was found between measured and simulated concentrations of water quality parameters. However, discrepancies noticed during model calibration were attributed to the assumptions adopted in the model formulation, to lack of field data, and to exclusion of some variables in model building.

ISSN:0262-6667    

DOI:10.1080/02626668909491375

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A risk assessment procedure is described for use in managing a system of pumped-storage reservoirs in the Thames basin during a drought. Historical daily rainfall sequences are used as equi-probable scenarios of future rainfall. These are transformed to flow, reservoir level, and demand restriction sequences through the use of rainfall-runoff and water resource system models. The risk assessment information required is then obtained through a statistical analysis of these sequences. A novel technique is presented for incorporating monthly rainfall forecasts, presented as probabilities of rainfall being above average, average, or below average, into the risk assessment scheme. Information on current hydrological conditions is incorporated in the procedure through the use of recently observed natural flows to adjust the internal state variables of a conceptual rainfall-runoff model to achieve agreement between observed and model flow. The overall procedure is accommodated within a decision support system for drought management which is implemented on a microcomputer and makes extensive use of interactive menus, forms and colour graphic displays. A key feature of the system is the maintenance of an up-to-date archive of hydrometric data which is achieved through a real-time communication link with a second computer dedicated to real-time data acquisition via telemetry. Monitoring the reliability of the water resource system during droughts is made a quick and easy task, and the effect of a change in the operating policy on system reliability can be readily assessed. The information obtained provides valuable support for tactical decision-making within the overall long-term operating strategy.

ISSN:0262-6667    

DOI:10.1080/02626668909491376

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491377

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491378

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491379

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491380

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor