摘要:

This paper emanates from attempts at fitting empirical equations to describe the patterns of groundwater recharge in the regolith of the Middle Osun Valley in the Nigerian Basement Complex. Equations of both the temporal and spatial patterns of groundwater recharge were derived empirically by analysing sample data on saturated zone thickness using a least-squares curvilinear regression technique. The temporal pattern for the study period conforms with the prevailing rainfall regime and is optimally described by fourth-degree polynomial regression equations. The spatial pattern is optimally described by quadratic equations and suggests that an almost uniformly thick annual groundwater recharge zone of about 2.4 m overlies the gross spatial distribution of saturated zone thickness from the major river channel to the major water divide. The quantitative methodology of this study is universally applicable and could greatly facilitate direct calculation of groundwater recharge and rainfall-recharge correlation if reliable information about relevant parameters of Basement Complex regolith aquifers is available.

ISSN:0262-6667    

DOI:10.1080/02626668609491023

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A hierarchical scheme for the systematic testing of hydrological simulation models is proposed which ties the nature of the test to the difficulty of the modelling task. The testing is referred to as operational, since its aim is merely to assess the performance of a model in situations as close as possible to those in which it is supposed to be used in practice; in other words, to assess its operational adequacy. The measure of the quality of performance is the degree of agreement of the simulation result with observation. Hence, the power of the tests being proposed is rather modest, and even a fully successful result can be seen only as a necessary, rather than a sufficient, condition for model adequacy vis-à-vis the specific modelling objective. The scheme contains no new and original ideas; it is merely an attempt to present an organized methodology based on standard techniques, a methodology that can be viewed as a generalization of the routine split-sample test. Its main aim is to accommodate the possibility of testing model transposability, both of the simple geographical kind and of more complex kinds, such as transposability between different types of land use, climate, and other types of environmental changes.

ISSN:0262-6667    

DOI:10.1080/02626668609491024

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The sharp rise in the level of Lake Victoria between 1961 and 1964 has been found difficult to explain in terms of the components of the water balance. After reviewing lake inflows and the method of calculating lake rainfall from lakeside gauges, the historic lake water balance has been reproduced. The rise in lake level can be explained through rainfall and resulting tributary inflows, which would allow projections of possible future levels to be made by analysis of rainfall series.

ISSN:0262-6667    

DOI:10.1080/02626668609491025

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A study of suspended sediment transport in the 8.5 km2River Lubwe catchment was carried out during the wet season 1983–1984. The suspended sediment yield was estimated using the suspended-sediment rating curve technique and detailed observations of 10 runoff events. The River Lubwe is characterized by periodic high magnitude floods, during which the bulk of the load is transported. The total suspended load for the hydrological year 1983–1984 is estimated at 108 t, representing a sediment yield of 12.7 t km−2year−1.

ISSN:0262-6667    

DOI:10.1080/02626668609491026

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The Thornthwaite water balance technique is used to predict monthly stream runoff from Rio Macho basin in Costa Rica. The method was tested by comparing observed and predicted runoff over a 15 water-year period. The study shows that this method provides mean annual and monthly estimates in close agreement with measured values. Generally these mean estimated values fall between the 90% confidence intervals for the measured runoff. These results indicate that the Thornthwaite method can be satisfactorily applied to estimate mean monthly streamflow in the uplands of Costa Rica.

ISSN:0262-6667    

DOI:10.1080/02626668609491027

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The mean mechanical and chemical erosion rates of the Girou basin are calculated from the amount of suspended and dissolved material transported by the river. The chemical and mineralogical characteristics of the river load and its behaviour are studied during the water year 1980–1981. Finally, the origins of major compounds in the drainage basin are determined and the contribution of mechanical and chemical erosion to the fluvial transport of each compound are calculated. The separation of the streamflow components on the storm hydrograph allows the calculation of the suspended sediment concentration in the surface runoff.

ISSN:0262-6667    

DOI:10.1080/02626668609491028

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Specific conductance is shown to bear a well-defined, linear relationship to total dissolved solids for cold, low ionic strength streams. Unless the water temperature is constant it is necessary first to correct the conductivity data to 25°C. This temperature correction may be taken as linear, even below 4°C, but not necessarily to be 2% per °C as is commonly used in many instruments. The error incurred by assuming the latter figure for cold streams could be large (>5%). Values of specific conductance calculated using data for the limiting equivalent conductivities of the individual ions are shown to be poor estimates of the actual specific conductances even for these dilute waters. Relationships between total dissolved solids and specific conductance may be impaired by the changing proportions of ionic species of the samples. In general, however, an empirical straight line was found to provide a good fit.

ISSN:0262-6667    

DOI:10.1080/02626668609491029

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The aim of the present work is that of analysing the data of snow-cover measurements carried out in the northeastern Alps by the Italian National Electricity Board (ENEL) since 1966, in order to select a reduced number of measurement stations from which to evaluate the water equivalent amount. The selection was based on cluster methods for identification of homogeneous areas and afterwards on principal component analysis for individualization of representative stations. The results confirm that by employing a set of reduced input data the output is only moderately affected.

ISSN:0262-6667    

DOI:10.1080/02626668609491030

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668609491031

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668609491032

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor