摘要:

The level of Lake Malawi has varied widely throughout this century, and has risen dramatically in the period 1976–1980. The causes of the change in level have been investigated using simple numerical models based on the lake's water balance. It has been shown that the recorded changes in rainfall were sufficient to have caused the observed changes in lake level, and that man-made changes in runoff and outflow have been comparatively unimportant.

ISSN:0262-6667    

DOI:10.1080/02626668409490918

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Precipitation and runoff data from the Sleepers River Watershed in northeastern Vermont are presented and discussed with emphasis given to extreme wet and dry period relationships. The significance of these extreme periods is determined by comparison with an 87-year precipitation record 2 km from the basin. Precipitation and runoff increased with elevation for both wet and dry periods. The rate of increase was greater during a wet period than during a dry period for all seasons. Variations in measured flow at the eight sub-basins examined were due to the complex basin and climatological conditions typical of New England basins. However, the variations may be adequately described using elevation alone as the index. The increase in summer precipitation with elevation was significantly greater than the increase in runoff. This suggests that evapotranspiration increases with elevation. The greater magnitude of precipitation at higher elevations results in more potential and thus more actual evapotranspiration.

ISSN:0262-6667    

DOI:10.1080/02626668409490919

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Data are presented for the4He and222Rn contents and14C ages of groundwater from two artesian aquifers in southern Africa. The relative importance of helium derived from the decay of uranium and thorium in the aquifers is assessed, as well as “weathering” release of stored helium, fluxes into the aquifer, and diffusive losses. It is demonstrated that a4He flux originating from rocks below the aquifer is the most important source. The magnitude of this flux is relatively constant over the sampled intervals and is qualitatively estimated to be in the range 1 x 10−3to 3 x 10−2m1nHe m−2year−1(9 x 104to 3 x 106atoms He cm−2s−1). The4He data cannot be used to calculate the absolute age of the groundwater, but may be used to estimate the relative age and flow direction of very old groundwater if the4He flux rate is assumed, or known to be reasonably constant. Examination of the222Rn data suggests that they may have a useful application in the qualitative determination of the uranium content and porosity of aquifers.

ISSN:0262-6667    

DOI:10.1080/02626668409490920

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Streamflow in the River Feshie (106 km2) shows persistent diurnal oscillations from March to June when runoff augmented by snowmelt greatly exceeds precipitation. Diurnal amplitude and maximum daily runoff are comparable to a similar-sized Swiss glacier basin. Daily discharges in the springs of 1979 and 1980 are successfully simulated from daily air temperatures and precipitation using a lumped degree-day model based on Martinec's model but with endogenous snowpack shrinkage at a rate proportional to melting. A best fit of R2= 0.88 was achieved over 53 days in the unusually snowy season of 1979. The biggest errors are in simulating runoff from precipitation for which only lumped data are available. Best-fit parameter values are physically reasonable and only two parameters, describing the initial snowpack, need vary from year to year.

ISSN:0262-6667    

DOI:10.1080/02626668409490921

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The effect of basin size on runoff characteristics is investigated. The maximum observed floodflow, the maximum annual constant loss, the lag time and the unitgraph peak for a certain storm duration of basins in the western and northwestern regions of Greece are increasing power functions of the basin size. These functions explain significantly the variation in the runoff characteristics. For both regions single relationships are derived for the latter two characteristics, whereas for the two former ones they vary regionally in accordance to the climatic conditions. Thus, care is needed in transferring such relationships outside the location of their derivation; besides, the transferability of the values of their parameters is doubtful. The derivation of the relationships in the specific area of interest is thus suggested. The regional relationships are used in predicting accurately design floodflows, annual runoff yields and unitgraphs of various storm durations for ungauged basins in the regions studied, needed for the hydrological design of water resources development systems.

ISSN:0262-6667    

DOI:10.1080/02626668409490922

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The compounded Gumbel distribution is found to provide a good description of flood frequency in areas where the annual peak flows are produced by both snowmelt and rainfall. The spatial variation of the flood generating processes can be represented by trend surfaces fitted to the compounded Gumbel parameters. This method offers a practical tool to predict flood frequencies for ungauged basins in such areas.

ISSN:0262-6667    

DOI:10.1080/02626668409490923

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A modification is made to the conventional evaporation equation to allow the calculation of evaporation from saline lakes. The modified equation shows how, for a given set of meteorological conditions, the evaporation rate, the partitioning of available energy into sensible and latent heat, and the surface temperature, can all be related to solute concentrations. To illustrate the operation of the equation the recent and proposed changes to the hydrology of the Dead Sea were used as a case study.

ISSN:0262-6667    

DOI:10.1080/02626668409490924

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668409490925

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668409490926

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668409490927

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor