摘要:

AbstractA hierarchical sampling programme (including continuous monitoring, twice‐daily sampling and sampling at hourly intervals over selected 24 hour periods) was devised to support hydrochemical and hydrological research programmes on an alpine proglacial stream. The rationale for the research and for the sampling programme are explained and the hydrochemical time series generated over an ablation season are analysed to assess the degree to which they support the study aims. It appears that there is no satisfactory substitute for the chemical analysis of at least two water samples taken at approximately maximum and minimum discharge every day, if seasonal variations in meltwater chemistry are to be effectively characterized. Such time series data can be used to estimate Box‐Jenkins transfer function‐noise models between particular solutes (SO2−4, Ca2+, Mg2+, Na+and possibly K+) and either discharge or electrical conductivity, which can then be used to fill any short gaps in the data. This approach is not satisfactory even for filling short gaps in the twice‐daily determinations of pH, HCO−3and NO−3. At the diurnal time‐scale (based on hourly determinations over 24 hour periods) electrical conductivity seems to provide a good surrogate for most of the solutes studied. HCO−3, SO2−4, Ca2+and Mg2+were found to be particularly strongly related to electrical conductivity and there was little if any significant serial autocorrelation in the residuals from all of the simple linear regression relationships that were estimated between individual species and conductivity. It is concluded that the hierarchical sampling design was suitable for the purposes of the study, and that the continuous monitoring of electrical conductivity provides excellent supporting information to the chemical analysis of water samples if it is used carefully as a means of short term calibration and interpolation o

ISSN:0885-6087    

DOI:10.1002/hyp.3360080102

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA lumped model for streamflow routing in arid ephemeral channels has been developed. The governing equations for movement of flood waves subjected to transmission losses are simplified through a time averaging process to develop an ordinary differential equation describing transmission losses as a function of distance, inflow, channel width, time parameters of flow and effective hydraulic conductivity. The resulting equation has an analytical solution and simulates runoff volume and peak discharge rates for individual storm events. The outflow hydrograph is fairly well approximated with a triangular approximation. The model is simplified and constructed to require a minimum of observed data for calibration. It can also be used for ungauged basins in arid regions through parameterization.

ISSN:0885-6087    

DOI:10.1002/hyp.3360080103

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractHydrodynamic models of overland flow and channel flow are based on the shallow water wave theory described by the St Venant (SV) equations. These models are derived from either the kinematic wave (KW) approximation, the diffusion wave approximation (DW), or the dynamic wave (DYW) representation of the SV equations. In studies reported to date, different criteria have been established to evaluate the adequacy of the KW and DW approximations, but no explicit relations either in time or in space between these criteria and the errors resulting from these approximations have yet been derived. Furthermore, when carrying out hydrological modelling, it is not evident if the KW and the DW approximations are valid for the entire hydrograph or a portion thereof. In other words, these criteria take on fixed point values for a given rainfall‐runoff event. This paper attempts to derive, under simplified conditions, error equations for the KW or DW approximations for space independent flows, which provide a continuous description of error in the flow discharge hydrograph. The KW, DW and DYW solutions are parameterized through a dimensionless parameter γ which reflects the effect of the initial depth of flow, channel bed slope, lateral inflow and channel roughness. By comparing the kinematic wave and diffusion wave solutions with the dynamic wave solution, equations are derived in terms of γ for the error in the kinematic wave and diffusion wave approximations. The error equations turn out to be the Riccati equat

ISSN:0885-6087    

DOI:10.1002/hyp.3360080104

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn developing a method for establishing reliable flow estimates from monthly current metered discharge measurements and continuous stage records at a site subject to seasonal aquatic weed growth, a 25 year series of estimates of the resistance of the channel to flow was generated. Analysis of this data set produced estimated relationships between flow resistance, discharge and stage which support the models developed from shorter term research investigations. In addition, the annual cycle in flow resistance at the section studied was found to range from a minimum resistance in January to a maximum in August and September.

ISSN:0885-6087    

DOI:10.1002/hyp.3360080105

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe differences between δ18O in throughfall and open rainfall were studied for 16 selected spring and summer storms in deciduous, pine and spruce forests in central Pennsylvania, USA. Throughfall δ18O averaged 0.17, 0.32 and 0.24%ogreater than δ18O of open rainfall for all storms at the deciduous, pine and spruce sites, respectively. Throughfall18O enrichment was greater in low intensity spring rainfall events than higher intensity growing season storms and greater in the coniferous stands than the deciduous hardwood stand. Maximum throughfall18O enrichment of l.61%ooccurred in the spruce forest during one spring event. The differences between rainfall and throughfall18O observed in this study for individual storm events may have important implications for isotope flow separation studi

ISSN:0885-6087    

DOI:10.1002/hyp.3360080106

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAn analytical approximate model for unsaturated flow in a spatially variable field, coupled with infiltration and evapotranspiration at the upper boundary and a fluctuating water‐table at the lower boundary, has been developed. The unsaturated flow equations depend on parameterizations of θ(Φ) and K(Φ). They are based on the notion of a moving, discontinuous front. The field heterogeneity refers to saturated hydraulic conductivity only. Horizontal variability is considered, and the flow medium is approximated as a set of uncorrelated, vertically homogeneous columns. Expectations and variances obtained with this approach have been compared with observations of the field hydrological processes. Three important aspects of the hydrology in this lateritic terrain are rapid water‐table response, Hortonian surface runoff generation and soil suction variability. The stochastic conceptualization used explains to a high degree these characteristics, although some limitations are demons

ISSN:0885-6087    

DOI:10.1002/hyp.3360080107

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360080101

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY