SUR LES PROJECTS FUTURS DE L'AISH / ON THE FUTURE PLANS OF IAHS

Abstract

The baseflow characteristics of some of the numerous small basins in southeastern Nigeria have been analysed to estimate the developable groundwater in the basins. It is shown that from 5.62 × 10⁴ to 1.59 × 10⁶ m³ of groundwater can be developed per square kilometre of basin per annum. The relationship between the baseflow characteristics and other attributes of the basins, such as geology and stream density, were studied statistically, leading to the development of empirical equations for predicting the hydrological features of the several ungauged streams in the region. It is shown, for example, that the basin geology (represented as the percentage of sands), the drainage density, the basin area, the baseflow depletion rate and the total groundwater stored in the basin, Q_tp, are related by the equation:

Q_tp = ?1.85 × 10⁹?7.96 × 10⁸ dd+4.18 × 10⁷ gf?2.01 × 10⁶ df+6.25 × 10⁵ wa

where dd is drainage density; gf geological factor; df depletion factor; and wa basin area.     

SUJETS A TRAITER POUR L'ASSEMBLÉE DE 1960

ABSTRACT

The present paper reports on some practical experiences gained in computing unit hydrographs (UH) according to the “classical” linear theory. The sizes of the drainage basins varied from 50 to 800 km² of hilly country.     

A comparison between the stresses computed for finite sized precast concrete pavement units using westergaards equations and a numerical design method

Westergaards equations are widely used in the design of rigid concrete highway and aircraft pavements. The equations assume that the pavements are either infinite or semi-infinite in extent. Recently, a numerical design procedure using finite elements has been introduced for finite sized precast concrete pavement units [raft units]. The present paper compares the computed stress results from the two methods for the interior loading on a two metre square raft unit. The results show that there is no simple “slab-size correction factor” to correlate the stress output from the two design methods as suggested by other authors. Westergaards analysis should not be used to design finite sized raft units; the numerical design procedure is recommended.     

Local And Global Diffusion Along Resonant Lines in Discrete Quasi-integrable Dynamical Systems

We detect and measure diffusion along resonances in a quasi-integrable symplectic map for different values of the perturbation parameter. As in a previously studied Hamiltonian case (Lega et al., 2003) results agree with the prediction of the Nekhoroshev theorem. Moreover, for values of the perturbation parameter slightly below the critical value of the transition between Nekhoroshev and Chirikov regime we have also found a diffusion of some orbits along macroscopic portions of the phase space. Such a diffusion follows in a spectacular way the peculiar structure of resonant lines.     

Northern Ireland lignite

Conclusion There is no doubt that Northern Ireland's lignite deposits are of high quality and constitute a natural resource of considerable potential value in this small, peripheral part of the European Community. Whether or not one or more will be used commercially and, if so, when depends on an interacting complex of economic, social and political factors. In purely economic terms, use will be effectively determined by lignite's economic competitiveness as a fuel dor electricity generation and on the relationship between capital and fuel costs. The economics of other possibly viable products such as lignite briquettes will be heavily dependent on the use of by-products of electricity generation, most notably surplus heat.The availability of lignite offers an alternative fuel option to those charged with formulating the Province's energy policy. If, as now seems likely, it is no longer a serious competitor for the power station planned for the mid-1990's, it most certainly is a competitor for the early part of the next century. This is particularly so in view of its low sulphur content which is about half that of Scottish coal on an energy equivalent basis. Lignite also offers security of supply at predictable prices, an important advantage, and thus carries a premium over coal, oil and natural gas which are imported at prices determined wholly exogenously.As the Province has by far the highest rate of regional unemployment in the United Kingdom, one argument advanced for the use of indigenous lignite is that its use in electricity generation would create much needed additional employment — an estimated 400 jobs being associated with the mining operations needed to support a 450 MW power station. But the Coagh example shows that other considerations must be taken seriously. It is extremely unlikely that the lignite in this area will ever be worked unless local attitudes change dramatically or there is some national fuel crisis which would over-ride local opposition. It is difficult enough developing lignite without having to contend with such strong resistance at the local level.This study has shown that certainly in the Northern Irish context it is highly important for the policy makers not only to consider the economic factors involved in choice of an energy fuel but to work closely with local communities and the various environmental bodies, to take their perceptions, right or wrong, into consideration.     

Long-distance traffic routes to and from Berlin

After the reunification of Germany on October, 3rd. 1990 Berlin becam a unified city again. Most of the ambitious plans of the pre-war time concerning the urban infrastructure could not be taken up again after fourty years of division. The article describes the long-distance traffic system in the former capital of the Reich, the division and duplication of the transportation facilities in the decades of division and gives an overview of concepts of reconstruction and new plans for the reunited Berlin and its hinterland.     

Short‐term forecasting with a multi‐level spectral primitive equation model part I ‐ model formulation

A global baroclinic primitive equation model using the spectral technique has been constructed for short‐ and medium‐range numerical weather prediction. The spectral technique, which is a special case of the Galerkin method, employs spherical harmonic basis functions in the evaluation of all horizontal derivatives. The use of a transform technique allows all the horizontal operations to be performed efficiently and allows physical processes to be evaluated in real space. The model employs a semi‐implicit algorithm for time integration and finite differencing in the vertical. Physical processes include orography, moist convection, large scale precipitation and boundary layer processes.