bluuebunny/crossref_metadata_2025 huggingface dataset:
Rain Distribution in a Mountainous Watershed
Authors: Loukas A. , Quick M.C.
Published: May 2018

The orographic and temporal gradients of rainfall in a mountainous watershed in southwestern British Columbia have been analyzed and streamflow has been estimated using a watershed model. The study watershed is the Jamieson Creek watershed located approximately 30 km north of Vancouver in the Coastal Mountains. The purpose of the study was to determine whether rainfall follows a definable pattern in this mountainous watershed. Regression analysis has been performed for the total rainfall depth per event and hourly intensity for the period 1972-1975. Data is taken from the rainfall season of June to mid-November in order to avoid complications of combined rain and snow events. In this analysis, the rainfall data from a gauge at the lower elevation was used as the set of independent variables and the data from the other four gauges in the watershed as dependent variables. The results showed that the rainfall depth per event increased up to the mid-elevation of the watershed, and then decreased at the upper elevations. On the other hand, the hourly rainfall intensity was found to decrease with increase of elevation in the watershed, so that longer duration of rainfall events occurs at the middle and upper watershed. The regression equations, developed from the analysis of the distribution of the hourly intensity, were used for the prediction of rainfall events of the years 1976-1977. The agreement between the predicted and the observed rain was statistically good. Also, the simulation of the watershed streamflow using the predicted rainfall gave good results. Consequently, because the rainfall follows a definable distribution as a function of elevation, it is possible to use data from one station located at the lower elevation in combination with the developed predictor equations to accurately describe the rainfall over the watershed.
Relocation of Major Ions in Snow along the Tundra-Taiga Ecotone
Authors: Pomeroy J. W. , Marsh P. , Lesack L.
Published: May 2018

The chemistry of seasonal snowcovers north of Inuvik, Northwest Territories, Canada was stratified by biophysical landscape. In this region, deposition of ions in winter occurs largely through the redistribution of wind-blown snow with accumulations in forest-edges and valley sides 8 to 12 times that of the open tundra. While dominated by this snow redistribution, the loading of most ions, except for SO42−, does not scale exactly with that of snow, there being several mechanisms by which ion concentrations become relatively enriched or depleted in various landscape units. Vaporisation during temperature-gradient metamorphism in shallow-snow and uptake during either photochemical reactions or gaseous scavenging to well-exposed snow transformed concentrations of NO3−− by 50%. Dry deposition of aerosols to forested terrain and valley bottoms enriched Cl−, Na+, Mg2+, K+ and Ca2+ concentrations up to more than two-fold, however scavenging of aerosols to blowing snow particles contributed an additional 40% to the sea-salt enrichment and 20% to the Ca2+ enrichment in wind-blown treeline forests. It is concluded that central measurements of snow chemistry in the Arctic cannot be reliably extrapolated without reference to changes caused by over-winter physical and chemical metamorphic processes. Associating the physical/chemical changes with readily identifiable Arctic landscape units suggests a simple and robust method for spatial extrapolation.
Strength Variability of Major River-Ice Types
Authors: Prowse T.D. , Demuth M.N.
Published: May 2018

This paper describes the spatial and temporal variability of strength in a typical river-ice cover during the pre-breakup period affected by radiation decay. Strength was determined using the borehole jack – a field-portable ice indentor system. Two cover types were analyzed: a granular white-ice/freeze-up jam and a columnar black-ice cover. Despite a protracted period of intense radiation, the strength of the highly-reflective ice in the freeze-up jam experienced no measurable change. The low-albedo, highly-transparent columnar cover, however, decreased in strength by approximately 50 % due primarily to the development of inter-granular void space. Changes are related to porosity and a comparison made to previous theoretical and laboratory work. Spatial variations in strength are discussed with respect to break-up advance and ice jamming. Possible control of break-up through modification of freeze-up processes is also presented.
Short- and Long-Term Variability of Snow Albedo
Authors: Winther Jan-Gunnar
Published: May 2018

The progress of snow albedo for the 1991 winter from Helligdagshaugen research site, Norway, is presented. The temporal reduction of albedo decreases as the snow undergoes a process of metamorphosis, as long as the snow depth is large enough to prevent absorption of solar radiation by the underlying terrain. Later, as the snow depth becomes less than about 10 cm and the area of bare patches grows, there is an increase in the temporal rate of reduction in albedo. An accumulated daily maximum temperature index is shown to be a good predictor of both the long-term development of the snow albedo and the daily mean albedo. The actual albedo deviates from the predicted long-term albedo due to variable meteorological conditions of which solar radiation is the most important one. Solar radiation and snow albedo are negatively correlated. Linear regression is performed for a winter period with no melting and for two distinct melting periods. Snow albedo was first determined as a function of temperature index alone. An improved accuracy of 2-6 per cent in estimated snow albedo was obtained when solar radiation was included. Very similar regression coefficients were found for two different periods.
Non-Parametric Statistics on Extreme Rainfall
Authors: Arnbjerg-Nielsen K. , Harremoës P. , Spliid H.
Published: May 2018

This article focuses on rain as input data to problems related to urban storm drainage. The rain data originate from a monitoring program consisting of 56 gauges in Denmark. The gauges have observation periods ranging from 2 to 14 years. The gauges sample rain in a quantity of 0.2 mm with a resolution in time of 1 minute.

Two variables have been investigated: peak intensity and depth. Design values for return periods in the range from 0.1 to 2 years have been estimated for each gauge separately by means of the bootstrap resampling method. The estimation includes expected value, standard deviation and confidence intervals of the design value.

For large return periods the uncertainty of the estimates prevents a distinction by gauge between different statistical populations. However, for small return periods a test shows significant variation between gauges, i.e. the uncertainty of the estimates may not be assumed to be due to sampling variability only.
Cumulative Semivariogram Models of Trace Elements from Springs in Saudi Arabia
Authors: Bazuhair Abdulghaffar S. A. , Şen Zekâi
Published: May 2018

Trace elements are rarely distributed in earth's crust and they are invariably in low concentrations. Due to this low concentration they are not analyzed by conventional hydrochemical methods but by rather special techniques with great care. The trace elements are especially useful in detecting the origin of the groundwater in an area. Their regional distribution helps to obtain significant clues on the groundwater movement and mixture processes. It is proposed, herein to assess the trace element concentration available at far distant points by employing the cumulative semivariogram models. These models furnish further systematic interpretations about trace element areal extends, concentration directions, groundwater movement and its continuity.
Optical Precipitation Gauge
Authors: Lundberg A. , Johansson R.-M.
Published: May 2018

There exists a great need for automatic precipitation gauges for effective road maintenance during the winter period. These gauges should be inexpensive, not require mains supply, need little attendance, give information about presence of precipitation and determine type (snow, rain or sleet) while there is no need for high accuracy of the precipitation intensity. Light attenuation precipitation sensors (optical gauges) fulfil several of these requirements and are used in the Swedish National Road Administration Road Weather System. The optical gauges measure the time it takes for particles of snow etc. to pass (attenuate) a light beam and relate this time to precipitation type and intensity. The rain precipitation mass is approximately proportional to the accumulated attenuation time. To investigate whether or not optical gauges could also be used for solid precipitation, the precipitation mass for snow, rain and sleet was measured with a reference gauge and compared to the attenuation time. The passage time of individual hydrometeorologic particles (snow, rain and sleet) was compared with precipitation type and wind speed. Air temperature could be used as a rough guide to distinguish three precipitation categories for the following temperatures: rain (>+2 °C), sleet (0 to +2 °C) and snow (≤ 0 °C) At low wind speeds (< 3 m/s) the passage time of individual particles could be used to distinguish between rain and snow. The accumulated attenuation time for the same precipitation mass was approximately 25 and 5 times greater for snow and sleet respectively compared to rain. With the attenuation time for the snow-fall corrected for wind influence the quotient between the attenuation time for snow and rain is decreased from approximately 25 to approximately 12 times.
Assessment of Spatial Variability of Major-Ion Concentrations and DEL Oxygen-18 Values in Surface Snow, Upper Fremont Glacier, Wyoming, U.S.A.
Authors: Naftz D. L. , Schuster P. F. , Reddy M. M.
Published: May 2018

One hundred samples were collected from the surface of the Upper Fremont Glacier at equally spaced intervals defined by an 8,100 m2 snow grid to assess the significance of lateral variability in major-ion concentrations and del oxygen-18 values. For the major ions, the largest concentration range within the snow grid was sodium (0.5056 mg/l) and the smallest concentration range was sulfate (0.125 mg/l). Del oxygen-18 values showed a range of 7.45 per mil. Comparison of the observed variability of each chemical constituent to the variability expected by measurement error indicated substantial lateral variability within the surface-snow layer. Results of the nested ANOVA indicate most of the variance for every constituent is in the values grouped at the two smaller geographic scales (between 506 m2 and within 506 m2 sections). Calcium and sodium concentrations and del oxygen-18 values displayed the largest amount of variance at the largest geographic scale (between 2,025 m2 sections) within the grid and ranged from 14 to 26 per cent of the total variance. The variance data from the snow grid were used to develop equations to evaluate the significance of both positive and negative concentration/value peaks of nitrate and del oxygen-18 with depth, in a 160 m ice core. Solving the equations indicates that both the nitrate and del oxygen-18 ice-core profiles have concentration/value trends that exceed the limits expected from lateral variability. Values of del oxygen-18 in the section from 110-150 m below the surface consistently vary outside the expected limits and possibly represents cooler temperatures during the Little Ice Age from about 1810 to 1725 A.D.
Modeling Surface Runoff
Authors: Koivusalo Harri , Karvonen Tuomo
Published: May 2018

The objective of this study was to compare approaches to modeling surface runoff due to summer and autumn storms on a cultivated field. The data consisted of measurements performed every 15 minutes during rainfall-surface runoff events in 1993. A transfer function model was formulated using measured rainfall or rainfall excess as an input and surface runoff as an output. The physical models were based on the kinematic wave approximation of the Saint Venant equations. Surface runoff was assumed to flow first as an overland flow on a level field and second in rills. The results showed that the transfer function model using rainfall excess as an input, and the implicitly solved rill flow model performed the best with respect to the fitness coefficients, which denoted the efficiency of the model. The testing of the models using fixed parameter combinations indicated that an event based parameter estimation was not applicable in verifying the models to changing conditions.
Uncertainty Analysis in Water Quality Modelling
Authors: Høybye Jan A.
Published: May 2018

An important part of regional planning of water resources and quality is efficient design of monitoring systems and proper use of hydrologic models (Beven 1993). In the design of monitoring systems as well as validation of numerical models, based on, for example, the equation of continuity such as hydrologic routing models and mass balance nutrient models, it is essential to estimate the uncertainties of the model-predictions. This paper presents an implementation of a first-order analysis for estimating the error-propagation when introducing mass balance models as to predict nutrient-concentrations. The uncertainty assessment, developed from a first order theory, is implemented in the analysis and modelling of Hjarbaek fjord in Denmark. The project includes hydrological modelling of input of water and nutrients to the fjord from tributaries, and a hydrodynamic estimation of water levels and velocities in the fjord. A two-system water quality box-model is used for estimation of concentrations in water and sediment phases. The system uncertainties are analysed, starting with input data uncertainties and the error propagation to the final concentration estimates, in order to optimise the future monitoring programme, and to control the model results.
A Graphical Method for Storage Coefficient Determination from Quasi-Steady State Flow Data
Authors: Şen Zekâi
Published: May 2018

A simple, approximate but practical graphical method is proposed for estimating the storage coefficient independently from the transmissivity value, provided that quasi-steady state flow data are available from a pumping test. In the past, quasi-steady state flow distance-drawdown data have been used for the determination of transmissivity only. The method is applicable to confined and leaky aquifers. The application of the method has been performed for various aquifer test data available in the groundwater literature. The results are within the practical limits of approximation compared with the unsteady state flow solutions.
Thermal Regime of Ice Covered Swedish Lakes
Authors: Bengtsson Lars , Svensson Thorbjörn
Published: May 2018

Temperature conditions and heat fluxes in ice covered lakes are discussed analyzing measurements in eight Swedish lakes. Heat fluxes from sediments and heat fluxes from water to ice are determined from temperature profiles. The contribution of solar radiation is estimated from heat-budget calculations. It is found that the heat content of most of the lakes changes very little when they are ice covered, but that the lake-water temperature slightly increases. All heat fluxes are small. The heat flux from the sediments is the highest flux in early winter, but is later in the winter balanced by the heat loss from the water to the underside of the ice. Solar radiation is an important heat source in late winter, when the snow cover is thin.
Nutrient Exports from Two Agriculture-Dominated Watersheds in Southern Sweden
Authors: Ulén Barbro
Published: May 2018

Nutrient concentrations and exports were monitored for eight years in two agriculture-dominated watersheds in the central part of the Västgöta Plain in Sweden. The hydrology and the nutrient concentrations in the streams were very similar. Concentrations (monthly flow-weighted) of dissolved phosphate-phosphorus (PO4P) varied substantially during the year (from 0.03 to 0.27 mg 1−1) whereas concentrations of particulate phosphorus (PartP) varied less (from 0.03 to 0.16 mg −1). No trends in nutrient export during the eight years were found after flow-normalization of export data. Three wet periods dominated the long-term loads of the streams. Although a few events dominated annual yields of suspended solids (SS) from drainage pipes, standard deviation of annual mean SS concentration was reasonably constant between different years. However, when further developing phosphorus load models the variation in SS concentration should probably be considered. In-stream processes may contribute nearly as much to the phosphorus export as those occurring on and in arable soils in terms of their impact on the magnitude of phosphorus export. Total nitrogen (TotN) mean concentration was 5 mg 1−1 and was similar in drainage pipes and in the streams.
3D Hydrogeological Modelling with an Expert GIS Interface
Authors: Gumbricht T. , Thunvik R.
Published: May 2018

Geographical Information Systems provide a powerful tool for creating three-dimensional (3D) datasets for sophisticated hydrogeological models. The article describes a GIS with an expert system interface developed for generating 3D hydrogeological frameworks. The system integrates 2D images of elevation and geology and vertical profile data. Application of the expert GIS to a complex aquifer in South Eastern Sweden is described.
Geoelectrical Investigations in a Hard Rock Area Containing Pockets of Saline Groundwater
Authors: Ballukraya P. N.
Published: May 2018

Areas of fresh and brackish groundwaters have been delineated in an area underlain by granulitic rocks using electrical resistivity method. A sharp boundary between fresh and brackish waters has been identified on one side of the area. Sedimentological studies have indicated that the area having brackish to saline groundwaters of chloride-/sulphate type is covered by clays of marine origin. A hydrogeological boundary with limited permeability has been identified, which seems to help the fresh water area from getting contaminated by the saline waters. The study shows that the saline groundwaters may be the result of marine environment that may have existed in the area during the geological past. It is observed that the aquifer resistivity pattern of the area compares well with the electrical conductivity pattern of the groundwater.
Estimation and Scaling of the Near-Saturated Hydraulic Conductivity
Authors: Olsen Per Atle
Published: May 2018

The hydraulic conductivity in structured soils is known to increase drastically when approaching saturation. Tension infiltration allows in situ infiltration of water at predetermined matric potentials, thus allowing exploration of the hydraulic properties near saturation. In this study, the near saturated (ψ≥-0.15 m) hydraulic conductivity was estimated both in the top- and sub-soil of three Norwegian soils. A priory analysis of estimation errors due to measurement uncertainties was conducted. In order to facilitate the comparison between soils and depths, scaling analysis was applied. It was found that the increase in hydraulic conductivity with increasing matric potentials (increasing water content) was steeper in the sub-soil than in the top-soil. The estimated field saturated hydraulic conductivity was compared with laboratory measurements of the saturated hydraulic conductivity. The geometric means of the laboratory measurements was in the same order of magnitude as the field estimates. The variability of the field estimates of the hydraulic conductivity from one of the soils was also assessed. The variability of the field estimates was generally smaller than the laboratory measurements of the saturated hydraulic conductivity.
Photogrammetric Analysis of a Slush Torrent in the Kärkevagge, Northern Sweden
Authors: Scherer Dieter , Groebke Lukas , Parlow Eberhard
Published: May 2018

Slushflows have been investigated in various regions of the Earth for more than forty years. Most of the observed events occurred in mountainous drainage basins at high latitudes, so relatively few observations and measurements are presented in the scientific literature. This particularly holds for slush torrents which are major slushflow events reaching supercritical flow velocities. Thus, information on dynamical features of slush torrents are rather limited, and most results are based on qualitative observations.

On June 3,1995, during a field campaign in the Kärkevagge, a drainage basin in Swedish Lapland, a slush torrent could be observed and documented by a time series of photographs and by video recordings. Quantitative results from a photogrammetric analysis of the photographs show that the first wave front of that slush torrent reached peak velocities of more than 40 ms−1. A second wave front was able to reach even higher velocities due to the fact that the first wave had almost completely removed all snow from the transport path. Consequently, the viscosity of the flow was significantly reduced. To the author's best knowledge, these results are the first quantitative measurements of a slush torrent during its movement.
Spatial Rainfall Pattern Identification by Optimum Interpolation Technique and Application for Turkey
Authors: Şen Zekai , Habib Zeyad
Published: May 2018

The spatial interpolation of hydrometeorological data aims at estimating the value of rainfall at a given site based on the observation at neighboring stations. This is a problem of operational hydrometeorology that is regularly encountered in the spatial estimation procedures. In this paper, an optimum interpolation method is validated for the analysis of monthly rainfall amounts over Turkey. Hence, a two dimensional statistically optimum interpolation scheme is generated for the analysis of monthly rainfall amounts over Turkey. Monthly spatial correlation functions are used for the analysis and modelling of the spatial monthly rainfall variability.
Solute Transport Measurements in Different Soil Types using Time Domain Reflectometry
Authors: Persson Magnus
Published: May 2018

During recent years, time domain reflectometry (TDR) has proved to be a valuable tool for both water content (θ) and bulk electrical conductivity (σa) measurements. To allow resident solute concentration (Cr) measurements, a calibration procedure is necessary for the relationship between σa and Cr. Two main calibration approaches exist. Direct calibration allows for Cr measurements with varying θ, while the indirect calibration method is used for conditions with constant θ. In this paper, three methods of achieving direct calibration parameters are presented and evaluated in three different soil types. Calibrations are made in both disturbed and undisturbed soil columns as well as in the field. It was shown that there were only small differences between calibration methods in homogeneous sand. In other soils, choosing the correct calibration is important. In clay soils solute transport measurements are difficult to take under conditions with varying θ, therefore it is suggested that only the indirect calibration approach should be used. When using TDR it is important to be aware of the accuracy of the TDR system in order to interpret data correctly. Some error sources are thus also briefly discussed.
The Influence of Polluted Water Flows on Hydrological and Hydrochemical Conditions of Purtse Catchment Rivers, NE Estonia
Authors: Rätsep Aavo , Liblik Valdo
Published: May 2018

The correlation between natural (meteorological, hydrological), mining-technological, hydrogeological and geochemical factors in the oil shale mining region in the Purtse catchment area for the period of 1990-1998 was studied. As a result of the interactions between these factors (correlation coefficients r=0.56-0.86), a so-called hydrogeological circulation of water has formed in the catchment area. It was found that the circulation flow forms 25-40% of the total amount of mine water pumped out from the mines at present. On the basis of average data, a new balance scheme of water circulation (cycles) for the Purtse catchment was developed. Under the influence of different water flows a new, anthropogenic biogeochemical matter cycling from the geological environment into the aquatic environment of the rivers has formed in this catchment area. The pollution of the Purtse River from oil shale thermal processing is combined with the harmful impact of oil shale mining. The anthropogenic hydrochemical conditions arising in the rivers of this catchment will not disappear even after oil shale mining stops. A multiple regression formula was derived for prognosticating the flow regime (mean annual discharge) of the Purtse River using meteorological and miningtechnological data.
Estimating Soil Moisture in Small Watersheds, Using a Water Balance Approach
Authors: Rim Chang-Soo , Gay L.W.
Published: May 2018

Soil moisture content was estimated daily by a energy balance and water budget (EBWB) analysis of two small subwatersheds in the Walnut Gulch Experimental Watershed near Tombstone, Arizona. One watershed was 8.1 ha and covered with grass, and the other was 48.6 ha and covered with shrubs. The four-week experiment took place in July and August, during the summer rainy season that dominates the precipitation pattern of southern Arizona.

Mean daily soil moisture (SM, mm) was estimated by a water balance at each watershed, using precipitation (P), runoff (RO) and evapotranspiration (ET). Daily ET estimates were derived from an energy balance on each watershed, using measured net radiation (Qn), soil heat flux (Qg) and sensible heat flux (Qh) to solve for latent energy (QLE, and hence ET) as a residual term. Next, independent estimates of watershed SM were obtained from Time Domain Reflectometry (TDR). The results of simple correlation analyses between the methods showed that the simple correlation coefficients for Lucky Hills and Kendall are 0.764 and 0.791 respectively. The agreement of the two sets of soil moisture measurements confirms that simple water and energy balance measurements can yield appropriate estimates of soil moisture in small watersheds.
Hydroclimatic Variability of Regional Droughts in Greece Using the Palmer Moisture Anomaly Index
Authors: Loukas Athanasios , Vasiliades Lampros , Dalezios Nicolas R.
Published: May 2018

The hydroclimatic variability of droughts at a regional scale in the semiarid climate of Greece was examined in this paper. The moisture anomaly Z-index of the Palmer Drought Severity Index (PDSI) was employed for a quantitative description of droughts by using monthly time series of precipitation and temperature at 28 meteorological stations over Greece for the period 1957-1983. The country was classified into five homogenous regions by using factor analysis and ascending hierarchical clustering technique. The resultant groupings appeared to be in agreement with local topography and climatic classification of Greece. The variability and the change of droughts within each region were assessed using various statistical methods. Linear trend analysis showed that only the increasing trends are statistically significant indicating that, in general, drought severity is decreased during the analyzed period. Application of the third-order trends to the Z-index time series revealed the low frequency fluctuations and application of the Mann-Whitney test showed that there are not any significant shifts or jumps in the Z-index time series. Spectral analysis indicated that, in all regions, statistically significant high frequency cycles of two to seven months dominate, although frequency cycles from 22 to 37 months are also present in all regions, which may be attributed to the quasi-biannual oscillation. Severity and frequency analysis of the monthly Z-index in the five classified regions of Greece indicated that, on average, more than 40% of the months in all stations experienced droughts and their severity increases from the northern to the southern and from the western to the eastern regions of Greece. Analyses of the common consecutive drought periods for all stations within a climatic region indicated that droughts, with duration of one to three months, are extended over the whole region irrespective to region and are the most frequent drought durations for all regions. Finally, the common monthly droughts are, usually, mild and moderate for all regions and only the western and the Peloponnesian regions of Greece experience severe droughts.
End-depth in inverted semicircular channels: experimental and theoretical studies
Authors: Dey Subhasish , Kumar D. Nagesh , Singh D. Ram
Published: May 2018

The flow upstream of a free overfall from smooth inverted semicircular channels is theoretically analysed to compute the end-depth ratio (EDR), applying an energy equation based on the Boussinesq assumption. This approach eliminates the need for an experimentally determined pressure coefficient. Experiments were conducted with horizontal channel conditions. The EDR related to the critical depth, which occurs upstream from the end section, is found to be around 0.695 for a critical depth-diameter ratio up to 0.40. A simple method is presented to estimate the discharge from a known end-depth. The theoretical model corresponds closely with the experimental data.
Estimating latent heat over a melting arctic snow cover
Authors: Semadeni-Davies Annette , Maréchal David , Bruland Oddbjørn , Kodama Yuji , Sand Knut
Published: May 2018

The latent heat flux over snow near Ny-Ålesund, Spitsbergen, was investigated for the 1999 snowmelt season to assess different methods of modelling the flux. Snow evaporation had hitherto been estimated as the residual of plot water balance calculations and was subject to measurement errors: hence a modelling solution was sought to make use of existing data. Precipitation, snow depth and albedo were measured daily. Runoff from the plots was recorded continuously. Wind speed, relative humidity and air temperature were measured at two levels (2 and 10 m) every 10 minutes; wind direction was noted hourly. Three models which simulate latent heat were assessed against evaporation and condensation measured by weighing several snow-filled containers each day. Two employ the bulk profile method (within the SNTHERM and CROCUS snowmelt models), while the third is the aerodynamic profile method (APM). Each follows the measured evaporation until snow-free patches develop after which the APM predicts evaporation whereas the snowmelt models predict condensation. The effect of wind is also noted. A major conclusion of this work is that the complexity of the land surface/atmosphere interactions, particularly when the snow cover breaks up, precludes the use of simple models for determining latent heat.
Hydraulic considerations in restoring boreal streams
Authors: Järvelä Juha , Helmiö Terhi
Published: May 2018

The physical habitat that controls ecosystem functioning is determined by local hydraulics and channel morphology. Hydraulic field studies were conducted in a boreal stream (1) to test the hypothesis that the local hydraulic conditions are determined by cross-sectional geometry and flow resistance in boreal conditions by analysing the relationship between flow velocities, cross-sectional geometry and flow resistance, and (2) to suggest success criteria for the restoration of local hydraulic conditions. Results suggest that, in the case of small channels, cross-sectional geometry and flow resistance are weakly interconnected and influenced by factors such as local roughness elements and channel forms. The study showed that both flow resistance and cross-sectional geometry are vital factors in determining local hydraulics. In stream restoration, a design based on consideration of only one of these two factors is inadequate and may result in a failure to replicate natural hydraulic conditions. Simple success criteria for the restoration of local hydraulics are developed.
Mass balance observations at Mittivakkat Gletscher, Southeast Greenland 1995–2002
Authors: Knudsen Niels Tvis , Hasholt Bent
Published: May 2018

During the period 1995–2002 mass balance observations were made at Mittivakkat Gletscher, Southeast Greenland. The results comprise observations of winter, summer and net balance. The means of measured winter, summer and net balance were 1.25 m, 1.91 m and −0.66 m water, respectively. Mass balance changes are related to meteorological observations at the weather station in the nearby coastal village of Tasiilaq, about 20 km south of the glacier. The results establish a significant linear correlation between accumulation and measured precipitation during the winters 1995/96–2001/02 and a poor relation between summer balance and temperature during the summers 1996–2002. During the period of mass balance measurements the glacier lost about 4% of the ice volume determined in 1994.
Modelling albedo and distributed snowmelt across a low hill in Svalbard
Authors: Essery Richard , Blyth Eleanor , Harding Richard , Lloyd Colin
Published: May 2018

A land-surface model is used to simulate the albedo and mass of patchy snowcovers during radiation-driven melt for three years at a site in Svalbard. Performing single energy and mass balance calculations for the combined snow-covered and snow-free parts of the surface gives a faster decrease in albedo than observed because too much of the solar radiation absorbed by the composite surface is used to melt snow. Representing the snowcover separately allows the model to be calibrated to give a good match to the observed albedo for each of the years studied. A single set of model parameters cannot, however, give a good simulation for all of the years. The average snow mass and snowcover fraction measured on a grid of points can be simulated using either a distributed version of the model or a more efficient tiled version supplied with the observed relationship between snow mass and fractional coverage. Parameters obtained by optimising the snow mass simulations are more consistent from year to year than from the albedo simulations.
The relations between soil water retention characteristics, particle size distributions, bulk densities and calcium carbonate contents for Danish soils
Authors: Jensen Niels Henrik , Balstrøm Thomas , Breuning-Madsen Henrik
Published: May 2018

A database containing about 800 soil profiles located in a 7-km grid covering Denmark has been used to develop a set of regression equations of soil water content at pressure heads −1, −10, −100 and −1500 kPa versus particle size distribution, organic matter, CaCO3 and bulk density. One purpose was to elaborate equations based on soil parameters available in the Danish Soil Classification's texture database of particle size distribution and organic matter. It was also tested to see if inclusion of bulk density or CaCO3 content (in CaCO3-containing samples) as predictors or grouping in surface and subsurface horizons or textural classes improved the regression equations. Compared to existing Danish equations based on much fewer observations the accuracies of the new equations were better. The equations also predicted the soil water content at the measured pressure heads more accurately than the pedotransfer functions developed in HYPRES (Hydraulic Properties of European Soils). Introducing bulk density as a predictor improved the equation for the pressure head of −1 kPa but not for the lower ones. The grouping of data sets in surface and subsurface horizons or in textural classes did not improve the equations. Based on the equations a set of van Genuchten parameters for soil types in the Danish Soil Classification was elaborated. The prediction of soil water content, especially at pressure head −1 kPa, is more accurate using these van Genuchten parameters than using the pedotransfer functions developed in relation to the HYPRES database from a broad range of European soils.
Operational hydrodynamic model for forecasting extreme hydrographic events in the Oder Estuary
Authors: Kowalewska-Kalkowska Halina , Kowalewski Marek
Published: May 2018

A 3D operational hydrodynamic model, developed at the Institute of Oceanography, University of Gdansk, was used to forecast extreme hydrographic events in the Oder Estuary. The model was based on the coastal ocean circulation model known as the Princeton Ocean Model (POM); it was adapted to Baltic conditions and to a 48-h numerical meteorological forecast. Wind-driven water backup in the Oder mouth necessitated working out a simplified operational model of river discharge, based on water budget in a stream channel. The model generates 60-h forecasts of water levels, currents, water temperature and salinity in the estuary. As the model adequately approximates hydrographic variability in the estuary, it can be regarded as a reliable tool for storm surges forecasting and for the assessment of Oder water spread in the Baltic. The forecast is rapidly accessed on its designated website, thereby providing assistance in decision-making by emergency situation centres and bodies that are responsible for navigation safety, port operation and environmental and flood protection of coastal areas. It is intended to fine-tune the model so that a better fit between the observed and computed data is obtained.
Well storage effect isolation and straight-line method applications
Authors: Çimen M.
Published: May 2018

In the case of a significant well storage, the initial period of the drawdown observation is significantly influenced by the well storage. The duration of this period is so far estimated with formulae which use the transmissivity of the aquifer. But this parameter should be determined with the interpretation of the ongoing pumping test. This paper gives an alternative formula, which does not use the aquifer parameters. The formula uses only parameters which can be determined easily during a pumping test. Furthermore, the derived formula is also valid for a large diameter pumping well. In addition, a straight-line equation with well storage effect is given for the estimation of aquifer parameters. This explicitly shows the effect of pumping well storage on observation wells and becomes equivalent to the well-known Cooper and Jacob (CJ) method after large pumping duration. Moreover, simple unique formulae are offered for estimating both transmissivity and storativity parameters at large observation times. The application of the developed methodology is presented for the pumping test data, which are available in the literature.
Storm effects on regional beach water quality along the southern California shoreline
Authors: Noble Rachel T. , Weisberg Stephen B. , Leecaster Molly K. , McGee Charles D. , Dorsey John H. , Vainik Patricia , Orozco-Borbón Victoria
Published: May 2018

Two regional studies conducted during dry weather demonstrated that the Southern California Bight (SCB) shoreline has good water quality, except near areas that drain land-based runoff. Here, we repeat those regional studies 36 h after a rainstorm to assess the influence of runoff under high flow conditions. Two hundred and fifty-four shoreline sites between Santa Barbara, California and Ensenada, Mexico were sampled using a stratified-random sampling design with four strata: sandy beaches, rocky shoreline, shoreline adjacent to urban runoff outlets that flow intermittently, and shoreline adjacent to outlets that flow year-round. Each site was sampled for total coliforms, fecal coliforms (or E. coli), and enterococci. Sixty percent of the shoreline failed water quality standards after the storm compared to only 6% during dry weather. Failure of water quality standards increased to more than 90% for shoreline areas adjacent to urban runoff outlets. During dry weather, most water quality failures occurred for only one of the three bacterial indicators and concentrations were barely above State of California standards; following the storm, most failures were for multiple indicators and exceeded State of California standards by a large margin. The condition of the shoreline in Mexico and the United States was similar following rainfall, which was not the case during dry weather.
Confirmed detection of Cyclospora cayetanesis, Encephalitozoon intestinalis and Cryptosporidium parvum in water used for drinking
Authors: Dowd Scot E. , John David , Eliopolus James , Gerba Charles P. , Naranjo Jaime , Klein Robert , López Beatriz , de Mejía Maricruz , Mendoza Carlos E. , Pepper Ian L.
Published: May 2018

Human enteropathogenic microsporidia (HEM), Cryptosporidium parvum, Cyclospora cayetanesis, and Giardia lamblia are associated with gastrointestinal disease in humans. To date, the mode of transmission and environmental occurrence of HEM (Encephalitozoon intestinalis and Enterocytozoon bieneusi) and Cyclospora cayetanesis have not been fully elucidated due to lack of sensitive and specific environmental screening methods. The present study was undertaken with recently developed methods, to screen various water sources used for public consumption in rural areas around the city of Guatemala. Water concentrates collected in these areas were subjected to community DNA extraction followed by PCR amplification, PCR sequencing and computer database homology comparison (CDHC). All water samples screened in this study had been previously confirmed positive for Giardia spp. by immunofluorescent assay (IFA). Of the 12 water concentrates screened, 6 showed amplification of microsporidial SSU-rDNA and were subsequently confirmed to be Encephalitozoon intestinalis. Five of the samples allowed for amplification of Cyclospora 18S-rDNA; three of these were confirmed to be Cyclospora cayetanesis while two could not be identified because of inadequate sequence information. Thus, this study represents the first confirmed identification of Cyclospora cayetanesis and Encephalitozoon intestinalis in source water used for consumption. The fact that the waters tested may be used for human consumption indicates that these emerging protozoa may be transmitted by ingestion of contaminated water.
Detection, integration and persistence of aeromonads in water distribution pipe biofilms
Authors: Bomo A.-M. , Storey M. V. , Ashbolt N. J.
Published: May 2018

The occurrence of Aeromonas spp. within biofilms formed on stainless steel (SS), unplasticized polyvinyl chloride (uPVC) and glass (GL) substrata was investigated in modified Robbins Devices (MRD) in potable (MRD-p) and recycled (MRD-r) water systems, a Biofilm Reactor™ (BR) and a laboratory-scale pipe loop (PL) receiving simulated recycled wastewater. No aeromonads were isolated from the MRD-p whereas 3–10% of SS and uPVC coupons (mean 3.85 CFU cm−2 and 12.8 CFU cm−2, respectively) were aeromonad-positive in the MRD-r. Aeromonads were isolated from six SS coupons (67%) (mean 63.4 CFU cm−2) and nine uPVC coupons (100%) (mean 6.50×102 CFU cm−2) in the BR™ fed with recycled water and from all coupons (100%) in the simulated recycled water system (PL). Mean numbers of aeromonads on GL and SS coupons were 5.83×102 CFU cm−2 and 8.73×102 CFU cm−2, respectively. No isolate was of known human health significance (i.e. Aeromonas caviae, A. hydrophila or A. veronii), though they were confirmed as Aeromonas spp. by PCR and fluorescence in situ hybridization (FISH). Challenging the PL biofilms with a slug dose of A. hydrophila (ATCC 14715) showed that biofilm in the PL accumulated in the order of 103–104A. hydrophila cm−2, the number of which decreased over time, though could not be explained in terms of conventional 1st order decay kinetics. A sub-population of FISH-positive A. hydrophila became established within the biofilm, thereby demonstrating their ability to incorporate and persist in biofilms formed within distribution pipe systems. A similar observation was not made for culturable aeromonads, though the exact human health significance of this remains unknown. These findings, however, further question the adequacy of culture-based techniques and their often anomalous discrepancy with direct techniques for the enumeration of bacterial pathogens in environmental samples.
Waterfowl and the bacteriological quality of amenity ponds
Authors: Abulreesh H. H. , Paget T. A. , Goulder R.
Published: May 2018

This study investigated the impact of waterfowl on the bacteriological quality of village ponds in East Yorkshire, north-east England. Water and sediment samples were collected from ponds with and without resident ducks and geese; faecal indicator and potentially pathogenic bacteria were assayed by membrane filtration and by selective enrichment. Escherichia coli, faecal streptococci and, to a degree, Clostridium perfringens were more abundant in ponds with waterfowl; Salmonella was isolated in June–August from the sediment of a pond with waterfowl. The results suggested that the bacteriological quality of village ponds might be adversely affected by waterfowl. All water samples from ponds with waterfowl had faecal indicators at higher concentrations than EU requirements for bathing waters. Although these ponds are not bathing waters we suggest skin contact and accidental ingestion of water should be avoided.
Isolation and identification of freshwater bacteria antagonistic to Giardia intestinalis cysts
Authors: Revetta Randy P. , Rodgers Mark R. , Kinkle Brian K.
Published: May 2018

We have isolated three freshwater bacterial strains that demonstrate the ability to degrade Giardia intestinalis cysts. These strains have been identified by 16S rRNA sequencing and phylogenetic analysis as belonging to the Flavobacterium columnare clade of the Cytophaga-Flavobacterium group. While the cyst degradation mechanism is unclear, two different effects on the cysts were observed: non-viability and lysis. Cysts exposed to bacterial strains BR1 and SC1 were generally non-viable, but remained structurally intact. In contrast, cysts exposed to strain SR1 were clearly lysed. Increases in bacterial densities with a concomitant decrease in cyst viability suggest that these bacterial strains are capable of using the cysts to enhance their growth. We propose that the presence of bacterial strains such as SR1, BR1 and SC1 may play a role in reducing the viability of G. intestinalis cysts in natural waters.
Recreational water quality in the Caspian Sea
Authors: Pond Katherine R. , Cronin Aidan A. , Pedley Steve
Published: May 2018

Health-based monitoring of the Caspian Sea in Turkmenistan and Iran suggests that bathers are intermittently subject to increased levels of faecal pollution which may lead to gastrointestinal illness. This is the first co-ordinated monitoring programme of recreational waters in the Caspian region and highlights the need to extend such a programme to all countries bordering the Caspian Sea. The novel approach of monitoring that combines risk assessment (water quality monitoring plus a sanitary survey) and risk management, as applied here, allows the identification of possible sources of pollution and the levels of microbiological risk that bathers are subject to. Hence, this allows suitable management interventions to be identified and implemented in the long term.