bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibitory effects of different medicinal plants on Candida albicans growth
Authors: TAMBUR ZORAN , MILOŠEVIĆ DESANKA CENIĆ , MILEUSNIĆ IVAN , DODER RADOJE , MARJANOVIĆ MARJAN , SELIMOVIĆ BILJANA MILJKOVIĆ , KULIŠIĆ ZORAN , OPAČIĆ DOLORES
Published: May 2018

The objective of this study was to evaluate the in vitro antifungal properties of ethanol extracts and essential oils of medicinal plants from Serbia against Candida albicans (C. albicans) ATCC 10231. Ethanol extracts of fifteen plants were investigated, and their effects were compared with those of three different essential oils. The sensitivity of C. albicans to all plants was tested by the agar dilution method. The assay plates were estimated to contain 300, 150, 75, and 37.5 µg/ml of active extracts and 100, 50, 25, and 12.5 µg/ml of active essential oils. Inocula were applied to agar surfaces, giving approximately 106 cfu/ml of C. albicans. No inhibitory effects were observed for ethanol extracts of Hypericum perforatum and Salvia officinalis (MIC > 300 µg/ml). The most effective were the ethanol extract of Aesculus hippocastanum (MIC = 37.5 µg/ml) and the essential oil of Satureja kitaibelii (MIC = 12.5 µg/ml). Other plants showed MIC from 25 to 300 µg/ml. As far as we know, the inhibitory effects of these medicinal plants against the reference strain of C. albicans have not been commonly investigated in our country. Although the essential oil of Satureja kitaibelii shows strong activity against C. albicans, these results need clinical evaluation..
Introducing Hydroinformatics
Authors: Abbott Michael B.
Published: May 2018

Hydroinformatics is the name of a new way of applying knowledge as this knowledge is utilised in the worlds of the waters. This new way of applying knowledge, which is developing generally within our present-day societies, is concerned with ways to access and employ electronically encapsulated information, which itself becomes knowledge just to the extent that it is genuinely accessed and authentically employed. The knowledge of how to apply knowledge in the new way is thus itself a certain kind of ‘metaknowledge’.
Data-based mechanistic modelling and forecasting of hydrological systems
Authors: Lees Matthew J.
Published: May 2018

The paper presents a data-driven approach to the modelling and forecasting of hydrological systems based on nonlinear time-series analysis. Time varying parameters are estimated using a combined Kalman filter and fixed-interval-smoother, and state-dependent parameter relations are identified leading to nonlinear extensions to common time-series models such as the autoregressive exogenous (ARX) and general transfer function (TF). This nonlinear time-series technique is used as part of a data-based mechanistic modelling methodology where models are objectively identified from the data, but are only accepted as a reasonable representation of the system if they have a valid mechanistic interpretation. To this end it is shown that the TF model can represent a general linear storage model that subsumes many common hydrological flow forecasting models, and that the rainfall-runoff process can be represented using a nonlinear input transformation in combination with a TF model. One advantage of the forecasting models produced is that the Kalman filter can be used for real-time state updating leading to improved forecasts and an estimate of associated forecast uncertainty. Rainfall-runoff and flood routing case studies are included to demonstrate the power of the modelling and forecasting methods. One important conclusion is that optimal system identification techniques are required to objectively identify parallel flow pathways.
A hydroinformatician's approach to computational innovation and the design of genetic algorithms
Authors: Goldberg David E.
Published: May 2018

The paper discusses how a computational hydralician got involved in the design, implementation, and application of genetic algorithms – search procedures based on the mechanics of natural selection and genetics – and how that involvement depended critically upon the modern hydroinformatician’s sense of appropriate modeling of complex phenomena such as fluid mechanics. The paper starts by briefly reviewing the mechanics of genetic algorithms and then connects that mechanics to the fundamental intuition that GAs have something in common with human innovative processes. The paper continues with a short aside on a difference in the way hydroinformaticians and computer scientists are taught to reason with models. This leads to a discussion of the race between selection and recombination in a GA, and how understanding the race leads immediately to the construction of a critical dimensionless quantity in GA analysis. This dimensionless quantity is then sketched in the GA’s control map, and the paper concludes with a brief discussion of how such knowledge leads to the design of competent GAs – GAs that solve hard problems, quickly, reliably, and accurately. The paper concludes with an invitation to hydroinformaticians to both use genetic algorithms in the solution of difficult hydroinformatics problems and to apply their analytical skill to the design of ever more capable genetic and evolutionary algorithms.
Numerical conformal mapping and mesh generation for polygonal and multiply-connected regions
Authors: Lin B. , Chandler-Wilde S. N.
Published: May 2018

Details are given of a boundary-fitted mesh generation method for use in modelling free surface flow and water quality. A numerical method has been developed for generating conformal meshes for curvilinear polygonal and multiply-connected regions. The method is based on the Cauchy-Riemann conditions for the analytic function and is able to map a curvilinear polygonal region directly onto a regular polygonal region, with horizontal and vertical sides. A set of equations have been derived for determining the lengths of these sides and the least-squares method has been used in solving the equations. Several numerical examples are presented to illustrate the method.
The democratisation of decision-making processes in the water sector I
Authors: Abbott Michael B.
Published: May 2018

The paper introduces an inversion of the structure of the decision making process in the water sector that has been so far followed in most countries, and in almost all so-called ‘third world’ societies. It is commonly observed that the general population becomes alienated and effectively disempowered through this existing ‘top-down’ knowledge transmission process. The disenfranchisement of large parts of the general population and the grievous harm done to these parts through their resulting disempowerment has led to an outcry against the water professionals, who are seen at the very least as accomplices, and often as initiators in ‘crimes against humanity’. Empowering the population as a whole as genuine stakeholders in water resources then becomes the basic objective of water professionals in introducing an alternative paradigm, as exemplified in the second part of this paper (this issue, pp. 35–48) by the design of a new system capable of supporting ‘knowledge-intensive’ agricultural practices. What is being proposed here thus corresponds to an inversion of the so-far established order of knowledge/power in that it corresponds to an inversion in power relations that is realised by an inversion in knowledge relations. The system proposed here by way of an example is then primarily a means of realising this inversion. The economic sustainability of such a system within a ‘third world’ context necessitates the consideration also of knowledge/value relations, and these are also briefly introduced. The system itself is essentially a knowledge self-management system, comprising three principal components:a knowledge centre connecting to (other) knowledge providers;an inner knowledge periphery that receives, processes and transmits knowledge passing between the centre and;an outer knowledge periphery situated primarily at the end-user level.The use of ‘scientific discourse’ at the centre and of ‘narrative discourse’ at the outer periphery sets the overall specification of the inner periphery.
Fuzzy mapping of momentum fluxes in complex shear flows with limited data
Authors: Hankin B. G. , Kettle H. , Beven K. J.
Published: May 2018

This study is divided into three parts centred around modelling the complex turbulent fluxes across strong shear layers, such as exist between the channel and floodplain flow in an over bank flood flow. The three stages utilize Adaptive Neuro-Fuzzy Inference Systems (ANFIS) to make fuzzy mappings between the fluxes and different data types. The de-fuzzification stage commonly used in Fuzzy Inference Systems is adapted to avoid the generation of crisp outputs, a process which tends to hide the underlying uncertainty implicit in the fuzzy relationship.

Each stage of the study utilizes conditioning data that makes the fuzzy mappings more tenuously linked with what would normally be considered physically based relationships. The need to make such mappings in distributed models of complex systems, such as flood models, stems from the sparsity of available distributed information (e.g. roughness) with which to condition the models. If patterns in distributed observables which clearly affect, or are affected by, the river hydraulics can be linked to the local fluxes, then the conditioning of the model would improve. Mappings such as these often suffer from scaling effects, an issue addressed here through training the fuzzy rules on the basis of both laboratory and field collected data.
Fuzzy rule-based model for contaminant transport in a natural river channel
Authors: Kettle Helen , Hankin Barry , Beven Keith
Published: May 2018

Fuzzy rules are used to model solute dispersion in a river dead zone, such that the turbulent diffusion is determined by a fuzzy inference system which relates the local mean velocity shear to the longitudinal velocity fluctuations. A finite-volume hybrid scheme is applied to a non-orthogonal grid for which a mean velocity field is produced using the computational fluid dynamics (CFD) package Telemac 2D. At each cell face fuzzy rules predict a fuzzy number, and these numbers reflect the possible magnitudes of turbulent velocity fluctuations. These are input to the finite-volume model using a single-value simulation method. Multiple model runs produce a fuzzy number for the solute concentration in each cell. The results of the fuzzy model are then compared with data collected in a field experiment with rhodamine dye in the River Severn.
An optimization approach to wastewater systems planning at regional level
Authors: Sousa Joaquim , Ribeiro Alexandra , da Conceição Cunha Maria , Antunes António
Published: May 2018

A regional wastewater system planning problem consists of finding the minimum-cost configuration for the system needed to drain the wastewater produced at the communities located within a region, while meeting the quality standards defined for the receiving water bodies and complying with all (other) relevant regulatory aspects. There are several possible solutions to this kind of problem. They range from solutions where each community treats its wastewater separately, to solutions where all the wastewater produced in the region is sent to a single treatment plant. It is likely that the most effective solution both in terms of public expenditure, equipment reliability, and environmental impact will be found somewhere between these two extremes. This paper presents an optimization approach to wastewater systems planning at regional level. The approach applies only to sanitary sewer networks. A simulated annealing algorithm is used to solve the optimization model upon which the approach is based. For the application of this approach a user-friendly computing tool was developed. Within this tool, both the acquisition of data and the output of results are made through a flexible GIS interface.
Pollution of underground water—a computational case study using a transport model
Authors: Balla Katalin , Kéri Gerzson , Rapcsák Tamás
Published: May 2018

Damage of the waterproofing system in a waste material depository or sewage sludge composting plant and the penetration of pollutants into the soil and groundwater may cause an environmental mishap. Although the standard waterproofing technologies are extremely safe, one cannot disregard possible malfunctions. For a well-established plan of managing unexpected events, the impact of such damage must be forecast. With the help of models described in the relevant literature, we propose the basic ideas used in simulations for two planned regional waste material depositories, a planned sewage sludge composting plant and an active aluminium dross depository of a foundry.
Managing water quality in a New York City watershed
Authors: Hermans Leon M. , Beroggi Giampiero E. G. , Loucks Daniel P.
Published: May 2018

Currently economic growth in a New York City watershed is limited due to phosphorus concentrations exceeding standards. The phosphorus concentration in the Cannonsville reservoir in New York State must be reduced to safeguard New York City's drinking water supply, and to enable economic growth to continue in the reservoir's watershed. In Delaware County, where the reservoir is located, the problem of finding and selecting promising measures to reduce phosphorus loads is extremely complex and involves numerous stakeholders. A two-level modeling approach based on Visual-Interactive Decision Modeling (VIDEMO) was used to analyse the problem, using game theory and optimization. The analysis resulted in practical guidelines for land use management, taking into consideration the possible strategies by other parties and stakeholders.
Estimation of the impact of short-term fluctuations in inputs on temporally aggregated outputs of process-oriented models
Authors: Forsman Å. , Andersson C. , Grimvall A. , Hoffmann M.
Published: May 2018

Process-oriented models driven by highly resolved meteorological inputs and comprising a short internal time step are sometimes used to predict substance fluxes in air, soil and water over fairly long periods of time. To ascertain whether regression-based input–output analyses in such cases can provide adequate parametric models of the impact of daily and monthly fluctuations in inputs on annual outputs, we studied the SOIL/SOILN model of vertical transport of heat, water and nitrogen through arable soils. Annual leaching of nitrate from the root zone was regarded as the response variable, and regressors were selected from among the set of all linear combinations of daily or monthly values of five different meteorological inputs. We found that, although several of the underlying processes described by the SOIL/SOILN model are non-linear, both ordinary and partial least squares regression (OLS and PLS) identified the subsets of input variables with the strongest influence on the model output, and the dominating time lags between model inputs and outputs. Furthermore, highly resolved explanatory variables were a prerequisite for good performance of linear predictors of temporally aggregated outputs and, to discern the full dynamic behaviour of the model, it was necessary to analyse the response to artificially generated daily meteorological data representing a very large number of different weather conditions. PLS had one advantage over OLS: a smooth pattern in the regression coefficients facilitated physical interpretation of the derived impulse–response weights.
EC-SVM approach for real-time hydrologic forecasting
Authors: Yu Xinying , Liong Shie-Yui , Babovic Vladan
Published: May 2018

This study demonstrates a combined application of chaos theory and support vector machine (SVM) in the analysis of chaotic time series with a very large sample data record. A large data record is often required and causes computational difficulty. The decomposition method is used in this study to circumvent this difficulty. The various parameters inherent in chaos technique and SVM are optimised, with the assistance of an evolutionary algorithm, to yield the minimal prediction error. The performance of the proposed scheme, EC-SVM, is demonstrated on two daily runoff time series: Tryggevælde catchment, Denmark and the Mississippi River at Vicksburg. The prediction accuracy of the proposed scheme is compared with that of the conventional approach and the recently introduced inverse approach. This comparison shows that EC-SVM yields a significantly lower normalised RMSE value of 0.347 for the Tryggevælde catchment runoff and 0.0385 for the Mississippi River flow compared to 0.444 and 0.2064, respectively, resulting from the conventional approach. A slight improvement in accuracy was obtained by analysing the first difference or the daily flow difference time series. It should be noted, however, that the computational speed in analysing the daily flow difference time series is significantly much faster than that of the daily flow time series.
Simulating development strategies for water supply systems
Authors: Tillman D. E. , Larsen T. A. , Pahl-Wostl C. , Gujer W.
Published: May 2018

The objective of this paper is to point out existing risks of current design and management strategies in water supply systems and to identify possible ways of designing and operating schemes which minimize these risks. This paper is motivated by the observation that existing design principles and engineering rules (best practice) seem to cope insufficiently or even conflict with current trends of declining water demand. In order to evaluate this situation, an agent-based model comprising the current rules of best practice was developed in a participatory process. Once the model was validated with data sets from a real utility, multiple-scenario testing was used to explore different design strategies, thus allowing ideas for developing alternative management and design schemes to be generated. The simulations show that the traditional risk of insufficient supply security must be supplemented by considering the opposite risk of excessive security (over-capacity). The introduction of demand-side measures may help to calibrate existing best practice with the trends of the current operating environment. Ideas are brought forward on how to shape incentive systems for stakeholders in order to facilitate such a shift.
Chaos in rainfall: variability, temporal scale and zeros
Authors: Sivakumar B.
Published: May 2018

A recent study on rainfall observed at the Leaf River basin reports that the presence of a large number of zeros in the data significantly underestimates the correlation dimension. The present study attempts to verify such a claim, by making predictions and comparing the results with the correlation dimensions. A nonlinear prediction method, which uses the concept of reconstruction of a single-variable series in a multi-dimensional phase space to represent the underlying dynamics, is employed. Correlation dimension analysis of only the non-zero rainfall series is also carried out for further verification. Rainfall data of four different temporal resolutions (or scales), i.e. daily, 2-day, 4-day and 8-day, are analyzed. The predictions for the finer-resolution (i.e. higher-resolution) rainfall are found to be better than those obtained for the coarser-resolution (i.e. lower-resolution) rainfall and seem to be consistent with the variability vs. predictability logic in a deterministic sense, i.e. higher prediction accuracy for data with lower correlation dimension and vice versa. An important implication of this result is that the presence of (a large number of) zeros in the rainfall data may not always result in an underestimation of the correlation dimension. The correlation dimensions estimated for the non-zero rainfall series are not significantly different when compared to those obtained for series including zero values, supporting the above. These results suggest that the low correlation dimensions for rainfall (in particular finer-resolution ones that commonly have a large number of zeros), as reported by past studies, could well be, or at least closer to, the actual dimensions of the rainfall processes studied.
AIRCRAFT GAMMA-RAY SURVEY OF SNOW COVER
Authors: DMITRIEV A. V. , KOGAN R. M. , NIKIFOROV M. B. , FRIDMAN Sh. D.
Published: May 2018

The physical basis for and the various methods of measuring the water equivalent of the snow cover by means of gamma-rays survey from aircraft are discussed.

Problems of mapping the water equivalent over large areas are also discussed.
THREE-DIMENSIONAL STABILITY ANALYSIS OF OPEN CHANNEL FLOW OVER AN ERODIBLE BED
Authors: ENGELUND FRANK , FREDSØE JØRGEN
Published: May 2018

The formation of ripples and dunes (lower range bed waves) is assumed to be related to the transport of sediment as bed load. From the present theory it is concluded that the formation of the upper range bed configurations (standing waves, antidunes) may be explained on the assumption that the predominant part of the sediment transport is in suspension. The paper presents a mathematical model of the formation of double-periodic antidunes, first-order potential flow theory being applied. It differs from previous models in taking account of the non-uniform distribution of the suspended load. The theory predicts regions of stability and instability. Results are compared with measurements made by different observers.
THE STOCHASTIC APPROACH TO WATERSHED MODELING
Authors: DeCoursey Donn G.
Published: May 2018

The stochastic approach to watershed modeling refers to the techniques used to generate synthetic hydrologic data. These data may be used either for input to a parametric watershed model or to provide directly an estimate of the output of a hydrologic process. In both cases the basic techniques of the generation processes are the same. The type of process depends primarily on the purpose for which the data are being generated and on the quality and quantity of sample data.

Techniques are presented which can be used to generate data for one or any number of variates. The data generated can be normal, skewed, or log normal, and include serial correlation. If two or more variates are involved, cross correlation may also be considered.

Brief discussions concerning missing data, statistical tests, random number generation, and interpretation of results are presented along with a review of the generation schemes that have been used in the stochastic generation of hydrologic data.
GEOHYDROLOGIC WELL-LOGGING
Authors: HOUTKAMP H. , JACKS G.
Published: May 2018

Well-logs have been used to gain geohydrologic information mainly in Precambrian rocks. The logs used are the self-potential, the diameter, the temperature, and the electric conductivity of water. Applications have given general information on the occurrence of ground water in hard rocks. The logging technique seems to be of particular value in connection with underground constructions in rock when detailed local information is necessary in order to avoid ground water leakage even in minor quantities.
EVALUATION OF PUMPING TESTS IN PARTIALLY PENETRATING WELLS
Authors: MUCHA IGOR
Published: May 2018

Pumping tests in wells that partially penetrate aquifers have been evaluated by means of type curves and a simplified solution of nonsteady flow. The influence of skin effect on pumping tests in the partially penetrating wells and the application of the method to unconfined aquifers are discussed.
FILLING IN GAPS IN RAINFALL RECORDS BY SIMULATED DATA
Authors: SAMUELSSON B.
Published: May 2018

The concept of the rainfall coincidence rate is introduced and is used as a tool for correcting the errors in the rainfall records which are due to shifts. A method of simulating missing rainfall data without smoothing out the rainfall distribution pattern is presented. Dates are allocated to the generated raindays according to a procedure which takes into account the coincidence rate as well as the occurrence of rainfall over groups of consecutive days.
THE MEANDERING OF ALLUVIAL RIVERS
Authors: HÅKANSON LARS
Published: May 2018

To explain the formation of meanders, the author has synthesized relevant knowledge and utilized basic physical principles of flowing turbulent water and its interaction with the river bed.

Starting from an initially straight and smooth channel, one can argue that the most probable site of the first erosional scar will be lateral from the centre of the river. This scar will then develop into a cavity, which in turn will affect the streamline situation of the flow. In front of the cavity the streamlines will converge, and behind it they will diverge. The diverging streamlines, together with unaffected or less affected streamlines, will then create a new convergence zone behind the first cavity but on the opposite side of the river's centre line. The ultimate and most probable and stable result will be a meander.
INSULATION AGAINST ICE AT MEASURING WEIRS
Authors: TVEIT JOHN
Published: May 2018

This article deals with the problem of insulating measuring weirs to avoid ice disturbances.

The development of a simple method for insulating a conventional V-weir is described. This method will serve its purpose in many cases. For more difficult cases a special type of a fully insulated weir is described. The experiments described were carried out by The Division of Hydraulic Engineering, The University of Trondheim, The Norwegian Institute of Technology, at the River and Harbour Laboratory of the University, and at the IHD representative basin Sagelva.
COMPARISON OF MEAN RAIN CATCH OF VARIOUS GAUGE NETWORKS
Authors: SEVRUK BORIS
Published: May 2018

After the substitution of stereo for horizontal orifices of rain gauges on open steep slopes, the mean network catch in a subbasin with prevailing windward exposure was increased by 11%. In a subbasin with leeward exposure it was increased by only 4%. The mean network catch of ground level stereo gauges corrected for wetting losses was about 17% greater than that of elevated gauges with horizontal orifices. There was little difference between the mean network catch of ground level stereo gauges in the two subbasins. The isohyetal map from the data of these gauges was less complicated than the map drawn from the data of elevated gauges with horizontal orifices in the same subbasin.
RAINFALL INTERCEPTION IN A FOREST IN THE VELEN HYDROLOGICAL REPRESENTATIVE BASIN
Authors: BRINGFELT BJÖRN , HÅRSMAR PER-OLOF
Published: May 2018

In the summer and autumn of 1973, 25 rain troughs were operating below canopy and four in clearings of a predominantly coniferous forest in the Velen hydrological research area. The collected rain water amounts were measured 14 times (about once a week). Using these data and the records from a tipping-bucket rain gauge in a simple model for throughfall, it was found that the overall water storage capacity of the forest canopy was about 2 mm and that the free throughfall coefficient p was about 0.5. Results from 50 photographs taken upward from the troughs indicate a smaller p-value. The time for evaporation of the intercepted water after an average rain storm is roughly estimated as 5 h. About 26 % of the total rainfall was intercepted and evaporated.
ACTUAL EVAPOTRANSPIRATION IN RELATION TO LEAF AREA
Authors: KRISTENSEN K. J.
Published: May 2018

The ratio of leaf area to ground area required for maintaining potential evaporation has been studied in a 4-year investigation, and the influence of leaf area index on the water use and the actual water balance is discussed.
TRANSPORT OF SUSPENDED SOLIDS ALONG THE VISTULA RIVER
Authors: BRAŃSKI JAN
Published: May 2018

A short description is given of a method for preparing a balance of transported solids along the Vistula river on the basis of many years' monitoring and observations of transportation of suspended solids. This method is based on direct monitoring of the transported solids and denudation indices determined for non-observed areas of the river basin. The Vistula balance is shown in tables and on a graph. The individual sections of the Vistula river bed are also characterized from the viewpoint of its stability. Finally, it is pointed out that working out the balance in this way permits general evaluation of the denudation processes in the river basin, and the mean denudation index of the Vistula river basin is calculated with regard to the volume of solids sedimented in water reservoirs.
WATER USE IMPLICATIONS FOR NUCLEAR POWER STATIONS IN THE UNITED STATES OF AMERICA
Authors: HALASI-KUN GEORGE J.
Published: May 2018

The problems in selecting reactor sites are discussed in terms of population density, coolant water demand, thermal pollution and engineered safeguard measures during construction and operation.
ECONOMIC OPTIMUM RECORD LENGTH
Authors: JACOBI SVEN
Published: May 2018

Uncertainty in hydrologic design parameters is reflected as an increase in expected project costs. The Bayesian or statistical decision approach produces a minimum-cost decision for a specific design, yielding the expected opportunity loss, EOL, a measure of the uncertainty inherent in the decision process. The uncertainty stems from the fact that the population value of the design parameters is unknown. Additional information can be obtained by collecting more data, and the value of these data is measured by the decrease in EOL. But there are costs involved in getting additional data: the cost of continued data collection and the cost of delaying the construction of the project (benefits foregone). The expected economic optimum record length is defined at the point where the marginal benefits of additional data are equal to the marginal costs of obtaining those data. The theory is applied to sediment load data used to design the sediment storage portion of a reservoir. Based on an economic efficiency criterion, the expected optimum record length is found to be 12 years, given that 5 years of data are available at the time of the analysis. Objectives like environmental quality and social benefits are disregarded in this analysis.
WEATHERING AND HYDROGEOLOGY OF THE BRUMUNDDAL SANDSTONE, SOUTHERN NORWAY
Authors: ENGLUND J. O. , JØRGENSEN P.
Published: May 2018

During the last decades several wells giving yields up to 100,000 1/h have been drilled in the reddish Brumunddal Sandstone, which covers an area of approximately 10 km2 near lake Mjøsa, Southern Norway.

Most of these wells have yields below 10,000 1/h, and those with higher yields are situated along prominent fracture zones. Textural data strongly support the assumption of an eolian origin for this sandstone, but water-deposited sediments are found within the formation.

Most of the grains are coated with a hematite pigment, which was probably epigenetically formed. Post-sedimentary but preglacial weathering processes have transformed plagioclase to montmorillonite. This has changed the porosity as well as the permeability and increased the cationic exchange capacity. A transformation of plagioclase is in agreement with the groundwater composition.
THE RATE OF SPREAD OF FUEL OIL NO. 1
Authors: SELLBERG BJÖRN
Published: May 2018

Experiments have been made in the field to determine the way in which fuel oil No. 1 spreads in some common unconsolidated deposits in Sweden, such as esker material, bottom varves of glacial clay and sand on clay. In the investigations, the velocity of fuel No. 1 in reasonably homogeneous medium sand with a good ground water flow was found to be 1.0–1.6 m/day, but usually the velocity was as low as 0.1–0.2 m/day. Experiments covering a longer period showed that the maximum concentration diminished very much in transport up to a distance of about 20 m.
THE DEVELOPMENT OF A SNOW ROUTINE FOR THE HBV-2 MODEL
Authors: BERGSTRÖM STEN
Published: May 2018

The development of a snow routine for the HBV-2 rainfall-runoff model is described. Experiences from field investigation that have contributed to the work are briefly discussed.

In the snow routine, snow accumulation and snowmelt are simulated using daily totals of precipitation and mean daily temperatures. The application of the model to a 2178 km2 forested basin in central Sweden is shown. A critical study of the interaction and effects of the parameters is carried out.
NORTHERN RESEARCH BASINS
Authors: FORSMAN ARNE
Published: May 2018

Following recommendations of a preliminary meeting in Calgary, Canada, in February 1974 between representatives of the IHD Committees of Canada, USA and Sweden, and discussions at the Unesco House in Paris, France, in September 1974 between representatives of the IHD Committees of Canada, USA, Finland, Norway and Sweden, a Workshop Symposium on Northern Research Basins - Objectives and Measurements was organized at Edefors, Sweden, 7–11 April 1975.

The meeting was convened jointly by the Swedish IHD Committee and the Swedish Meteorological and Hydrological Institute and organized by the Swedish Meteorological and Hydrological Institute. It was held close to the Lapptrasket Research Basin.

Participation in the workshop was arranged through the National IHD Committees of the participating countries: Canada, USA, Norway, Finland, the Soviet Union and Sweden.
Nitrogen Movement and Leaching in Soil
Authors: Jensen H. E.
Published: May 2018

Movement and leaching of residual nitrogen in soil has been studied in some details in a lysimeter experiment. Profile measurements of soil water and of nitrogen concentration in addition to measurements of amount and composition of the drainage water were carried out.

The leaching process could be described by an equation of Day. For a flow rate of approximately 1 cm/day, a dispersion coefficient of 11.5 cm2/day was obtained independent of the concentration level. Using this value, the equation satisfactorily predicted concentration of nitrogen and leached amount of nitrogen in the drainage water. The equation, although the assumptions inherent in the theory are not completely fulfilled, may therefore be used for predictive purposes under field conditions.

An excess of precipitation, approximately equal to field capacity, is predicted necessary for leaching 50 per cent of an amount of dissolved nitrogen initially localized at the surface of the soil. Consequently, under many soil/climate conditions, the composition of drainage water is influenced by agricultural practices from previous years, which makes difficult interpretation of the results. This has been illustrated by relating some available data on drainage water quality from field experiments to the concentration of nitrogen in the soil water, as predicted by the theory.
Reservoir Mechanism
Authors: Eliasson Jonas , Kjaran Snorri Pall
Published: May 2018

The physical problem dealt with in this article is the unsteady groundwater flow in an isotropic, nonhomogenous aquifer of limited horizontal extent and arbitrary boundary shape.

The unsteady ground-water level is described by a differential equation which is solved by the Galerkin finite element method, combined with orthogonal eigenfunctions. Unlike many numerical procedures the physical properties of the aquifer are not lost. Boundary conditions are provided by nature in the form of watertight rocks, rivers, lakes or any kind of constant water level in hydraulic contact with the aquifer, or given boundary inflow or outflow.
Economic Value of Low Flow Data
Authors: Refsgaard Jens Chr , Hansen Eggert
Published: May 2018

By means of the Bayesian decision approach the economic value of low flow data is considered with special reference to the design of treatment plants for typical Danish conditions. For a specific case the worth of primary data in form of direct observations of low streamflows has been investigated in terms of an expected opportunity loss (EOL). Indirect information concerning the low flow properties of interest may be obtained by means of a secondary data set in combination with a regression model. In this study is suggested a heuristic method for the economic evalution of a secondary set of data taking into account the uncertainty embedded in the regression model.
The Use of Environmental Isotope Techniques together with Conventional Methods in Regional Groundwater Studies
Authors: Sigbjarnarson Guttormur , Theodorsson Pall , Arnason Bragi
Published: May 2018

Regional hydrological investigations of the subsurface drainage in the neovolcanic area around lake Thorisvatn on the central Icelandic plateau have been carried out as well as geological exploration. Environmental isotopes, deuterium and tritium, proved decisive in finding the groundwater flow pattern and in separating the different groundwater systems and explaining local deviations as barriers and perched aquifers. The regional groundwater flow is only slightly dependent on the. topography but highly on the geological conditions, as it virtually flows under mountain ranges as well as under the river Tungnaa.
The Variability of the Net Radiation Ratio
Authors: Mc Cuen Richard H. , Asmussen Loris E.
Published: May 2018

Prediction equations for estimating evaporation from bodies of water, often require values of net radiation. Solar radiation data are usually more accurate and more readily available than measurements of net radiation. Measured solar radiation and the mean ratio of net radiation to solar radiation have been used to estimate the net radiation levels required to predict evaporation rates. However, although the average net radiation ratio is relatively stable from year to year the effect of daily variation in the net radiation ratio on evaporation estimates has not been investigated. An empirical energy balance and measurements of pan evaporation and meteorological factors are used to examine the effect of the average daily variation on evaporation rates computed with the mean net radiation ratio. The results indicate that the average daily variation from the mean net radiation ratio may produce an error of approximately 13 per cent in an estimate of daily evaporation when the mean net radiation ratio is used. However, daily variability in the net radiation ratio has little influence on the regeneration of a large number of evaporation estimates. Estimated values of the net radiation ratio and its variability are compared with observed values from polar climates.
Multivariate Distributions in Hydrology and River Regulation
Authors: Kartvelishvili N.A. , Gottschalk L.T.
Published: May 2018

It is assumed that the river runoff process can be approximated by a Markov process. The process is thus described by M distribution functions:

Fn (qt, t ; qt-1; t-1;…;qt-n, t-n), t ≡ 1, 2, …, M where M is the number of time intervals within the year, n - the order of the Markov process and qt, in general, is a vector representing runoff at several sites in a river or neighbouring rivers.

Fundamental hypothesis of relations between multivariate distributions and corresponding marginal distributions is given.

A finite difference scheme for multisite and multilag generation of river runoff is derived. The derivation is based on the multivariate normal distribution.

Different methods for determination of the order of the finite difference scheme are discussed as well as the influence of model order and method of parameter estimation on properties of the model.
Transjøen, a Groundwater Influenced Lake with Special Redox and Sulphate Conditions
Authors: Bremmeng G. S. , Kloster A. E.
Published: May 2018

Transjøen, a lake in S.E. Norway investigated hydrographically from October 1969 to October 1971, consists of two basins, both of which are meromictic (lake with lower layer which does not participate in the periodic circulations). The lake has a large influx of groundwater of very varying chemical composition. The calcium content is high and precipitated calcium carbonate and electrolyte rich groundwater is assumed to be the main reason for the meromictic stability. The redox potentials of monimolimnion (the lower layer which does not participtate in the periodic circulation) are extremely low, but in spite of this fact the content of sulphate is high.
The Ionic Composition of Lakes Fed by Ground Water and Precipitation in the Upper Romerike District
Authors: Hongve Dag
Published: May 2018

In the Upper Romerike District the lakes possess widely different chemical characteristics depending on their hydrological conditions. The most dilute lakes are fed only by precipitation, and the more concentrated ones by ground water. In the precipitation fed lakes the total ionic concentration was similar to that of the average precipitation, but the ionic ratio was different. Ionic sorption and exchange affected mostly calcium which decreased in concentration while the monovalent ions increased. The ground water fed lakes were dominated by bicarbonate, and their ionic proportions were constant regardless of total concentrations. The percentage composition was: Ca: 82%, Mg: 10.1%, Na: 6.5%, K: 1.4%, HCO3: 78.3%, S04: 17.1%, Cl: 4.6%.
Management of Urban Runoff and Wastewater in the Oslofjord Area
Authors: Balmér Peter , Glomnes Jørn , Lindholm Oddvar , Saltveit Nils A.
Published: May 2018

To alleviate the pollution in the Oslofjord region it is planned to transport wastewater to a central treatment plant by a 35 km tunnel system. The objective of the study was to analyze the consequences of a reduced treatment plant capacity vs. the utilization of the tunnel as a retention basin. The analysis was performed by the use of a recently developed mathematical model for urban runoff and drainage. Simulations were performed for large rain events and for all rains during a summer season. The most important result of the study was that the treatment plant could be reduced to half its original capacity if the tunnel was utilized as a retention basin without any increase, in fact a decrease, in the total pollution load on the fjord.
The Physics of Long Term Drawdowns in Pumping from Artesian Aquifers
Authors: Kærgaard Henrik
Published: May 2018

The applicability of the Theis-formula (1935) and the Jacob-Hantush leakage-formula (1946 and 1956) as tools for the description of water-level variations due to pumping from artesian aquifers, is shown to be rather limited, especially in long term pumping situations. The limitations are discussed and illustrated through a review of some mathematical models with more reliable and physical realistic preconditions, and a general perception of the physics governing the drawdowns in pumping from leaky artesian aquifers is hereby established. Data from 10 years of heavy pumping from a leaky artesian multi-aquifer at Egebjerg near Horsens, Denmark, are analysed, and the result turns out to be in good agreement with the theoretical discussion.
Upper Layer Observations and Simulation Using Kraus and Turner's Model in the Gulf of Finland
Authors: Tyrväinen Marjatta
Published: May 2018

There are strong seasonal variations in the depth of the thermocline and in the sea surface temperature in the western part of the Gulf of Finland. A numerical model, developed by Kraus and Turner, was used to calculate the depth of the thermocline and the temperature of the mixed layer from June to October in 1969 and 1974. Observed daily mean values of total incoming radiation, air temperature, wind velocity, air humidity and cloudiness were used as input data from which the thermal energy balance on the sea surface was calculated. The model is sensitive to the drag coefficient of the wind and to the absorption coefficient of the solar radiation for which the values cD =0.8.10−3 and ß=0.25 m−1 were used in this work. For the mixed layer temperature the results of the model are 2-4° C too small. The depth of the thermocline can be predicted with an accuracy of ±5 meters.
Application of a Snowmelt-Runoff Model Using Landsat Data
Authors: Rango A. , Martinec J.
Published: May 2018

The snowmelt-runoff model developed by Martinec (1975) has been used to simulate daily streamflow on the 228 km2 Din woody Creek basin in Wyoming, U.S.A. using snowcover extent from Landsat and conventionally measured temperature and precipitation. For the six-month snowmelt seasons of 1976 and 1974 the simulated seasonal runoff volumes were within 5 and 1%, respectively, of the measured runoff. Also the daily fluctuations of discharge were simulated to a high degree by the model. Thus far the limiting basin size for applying the model has not been reached, and improvements can be expected if the hydrometeorological data can be obtained from a station inside the basin. Landsat provides an efficient way to obtain the critical snowcover input parameter required by the model.
Deterioration in the Water Quality of Groundwater in Some Municipal Water Extraction Plants in Finland
Authors: Lahermo Pertti , Parviainen Jouko
Published: May 2018

In this study the changes in the quality of groundwater are described on the basis of material collected at some groundwater extraction plants situated mainly in urban areas. The causes of the marked increase in the content of dissolved solids are evaluated from the 1960s onwards.
A Comparison of Rainfall-Runoff Models
Authors: Weeks W.D. , Hebbert R. H. B.
Published: May 2018

Five different rainfall - runoff models including three sophisticated conceptual models (Sacramento, Stanford and Monash Models), a simple conceptual model (Boughton Model) and a black-box or purely mathematical method involving a recursive time series alogirithm were tested on three catchments in the south-west region of Western Australia. A variety of techniques were used to assess the performance of each of the models which were calibrated on about six years of data and then tested on a further six or seven years of extra data. As well as the objective comparison of the models, a subjective assessment of the user and computation aspects of model calibration is presented. All of the models except the Boughton Model performed in a satisfactory manner with the Sacramento Model and Time Series Method being given overall recommendation.
Limitations in Hydrological Interpretations of the Snow Coverage
Authors: Martinec J.
Published: May 2018

Patterns of the disappearing seasonal snow cover are similar year after year. This could lead to the assumption that a certain areal extent of snow indicates always a corresponding volume of snow or of water stored in a given basin. Such possibility of seasonal runoff forecasts had to be dismissed in an alpine basin. Within a few years, the stored water volume and the subsequent runoff varied in the ratio of 1: 2 for a snow coverage always within the range of 40 to 45%. The areal extent of the snow cover seems to be linked rather with the ratio of the current water equivalent to its maximum value of the respective year.
Spatial Simulation of Snow Processes
Authors: Thomsen Anton G.
Published: May 2018

A spatially distributed model for the simulation of snow accumulation and melt is presented. Watershed information on topography, vegetation and soils in digital terrain models (overlays) serve as the data base for watershed analysis, classification of snow in Landsat imagery and automatic generation of parameter decks for operating distributed simulation models of snowcover dynamics and streamflow generation. Snow processes are simulated within variable size grid-cell elements. The hydrograph resulting from spring snowmelt is simulated by a lateral flow model of streamflow generation driven by simulated snowmelt and rain inputs. Options are avilable for simulating the effects of forest management alternatives on selected areas. Snow course measurements and classified Landsat imagery are used for updating simulated parameters.