ISSN:0885-6087    

DOI:10.1002/hyp.3360010102

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractRapid drainage flow increases at the 2·4 m depth in the Coshocton lysimeters were related to the storms that most likely initiated them. The time lapsed between the onset of the storm and rapid drainage response was less than 2 days in 98 per cent of the 389 cases observed in five lysimeters between 1976 and 1982.A pronounced seasonal variation in the frequency of rapid responses was found, with the first quarter of the year comprising the highest number of events. During winter, when soil moisture is generally high, a storm yielding 6 mm/d was already sufficient to initiate this response while summer storms producing more than 50 mm/d did not always initiate a drainage response. Average drainage yield per event was found to be more closely related to the type and usage of a soil than to seasonal effects

ISSN:0885-6087    

DOI:10.1002/hyp.3360010103

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract‘Old’ water contributions to snowmelt runoff in a stream can be defined as water which was stored in the catchment prior to the start of the runoff event in question. We used mass balance techniques for natural oxygen‐18 and several chemical parameters (electrical conductivity, Ca and Mg) to estimate the magnitude and timing of ‘old’ water contributions to snowmelt runoff in the Apex River watershed during the 1983 field season. The Apex River catchment is located in the southern part of Baffin Island, Northwest Territories, Canada. The watershed has an area of 60 km2, it is in the zone of continuous permafrost, and the geology is dominantly Precambrian gneiss with sporadic, thin, glacial overburden. The isotopic data indicate that for the snowmelt season of 1983 (third highest peak discharge of 11 years of record), approximately 50 per cent of the peak stream discharge consisted of ‘old’ water. Our data also suggest that about 60 per cent of the entire 1983 hydrograph was ‘old’ water. The chemical parameters give old water contributions which are at least 10 per cent less than the isotopically‐derived estimate, but they are consistent with the isotopic estima

ISSN:0885-6087    

DOI:10.1002/hyp.3360010104

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThere is a dearth of knowledge on the runoff processes of eucalypt woodland communities in the semi‐arid tropics of Australia. The work was undertaken on a 100 m transect of a 0·8 degree hillslope typical of the ‘smooth plainlands’ of central‐north Queensland. This paper introduces a new experimental design for measuring overland flow in such areas by way of a cascade system of unbounded runoff plots which allow the inputs and outputs between troughs to be calculated. Most storms generate overland flow. Time to overland flow ranges between 1 and 18 min where rain intensities are above 10mm hr−1and when the average detention storage of 3·6 mm is exceeded. The bare soil surfaces within the scattered grass understory control the runoff generation process through the temporal variability of field saturated hydraulic conductivity. The study demonstrated that overland flow is mainly redistributed over the freely‐draining oxic soil. Some areas export more overland flow than they gain from upslope (runoff), others gain more overland flow than they export (runon). Over the study period only 2 per cent of total rain is transferred out of this 100 m transect as overland flow due to the short duration of storms, the relatively high soil permeability, and the low slope angle. The remainder adds to the large soil water store or deep drainage. The variability of runoff–runon over these ‘smooth plainlands’ highlights how results from bounded plots would be misle

ISSN:0885-6087    

DOI:10.1002/hyp.3360010105

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractEvaporation from a regenerating forest was determined concurrently by atmospheric measurements of the Bowen ratio, soil water depletion, and by weighing lysimeter. The methods agreed closely over 18 days in spring and 11 days in summer. Accordingly, the Bowen ratio technique was then used as the control against which any effect on evaporation by enclosure of the lysimeter with a chamber of varied ventilation rate could be quantified hourly and daily. Accuracy of gas analysis was checked against lysimeter values.Daily evaporation by the lysimeter was generally unaffected by enclosure—on a few afternoons there was a statistically significant enhancement of hourly values by the chamber. This was accounted for by difference in turbulence between chamber and forest. The general agreement in daytime hourly values is attributed to the frequent occurrence of equilibrium evaporation (rate at which evaporation is independent of ventilation). At night, evaporation was higher during enclosure. Comparisons were not possible with rain or dew. Determination of evaporation by gas analysis agreed within about 5 per cent of lysimeter values during a dry period.We conclude that the ventilated chamber as used provides realistic estimates of evaporation by forests. We show how periods of bias can be anticipated and corrected by theor

ISSN:0885-6087    

DOI:10.1002/hyp.3360010106

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractSurface hydrological studies are seen as inadequate in hyperarid and arid areas to provide reliable estimates of recharge. In most such areas surface discharges are not present so that assessments of groundwater resources are dependent upon ground interpretation and denied the flow control found in assessments elsewhere. Groundwater models show that gradients are sustained by long‐term dewatering and very small amounts of modern indirect recharge. Recharge indications are well within the error of a hydrological balance. Discharges appear equally small.The development of groundwater in arid areas frequently faces problems of salination due to recycling of irrigation water and rising groundwater heads. Abstraction is often inadequately managed so that uncontrolled mining of groundwater occurs. The advantage that groundwater has, however, is that it offers staged development and staged appraisa

ISSN:0885-6087    

DOI:10.1002/hyp.3360010107

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA new concept in recording data from a large network of transducers in the field is described. Each transducer is equipped with an addressable switching unit enabling parallel connection by a single four wire cable and sequential interrogation from a micro‐computer controlled data logger. A simple water level transducer suitable for both large stilling wells and piezometers, which returns an audio frequency signal with pulse width proportional to water level, is described. The use of audio frequency signals enables telephone grade circuits to be used and avoids many of the problems associated with direct current signals, whether current or voltage, commonly used at present.A field installation of 30 piezometers, a tipping bucket raingauge, a weir‐stage recorder and logger controlled water sampler is described and examples given of the data collected from a single piezometer transect during a major storm ev

ISSN:0885-6087    

DOI:10.1002/hyp.3360010108

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractAmbiguity in parameter identification represents a potentially serious limitation to the application of models of surface water acidification. Previous work has concentrated on manipulation of two of the three factors affecting model identifiability, namely model structure and estimator properties. A new technique is proposed which uses different modes of response within the data to improve parameter identification. Preliminary results, obtained using the Birkenes model of surface water acidification, appear to show promise. The technique is robust in recovering model parameters from synthetic data, with and without error, and in assimilating problems of structural error.

ISSN:0885-6087    

DOI:10.1002/hyp.3360010109

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA computer model has been used to estimate soil loss and sediment yield from irregular field‐size units of small watersheds. Input to the model includes spring data (i.e. relating to February through May) for the independent variables of the Universal Soil Loss Equation, and for factors such as surface roughness, an index of overland runoff, and proximity to the stream. Output from the model includes maps of seasonal estimates of potential soil losses, field sediment delivery ratios, and expected sediment yields. On the basis of selected erosion and sediment yield tolerances, the output information has been analysed to identify watershed areas which (1) exhibit both erosion and sediment yield problems; (2) exhibit only erosion problems; (3) exhibit only sediment yield problems; and (4) exhibit neither erosion nor sediment yield problems. The percentage of the watershed area in each category and the percentage of the watershed soil loss and sediment loads contributed by each category are also identified. Application of the procedure for planning remedial control programs for five watersheds is discusse

ISSN:0885-6087    

DOI:10.1002/hyp.3360010110

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360010101

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY