bluuebunny/crossref_metadata_2025 huggingface dataset:
A world model of soil carbon dioxide
Authors: Brook George A. , Folkoff Michael E. , Box Elgene O.
Published: February 2007

Mean growing season soil PCO2 data were obtained for 19 regions of the world in nine countries. Bivariate and multiple linear regression analysis with soil log(PCO2) as the dependent variable and TEMP, PRECIP, log(AET), and log(PET) as the four climatic independent variables demonstrated that AET was the best independent predictor of soil PCO2. An improved soil PCO2‐AET model was developed by assuming (1) that as AET approaches zero, soil PCO2 approaches the atmospheric value and (2) that there is an upper limit to soil PCO2 at very high AET. This model has the form log(PCO2) = −3·47 + 2·09 (1 −e−0·0172 AET) where AET is in mm. It explains 67 per cent of the initial variation in the soil PCO2 data, predicts a soil log(PCO2) of − 3·47 at AET = 0, and an upper limit of 3·5 per cent (log(PCO2) = − 1·45) for mean growing season soil PCO2 at AET values of 2000 mm and above. The results of this study suggest that soil PCO2 levels in tropical areas are, on average, higher than those in temperate, alpine, and arctic regions.
Soil water residence times and solute uptake on a dolomite bedrock—preliminary results
Authors: Trudgill Stephen T. , Laidlaw Ian M. S. , Smart Peter L.
Published: February 2007

Calcium and magnesium levels have been monitored in slope foot drainage waters on a dolomite bedrock. Both calcium and magnesium rich pulses occur. Short term dissolution experiments demonstrate high calcium levels in solution while other authors have suggested that long residence time groundwater has relatively high levels of magnesium due to calcite precipitation. Patterns of field fluctuations in Ca: Mg ratios can thus be tentatively interpreted in terms of short residence time water of high calcium content mixing with long residence time water of high magnesium content. Fluorometric dye tracing has been used to indicate the orders of magnitude of soil water residence times, suggesting that quickflow components are resident in the system for a few hours to a few days. Further work is in progress.
Resistance to flow in rough supercritical sheet flow
Authors: Savat Jan
Published: February 2007

Shallow water depths on steep slopes of as much as fifty per cent can be measured easily by weighing a light flume and the water it contains. Because water accelerates along the flume, a good approximation of the steady state depth is obtained when the recording balance is fixed to its bottom end.

From the unit discharge and the depth, and not from measurements of the surface velocity, the Darcy‐Weisbach friction coefficient can be calculated. The present results show that this friction coefficient is larger in thin sheet flows than that calculated from the equation for rough turbulent flow. This latter could fit at a Reynolds Number of 50,000. When the regime is laminar (Re < 2,440) the Darcy‐Weisbach friction coefficient always exceeds the theoretical value of 96/Re. The great relative depth of standing and travelling waves could account for this discrepancy together with turbulence and wake formation around bottom grains.

Herein it is assumed that a regime can prevail where a laminar superlayer glides over a turbulent sublayer in the vicinity of bottom grains, because the ratio of the surface velocity to the mean velocity can greatly exceed 1.5, especially on steep slopes.

Until photographs of the streamlines are taken, no statement about flow regimes in supercritical sheet flow can be made.
The application of erosion slowness theory to hillslope formation
Authors: Carter G. , Nobes M. J.
Published: February 2007

A method of analysis for predicting the time development of hillslope profiles is presented. The technique is based upon the assumption of weathering limited erosion and assumes that the local surface normal erosion rate is dependent upon the local flux of erosional agent and a function of the local slope gradient. This technique has been previously applied with success to analogous erosional processes in the sand blasting, chemical and energetic atom bombardment induced ablation of solids. The analysis shows how linearly segmented profiles can develop from initially curved surfaces and indicates the progress of profiles to stable end forms. Actual application to geomorphological situations is limited by lack of knowledge of micro‐environmental erosion fluxes and the gradient dependence of erosion and it is suggested that field observations and laboratory simulations could be helpful in determining the utility of the analysis technique outlined here.
The role of topography in controlling throughflow generation: A discussion
Authors: Speight J. Garry
Published: February 2007

The distributions of specific catchment area and specific dispersal area values over the hillside studied by Anderson and Burt (1978) relate much more closely to the observed distributions of soil water matric potential than do the occurrences of contour concavity on which the authors rely. Highest potential always occurred in the zone of large specific catchment area except immediately after rainfall, when it occurred in the zone of small dispersal area. Isolines of low potential persistently conformed to those of specific dispersal area.
Processes of accelerated pluvial erosion on desert hillslopes modified by vehicular traffic
Authors: Iverson Richard M.
Published: February 2007

Accelerated pluvial erosion on hillslopes modified by off‐road vehicles (ORVs) is analysed using results from 50 rainfall simulation experiments conducted in the Mojave Desert, California. Sediment yield from 1 m2 hillslope plots subjected to intense, 20‐minute rainfalls is typically increased 10 to 20‐fold following ORV use. Salient effects of vehicle traffic, which reduce infiltration, increase runoff sediment transport efficiency, and enhance gully formation, are further studied by combining simple theoretical relations with experimental data. This analysis helps identify factors controlling erosion on natural desert hillslopes, as well as those used by ORVs.

Erosion of natural or vehicle‐used desert surfaces is heavily influenced by runoff hydraulics. Calculated Darcy‐Weisbach friction factors decrease by an average of 13‐fold following vehicular slope modification, whereas runoff Reynolds numbers increase by an average of 5 1/2‐fold. The capacity of overland flow to transport sediment is related to runoff power and its degree of localization, which usually increase considerably following ORV activity; however, the ability of overland flow to move large grains (competency) is related to a combination of factors not always systematically influenced by ORV use. Kinematic runoff routing, which is used to extrapolate experimental results to longer slope lengths, leads to the suggestion that the hydraulic roughness of desert hillslopes strongly influences their erosional behaviour.
First‐order drainage basin morphology—definition and distribution
Authors: Marcus Alan
Published: February 2007

First‐order drainage basin morphology consists of two complementary regions: a headwater region, the valley head; and a stream region, the channelway (Figure 1). Each subbasin's morphology is represented by a set of principal components factors that include the properties of area, length, slope, relief, elongation, and plan curvature. The channelway region is a highly‐integrated morphological unit that is dominated by a size‐shape factor, indicative of an organized flow system and the presence of a permanent channel. The valley head region shows little integration of its morphological factor set, and this is reflected by its lack of a permanent channel. The valley head‐channelway definition is utilized to classify first‐order basins into three morphological groups or types. Basin type is related to basin location within the larger drainage network, and this relation helps to explain variations in subbasin morphology. The channelway's morphologic properties are influenced by the location of the first‐order basin's bifurcation or junction within the higher‐ordered network; and valley head morphology is related to the location of the basin's divide position within the drainage net.
Options listings and individual equity volatility
Authors: Jubinski Daniel , Tomljanovich Marc
Published: February 2007

This article examines the effect of options introduction on the conditional volatility of 1,576 individual firms over the 1973–1996 time period. With the use of a GJR‐GARCH specification for daily volatility, it is found, for the majority of firms, that option listing does not impact the underlying equity security. Listing effects are identified for a small subset of firms, specifically smaller firms with high trading volume and/or volatility. For these firms there is evidence of a change in the conditional volatility process after option listing, and it is concluded that options continue to provide additional information about the underlying equity for these companies. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27: 1–27, 2007
Effects of single SNPs, haplotypes, and whole‐genome LD maps on accuracy of association mapping
Authors: Maniatis Nikolas , Collins Andrew , Morton Newton E
Published: February 2007

We describe an association mapping approach that utilizes linkage disequilibrium (LD) maps in LD units (LDU). This method uses composite likelihood to combine information from all single marker tests, and applies a model with a parameter for the location of the causal polymorphism. Previous analyses of the poor drug metabolizer phenotype provided evidence of the substantial utility of LDU maps for disease gene association mapping. Using LDU locations for the 27 single nucleotide polymorphisms (SNPs) flanking the CYP2D6 gene on chromosome 22, the most common functional polymorphism within the gene was located at 15 kb from its true location. Here, we examine the performance of this mapping approach by exploiting the high‐density LDU map constructed from the HapMap data. Expressing the locations of the 27 SNPs in LDU from the HapMap LDU map, analysis yielded an estimated location that is only 0.3 kb away from the CYP2D6 gene. This supports the use of the high marker density HapMap‐derived LDU map for association mapping even though it is derived from a much smaller number of individuals compared to the CYP2D6 sample. We also examine the performance of 2‐SNP haplotypes. Using the same modelling procedures and composite likelihood as for single SNPs, the haplotype data provided much poorer localization compared to single SNP analysis. Haplotypes generate more autocorrelation through multiple inclusions of the same SNPs, which could inflate significance in association studies. The results of the present study demonstrate the great potential of the genome HapMap LDU maps for high‐resolution mapping of complex phenotypes. Genet. Epidemiol. 2007. © 2007 Wiley‐Liss, Inc.
Tectonostratigraphy and kinematics of the eastern end of the Sivas Basin (central eastern Turkey): Implications for the so‐called ‘Anatolian block’
Authors: Temiz Haluk , Guezou Jean Claude , Poisson Andre M. , Tutkun Zeki
Published: February 2007

The eastern end of the Sivas Basin, just west of Erzincan, is known as the Kemah Basin. The lithostratigraphy of the Kemah Basin thus corresponds with the general characteristics described for the Sivas Basin: the upper stratigraphic sequence begins with the Kemah Limestones of Burdigalian age. Above these, the sediments (grey limy marls, sandstones and conglomerates) are not yet dated, but probably span Late Miocene to Plio‐Quaternary times. The lower sequence is made of (Late Oligocene?) non‐fossiliferous, mainly continental deposits (variegated clays, silts and gypsum at the base; conglomerates, sandstones and some volcanics in the footwall of the limestones).

Both the basin deposits and substratum (arc volcanics, volcanoclastics and ophiolites) are involved in thrust systems with displacements consistently directed to the SSE. The sequence of thrusting deduced from the geometrical pattern of the imbricate zone and from the stratigraphic record includes at least two stages of thrust propagation. The sequence shows the rise of successive waves of active new thrusts and folds from the north, cutting through earlier thrusts in a general ‘break‐back’ sequence. The southern edge of the Neogene basin against the ophiolites covering the Munzur Limestones (Taurides) shows a moderate northward tilting.

A first attempt at a (incomplete) balanced cross‐section and restoration along the Burdigalian limestones as datum gives a minimum displacement of 11 km along a section length of 12 km. The kinematics and the contraction ratio question the concept of an ‘Anatolian block’ and related displacement models during the Late Neogene.
Remobilization of two mélanges in Central Anatolia
Authors: Norman Teoman N.
Published: February 2007

Mélanges are usually dated from the ages of contained blocks and of the oldest unconformably overlying cover rocks. Anomalies associated with this approach are illustrated in this study of the principal mélange belts developed in Anatolia.

The Karakaya Mélange belt of supposed Middle Triassic inception and the Ophiolitic Mélange belt of supposed Late Cretaceous age are readily distinguished in western Turkey but their outcrops converge eastwards, the two belts merging in Central Anatolia and becoming intermingled further east, near Sivas, where the ages and natures of the mélange belts are problematic. Thus parts of the mélange attributed to the Karakaya belt contain blocks of younger limestone (Jurassic to Early Cretaceous or even younger), whereas outcrops attributed to the Ophiolitic Mélange include blocks of clastics of Late Palaeocene‐Early Eocene or even Mio‐Pliocene age. This situation confers apparently ‘younger’ ages of formation on these mélanges. It is suggested that such anomalies result from contamination by younger blocks as a result of local remobilization of the mélanges during subsequent tectonic disturbances.

A north‐south oriented area, 45 km long and 20 km wide, crossing the complex mélange zone east of Sivas, has been mapped at a 1:25 000 scale and provides critical evidence on this question. It appears that the Karakaya Mélange (or its equivalent) may have been remobilized at least four times and the Ophiolitic Mélange at least three times since their inception. During each subsequent tectonic event the mélanges have incorporated some parts of the younger deposits which formed on top of them in the intervening geological periods.
Surface deformation and tectonic setting of the 13 March 1992 Erzincan earthquake, Eastern Turkey
Authors: Tatar O. , Temiz H. , Tutkun S. Z. , Park R. G. , Stimpson I. G.
Published: February 2007

The earthquake of 13 March 1992 (Ms = 6·8) in the densely populated Erzincan region of eastern Turkey resulted in about 500 deaths, at least 2000 people injured and widespread destruction of buildings. The results are presented of field observations carried out within the Erzincan Basin immediately after the earthquake. The main area of surface deformation is about 55 km2 in extent and lies 15 km south‐east of Erzincan. Surface fractures with significant displacements were observed with orientations as follows: strike‐slip 095–110° (dextral), 040° (sinistral) and 090° (sinistral); extensional 150–180°. Most of the observed fractures are consistent with the Harvard centroid moment tensor solution for the main shock, which indicates north‐south compressional and east‐west extensional principal horizontal stress axes. It is suggested that the earthquake probably occurred as a result of dextral strike‐slip motion on a segment of the North Anatolian Fault Zone.
Morphology and structural setting of Quaternary travertines at Pamukkale, Turkey
Authors: Altunel E. , Hancock P. L.
Published: February 2007

Pamukkale (Cotton Castle), in the west Anatolian sector of the Aegean extensional province, is so named because snow white travertines are accumulating there. Travertine deposition at Pamukkale, one of Turkey's most important tourist destinations, has been in progress for at least the last 400 000 years, and has partially overwhelmed the Roman city and necropolis of Hierapolis. The travertine originates from hot waters that emerge at 35–56°C from open fissures and at least one fault zone. The five principal morphological varieties of travertine mass are: (1) terraced‐mound travertines; (2) fissure‐ridge travertines; (3) range‐front travertines; (4) eroded‐sheet travertines; and (5) self‐built channel travertines. The first two varieties are similar to those reported from well known travertines at Tivoli, east of Rome, and Mammoth Hot Springs, Wyoming, but the last three varieties have not previously been reported.

The orientations of fissure‐ridge travertines directly reflect neotectonic directions of stretching that are north‐south in the south and north‐east‐south‐west in the north of the Pamukkale plateau. The deposition of about 10 km2 of travertines at Pamukkale is attributed to the presence beneath Pamukkale of carbonate bedrocks and an anastomosing network of fissures intersecting at numerous nodes that provide conduits for the escape of water. These fissures are parallel to the normal faults framing the west‐trending Menderes graben and the north‐west trending Gediz graben, whose confluence is near Pamukkale.
Geological setting, petrographic and geochemical characteristics of the Cretaceous and Tertiary igneous rocks in the Hekimhan‐Hasançelebi area, north‐west Malatya, Turkey
Authors: Yilmaz Sabah , Boztui̇ Durmuş , Öztürk Ali
Published: February 2007

Upper Cretaceous to Tertiary igneous rocks outcrop in the Hekimhan‐Hasançelebi area, about 80 km to the north‐west of Malatya, Central‐Eastern Anatolia. These igneous rocks consist of Maastrichtian Bahçedam volcanics, the Palaeocene(?) Hasançelebi pluton and the Neogene Yamadaǧ volcanics. These latter rocks are subdivided into, from bottom to top, the Karadaǧ volcanics, Leylekdaǧ volcanics and Koçasar volcanics. The Hasançelebi pluton consists mainly of syenite, quartz syenite, monzonite and quartz monzonite. According to chemical criteria, the Hasançelebi pluton is classified as an alkaline oversaturated subtype of the cafemic association with a felsic I‐type character. Some trace element data indicate an apparent within‐plate origin. The Bahçedam volcanics are made up of tephrite basanite, basalts, trachybasalt and basaltic trachyandesite with an alkaline character. Other trace element criteria indicate both an arc and within‐plate origin. Mid‐ocean ridge basalt normalized distribution patterns of some incompatible elements indicate some conspicuous enrichment in the concentrations of K, Rb, Ba, Th and Nb; a slight enrichment in Zr; and some depletion in Sr, P and Ti. The Karadaǧ volcanics are composed mainly of alkaline trachyandesites. The Leylekdaǧ and Koçasar volcanics consist essentially of calc‐alkaline andesitic rocks. Some trace element discrimination diagrams reveal a possible arc origin for both sets of volcanics. The Hasançelebi pluton is assumed to be part of the Cretaceous‐Palaeogene Central‐Eastern Anatolian alkaline province. The Leylekdaǧ and Koçasar volcanics can be considered to be collision‐related igneous rocks by taking into account the regional tectonic regime in Central‐Eastern Anatolia. However, their trace element discrimination patterns indicate an arc origin. It is suggested that a study of the absolute age dates, rare earth element determinations and isotope geochemistry would lead to a better understanding of the tectonomagmatic evolution of this area.
Magnetic crustal character in Central Ireland
Authors: Morris P. , Max M. D.
Published: February 2007

The simplest magnetic model for the upper 20 km of crust in central Ireland is of two layers. A thin, weakly magnetic upper layer carrying a number of magnetic bodies that can be related to surface geology overlies a magnetic crustal zone whose gross magnetization increases towards the north. The deeper trace of the lapetus Suture in central Ireland forms the boundary between a more magnetic northern crustal area and a less magnetic southern area. A pre‐Carboniferous major dextral offset of this suture boundary occurs in the Limerick area. The suture is traced beneath the Dingle peninsula in the far south‐west of Ireland.

In east‐central Ireland, between the Iapetus Suture and Southern Upland Line, the crust contains a large, south‐dipping magnetic body with no surface expression, which produces the Virginia magnetic anomaly.

The development of magnetic bodies — in particular, volcanic rocks of Carboniferous age — has been controlled by regional stress patterns. The major volcanic centre at Limerick lies at the intersection of two major Caledonian block fault systems just to the north of the surface trace of the Hercynian Front.
Evaluation of the ventilated chamber for measuring evaporation from a forest
Authors: Dunin F. X. , Greenwood E. A. N.
Published: February 2007

Evaporation 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 theory.
A review of aridity and groundwater
Authors: Lloyd J. W.
Published: February 2007

Surface 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 appraisal.
Electronic acquisition of hydrologic data from intensively instrumented hillslopes
Authors: Durham I. H. , O'Loughlin E. M. , Moore I. D.
Published: February 2007

A 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 event.
Vegetation characteristics and the prediction of runoff: Analysis of an experiment in the New Forest, Hampshire
Authors: Gurnell A. M. , Gregory K. J.
Published: February 2007

Vegetation characteristics have not been sufficiently utilized in catchment runoff models. An analysis of storm hydrograph data from nested subareas of the Highland Water catchment, New Forest, U.K., indicates that depth of runoff and peak discharge from areas under heathland cover is substantially greater than from areas under woodland cover at several spatial scales. The significance of heath vegetation composition in the identification of runoff contributing areas is illustrated by an analysis of vegetation composition, water table depth, baseflow discharge and storm runoff from areas predominantly covered by heathland. Methods are proposed to employ the hydrological characteristics of heathland to refine and develop the Flood Studies Approach to discharge estimation in ungauged heathland catchments. Such an approach is greatly facilitated by the use of remotely‐sensed data.
Soil water dye tracing, with special reference to the use of rhodamine WT, lissamine FF and amino G acid
Authors: Trudgill S. T.
Published: February 2007

Three fluorescent dyes (Rhodamine WT, Lissamine FF and Amino G Acid) are compared for use in soil water tracing. Severe limitations are evident, but practical applications are possible. Background fluorescence, adsorption, desorption, pH and other non‐adsorptive effects are reviewed in the contexts of soil column work and field tracing of soil water. Lissamine FF and Amino G Acid are to be preferred for soil column work because of their lower adsorption; Rhodamine WT exhibits higher adsorption but is useful in field situations where organic fluorescence backgrounds are high. Semi‐quantitative work may be undertaken in soil columns once a priming and flushing procedure has been adopted.
Scale effects in fluvial sediment‐associated chemical data
Authors: Ongley E. D.
Published: February 2007

Assessment of man's impact on fluvial systems frequently involves extrapolation in time and space from data collected as part of a water quality network. Extrapolation represents information transfer and is used for scenario building and risk assessment. Transfer functions for non‐conservative quality variables are poorly understood. Metals, phosphorus, and organic contaminants, which are preferentially transported in association with suspended sediment, are especially susceptible to extrapolation errors. Information loss, which is inherent in extrapolation procedures, is characterized for sediment‐associated substances by examining the assumptions and limitations of the sediment delivery ratio. A practical demonstration of scale effects and interpretive difficulties is provided using data from the Bow River, Alberta. Guidelines for data assessment and extrapolation are summarized for temporal effects and for three different spatial scales.
Mathematical model for evaluation of the effect of soil erosion on soil productivity
Authors: Todorovic P. , Woolhiser D. A. , Renard K. G.
Published: February 2007

This paper is concerned with the development of a stochastic model for evaluating the long‐term effect of soil erosion on soil productivity. Due to random variations in annual crop yield, the effect of erosion on crop production is not easily detectable in the short run, but becomes gradually evident over a sufficiently long time period. Under these circumstances, it seems that an experimental approach to this problem may be very difficult. The long period of time over which such an experiment has to be conducted may result in prohibitively high costs. In addition, it also means that eventual resolution of this problem must be postponed until a distant future time. The stochastic model formulated here provides us with a useful tool to assess the trend in quantitative changes in crop production due to erosion and to project future crop losses. The model is a discrete parameter stochastic process. Its derivation is based on a single assumption that the annual loss rates form a sequence of independent random variables {Zi}1∞ (in this paper, we consider only two particular cases: (a) {Zi}1∞ is a sequence of constants; (b) {Zi}1∞ is a sequence of independent identically distributed random variables). For these particular cases, we obtained its marginal n‐dimensional distribution function and correlation function. One of the principal model features is its simple structure and remarkable lack of restrictive and unrealistic assumptions.
An evaluation of the universal soil loss equation and field techniques for assessing soil erosion on a tropical alfisol in western Nigeria
Authors: Mtakwa P. W. , Lal R. , Sharma R. B.
Published: February 2007

Four techniques for soil erosion assessment were compared over two consecutive seasons for bare‐fallow plots and a maize‐cowpea sequence in 1985 at IITA, Ibadan, Nigeria. The techniques used were: tracer (aluminium paint), nails (16 and 25), the rill method, and the Universal Soil Loss Equation (USLE). Soil loss estimated by these techniques was compared with that determined using the runoff plot technique.

There was significantly more soil loss (P < 0·01) in bare‐fallow than in plots under maize (Zea mays) or cowpea (Vigna unguiculata). In the first season, soil loss from plots sown to maize was 40·2 Mg ha−1 compared with 153·3 Mg ha−1 from bare‐fallow plots. In the second season, bare‐fallow plots lost 87·5 Mg ha−1 against 39·4 Mg ha−1 lost from plots growing cowpea. The techniques used for assessing erosion had no influence on the magnitude of soil erosion and did not interfere with the processes of erosion. There was no significant difference (P < 0·05) between soil erosion determined by the nails and the runoff plot technique. Soil loss determined on six plots (three under maize, three bare‐fallow) by the rill technique, at the end of the season, was significantly lower (P < 0·05) than that determined by the runoff plot technique. The soil loss estimated by the rill method was 143·2, 108·8 and 121·9 Mg ha−1 for 11, 11, and 8 per cent slopes respectively, in comparison with 201·5, 162·0, and 166·4 Mg ha−1 measured by the runoff plot method. Soil loss measured on three bare‐fallow plots on 10 different dates by the rill technique was also significantly lower (P < 0·01) than that measured by the runoff plot. In the first season the USLE significantly underestimated soil loss. On 11, 11, and 8 per cent slopes, respectively, soil loss determined by the USLE was 77, 92, and 63 per cent of that measured by the runoff plot. However, in the second season there was no significant difference between soil loss determined by the USLE and that determined by the conventional runoff plot technique.
Hydrologic parameters of salt marsh peat
Authors: Knott Jayne Fifield , Nuttle William Kensett , Hemond Harold Field
Published: February 2007

Because of their profound influence on water movement and nutrient cycling in salt marshes, the two key physical properties of hydraulic conductivity and compressibility were studied in the Great Sippewissett Marsh and in the Ebben Creek Marsh in Massachusetts. Hydraulic conductivity was the most variable property: most frequently observed conductivities were of the order of 10−3 cm s−1 in both marshes, but extremes ranged from about 10−1 to 10−5 cm s−1. Compressibility was much less variable, and contributed of the order of 10−3 cm−1 to the specific storativity of marsh sediment, making compression a major mechanism for changes in water storage in the sediment. Surface sediments frequently exhibited below‐average conductivity, in contrast to freshwater bog peats which are usually most conductive at the surface. These measured properties may be applied to estimate the importance of many critical processes, such as the extent of infiltration occurring on the marsh surface, the hydrologic influence of the tidally varying creeks, and the hydrologic response to spring‐neap tidal cycles.
The erodibility of some Nigerian soils: A comparison of rainfall simulator results with estimates obtained from the Wischmeier nomogram
Authors: Vanelslande A. , Lal R. , Gabriels D.
Published: February 2007

The erodibility (K) of 55 surface soils, sampled from different regions of Nigeria, was assessed using a rainfall simulator, and compared with estimates (Kc) obtained using the Wischmeier nomogram method (Wischmeier et al., 1971). Soil erodibility values ranged from 0.000 to 0.535. The actual measured erodibility was greater than that estimated, often by several orders of magnitude. In soils with high silt content, however, the estimated Kc was slightly higher than the measured K. The K factor was significantly and negatively correlated with the infiltration rate, organic carbon content, sand fraction, wet density, and percentage stable aggregates. In contrast, the K factor was positively correlated with per cent reduction in infiltration rate, clay, and silt content, and the instability indices proposed by Henin and De Leenheer‐De Boodt. Slaking of aggregates and surface sealing were important factors governing runoff rate and sediment transport. Possible modifications to the nomogram for adaptation to tropical soils are also discussed.
A computer‐based datalogging system used to investigate the infiltration process under natural rainfall conditions
Authors: Essery C. I. , Wilcock D. N. , McClean W.
Published: February 2007

The system described in this paper uses a commercial, portable computer to monitor rainfall, surface runoff, soil moisture potential, soil temperature, and water table levels. The system is designed as a permanent field instrument which reads 16 analogue and two digital channels. It offers 10‐bit accuracy and records data on both magnetic tape and paper for greater security. The computer program is in Microsoft BASIC and can therefore be readily altered to change the measurement regime. Although designed to investigate the infiltration process the system is easily adapted to monitor other environmental processes.
Exceedance probability distributions of steady conduit flow in karst aquifers
Authors: Smart C. C.
Published: February 2007

Discharge 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.
Some aspects of the hydrology of one‐day annual minimum low flows of malawian rivers
Authors: Sefe F. T. K.
Published: February 2007

Five aspects of the hydrology of one‐day annual minimum flows QIM, 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 of QIM(May), can be better estimated from simple regression than from an empirically determined recession constant.
Soil saturation patterns in steep, convergent hill‐slopes under forest and pasture vegetation
Authors: Petch R. A.
Published: February 2007

The 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 topography.
A model of river flow forecasting for a small forested mountain catchment
Authors: Fukushima Yoshihiro
Published: February 2007

A model for quantitatively expressing the hydrological cycle in a forested mountain catchment is proposed as a HYCYMODEL. HYCYMODEL is able to predict both short‐ and long‐term hydrographs because the model parameters remain independent of time. It shows a good applicability for ten years of continuous data at both hourly and daily intervals for the Kiryu catchment—a forested mountain basin. Since HYCYMODEL does not need hydrograph separation between storm flow and base flow, it is a particularly attractive model.
Drainage basin peak discharge rating curve
Authors: Rogers Wilbur F. , Singh Vijay P.
Published: February 2007

The stream gauge rating curve for a drainage basin can be transformed into a drainage basin peak discharge rating curve that is more stable than the rating curve from which it is derived. The resulting drainage basin peak discharge rating curve can be used to predict peak discharge, identify anomalous discharges caused by channel obstructions or other causes, evaluate the effect of flood retarding structures, and evaluate historical records. The drainage basin peak discharge rating curve is valid for drainage basins of any size, for any discharge up to the time of concentration, and for snowmelt.
Stream nitrate levels in a small catchment in south west England over a period of 15 years (1970‐1985)
Authors: Burt T. P. , Arkell B. P. , Trudgill S. T. , Walling D. E.
Published: February 2007

Stream nitrate levels in a small catchment of mixed land use (the Slapton Wood catchment) have been studied since September 1970; a record of this length is possibly unique in the United Kingdom for such a small basin (94 ha). A sustained increase in nitrate concentration has been observed during the study period. In addition to this long‐term trend, short‐term changes in nitrate concentrations relate to stream discharge levels and to seasonal variations. Multivariate statistical analysis has been used to quantify these trends and to identify those factors controlling the production and loss of nitrate from the catchment system. The main period of nitrate removal occurs in winter when high concentrations coincide with the main period of throughflow generation. The influence of climatic variability is illustrated by reference to the 1975/76 drought and post‐drought period.
Field application of a numerical method for the derivation of baseflow recession constant
Authors: Bako M. D. , Owoade Ayodele
Published: February 2007

In an earlier paper (Bako and Hunt, 1988), a method for the derivation of the baseflow recession constant (K) using one‐way analysis of variance was presented. This paper presents the results of the field application of this method. The K values obtained by using the numerical equation of Bako and Hunt (1988) were inserted in the exponential recession equation (Barnes, 1939) to generate a series of baseflows. The fit between the model and the historical flows was found to be greater than 99 per cent thus confirming the applicability of the numerical method under field situation. The main advantage of this technique is its amenability for computerized application thus making it relatively faster than any of the existing techniques of fitting the recession equation. For this reason, the subjectivity inherent in most of the existing techniques is eliminated and a measure of procedural consistency can be guaranteed. Consistency is necessary if intercatchment comparison or interpolation of K values is to be meaningful.
Effect of groundwater interception and irrigation on salinity and piezometric levels of an aquifer
Authors: Ghassemi F. , Thomas G. A. , Jakeman A. J.
Published: February 2007

