ISSN:0885-6087    

DOI:10.1002/hyp.3360050302

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractUsing data sets assembled within the WMO Solid Precipitation Measurement Intercomparison, the paper deals with the wind related losses in national methods of solid precipitation measurement. Fourteen different types of precipitation gauges are included in the Harzgerode/GDR intercomparison field. Initial results of the comparisons between the Valdai double fence reference method and the other gauges in terms of dependence on wind speed and type of precipitation are presented. These results reveal that the national unsheltered HELLMANN gauge catches only 24 per cent to 70 per cent of the daily totals of solid precipitation as compared with the reference gauge. Results of the analysis of monthly totals and individual events reveal a similar dependence of gauge deficiencies on wind speed and type of precipitation. Case studies of single snow falls and the wind field conditions around and within the double fence reference are also described.

ISSN:0885-6087    

DOI:10.1002/hyp.3360050303

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe methods of correcting for systematic errors in precipitation measurements using the Czechoslovak gauge METRA 886 are presented. This gauge has an orifice area of 500 cm2and is elevated 1 m above the ground. The wetting correction amounts to 0.1–0.2 mm per measurement. The evaporation correction ranges from 3 per cent in frost‐free periods to 10 per cent in frost periods. The wind‐induced correction amounts to 5 per cent for rain and 45 per cent for snow. The total sum of corrections on average 10–15 per cent per year in lower loc

ISSN:0885-6087    

DOI:10.1002/hyp.3360050304

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe high density, static memory raingauge network of the EPSAT‐NIGER experiment was designed with the aim of: (1) studying the rainfall spatial variability in the Sahel, as may be seen from ground networks of varying density, and (2) providing reference values for the calibration of a C band radar system. A first subset of 37 raingauges was installed in 1988 and the remaining 43 in 1989, thus providing a network of 80 stations, spread over a 100 × 100 km square area. The data analysis is based on the indentification of the structural function for each rainfall event. This permits classification of the events into three main categories with respect to their spatial organization. Furthermore the differences between the shower body and the trail are important and it is shown that the analysis of the spatial organization at the event scale may not be applicable to the calibration of high temporal resolution radar data. Estimation of the areal rainfall over two reference areas is also carried o

ISSN:0885-6087    

DOI:10.1002/hyp.3360050305

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractMeteosat data for 1986 to 1988 have been used to estimate the daily rainfall over catchments of tributaries of the river Senegal in Mail and Guinea. The technique uses the methodology of the TAMSAT group of the University of Reading, which involves the selection of an appropriate cloud top temperature threshold to determine whether the cloud is producing rain and the rainfall is estimated from the period during which storm clouds remain over a site. After calibration against all available raingauges in the catchments, the daily rainfall estimates derived by this technique were used as inputs to rainfall‐runoff models. The results indicate that the streamflow models, which had themselves been calibrated using raingauge data, performed as well or better when the satellite derived estimates were used as inputs than when gauge data were used. An economical, automated operational system is describe

ISSN:0885-6087    

DOI:10.1002/hyp.3360050306

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe two‐component hydrograph separation method has been used to investigate the sources of storm runoff at Allt a Mharcaidh during storms in October 1987, September 1988, and June 1989. Results show that for the September and October storms, more than 88 per cent of storm runoff was contributed by pre‐event water and 54 per cent of the June storm runoff.Instantaneous contributions of pre‐event water at the hydrograph peak vary from 91 per cent in September 1988 to 41 per cent in June 1989. Detailed examination of soil and borehole water, however, shows that these subcomponents of pre‐event water do not always have similar chemistry and isotope concentrations. Therefore, information from the two‐component separation method alone should not be used to infer processes or pathways, although some broad indications can be obtained through the additional use of soil water and groundwater

ISSN:0885-6087    

DOI:10.1002/hyp.3360050307

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractWe describe an objective method for evaluating the spatial distribution of water equivalents of the snow cover within a small catchment. Regression analysis is used to quantify the relationship between elevation, presence or absence of forest, and potential direct solar radiation as independent variables and water equivalent as measured at a number of sites. First, this regression relationship is used to interpolate water equivalent data all over the basin area. Then we interpolate the residuals of the regression using a geostatistical approach. Superimposing the results obtained by interpolating the regression relationship and the interpolated residuals eventually yields the water equivalent distribution over the test area. The advantages of the interpolation method used lie in the optimal (effective, unbiased) estimation of the interpolated values as well as in the possibility to quantify the associated estimation variances.

ISSN:0885-6087    

DOI:10.1002/hyp.3360050308

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractColloidal materials and macromolecules that are less than 0.45 mircons in diameter can act to transport both hydrophobic and hydrophilic contaminations in subsurface waters. An automated hollow‐fibre ultrafiltration apparatus is described and evaluated regarding its ability to physically size and isolate colloidal materials from natural waters. Sufficient size‐fractionated colloidal samples can be obtained from 60 litre samples to perform inorganic, organic, and radionuclide characterizations, as well as allow the binding capacities of humic and fulvic materials to be evaluated. Samples processed in the field with the automated system were compared with laboratory analyses using single cartridge hollow‐fibre ultrafilters and found to agree well with each other. Typical sample reproducibilities were with 15 per cent. The results indicate that field collection of colloidal materials is feasible with minimal sample perturbation using the automated sa

ISSN:0885-6087    

DOI:10.1002/hyp.3360050309

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe release of dissolved organic carbon (DOC) into drainage waters was modelled using the hydrology of the Birkenes model of stream water chemistry and estimated parameters for the formation and decay of soluble organic matter in the soil. The model was first tested against soil water DOC concentrations over a three year period in the Loch Dee catchment in southwest Scotland. It predicted annual cycles in DOC at one site, but underestimated maximum DOC in the first year, overestimated in the following year, and predicted values very similar to the measured values in the third year. With small modifications to the parameters controlling organic matter addition and decay it successfully predicted DOC variations at two other soil water sites with smaller mean DOC.Further tests were made against short‐term DOC variations in a stream draining a subcatchment of Loch Ard in west‐central Scotland, using the same decay and addition parameters. Prediction of temporal variation was good, although predicted concentrations were about 25 per cent less than measured values. Considerable potential for the use of fully optimized models of DOC production in soil and stream waters is identified on the basis of these resu

ISSN:0885-6087    

DOI:10.1002/hyp.3360050310

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractInfiltration theory developed from Richards' equation for the movement of water in unsaturated soil is outlined and used as a basis for considering measurements made with ring infiltrometers, rainfall simulators and tension infiltrometers. In particular, the three‐dimensional soil‐water flow occurring with many of these measurement techniques is considered. Complicating factors of soil heterogeneity, soil swelling and shrinking, and soil aggregation, that limit the interpretation of field measurements using classical theory, are discus

ISSN:0885-6087    

DOI:10.1002/hyp.3360050311

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY