摘要:

AbstractFlow through a saturated idealized hillslope with a single soil pipe was simulated using a finite difference solution to the equation for three‐dimensional Darcian flow in saturated heterogeneous media. The proportions of hillslope discharge originating from flow through the soil matrix and from flow through a soil pipe were determined, considering such factors as the radius, depth and length of the pipe, pipe spacing, and the length and slope of the hillslope. Results demonstrate that soil pipes can contribute a significant amount, and in many instances, the majority of total subsurface stormflo

ISSN:0885-6087    

DOI:10.1002/hyp.3360050402

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe influence of stone cover on the generation and continuity of overland flow is a function of several variables, primarily stone size, distance (spacing) between stones, and stone position (on top of the soil surface or partially embedded). The initial hypothesis of the present study were that stone size affects overland flow generation by inducing ‘concentration overland flow’ and that the distance between stones affects overland flow continuity.With respect to stone size and distance between stones, opposing results have been found in the literature. Accordingly, the present paper reports on laboratory experiments which were conducted to investigate, systematically, the effect on overland flow of stone size, distance between stones, and stone position.The main conclusions were:1Stone cover tended to induce overland flow, relative to bare soil. Small stones, however, especially in a low‐cover percentage setting, and when resting on top of the soil surface, produced less overland flow than bare soil.2Overland flow was positively related to stone size, but inversely related to distance between stones.3Overland flow yield was always greater when stones were embedded than when on top of the soil surface.4The effect of stone size on increasing the degree of overland flow was of greater significance than the effect of the distance between stones on reducing overland

ISSN:0885-6087    

DOI:10.1002/hyp.3360050403

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe suspended sediment concentration response of three small streams draining quartzites and quartz‐schists in southwestern Nigeria to storms of varying magnitude are presented. A total of 1468 water samples from 62 storm responses with peak stream discharge values ranging from 80 to 120 l s−2were analysed and storm and suspended sediment concentration hydrographs and hysteresis loops were used to depict the response patterns. The six different types of responses identified include the single and multiple discharge peak rises with sediment lead and lag and also the mixed response patterns. Both valley slope and channel erosion constituted important sources of suspended sediment. However, sediment availability, exhaustion, and flushing effects determined the variation in the different response ty

ISSN:0885-6087    

DOI:10.1002/hyp.3360050404

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe objective of this research is to investigate spatial and temporal variation in the transport of phosphate by grain size fractions of suspended sediment in two Lake Erie tributaries. A sediment‐phosphate transport model is proposed to evaluate and quantify the kinetic control of dissolved phosphate by fluvial sediment. A first‐order assessment of the sediment‐phosphate export from Big Otter Creek and Big Creek to Lake Erie is presented. Output from this model was calculated using historical discharge and sediment data collected by Environment Canada in combination with adsorption coefficients derived from laboratory experiments for a range of sediment grain size fractions. Results of these calculations provide a quantitative interpretation of the influence of suspended sediment on phosphate dynamics in tributaries and the potential impact on water quality of receiving w

ISSN:0885-6087    

DOI:10.1002/hyp.3360050405

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractTo estimate seasonal changes in recharge to the underlying sandy aquifer, the soil water dynamics of the unsaturated zone was monitored down to a depth of 20 m over a period of three years (1985 to 1987). The measurements were made by a neutron probe at eight locations beneath a native vegetation in a semiarid region, Western Australia, receiving precipitation of 775 mm yr−1. A relatively simple method, based on the analyses of sequentially measured soil water profiles involving utilization of zero flux plane in the unsaturated zone, is presented and used to compute seasonal recharge rates.Drainage fluxes (recharge rates) below two specified depths were estimated. These were:R1(water flux at a depth of 10 m, just below the maximum rooting depth) andR2(water flux at a depth of 18 m, just above the water table). These two estimates were significantly different both on a seasonal and annual basis, but their cumulative values for the three year period were very similar. While the annual precipitation varied from 525 to 850 mm yr−1, the corresponding spatially averagedR1varied from 34 to 149 mm yr−1, andR2varied from 65 to 80 mm yr−1. A significant difference in recharge between the upslope and downslope positions on a hillslope was ascribed to differences in vegetation density of the understorey and differences in hydraulic properties of subsoils.For the three year period, the averageR1andR2were 13 per cent and 10 per cent of the precipitation respectively. These values compare favourably with a long‐term estimate based on an environmental tracer

ISSN:0885-6087    

DOI:10.1002/hyp.3360050406

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractAssessment of the water table in compressible and/or floating peatland mats requires a remote sensor that can measure simultaneously the elevation of the peat surface and the water level. A simple device, comprising two potentiometers, a float and ‘bog shoe’ was used to measure the water level and peat surface witin 0‐3 mm. The water table (depth of water level relative to the peat surface) was then calcu

ISSN:0885-6087    

DOI:10.1002/hyp.3360050407

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe magnitude of soil water repellency in a dry sclerophyll eucalypt forest was measured periodically over four years. The varying responses from a range of sites within the forest are discussed and the effect of amount and frequency of rainfall is shown.It was found that some weeks of consistently wet weather were required for water repellency breakdown, and a frequency of rainfall much greater than normal in the study area for it to remain broken down. Even after an extended period of breakdown, it was found that repellency can be reestablished after one week of hot dry weather.Laboratory tests were used to examine the major repellency processes; three were identified and the relative importance of each considered in the context of the field study. The relative influence of each depended on the physical and chemical characteristics of the sites.The repellent soil samples were more repellent to water of throughfall origin, and even more repellent to stemflow than to distilled water. The repellency response also varied with the type of vegetative cover present. The influence of these phenomena on the preservation of water repellency and the relevance of repellency in macropore infiltration processes are discussed.

ISSN:0885-6087    

DOI:10.1002/hyp.3360050408

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360050401

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY