摘要:

AbstractRunoff from natural soil pipes has been shown to be a significant contributor to stream discharge in parts of upland Wales. Attempts have been made to model pipeflow contributions using both theoretical and empirical approaches, but little progress has yet been made towards producing generally applicable models of complete pipeflow systems.The paper identifies some of the problems of devising general models with reference to data from the Maesnant Experimental Catchment. The data suggest that in‐pipe travel times are more important here than inferred elsewhere, and that neither simple hydraulic models nor kinematic wave theory can adequately explain the patterns of response. In particular, stormflow tends to begin first at the network outfall and even peak discharge often occurs at the outfalls before the headward zone

ISSN:0885-6087    

DOI:10.1002/hyp.3360020102

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractWater quality analyses for the Niger River for the 1980/81 hydrological year are presented. The samples were collected from the main river at Lokoja, and from two main tributaries, the Kaduna and the Benue Rivers.Different water types were distinguished by the concentrations of major ions. The type Ca>Na>Mg>K ‐ HCO3>SO4>Cl was represented at all stations during at least part of the year. Chloride was found to dominate the sulphate ion in the Kaduna and Niger, while the Benue maintained a higher concentration of sulphate relative to chloride all year round.Distinct patterns of seasonal variation in the ion concentrations were observed, particularly for the samples collected at Lokoja. Low ion concentrations were prominent during periods of high discharge, while low flow periods coincided with high dissolved ion concentrations.The contribution of rainwater to the total dissolved solids in the river waters was assessed indirectly using rainwater chemistry data from the Gulf of Guinea. The estimated rainwater contribution to the Lower Niger amounts to 5.15 mg 1−1.Geochemical weathering calculations involving reactions of the four major minerals of granitic rocks ‐ anorthite, biotite, albite, and K‐feldspar ‐ with carbon dioxide and water, can account for the average water composition of the Lower Niger. The proportion of the ionic components was also related to the occurrence of the respective element in the

ISSN:0885-6087    

DOI:10.1002/hyp.3360020103

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractDischarge exceedance probabilities are calculated for a simple model karst aquifer composed of a few multilevel conduits with recharge from a single sinking stream with an exponential flow exceedance distribution. It is assumed that outflow instantaneously matches inflow, so that the conduit volume is constant but discharge is governed by the head in a volumeless shaft at the top end of the system. It is shown that small single conduit aquifers will frequently overflow at the surface during floods and the exceedance probability of flow through the aquifer and over the surface can be defined as a function of the inflow distribution and the form of the aquifer. Systems with multiple conduits will overflow less frequently, but each conduit will exhibit a flow distribution characteristic of its form and position in the vertical hierarchy. Comparison of these findings with actual flow data from a conduit aquifer shows that the approach is valid, although imprecise. The model is unlikely to be applied directly, as it requires unusually detailed data. However, it provides for the first time an indication of typical flow durations for surface overflows and individual conduits in a karst aquifer. Contrasts in flow duration will have a profound influence on solutional and sedimentary processes in the karst system.

ISSN:0885-6087    

DOI:10.1002/hyp.3360020104

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIt is very interesting and meaningful to investigate the rainfall‐groundwater recharge process under the humid climatic condition of Japan, where mean annual precipitation is about 1600 mm. The present study has investigated soil water movement in the unsaturated zones of a volcanic ash layer, called the ‘Kanto Loam formation’, using environmental tritium as a tracer. The site selected is a flat ground surface on a terraced upland which has a deep unsaturated zone (about 20 m) with a relatively high water content (about 70 per cent) consisting of nearly uniform Kanto Loam formation.The tritium concentrations in groundwater, soil waters having different matric potentials, precipitation, and the seepage water moving through the formation into a man‐made cave were measured to characterize the rainfall‐groundwater recharge process and the effect of large pore spaces in the formation mentioned by previous studies.Because of the humid climate of Japan, there appears to be a unique soil water flow characteristic which may involve percolation through large pore spaces during heavy rainfall. However, in a fine grained and high water content soil like the Kanto Loam formation, the existence of this flow through large pore spaces does not have a significant effect upon the whole recharge process. The recharge model of displacement flow with dispersion is useful in estimating the tritium concentration profile of soil water. The calculated result shows a recharge rate of 2.5 mm/day. The value obtained reflects the hydrological characteristics of the uplands covered with vol

ISSN:0885-6087    

DOI:10.1002/hyp.3360020105

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSix sections of a residential road (75 mm bituminous macadam over 200mm lean mix concrete over 100 mm hoggin with a recent surface dressing of 10 mm granite chippings and K1‐70 binder) that drain to individual instrumented gully pots were irrigated along the kerb and then over the whole road approximately monthly for a year. The aim was the determination of terminal infiltration losses, initial losses, percentage runoff, and infiltration curves for the kerb and road surface. The results were not as expected from the literature.There is an annual cycle of infiltration losses at the kerb with a winter peak caused by frost action that is 3.2 times greater than the terminal loss rate at kerbs in summer. The terminal loss rate for an ‘average catchment’ was 6.4251 min−1from the road surface and 14.251 min−1in summer and 46.281 min−1in winter at the kerb. Evaporation was usually more than an order of magnitude less significant than infiltration.The wide variation in initial losses before runoff commenced was inexplicable. Two sections of road behaved in the classic manner with initial losses averaging 0.8 mm, two other catchments had highly variable initial losses in the range 1.2 to 8.8mm, and the last two pieces of road were even more erratic.The percentage runoff for those irrigations of over 15 mm of equivalent rainfall was never more than 10 per cent. The maximum per cent runoff was around 50 per cent following 10 mm of equivalent rainfall for kerbside irrigation and only 5 mm of irrigation over the whole road. There were no significant simple or multiple regression relationships between percentage runoff from the kerb or the whole road irrigations and irrigation amount, slope, UCWI, and SMD.Infiltration curves, for kerb and road irrigation, were so diverse that they do not represent the ‘simple impervious surfaces’ envisaged at the start of the experiment and described in the literature. Since the artificial irrigation of kerbs and roads has failed to substantiate existing theory, these experiments should be repeated at a variety of sites with a high rat

ISSN:0885-6087    

DOI:10.1002/hyp.3360020106

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractFive aspects of the hydrology of one‐day annual minimum flowsQIM, have been studied using data from twelve catchments in Malawi. Results indicate that the log‐normal distribution can be fitted to all twelve catchments. Four of the rivers studied are intermittent. Application of statistical methods developed in meterology to the dichotomous‐transformed data of these catchments revealed that two are ‘flow‐dominant’ and the other two are ‘dry‐dominant’. Another catchment is entirely dominated by a hydraulic gradient towards the Shire River and Elphant Marsh and so dries up every dry season for considerable periods of time despite the relatively high rainfall in the catchment.QIM, t‐days after the date of occurrence ofQIM(May), can be better estimated from simple regression than from an empirically determined

ISSN:0885-6087    

DOI:10.1002/hyp.3360020107

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe relationships between hillslope form and the development of zones of hillslope saturation are central to studies of process hydrology. These relationships are examined in two small, steep (30°) first‐order basins under forest and pasture vegetation. Hillslope saturation patterns are described using a probability analysis of observations of peak water table elevations made at individual sites in each basin. In both first‐order basins, the effects of topographic convergence on the spatial variability of hillslope saturation zones are most pronounced on shallow slopes and in steeper areas where hillslope form is strongly concave.The implications of vegetation type on the formation and variation of hillslope saturation are also examined. The differences in hillslope saturation patterns in each vegetation type are attributed primarily to differences in net rainfall and not soil physical properties or other features of topogr

ISSN:0885-6087    

DOI:10.1002/hyp.3360020108

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360020109

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360020101

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY