A.—A. I. H. S.—I. A. S. H.

Abstract

When a river flows into a reservoir, the solid materials it carries sink to the bottom thus reducing the potential reservoir capacity. The suspended load of eight major western rivers flowing into Kainji Lake was determined as a part of the investigation of the suspended sediment of the reservoir. The sediment content in each sample was determined in parts per million.

On the whole the results of this study is in agreement with the previous conclusion that the sediment load of the Niger was low. A range of 29–221 ppm was observed within the reservoir whereas the concentration in the inflowing rivers varied from 122–953 ppm. It was however not possible to determine the total sediment load because discharge data were lacking.

The data presented herein confirm the earlier conclusion that the rate of silting is slow but indicate that locally high rate of sediment supply should give cause for anxiety regarding the possible growth of deltas as the months of these rivers.

The full potential of this study is difficult to assess at this stage but it has revealed a number of problem areas worth looking into in future years. A number of future studies believed to be capable of giving the necessary data for operation and management of the reservoir are recommended.     

A) A.I.H.S.—I.A.S.H.

Abstract

Mathematical models are the means to characterize variables quantitatively in many groundwater problems. Recent advances in applied mathematics have perfected what is now called Adomian's decomposition method (ADM), a simple modelling procedure for practical applications. Decomposition exhibits the benefits of analytical solutions (i.e. stability, analytic derivation of heads, gradients, fluxes and simple programming). It also offers the advantages of traditional numerical methods (i.e. consideration of heterogeneity, irregular domain shapes and multiple dimensions). In addition, decomposition is one of the few systematic procedures for solving nonlinear equations. By far its greatest advantage is its simplicity of application. It may produce simple results for preliminary simulations, or in cases with scarce information. The method is described with simple applications to regional groundwater flow. Many applications in groundwater flow and contaminant transport are available in the literature.

Editor D. Koutsoyiannis; Associate editor Xi Chen

Citation Serrano, S.E., 2013. A simple approach to groundwater modelling with decomposition. Hydrological Sciences Journal, 58 (1), 1–9.     

A. I. H. S. 1957–1960

Abstract

This study was made to define the relation between floods in a humid region and the causative factors that account for their variability. The study covered the basic relationships between peak discharges and hydrologic factors as well as the practical working methods for generalizing the results on a regional basis. Statistical multiple-correlation techniques were applied to hydrologic data in New England. A field and library investigation of historical flood data extended the period of flood knowledge to as much as 300 years. The relation of many topographic and climatic factors to flood peaks was tested. Flood peaks with recurrence intervals at 9 levels, from 1.2 to 300 years, were related to 6 independent variables, 3 of which are topographic, 2 climatic, and 1 orographic.     

PROGRAMME DE L'ASSEMBLÉE DE TORONTO A. I. H. S.

Synopsis

A method of synthesis has been used to combine the variables characterising sediment transport in laboratory flumes into nondimensional functional equations. These equations are used to provide a basis for logical data correlations. By selecting appropriate nondimensional groups the effect of variation of individual variables such as flume width, sediment grain size, etc., can be determined. It has been found that work of this nature is hampered by the small amount of data available from rational experimentation. Much of the published data is unsuitable for direct use in correlations but may be of use in the future once the trend of results has been predicted by more limited but more basic data. When sufficient data for the transport of light weight materials is available correlations of the type presented may provide a secure basis for the choice of bed material for hydraulic models.     

G.S.I—等磁力仪故障的维修方法

G.S.I—等磁力仪是日本进口的用来精密测量地磁偏角D和倾角I的测磁仪器。放大器的输出端接上一个压电晶体耳机用来监测信号。由于某些原因造成晶体性能变差或损坏,观测时声小或无声,而本耳机为专用无磁性耳机,原机无备件,市场上难于购买,一旦损坏观测就得被迫停止。耳机的好坏可用万用表作简单的检查,从仪器上拔下耳机插头,用500型万用表×10KΩ档测量阻值应在1MΩ以上;表针一点不动可能是连接线断或插头和耳机有脱焊;如果阻值偏     

F.—PERSONALIA / F.—PERSONALIA

Abstract

Sampling in undisturbed soils of clearcuts and adjacent unlogged virgin forests in western Oregon indicates that clear cutting results in reduced soil moisture depletion and accelerated recharge.     

B.—U. N. E. S. C. O.

ABSTRACT

Sir Charles Cotton (1964) has pointed out that in an earlier paper (Carlston, 1963) which related drainage density to hydrology, there was insufficient emphasis on the role of climate in its effect on drainage density. Re-examination of the relation of drainage density to base flow in the 15 basins originally described has revealed additional evidence that base flow is affected by precipitation or recharge (a climatic variable), while varying inversely with drainage density.

Within the climatic region studied in the earlier paper (the Humid Subtropical Climate of the eastern U. S.), no evidence could be found that amount or intensity of rainfall affected the intensity of flood runoff or the scale of drainage density. In comparison with other climates, however, such as the Marine West Coast Climate, it is possible that the less intense precipitation of a marine climate may result in lower runoff intensities and lower drainage densities, however the lower mean temperatures of such climates may develop soils of generally higher infiltration capacity which would produce lower drainage densities.

A progressive increase in aridity results in a decrease in soil and vegetal cover which greatly magnifies the range of drainage densities characteristic of semi-arid regions. In such regions, where the land sur-face has a good infiltration capacity rainfall sinks readily into the dry soil (although recharge to ground water may be negligible), and runoff is virtually zero, as is drainage density, Impermeable terranes devoid of vegetal and soil cover reject the rain, runoff is briefly total and drainage density may be greatly magnified, as in the South Dakota Badlands, where drainage density runs into the hundreds. Arid or Desert Climates should produce erosional landforms with generally high drainage densities, though not reaching the magnitudes of drainage density found in the semi-arid badlands where rainfall intensities are much higher.