ISSN:0303-6936    

DOI:10.1080/02626667709491712

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0303-6936    

DOI:10.1080/02626667709491713

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0303-6936    

DOI:10.1080/02626667709491714

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Experimental work on electromagnetic streamflow measurements on the tidal Fraser River in British Columbia shows that the method of using the earth's magnetic field has two advantages: it gives an instantaneous value of the water velocity integrated over the entire cross section of the river and it is independent of temperature. In the Canadian climate both factors are important. The instrumentation is relatively inexpensive and it consists of a digital to analog converter, strip chart recorder, cable and silver electrodes. The instrumentation is essential for noise filtering and signal amplification. However, the final interpretation of the measured signal is quite difficult; it requires measurements from an electronic analog of the river cross section, resistivity of the ground below, conductivity of the water and a numerical hydrodynamic model. The flow velocities obtained from the measurements of induced potentials, caused by the Fraser River flowing across the earth's magnetic field, compared favourably with velocities computed from a proven hydrodynamic numerical model.

ISSN:0303-6936    

DOI:10.1080/02626667709491715

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

This paper examines the efficiency of various methods of calibrating a rainfall-runoff model. The model used is a 12 parameter version of the Boughton model which has been developed for large tropical basins. Attempts were made to improve the efficiency of calibration in three areas: selection of the best nonlinear programming algorithms; reduction of the number of objective functions required for calibration; and simplification of the model structure. The best algorithms were found to be those of Powell, Rosenbrock, and the simplex method of Nelder and Mead. The Davidon method did not perform well. The number of objective function evaluations can be reduced by performing a sensitivity analysis on the model and selecting a small group of parameters which are not interdependent and which the objective function is sensitive to. This may yield a substantial reduction in the computer time required to calibrate the model. Simplification of the model structure can also yield substantial savings, especially where it removes calculations which are redundant and reduces the number of model parameters.

ISSN:0303-6936    

DOI:10.1080/02626667709491716

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A method was sought for estimating low return period floods (0.2–5 years) from annual maximum data. The theoretical relationship between the peak over threshold and annual maximum return periods is re-examined and an empirical relationship based upon United Kingdom flood data is proposed.

ISSN:0303-6936    

DOI:10.1080/02626667709491717

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Evaporation in the Upper Harz experimental basins is computed and compared to the values calculated according to formulae. Potential evaporation is determined for mean daily and monthly values by different methods. For the computation of the terms generally lacking in water balance studies, such as actual evaporation and changes in snow and soil storage, a model was established on the basis of daily values. As a result water balances can also be drawn up for shorter periods such as single years or months.

ISSN:0303-6936    

DOI:10.1080/02626667709491718

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

This study was undertaken to test methods by which a representative basin could be used to develop a synthetic unit hydrograph for an ungauged basin within its hydrological region. Three synthetic hydrograph methods were tested in two hydrological regions using three basins in each region. The methods tested were: (1) a modified Snyder method, (2) Commons' dimensionless hydrograph, and (3) Soil Conservation Service dimensionless hydrograph.

ISSN:0303-6936    

DOI:10.1080/02626667709491719

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The application of many of the well-known methods of inversion to rainfall excess and direct runoff data often produces finite-period unit hydrographs whose ordinates are distorted by high frequency oscillations. A simple extension of the basic algorithm for the harmonic method of deriving the finite-period unit hydrograph provides a means of smoothing such oscillations. The modified method has computational advantages over the use of moving average smoothing schemes applied to the derived unit hydrograph.

ISSN:0303-6936    

DOI:10.1080/02626667709491720

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0303-6936    

DOI:10.1080/02626667709491721

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor