PUBLICATIONS DE L'ASSOCIATION INTERNATIONALE DES SCIENCES HYDROLOGIQUES

ABSTRACT

The evaporation losses from the container of an old galvanized Hellmann gauge, 7·1 cm² aperture area, were five times greater than the losses from the container of a new gauge, 1·8 cm² aperture area, of almost the same grey colour. The maximum evaporation from the old gauge amounted to 0·75 mm per day. The same evaporation losses in the Baye of Montreux basin over a period of 10 years from April to September amounted to 0·09 mm per measurement or to 0·7 per cent of the precipitation catch. There is a relationship between the monthly percentage evaporation losses and the ratio of evaporation time and rainfall duration (r = 0·803).     

PUBLICATIONS DE L'ASSOCIATION INTERNATIONALE DES SCIENCES HYDROLOGIQUES

ABSTRACT

The purpose of an hydrometric network is to obtain data giving answers to problems raised by the use of water. The methodology suggested in this paper is essentially based on the regional identification of the actual and potential uses of water, on the estimate of the intensity of their use and on the determination of the hydrological characteristics related to this demand.

The level of accuracy required for these characteristics is an important feature in the rationalization procedure.

The various types of stations are defined according to the purpose of their use and the network considered is on a dynamic basis depending on the evolution of uses. The major results obtained for Quebec by the application of this method are described.     

PUBLICATIONS OF THE INTERNATIONAL ASSOCIATION OF HYDROLOGICAL SCIENCES

Abstract

Explicit algebraic expressions of influence coefficients of an aquifer system are addressed. The methodology is straightforwardly exemplified using a one-dimensional (1D) semi-confined homogeneous aquifer model. It consists of the integration of the governing equation from two different viewpoints. On the one hand, the analytical solution to the governing equation is presented under an integral form involving the appropriate Green function. On the other hand, equations resulting from a finite difference discretization are processed to deduce a fully explicit algebraic expression of the nodal hydraulic head. This latter, arranged after the previously developed continuum solution, helps with deriving an explicit algebraic expression of influence coefficients corresponding to the studied aquifer model. Finally, the study is extended to an inhomogeneous aquifer model.     

PUBLICATIONS OF THE INTERNATIONAL ASSOCIATION OF HYDROLOGICAL SCIENCES

Abstract

Most commonly used biochemical oxygen demand (BOD) and dissolved oxygen (DO) models have been tested for their applicability in the River Kali, which is one of the most polluted rivers in India. A total of 732 field data sets were generated during field survey from March 1999 to February 2000. The modelling of BOD and DO in the River Kali involves derivation and solution of the governing equations that describe concentration change with time and space brought on by advective, decay, settling and loading functions. However, due to continuous discharges (e.g. from wastewater treatment plants) and steady-state flow conditions in the River Kali, the dispersion effects are found to be insignificant. In the analysis, the model parameters used in BOD-DO models were optimized using the Newton-Raphson technique and the performance of different models was evaluated using correlation statistics (r ²) and error estimation, viz. standard error (SE) and mean multiplicative error (MME). The results indicate that the BOD-DO models developed after Camp (1963) yielded the best agreement with the observed values as compared with several other approaches.     

CHANGES IN THE HYDROLOGICAL REGIME OF THE VOLGA ESTUARINE REGION

Abstract

Two of the geomorphic Laws of Drainage Net Composition are discussed and it is shown that they are essentially abstract mathematical relationships that hold for any bifurcating system. Some of the geomorphic factors that determine the value of the characteristic coefficients that are obtained by application of the Laws to single nets are also discussed.