摘要:

The Generalized Pareto distribution is fitted to Dutch peaks-over-threshold (POT) rainfall series. Maximum likelihood (ML) estimation of the parameters is discussed, with particular reference to bias reduction for the scale and shape parameter. The improvement of the fit in the right tail by left censoring of POT series is discussed, and the dependence of the shape parameter θ of the fitted Generalized Pareto distribution on (a) mean annual number of peaks, and (b) rainfall duration, with fixed or moving starting point, is quantified.

ISSN:0262-6667    

DOI:10.1080/02626668609491037

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Methods of description of the nonlinear effects in dynamic hydrological systems have been surveyed. Particular reference was given to those sorts of nonlinear methods which do not require significantly more computational effort in comparison with classical linear models. Original concepts in the field of nonlinear state-space models, Volterra series models and the general framework of multilinear models were tackled in more detail. Illustrative numerical examples of flood routing and rainfall-runoff modelling were presented.

ISSN:0262-6667    

DOI:10.1080/02626668609491038

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The method presented combines a black box analysis with a conceptual model approach. To describe the nonlinear behaviour of the systems, a model in the form of a second-order approximation of a cascade of nonlinear reservoirs was used. Such a model is equivalent to the first two terms of the Volterra series. Applications of the Volterra model based on a nonlinear cascade to the modelling of flow in open channels and of surface runoff systems indicate that the proposed model can be used to represent systems with nonlinear dynamic and linear static behaviour.

ISSN:0262-6667    

DOI:10.1080/02626668609491039

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Hydrogeochemical data of groundwater samples from 35 boreholes drilled in the Okposi-Uburu salt lake area are analysed. The data reveal that concentrations of dissolved geochemical constituents such as calcium (Ca2+), manganese (Mn2+), magnesium (Mg2+), chloride (C1−), and sulphate (SO2+4) ions show significant areal variations. Dissolved solids, chloride and manganese ions have concentrations up to and above the objectionable limits for drinking water in the salt lake area. Concentrations of dissolved solids in this zone are about 1200 mg 1−1. Concentrations of chloride and manganese ions are 350 mg 1−1and 1.0 mg 1−1respectively. These geochemical constituents and groundwater flow patterns show that transport of contaminants away from the source zone has been greatly influenced by advection, while in areas of high velocity dispersion is the controlling factor. Temperatures for the Okposi and Uburu salt springs are 34.4 and 37.5°C respectively. Bomb tritium indicated water of pre-1953 age. Deuterium and oxygen-18 showed high isotopic enrichment. The high concentrations of dissolved salts resulted from the combined effects of migration of dissolved salts through fractures at the lake floor and evaporation from the lake surface. These findings are related to the tectonic history of the Okposi-Uburu area.

ISSN:0262-6667    

DOI:10.1080/02626668609491040

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Remarks on the progress of scientific hydrology in the coming decades are formulated. This is accomplished both by extrapolating recent trends in research into hydrology and by isolating the present barriers to progress that are likely to remain at the centre of interest of hydrological sciences.

ISSN:0262-6667    

DOI:10.1080/02626668609491041

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Alternative ways of developing relationships between the parameters of conceptual hydrological flood routing models and the physics (understood as the hydrodynamic model or as the real system) have been examined. Three deterministic and two stochastic methods of synthesis of conceptual parameters were studied. The results offer aid in identification of conceptual parameters when modelling systems for which no historical time series of inflow-outflow data are available (e.g. ungauged rivers or river engineering design).

ISSN:0262-6667    

DOI:10.1080/02626668609491042

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Geomorphological instantaneous unit hydrograph (GIUH) theory has been applied for the estimation of the parameters of two conceptual models: a linear cascade model and a Laurenson-type model. Conceptual models, especially the linear cascade model, are more convenient for operational forecasting than the original GIUH model. A single linear reservoir model is suggested, with limited storage to represent the subsurface flow component. Subsurface flow is significant in Polish mountainous river catchments. Preliminary results of applying the model to operational flood forecasting are described.

ISSN:0262-6667    

DOI:10.1080/02626668609491043

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668609491045

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668609491046

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668609491047

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor