bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental analysis of reservoir release wave routing in upland boulder bed rivers
Authors: Gilvear D. J. 
Published: February 2007

AbstractReservoir release wave routing during 33 controlled reservoir releases, along 15 upland boulder bed river channel reaches, on five different regulated rivers were monitored to assess the importance of river channel roughness and reservoir release magnitude on reservoir release wave speeds. Wave speeds varied between 0.52 and 3.01 m s−1. Reservoir release wave translation, steepening, and attenuation occurred. With high channel roughness values reservoir release wave arrival speed is retarded in comparison to peak stage and wave steepening occurs, but with a reduction in channel roughness reservoir release wave front arrival is accelerated producing attentuation. The threshold between reservoir release wave front attenuation and steepening occurs at a pre‐release discharge/channel width of approximately 0.1, an index of channel roughness.The paper also demonstrates, via comparison of observed and calculated reservoir release wave speeds on the River Washburn, Yorkshire, the difficulty of accurately predicting flood wave movement in upland boulder bed channels using existing prediction equations. The calculated values, however, revealed systematic error with pre‐release discharge and reservoir release magnitude. Apparently the equations fail to account for the effects of high channel roughness together with pressure gradient forces, induced by rapid rates of stage change on the rising limb of reservoir releases. In order to accurately predict reservoir release wave movement in regulated rivers, this paper demonstrates that hydraulic studies need to be undertaken and pre‐release discharges prescribed to determine desired reservoir release wave routing behaviour. Manipulation of the reservoir release pattern at the dam alone, cannot dictate reservoir release wave front form downstream or wave speed.
Modelling water‐table movement in flat low‐lying lands
Authors: Youngs E. G. , Leeds‐Harrison P. B. , Chapman J. M. 
Published: February 2007

AbstractThe unsteady water‐table movement caused by intermittent rainfall and varying evaporation in flat lands intersected by a network of ditches is modelled using land‐drainage theory. The unsteady water tables are assumed to behave as a continuous succession of steady states with the flux through the water table given by the sum of components due to rainfall and evaporation through the soil surface and due to water released or taken up by the unsaturated soil above the water table. A simple steady‐state drainage equation is used for the relationship between water‐table height and flux, and the specific yield is assumed to have a constant value. The simulated seasonal water table using estimated hydraulic soil properties and meteorological records for a field site agreed with available dip‐well observations. The water table was much lower than the ditch‐water level during the summer months. The sensitivity of simulated results to model parameters is demonstrated.
The transport of heavy metals during flood events in the polluted river Geul (the Netherlands)
Authors: Leenaers H. 
Published: February 2007

AbstractFor a specific flood on the polluted River Geul in March 1988, the relationships between river discharge, sediment concentration, and associated metal levels have been investigated. It was found that river discharge has only a limited influence on the transport of sediment and Pb, Zn, and Cd. During flood peaks its role is prominent, but at the intermediate stages between peaks, the quantity and quality of transported sediment depend on the variable activity of various sediment sources upstream. Nevertheless, when data from more floods are assembled, sediment and metal rating curves are obtained, which provide correlation coefficients of 0‐63‐0‐92. Using these curves, mass transport calculations were carried out which demonstrate that the bulk of the annual transport of sediments and heavy metals occurs during a limited number of major floods.
Infiltration at the Tai rain forest (Ivory Coast): Measurements and modelling
Authors: Wierda A. , Veen A. W. L. , Hutjes R. W. A. 
Published: February 2007

AbstractInfiltration experiments have been performed at three sites along a well‐known catena under virgin tropical rain forest using a portable sprinkling infiltrometer.Experimentally determined infiltration curves are presented. Infiltration curves are also simulated on the basis of the Mein‐Larson equation. The parameters for this model have been obtained from the infiltration curves (saturated conductivity) and simple soil moisture determinations (fillable porosity). The agreement between experimentally determined and modelled infiltration is reasonable, provided (a) saturated conductivity as derived from the experimental data is corrected, (b) a storage parameter, also derived from the experimental data, is added to the Mein‐Larson model, and (c) the decline in soil porosity with depth is either small or occurs abruptly at shallow depth.Comparison of observed infiltration rates with rainfall intensity shows that Horton Overland Flow has to occur naturally at least on the middle and lower section of the catena.Despite the fact that most parameters can be estimated in principle from basic soil data, it remains advisable to obtain sprinkling infiltrometer field measurements, because of soil variability due to dynamic surface conditions, macroporosity, air entrapment, and irregularity of the wetting front.
The identification of runoff‐production mechanisms using environmental isotopes in a tussock grassland catchment, eastern otago, New Zealand
Authors: Bonell Mike , Pearce Andrew J. , Stewart Michael K. 
Published: February 2007

AbstractA previous hydrometric study of runoff production in tussock grassland drainage basins in Otago (45°50′S, 169°45′E), New Zealand, revealed a marked change of slope in storm hydrograph recessions. An environmental isotope study was initiated to investigate the runoff mechanisms operating and to test specific hypotheses to explain this break in the hydrograph recession. The results indicated that for quickflow volumes in excess of 10mm, the first part of the storm hydrograph can be attributed to two separate sources, namely, ‘old’ water from a shallow, unconfined groundwater reservoir and ‘new’ water from saturation overland flow on the lower wetlands of concave slopes. Despite the extensive area of wetlands, ‘old’ water runoff from the unconfined groundwater reservoir is delivered more rapidly to the stream than ‘new’ water from saturation overland flow. Substantial surface storage in the wetlands has first to be exceeded before rain becomes a significant part of stream discharge. For quickflow volumes less than 10mm, only ‘old’ water from groundwater contributes to the first part of the hydrograph recession. This means that only the largest 7 per cent of storms (in terms of quickflow volume) generate quickflow containing significant amounts of ‘new water’. The second part of the recession of the storm hydrograph consists of ‘old’ water derived from a remarkably well‐mixed shallow unconfined groundwater body.
Flood hydrograph estimation from arid catchment morphology
Authors: Nouh M. 
Published: February 2007

AbstractData on performance of a geomorphologic rainfall‐runoff model in simulating observed flash flood hydrographs in 32 arid catchments have been analysed. The catchments, which are located in the southwest region of Saudi Arabia, vary in their size, slope of land, and characteristics of soils, and are in zones of different rainstorm characteristics. The sensitivity of the model accuracy with various catchment and rainfall characteristics has been investigated. Size, followed by rate of infiltration and slope of land, are the most effective catchment characteristics affecting the accuracy. In addition, the accuracy varies with spatial and temporal rainfall variation, total rainfall depth, and length of the dry period between two successive rainstorms over catchment. It is sensitive to temporal rainfall variation more than spatial rainfall variation, and to the dry period more than total rainfall depth. Generally, the model did not display an accuracy approaching that of the observations, especially in simulating peak flowrates in large size infiltrating catchments having high temporal rainstorm variation. Guidelines on the best use of the model in arid catchments were proposed.
Partitioning of rainfall in a eucalypt forest and pine plantation in southeastern australia: IV the relationship of interception and canopy storage capacity, the interception of these forests, and the effect on interception of thinning the pine plantation
Authors: Crockford R. H. , Richardson D. P. 
Published: February 2007

AbstractA study of partitioning of rainfall into throughfall, stemflow, and interception was conducted in a dry sclerophyll eucalypt forest and an adjacent pine plantation over a period of seven years, on a rainfall event basis. The following three issues are discussed: (1) the relationship between canopy storage capacity and interception of continuous events, (2) interception, throughfall, and stemflow, and (3) the effect on interception of thinning the pine plantation.
The canopy storage capacity/interception interaction for the eucalypt forest was assessed by comparing a gravimetric estimate of canopy storage capacity with interception. The maximum possible value for canopy storage capacity was found to be a small proportion of interception for events of all sizes. This suggests that evaporation of intercepted water during the continuous events was responsible for most of the interception. This ‘within event’ evaporation appears to be responsible also for the net rainfall/gross rainfall estimate of canopy storage capacity being four times the gravimetric value. For the pines the regression estimate was more closely related to interception.
Interception, throughfall, and stemflow of these forests were measured for four years. Data are presented for each year with overall average interception being 11‐4 per cent of precipitation for the eucalypt forest and 18‐3 per cent for the pine plantation. Topography and rainfall event type are considered in the comparison.
Species composition and tree type are considered when comparing these results with published studies from similar forest types in southeastern Australia. The periodic (annual) variations of interception in this and the other studies makes comparison difficult.
The effect of thinning on the throughfall, stemflow, and interception in a Pinus radiata plantation is examined. Throughfall increased, interception decreased but not in proportion to the removed biomass; stemflow decreased on an area basis, but increased on a per tree basis. A positive relationshiip is established between interception and stemflow on the thinned plantation but not in the unthinned. Reasons for this are suggested. The results are compared to those reported from similar experiments in other forests.
The periodic variations in interception and errors inherent in its estimation suggest that caution should be exercised when using average interception figures in water balance studies.
Depletion and recharge of soil water in two stands of norway spruce (picea abies (l.) karst)
Authors: Nordén Lars G. 
Published: February 2007

AbstractDepletion and recharge dynamics of soil water were studied at two forest sites in Northern and Southern Sweden during three growing seasons. At each site, having a stand of Norway spruce (Picea abies (L.) Karst), soil water potential was measured with 90 gypsum blocks in 30 profiles at depths of 6, 20, and 50 cm from the soil surface. The size of the rectangular plots was 250 m2. The large variation in soil water potential during desiccation periods extended throughout the measuring range of the gypsum blocks. The soil water potentials, at different times and depths, were log‐normally distributed during only parts of the desiccation periods. Due to the large variation and skewed distribution of soil water potentials the nonparametric Spearman rank correlation statistics was used to analyse the pattern of desiccation and rewetting of the soil.In the beginning of a dry period the topsoil was more efficiently desiccated than the subsoil at both sites. This difference lasted throughout all droughts at the southern site and was explained by a higher root density in the topsoil. At the northern site, however, there was no difference in the degree of desiccation at different soil depths during an extended desiccation period. While certain microsites tended to be more depleted than others during desiccation periods, this did not prove to be significantly correlated to the rewetting of the soil after the different droughts. There was a vertical relationship in soil water desiccation in which an accentuated water depletion at the 6 cm soil depth was followed by a similar strong depletion 14 cm lower in the same observation profile. Strongly desiccated observation profiles were not necessarily situated close to each other but seemed randomly spread over the site. There was no relationship between extracted water at any of the three soil depths in the different observation profiles and proximity to trees or tree size.
Seasonal soil water dynamics in the jarrah forest, Western Australia. II: Results from a site with fine‐textured soil profiles
Authors: Ruprecht J. K. , Schofield N. J. 
Published: February 2007

AbstractSeasonal soil water dynamics were measured at a fine‐textured, upslope site within the jarrah forest of southwest Western Australia and compared to the results from a coarse‐textured hillslope transect. Gravity drainage dominated during winter and early spring. This reversed in early summer and an upward potential gradient was observed to 7 m depth. A shallow ephemeral saturation zone was observed above a clay pan at 1.5 m depth. This saturation zone persisted through late winter and early spring, contrasting with the short‐lived saturation in the duricrust on the hillslope transect. The annual maximum to minimum unsaturated soil water storage was about 530 mm, 50 mm greater than the hillslope transect and higher than most values reported elsewhere in Australia. Significant soil water content changes following winter rain were generally restricted to 6 m but at one site occurred to 9 m. These depths were significantly less than the coarser‐textured hillslope transect. Soil water drying rates averaged 5 mm day−1 during extended dry periods compared to 3.5 mm day−1 on the hillslope transect. The drying rate occurred uniformly through the profile until late summer when a significant decrease in the upper 3 m was observed.
Recharge processes during snowmelt: An isotopic and hydrometric investigation
Authors: Buttle J. M. , Sami K. 
Published: February 2007

AbstractResults from hydrometric and isotopic investigations of unsaturated flow during snowmelt are presented for a hillslope underlain by well‐sorted sands. Passage of melt and rainwater through the vadose zone was detected from temporal changes in soil water 2H concentrations obtained from sequential soil cores. Bypassing flow was indicated during the initial snowmelt phase, but was confined to the near‐surface zone. Recharge below this zone was via translatory flow, as meltwater inputs displaced premelt soil water. Estimates of premelt water fluxes indicate that up to 19 per cent of the premelt soil water may have been immobile. Average water particle velocities during snowmelt ranged from 6.2 × 10−7 to 1.1 × 10−6 ms−1, suggesting that direct groundwater recharge by meltwater during snowmelt was confined to areas where the premelt water table was within 1 m of the ground surface.Soil water 2H signatures showed a rapid response to isotopically‐heavy rain‐on‐snow inputs late in the melt. In addition, spatial variations in soil moisture content at a given depth induced a pronounced lateral component to the predominantly vertical transport of water. Both factors may complicate isotopic profiles in the vadose zone, and should be considered when employing environmental isotopes to infer recharge processes during snowmelt.
On the extraction of channel networks from digital elevation data
Authors: Tarboton David G. , Bras Rafael L. , Rodriguez‐Iturbe Ignacio 
Published: February 2007

AbstractChannel networks with artibtrary drainage density or resolution can be extracted from digital elevation data. However, for digital elevation data derived networks to be useful they have to be extracted at the correct length scale or drainage density. Here we suggest a criterion for determining the appropriate drainage density at which to extract networks from digital elevation data. The criterion is basically to extract the highest resolution (highest drainage density) network that satisfies scaling laws that have traditionally been found to hold for channel networks. Procedures that use this criterion are presented and tested on 21 digital elevation data sets well distributed throughout the U.S.
Rainfall interception by trees of Pinus radiata, and Eucalyptus viminalis, in a 1300 mm rainfall area of southeastern New South Wales: I. Gross losses and their variability
Authors: Pook E. W. , Moore P. H. R. , Hall T. 
Published: February 2007

AbstractInterception loss, I, was determined by continuous concurrent measurements of the canopy precipitation balances of a mature seed orchard tree of Pinus radiata, and a dominant tree of Eucalyptus viminalis at a mountainous high rainfall site (900 m a.s.l.) in Tallaganda State Forest of the Upper Shoalhaven Catchment. Approximate canopy storage capacity (Sc) of the pine was 54 l, and that of the eucalypt was 11·3 l. Gross pine I was 26·5 per cent and eucalypt I was 8·3 per cent of total incident rainfall over a period of 18 months, from June 1975 to December 1976. The exponential model that provided the best fit to overall data relating I to gross rainfall (Pg) was of good precision for the pine (r2 = 0·73) but rather poor precision for the eucalypt (r2 = 0·27). A consistent pattern in interception data of the two canopy types suggested that variation in I was related to change in pervasive conditions influencing rates of evaporation from wet canopies during rainfall. Multiple regression analyses confirmed that factors such as rainfall intensity and windspeed explained some of the variation in eucalypt I but little in pine I.Negative eucalypt I and corresponding low values of pine I over a wide range of Pg (up to 20 mm) suggest that capture of wind‐borne precipitation (cloud, mist, or fog) had also complicated the canopy precipitation balances.
Rainfall interception by trees of Pinus radiata and Eucalyptus viminalis in a 1300 mm rainfall area of southeastern New South Wales: II. Influence of wind‐borne precipitation
Authors: Pook E. W. , Moore P. H. R. , Hall T. 
Published: February 2007

AbstractAnalyses were made of the concurrent canopy precipitation balances of a seed orchard pine and a mature forest eucalypt during protracted rainfalls selected for their representativeness of the range of variation encountered in the two canopy types at Tallanganda State Forest (ca. 990 m a.s.l.) in the Upper Shoalhaven Valley of southeastern New South Wales. Although their canopy storage capacities were widely different there was consistent interception behaviour in the pine and the eucalypt in all events. Detailed weather data and the time courses of interception loss provided circumstantial evidence for a varying and, at times, substantial influence of cloud or mist deposition on the canopy precipitation balances during rainfall that made a significant contribution to the variation in rainfall interception data. Mean evaporation rates from the saturated canopies during rainfall varied from −0·02 mm hr−1 up to 0·68 mm hr−1 in the pine; and from −0·04 mm hr−1 up to 0·13 mm hr−1 in the eucalypt. The implications of cloud‐capture during rainfall for studies of rainfall interception in forests of southeastern Australia are discussed.
Streamflow generation in a headwater basin on the precambrian shield
Authors: Wels Christoph , Taylor Colin H. , Cornett R. Jack , Lazerte Bruce D. 
Published: February 2007

AbstractCurrent conceptual runoff models hypothesize that stormflow generation on the Canadian Shield is a combination of subsurface stormflow and saturation overland flow. This concept was tested during spring runoff in a small (3.3 ha) headwater basin using: (1) isotopic and chemical hydrograph separation and (2) field mapping and direct tracing of saturated areas. Isotopic and chemical hydrograph separation indicated three runoff components: (1) pre‐melt subsurface flow; (2) subsurface flow of new (event) water; and (3) direct precipitation on to saturated areas (DPS). During early thaw‐freeze cycles, their relative contributions to total flow remained constant (65 per cent, 30 per cent, and 5 per cent respectively). It is hypothesized that lateral flow along the bedrock/mineral soil interface, possibly through macropores, supplied large volumes of subsurface flow (of both old and new water) rapidly to the stream channel. Much higher contributions of DPS were observed during an intensive rain‐on‐snow event (15 per cent of total flow). Mapping and direct tracing of saturated areas using lithium bromide, suggested that saturated area size was positively correlated to stream discharge but its response lagged behind that of discharge. These observations suggest that the runoff mechanisms, and hence the sources of stream flow, will vary depending on storm characteristics.
Analysis of runoff pathways and flow contributions using deuterium and stream chemistry
Authors: Ogunkoya O. O. , Jenkins A. 
Published: February 2007

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 chemistry.
Evaluation of a water equivalent of snow cover map in a small catchment area using a geostatistical approach
Authors: Hosang Jürg , Dettwiler Katrin 
Published: February 2007

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.