The major strategy used to prevent the discharge of highly saline groundwater to the River Murray in southeastern Australia is groundwater interception and disposal. The basic design principle assumes that the extraction of groundwater from an aquifer hydraulically connected to the river, using a line of pumps positioned close and roughly parallel to the river, will decrease piezometric heads thereby reducing the discharge of saline groundwater to the river. The paper considers one of these schemes which was designed for the Mildura area on the basis of a hydrogeological investigation. It analyses the effects on piezometric head and groundwater salinity due to the groundwater interception scheme and adjacent irrigation activity over a period of several years from January 1980. It is shown that piezometric heads have decreased significantly in the stretch close to the river. A slight reduction in groundwater salinity is also apparent in this stretch except for an area between the river and a holding basin used for disposal of the saline effluents emanating from the groundwater interception scheme. This general reduction in groundwater salinity is mainly caused by pumping from the groundwater interception scheme and recharge from irrigation. The exception in the trend in groundwater salinity is due to the movement of a highly saline body of groundwater from the holding basin towards the River Murray. Results of this Australian experience should be helpful to the designers of similar salinity mitigation schemes elsewhere.
Measurement and analysis of depression storage on a hillslope
Authors: Sneddon J. , Chapman T. G.
Published: February 2007

A precise photogrammetric technique was used to determine the microtopography of seven 2.6 m × 1.2 m experimental units located on a hillslope. Surface elevations were determined with an accuracy of better than 1 mm, from which contours at 2mm intervals were interpolated. These contour plots were then manually interpreted to define depressions and associated storage volumes. Analysis of the results highlighted the complex variability of depression storage over the hillslope, for example there being little relation between depression storage volumes and unit slope. This study also highlights the sampling problem for the measurement of depression storage on natural surfaces, which appears not to have been formally recognized previously, and also emphasizes the practical difficulty of achieving depression storage estimates with coefficients of variation less than ten per cent to 50 per cent, much of this variability being due to problems of interpretation rather than measurement of the surface.
Calibration and use of pressure transducers in soil hydrology
Authors: Dowd J. F. , Williams A. G.
Published: February 2007

Laboratory and field experiments demonstrated that solid state pressure transducers are accurate and reliable devices for frequent measurements of soil suction. However, each transducer had to be individually calibrated before use and a hanging column procedure designed for this purpose is described. Analysis showed that each transducer had a linear response and that environmental conditions such as temperature had minimal influence. Twenty four tensiometers with pressure transducers were intalled in a forest soil to test their operation and their output was monitored by a data logger. An example of soil suction results measured during four storms is given to demonstrate their stability and their rapid response. The transducers were found to perform accurately and were only affected by temperatures below 0°C.
Water balance approach under extreme arid conditions — A case study of Tabalah Basin, Saudi Arabia
Authors: Abdulrazzak M. J. , Sorman A. U. , Alhames A. S.
Published: February 2007

Quantification of water balance components, under arid conditions, is essential to the development of water management policies. This study demonstrates the application of the mass water balance approach for the assessment of water resources in a typical watershed located in the southwestern region of Saudi Arabia.

The water balance approach was used, on an event basis, to express the amount of precipitation for 13 storms over a three year period, as a percentage of other hydrological components such as runoff, evaporation, and recharge. The study indicated that 63 per cent of precipitation is lost through evaporation from the water surface during flooding, and from the upper layers of the soil surface immediately after storms. Another 32 per cent is stored in the form of soil moisture in the unsaturated layers below the effective evaporation depth. Only 3 per cent of the precipitation was transformed into surface runoff; however, 75 per cent of this contributes towards groundwater recharge.

This study has illustrated that the mass water balance approach can be used, with reasonable accuracy, to quantify the components of the hydrological processes under arid conditions, where a reliable data base is available. This, in turn, will help in the development of appropriate water management policies for arid regions.
Particle size analysis of the sediment suspended in a proglacial stream: Glacier De tsidjiore Nouve, Switzerland
Authors: Fenn C. R. , Gomez B.
Published: February 2007

Hourly, at‐a‐point samples of suspended sediment taken from the outflow stream of Glacier de Tsidjiore Nouve, Switzerland, over a 60 day sampling period (n = 1440) are shown to be dominantly composed of silt‐sized particles. Particle size, SEM, and XRD analyses indicate a subglacial provenance for the suspended sediment. Temporal variations in particle size and sorting correspond poorly to fluctuations in water discharge, being dominated by erratic hour‐to‐hour fluctuations and clockwise hysteresis over diurnal flow events. Examination of grain size and sorting dynamics over snowmelt‐ and icemelt‐related ablation events, during precipitation events, and during glacier drainage events enables some inferences to be drawn regarding sediment source areas and supply regimes. We conclude that although the bulk of the suspended sediment in the proglacial stream of Glacier de Tsidjiore Nouve is derived directly from subglacial sources (with occasional contributions from the valley train during rapid snowmelt and heavy rainfall periods), a portion of the suspended load undergoes intermittent ‘flush‐fall’ transfer through the proglacial zone, which acts as a sediment source during rising flows and as a sink during periods of waning flow.