摘要:

This paper focuses on the identifiability problem of hydrological system modelling, taking implicit rainfall-runoff models as a target for study i.e. those models whose structures are nonlinear functions of their parameters. Because most implicit models and objective functions are very difficult as regards analytical solution or for finding high-order derivatives, a numerical analysis method is developed which not only can assess the identifiability problem but also can provide useful information for dealing with parameter optimization. The major studies involved are two-fold: (1) proposing a mathematical description and assessment method for the structural identifiability of hydrological models; and (2) providing a workable and robust identification technique using a rotating transformation of the parameter space. Using both generated error-free and watershed data in China, it has been verified that the approach is of significance and usefulness.

ISSN:0262-6667    

DOI:10.1080/02626668909491305

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The necessary and sufficient conditions for non-zero phase shift and non-zero attenuation in linear flood routing can be derived from the continuity equation alone and are found to depend on the existence of an imaginary part in the expression for frequency or in the expression for wave number. It is shown that in linear flood routing the phase lag between flow rate and area of flow is directly related to the attenuation per unit wave length. The effects of using various forms of the momentum equation, in addition to the continuity equation, are exemplified by deriving analytical expressions in terms of the frequency, both for attenuation per unit channel length and for phase shift, for the kinematic wave, the general diffusion analogy, and the complete St. Venant equation.

ISSN:0262-6667    

DOI:10.1080/02626668909491306

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The design quantiles of storms are derived directly in terms of design life and the risk of occurrence. Estimators for these quantiles based on exceedance series are discussed for the cases of Poisson and negative binomial storm arrival processes. The use of Bootstrap methods to estimate confidence intervals for the design quantiles is demonstrated.

ISSN:0262-6667    

DOI:10.1080/02626668909491307

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The water balances of four major African wetlands—Senegal, Niger, Sudd and Okavango—are compared through analysis of inflows and outflows, rainfall and evaporation. Annual and seasonal inflows are compared and marked differences are revealed. A simple relation between flooding area and volume is included in the water balance model in order to estimate monthly series of flooded areas over the period of records. These show great differences in the proportions of permanent and seasonal swamp, which help to explain the differences in vegetation distributions.

ISSN:0262-6667    

DOI:10.1080/02626668909491308

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

One topic within the field of deterministic flood modelling that appears to have been relatively neglected is the level of model sophistication that is needed to satisfy the requirements of different model applications. This study considers two isolated event models, both of which can be operated in lumped and semi-distributed format. The results of modelling 174 rainfall-runoff events from 16 medium sized catchments in the USA and South Africa are compared for these models. The lumped models perform as well as the semi-distributed when the rainfall input is relatively spatially uniform. The semi-distributed models show demonstrable improvements for storms with spatially variable rainfall if the rainfall input is adequately defined by the available data. The simpler model appears to perform as well as the more complex one. However, this is achieved at the expense of consistency of parameter values for a single catchment.

ISSN:0262-6667    

DOI:10.1080/02626668909491309

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The evolution, over periods of up to nine years, of tritium, nitrate and other pore-water profiles in the Chalk unsaturated zone at sites in three areas in Britain is presented and evaluated in terms of transport mechanisms.

ISSN:0262-6667    

DOI:10.1080/02626668909491310

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491311

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491312

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491313

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668909491315

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor