bluuebunny/crossref_metadata_2025 huggingface dataset:
Systemic knowledge management in hydraulic systems: I. A postulate on paradigm shifts as a methodological tool
Authors: Khatibi Rahman H.
Published: May 2018

Unravelling transparency among the various disciplines of science in the context of their evolving processes is a methodological problem and the focus of a series of two papers presented here. This first paper presents the concept of the paradigm as a generic problem-solving tool for creating transparency by postulating that a paradigm, after its formation, shifts through proliferating, norming and performing stages. Each stage is associated with generic features. A common conception of the paradigm is synonymous with frameworks in science and technology; this concept is revisited in this paper and is presented as a generic problem-solving framework. The paper argues that science selects and intertwines many paradigms and a paradigm is a particular form of evolution in action. In its pre-paradigm period there is randomness among the rudimentary components with no sense of direction. In its forming and proliferating stages, a paradigm is composed of workable components with a one-way flow of information subject to the law of natural selection. In the norming and performing stages, a conscious process of consolidation takes place among the components with emerging hierarchies and with influences on the orientation of the paradigm but without full determination of the overall direction. In this way, a picture emerges where science has generic foresight, the formation of which can be influenced but not be fixed. This paper substantiates this postulate through the paradigm of science and institutionalisation and the following paper substantiates it through hydraulic systems.
Quasi-three-dimensional numerical model for flow through flexible, rigid, submerged and non-submerged vegetation
Authors: Erduran K. S. , Kutija V.
Published: May 2018

The effects of the resistance caused by vegetation on flow velocity and water depth has become a major interest for ecologists and those who deal with river restoration projects. Some numerical and experimental works have been performed to analyse and formulate the drag effects induced by vegetation. Here we introduce a quasi-three-dimensional (Q3D) numerical solution, which is constructed by coupling the finite volume solution of the two-dimensional shallow water equations with a finite difference solution of Navier–Stokes equations for vertical velocity distribution. The drag forces are included in both sets of equations. Turbulence shear stresses are computed in two alternative ways: the parabolic eddy viscosity approach with a correction term introduced in this study, and a combination of the eddy viscosity and mixing length theories in the vertical direction. In order to deal with flexible vegetation, a cantilever beam theory is used to compute the deflection of the vegetation. The model COMSIM (complex flow simulations) has been developed and applied in experimental cases. The results are shown to be satisfactory.
Vision statement on open architecture for hydraulic modelling software tools
Authors: Khatibi Rahman , Jackson Dave , Curtin John , Whitlow Chris , Verwey Adri , Samuels Paul
Published: May 2018

This paper identifies the philosophy of open architecture as a feasible vision capable of transforming modelling software packages into living products. This vision, invoked within the specific context of software production in the field of flood forecasting within the Environment Agency, promotes the emerging requirements and consensus of users, academics and software producers. In the past, the philosophy of closed architecture dominated the use, development resources and investment in modelling systems by producers and users. As closed architecture encourages the development of monolithic software products with limited scope for innovation by third parties, investments often do not return the value of their full potential. A consensus is emerging that this is no longer tenable. The time is right: for the producers of hydraulic and hydrologic software tools to move from the culture of ‘doing things better’ to ‘doing things better and doing better things’; for users to design their own systems through assembling off-the-shelf software products; and for academics to have a less restrictive environment in which to innovate. The consensus view is rendered viable in a partnering culture undoing many barriers and restructuring many concepts. The paper postulates that software development is a paradigm and shifts through the forming, proliferating, norming and performing stages. This postulate is substantiated by citing evidence for the following associations:The forming stage is associated with the development of early computer programs.The proliferating stage is associated with closed architecture.The norming stage is associated with open architecture to create interoperability.The performing stage is associated with open source to freely share and improve source codes.
Vulnerability based management of water resources systems
Authors: Kanakoudis V. K.
Published: May 2018

Must the water networks be fail-proof or must they remain safe during a failure? What must water system managers try to achieve? The present paper introduces a methodology for the hierarchical analysis (in time and space) of the preventive maintenance policy of water supply networks, using water supply system performance indices. This is being accomplished through a technical–economic analysis that takes into account all kinds of costs referring to the repair or replacement of trouble-causing parts of the water supply network. The optimal preventive maintenance schedule suggested by the methodology is compared with the empirically based maintenance policy applied to the Athens water supply system.
Bayesian-based pipe failure model
Authors: Watson T. G. , Christian C. D. , Mason A. J. , Smith M. H. , Meyer R.
Published: May 2018

The efficient long term management of large-scale public funded assets is an area of growing importance. Ageing infrastructure, growth and limited capital all result in the need for a more robust and rigorous methodology to prioritise rehabilitation and renewal decisions and, as importantly, to forecast future expenditure requirements. The overall objective of this research is to develop a Bayesian-based decision support system that will facilitate the identification of efficient asset management policies. The Bayesian approach enables us to formally incorporate, express and update our uncertainty when determining such policies. This is particularly relevant for water utilities that have incomplete or unreliable historical failure data sets and, as a consequence, rely heavily on past engineering experience.

An object oriented discrete event simulation has been developed to analyse existing maintenance policies, test the Bayesian methodology and to develop and identify improved maintenance policies. This paper focuses on the areas of research relating to the long term management of water distribution systems and, in particular, will present: (1) an overview of the Bayesian approach, (2) development and initial results for an object oriented discrete event simulation and (3) proposed future research and development.
Fuzzy set based error measure for hydrologic model evaluation
Authors: Teegavarapu Ramesh , Elshorbagy Amin
Published: May 2018

Traditional error measures (e.g. mean squared error, mean relative error) are often used in the field of water resources to evaluate the performance of models developed for modeling various hydrological processes. However, these measures may not always provide a comprehensive assessment of the performance of the model intended for a specific application. A new error measure is proposed and developed in this paper to fill the gap left by existing traditional error measures for performance evaluation. The measure quantifies the error that corresponds to the hydrologic condition and model application under consideration and also facilitates selection of the best model whenever multiple models are available for that application. Fuzzy set theory is used to model the modeler's perceptions of predictive accuracy in specific applications. The development of the error measure is primarily intended for use with models that provide hydrologic time series predictions. Hypothetical and real-life examples are used to illustrate and evaluate this measure. Results indicate that use of this measure is rational and meaningful in the selection process of an appropriate model from a set of competing models.
User influences on knowledge structuring on the Internet: literature survey and case study of a global network of water professionals
Authors: Butcher Juliette , Jeffrey Paul , Stuetz Richard
Published: May 2018

This paper presents a review of the literature on information retrieval and knowledge structuring on the Internet and how end-user factors influence these processes. The review demonstrated that variations in users' professional and educational backgrounds are likely to have an important influence on Internet-based knowledge acquisition and structuring. A good knowledge of users is therefore necessary for the successful design of an on-line information service, particularly for multidisciplinary domains such as the water sector which cover a wide range of subject disciplines, and scientific, technological and industrial domains. The implications of the variety of individuals involved in the water sector for structuring information/knowledge on the Internet is demonstrated by analysing the International Water Association's membership database as a function of several variables, including title, job function, organisation type, nationality and fields of interest. The database revealed a wide range of cultural and professional backgrounds, as well as diverse interests between different organisations. As well as having a good understanding of their backgrounds and interests, analysis of how the different users' use the Internet, for example, by looking at web server log files, is recommended for the successful design of web based information/knowledge sharing structures for the water sector.
THE PARAMETRIC APPROACH TO WATERSHED MODELING
Authors: SNYDER WILLARD M.
Published: May 2018

The parametric approach to watershed modeling is shown to lie between the stochastic and deterministic approaches. Essentially, the parametric approach attempts to find functional relationships between numerically defined hydrologic and physical characteristics of a drainage area.

Successful parametric modeling requires progression through sequential stages of data processing, model formulation, optimization of parameters, examination of results, association of characteristics, and conversion to prediction procedures. Selected examples of the various stages are discussed.
RELATIONSHIP BETWEEN STREAM WATER TEMPERATURE AND AMBIENT AIR TEMPERATURE
Authors: CLUIS DANIEL A.
Published: May 2018

The water temperature of streams and rivers is required for various practical purposes and is frequently obtained by calculating the heat budget. This method is tedious and yields rather inaccurate values of the water temperature. This paper presents an alternative approach using cheap and simple means to measure air temperatures, which are believed to be a major factor controlling the water temperature. It is demonstrated that a useful separation can be made between the seasonal cyclic variations and the daily stochastic fluctuations of these temperatures.
GROUND WATER INVESTIGATION IN GNEISSIAN ROCK, SYSTEMATIC STUDY OF A SMALL AREA
Authors: LARSSON I. , LUNDGREN T. , GUSTAFSSON Y.
Published: May 2018

Careful investigations should precede drillings in hard rocks for drinking water. A description is given of a method for groundwater prospecting in hard rocks which integrates studies of petrography, tectonics, and groundwater chemistry with well-logging of well diameter, self-potential, electric conductivity, and groundwater temperature.
STATISTICAL INTERPRETATION OF HYDROMETEOROLOGICAL EXTREME VALUES
Authors: SAMUELSSON B.
Published: May 2018

The application of Jenkinson's method to extremal distributions for low probability annual extremes of rainfall and stream flow is studied and discussed.

A statistical method devised by Jenkinson has been examined and compared with other methods of fitting extreme value distributions to observed data. The Jenkinson method, being strictly objective, has the particular advantage of taking into account the extreme part of the extreme value distribution. The author shows, by applying the Jenkinson method to extreme values which significantly belong to several different kinds of frequency distributions, that this method could be applied as a standard one. Finally, the author indicates the possibility of using the Jenkinson method to extrapolate statistical characteristics from a series of statistically unstable short-term data.
FACTORS AFFECTING LONGITUDINAL WATER TEMPERATURE DISTRIBUTION DOWNSTEAM FROM A POWER STATION
Authors: AMATO CHARLES G.
Published: May 2018

The magnitude of reject heat, the distances to which sensible heat effects may be experienced in a river and alternate means of rejecting heat are discussed.
FITTING A THREE-PARAMETER LOG-NORMAL DISTRIBUTION BY LEAST SQUARES
Authors: SNYDER WILLARD M. , WALLACE JAMES R.
Published: May 2018

A three-parameter log-normal distribution is derived as an exact functional transform of an embedded normal distribution. The parameters of this function are evaluated by fitting to histograms of natural hydrologic data. The practice of transformation of data is made unnecessary and can be eliminated. Tolerance limits of extreme hydrologic events can be calculated as transforms of the exact tolerance limits of the embedded normal, permitting precise probabilistic statements on such statistics as T-year floods or droughts.
SYNTHESIS OF BASIN RESPONSE WITH INADEQUATE DATA
Authors: RAGHAVENDRAN R. , JAYARAMI REDDY P.
Published: May 2018

The present study is focussed on the problem of developing a basin response function with inadequate data. The case of a catchment with some measurements of output and with input data either totally absent or unemployable is specifically taken for the analysis. The method proposed by Delaine (1970) and demonstrated by him for an experimental drainage area of around 50 acres has been suitably extended to natural catchments from 25 mi.2 to 750 mi.2. It is shown that the synthesis is subjected to uncertainties and errors when the method is applied to larger catchments, though reasonably good results are obtained for smaller catchments. The authors suggest an alternate method applicable for all sizes of catchments assuming linearity and time invariance and that the parameters of the model are correlated with the catchment characteristics.
Snowmelt Estimated from Energy Budget Studies
Authors: Bengtsson Lars
Published: May 2018

The snowmelt at a point is estimated through a simplified energy budget. From the energy equation a degree-day method is derived. The rate of snowmelt is found as a constant multiplied by the temperature excess over an equilibrium temperature which depends on solar radiation.

The snowmelt events in Kiruna (3 years) and Luleå (4 years) are analysed utilizing energy balance computations and the degree-day method. First observed and calculated day when the ground was free of snow is for all seven years in good agreement. The rate of snowmelt calculated by the proposed degree-day method is almost identical to the rate found from energy balance computations. Snowmelt rates estimated by a simple degree-day method using a constant equilibrium temperature are too fast in the beginning and too slow at the end of the melting season.
A Decade's Investigation of the Stability of Erodible Stream Beds
Authors: Reynolds A. J.
Published: May 2018

This paper reviews work on the stability of a particulate stream bed to the erosive attack of a flow with a free surface. Attention is given to the development of the hydraulic, the potential-flow and the rotational-flow models, and to the roles of phase lags and transport laws. The relationship of the stability theory to the ultimate form of the stream bed is discussed, and the current level of understanding of bed features is examined. Some investigations relating to a wider range of erosive processes are noted, and an extensive bibliography is provided.
Estimating the Water and Salt Budgets of a Stratified Estuary
Authors: Virta J.
Published: May 2018

Small tidal range, low salinity, moderate temperature and salinity stratification during summer which becomes weaker during winter, abundant fresh water inflow and connection through a shallow sill with the adjacent sea are the characteristic features of some estuaries along the coast of the Baltic Sea. In this study the flow and transport of salt in the upper and lower layers of the outlet of an estuary of this type were determined. First the magnitude of the terms of the transport equations was estimated using the analogy between the transport of salt and heat. Then the important terms of the transport equation were computed with a model which is based on the measured slope of the water level and on the water budget of the estuary. Testing was carried out by comparing the measured and computed salt contents of the estuary. The operation of the model on Pohjanpitäjänlahti bay in southern Finland was found to be satisfactory.
Estimation of Parameters of a Uniformly Nonlinear Surface Runoff Model
Authors: Singh Vijay P.
Published: May 2018

The surface runoff model, based on the concept of uniform nonlinearity (Dooge 1967), has three parameters. It is shown that these parameters can be estimated from the informaion that can be easily obtained from a topographic map of the watershed. By applying the model to natural agricultural watersheds the reliability of estimating parameters in the proposed manner is reexamined.
Mixing Processes in Lakes
Authors: Ottesen Hansen Niels-Erik
Published: May 2018

A review of the available methods for analyzing turbulent mixing in lakes is presented. The different types of flow are classified and their turbulence characteristics described. The diffusion caused by turbulence is examined with the conclusion that no reliable analytical description is available for the moment, so for technical purposes field surveys are recommended. Entrainment processes in stratified lakes are analyzed by considering the turbulent energy exchange, and analytical expressions for common types of flow are presented. Finally windrows, their origin and their effect on the mixing are described.
Contents of Some Heavy Metals in Norwegian Rivers
Authors: Lenvik K. , Steinnes E. , Pappas A.C.
Published: May 2018

Concentration data for the elements arsenic, cadmium, cobalt, molybdenum, zinc, and uranium in eleven Norwegian rivers, determined by neutron activation analysis, are presented. The mean values of the various rivers show the following range for the elements studied (μg/1): As, <0.02-1.05. Cd, <0.06-0.43. Co, 0.09-0.46. Mo, <0.10-1.62, Zn, <2-53. U, 0.041-0.58. The weighted mean values in this work are similar to the estimated world averages for rivers in the case of Co and Zn. For As, Mo, and U, the present values are lower than the world averages by a factor of 3 or more. This may be due to lower abundance of sedimentary rocks and deposits in Norway compared with the drainage basins of some of the major rivers in the world.
Dynamics of an Ice Covered Lake with Through-Flow
Authors: Stigebrandt Anders
Published: May 2018

The dynamics of different regimes in an ice covered inland lake with through-flow are discussed. A new theory for selective withdrawal is tested with success. The mixing of the entering river with lake water is estimated and it is found that the net volume flux increases with about 60% through the mixing. The flow in the main part of the lake is discussed and some measurements are presented.
Accuracy of Point Precipitation Measurements
Authors: Allerup Peter , Madsen Henning
Published: May 2018

The normal-exposed Hellmann raingauge only catches about 85% of the true precipitation on yearly basis. This is mainly due to aerodynamic effects. A statistical model analysing the ratio of the daily amounts of precipitation measured at ground level and at standard height is set up for describing this influence. Corrections due to liquid and solid precipitation and three different kind of exposures are presented. Further the statistical errors on the corrections are estimated.
Analysis of the Rainfall-Runoff Transformation Process
Authors: Afouda Abel A.
Published: May 2018

Considerable effort has been expended on the theoretical aspects of the applicability of the unsteady flow equations to natural overland flow. The major difficulty when these equations are used to simulate watershed flow lies in estimating the friction factor for natural situation. In this paper a generalized friction factor is introduced and a kinematic relationship which describes the »kinematic state« of the watershed surface is proposed. The resulting equations for unsteady free surface flow is a kinematic wave approximation. These equations are solved analytically and the solution obtained in the form of integral series.
Evaporation from a Snow Cover
Authors: Bengtsson Lars
Published: May 2018

Possible evaporation rates from a snow surface with respect to available energy and vapour pressure deficit in the air are discussed. In literature reported measurements and measurements carried out at the University of Luleå are analysed. It is found that for northern areas the total amount of evaporation during the whole snow covered season amounts only to 10–20 mm.

Different formulas for estimating the evaporation from a snow surface are discussed. It is stressed that for forecasting purposes the aerodynamic formula and the profile method should be used only together with energy balance computations. The air density stratification reduces the evaporation rate considerably. A formula for the reduced evaporation rate is suggested. Finally, evaporation is analysed as a transient process, and possibilities of developing more soundly based evaporation models are discussed.
On the Values and Variability of Degree-Day Melting Factor in Finland
Authors: Kuusisto Esko
Published: May 2018

About 96,000 snow depth and 17,000 snow density measurements were used to study the most widely used variable in snowmelt forecasting, the degree-day factor. This data was collected on 12 stake stations each with 25 stakes in forest and 9 on open field during 1959 to 1978. The seasonal averages of degree-day factor are studied; they vary rather widely from station to station. The average for all forest sites is 2.42 mm°dC−1d−1 and for all open sites 3.51 mm°C−1d−1. A 10 per cent increase of canopy cover in forest decreases the degree-day factor on the average by 0.16 mm°C−1d−1. On rainy pentades the degree-day factor is larger especially in forest sites. Finally, the seasonal course of the degree-day factor and its dependance on snow density are discussed.
Seasonal Fluctuations of Physical and Chemical Parameters of a Weir Basin in a Regulated West Norwegian River
Authors: Baekken T. , Fjellheim A. , Larsen R.
Published: May 2018

Both before (1967-69) and after (1976-78) the regulation of the river Ekso in western Norway, physical and chemical analyses were made of the river water. After the regulation water samples for chemical analyses were taken at the inlet and outlet of a weir basin 375 m long which had recently been built to maintain the previous water level.

The reduced water discharges and the increased water temperatures which followed the regulation presumably increased the amount and the quality of food available to detritusfeeding animals.

The O2 content of the water was slightly reduced after the regulation. The pH was in the same range. Specific conductance (H20) and the concentrations of major ions before the regulation (Ca2+, Cl− NO3−-N, PO43−-P) and after the regulation (Ca2+, Mg2+, Cl−, SO42−, N03−-N. NH4+-N, PO43−-P) were also in the same range, but a distinct seasonal variation appeared after the regulation.

These variations were thought to have three main reasons: 1) water discharge, 2) biological production, 3) nonspecified physicochemical relationships.

Ionic fluxes through the weir basin were highest during the autumn. Only small differences were found between the inlet and outlet of the weir basin.

Regression analyses based on the concentrations of major ions and water discharge after the regulation were made separatly for the summer and the winter season. H20 and SO42−-concentrations were not correlated to water discharge, Cl−-concentrations were positively correlated, whereas Ca2+ showed a negative correlation. Mg2+ and NO3−-N were not correlated to water discharge during the summer season, but showed a significant negative correlation during the winter.
Diverging Overland Flow
Authors: Singh V. P. , Agiralioglu N.
Published: May 2018

The diverging overland flow model is utilized to predict surface runoff from several natural watersheds. The Lax – Wendroff scheme is used to obtain numerical solutions. This scheme is explicit, single step and second order. An analytical criterion is developed to determine time step for computation for a specified grid length in space. This criterion ensures numerical stability and convengence. The diverging geometry is specified from watershed topography. Thus the model contains one parameter which is optimized for each watershed by the Rosenbrock – Palmer optimization algorithm. The model results compare satisfactorily with runoff observations.
Is Evaporation an Important Component in High Alpine Hydrology?
Authors: Lang Herbert
Published: May 2018

The knowledge of evaporation in the high mountain areas of the European Alps is still rather poor. It is generally regarded as a component of secondary importance in the water balance. The available mean areal evaporation data are based on conventional water balance estimations and suffer from inaccuracies in the determination of precipitation. This is also obvious from the rate of decrease in mean annual evaporation with altitude indicated by different authors; these values range from 71 mm to 356 mm pro 1,000 m of altitude. From heat balance studies on glaciers it is evident that evaporation/condensation as a process of high specific energy exchange can be a determinative factor in the shortterm variations of melt rates. The scale width of the daily latent heat fluxes reaches at magnitudes equal to or larger than those of net radiation and sensible heat flux.
Accuracy of Snowmelt Runoff Simulation
Authors: Rango A. , Martinec J.
Published: May 2018

Results of runoff simulations from various basins using a snowmelt runoff model were analyzed in order to predict the accuracy of simulations in future applications of the model. It was found that the model can be applied to nearly any mountainous basin where snowmelt runoff is an important factor if input data on temperature, precipitation, and snow cover are available. The simulation accuracy will depend on the quality of the input data as well as on the density of observations, size of the basin, care in determination of the recession coefficient, and amount of precipitation during snowmelt. Most accurate simulations will result when: 1) temperature and precipitation are recorded at the basin mean elevation; 2) snow cover observations are available once per week; 3) several climatic stations are available for large basins; and 4) a few years of runoff records exist for determination of the recession coefficient. Decreases in simulation accuracy will be expected as these optimum conditions are compromised, however, acceptable simulations will result with the following minimum conditions: 1) temperature and precipitation data are available in the general vicinity of the basin; and 2) snow cover observations are available 2-3 times during the snowmelt season. The availability of satellite observations of snow cover extent has permitted successful application of the model to large basins.
The Importance of Refreezing on the Diurnal Snowmelt Cycle with Application to a Northern Swedish Catchment
Authors: Bengtsson Lars
Published: May 2018

A method for including night-time refreezing of the top layer of a snowpack in the degree-day method for computing daily snowmelt rates is presented. It is found that during days of large diurnal temperature variations the daily melt is more determined by the day-time conditions than by the daily mean conditions. Applications are made to an open area and a forested area. The refreezing-degree-day method is found to describe the snowmelt process very well, whereas the simple degree-day method shows a too fast snowmelt rate.
Diurnal Variations in Electrical Conductivity of Water in a Small Stream
Authors: Calles Ulla Maria
Published: May 2018

Diurnal fluctuations in electrical conductivity of water have been observed in a small stream draining a basin 12 km2 in size. An attempt to explain the cause of these variations is presented. The two influencing factors studied are evapotranspiration and earth tide effects.
Drainage Basins on Vatnajökull Mapped by Radio Echo Soundings
Authors: Björnsson Helgi
Published: May 2018

Maps are presented for the glacier surface and the bedrock of two areas on Vatnajökull - Tungnárjökull and Sylgjujökull in the western ice cap and Eyjabakkajökull in the northeast. The ice surface maps are obtained by precision barometric altimeter. They form the basis for delimitation of ice drainage basins. The bedrock maps are the results of radio echo soundings. Both maps are used for defining the water drainage basin which is estimated 121 km2 for the river Tungná, 85 km2 for the rivers from Sylgjujökull and 117 km2 for the rivers from Eyjabakkajökull.
Diurnal Fluctuations of Stage and Discharge in the Danish River Suså
Authors: Erup Jørgen
Published: May 2018

Distinct and regular diurnal fluctuations of stage and discharge have been observed in the river Suså during dry summer periods. Examples of the fluctuations are shown and some pertinent characteristics of the fluctuations are pointed out. The effect of various factors contributing to the generation of the diurnal fluctuations are discussed in this paper. It has been found that diurnal variations of the rate of evapotranspiration from riparian zones adjoining the river is the most significant single factor contributing to the fluctuations in the river. The mechanisms by which diurnal variations in the rate of evapotranspiration generate fluctuations in the river are discussed using simple qualitative models of the river-riparian zone.
Breaks in Resistivity Sounding Curves as Indicators of Hard Rock Aquifers
Authors: Ballukraya P. N. , Sakthivadivel R. , Baratan R.
Published: May 2018

In a previous paper (Nordic Hydrology, Vol. 12, 1981), the authors have discussed the inadequacies in the technique of resistivity method for location of sites for constructing deep water walls in hard rock areas. It was pointed out that the water bearing fracture zones in the bed rock could not be identified by merely considering geoelectrical parameters such as layer resistivity. An empirical study based on the correlation of minor irregularities or deviations – “BREAKS” – in the normally smooth sounding curves with the actual driller's logs reveals that under normal geo-electric conditions these water bearing zones (hard rock aquifers) are indicated in the curve by a perceptible lowering of apparent resistivity and hence could be used as a guide for locating well sites. As such breaks may also be caused by other conditions such as lateral inhomogeneities, certain methods for distinguishing them are discussed.
Correction of Measured Precipitation in the Alps Using the Water Equivalent of New Snow
Authors: Sevruk Boris
Published: May 2018

The Hellmann heated siphon pluviograph with wind shield shows 56 % less winter precipitation than measured on a snow board at an altitude of 2,540 m a.s.l. For the Swiss heated tipping bucket gauge and the storage gauge precipitation was 31 % less. A relationship between the deficit and wind speed was only found for the storage gauge. The effect of the parameter of snowfall structure, defined as the portion of snowfall on days with temperature lower than -8°C, is small. The results can be used to make a preliminary adjustment of precipitation sums at Alpine gauge sites where wind speeds and temperature can be assessed.
Simulation of Groundwater Response by Conceptual Models
Authors: Bergström Sten , Sandberg Göran
Published: May 2018

A conceptual runoff model is modified and applied to groundwater observations in an unconfined till aquifer, a confined aquifer under a clay deposit and a large unconfined esker aquifer. The results show that these types of aquifers can be modelled by one general model structure with only a few options. For the confined case the model is feasable for response simulation only while it gives a fair estimate of recharge of the unconfined aquifer.
Hydrological Data-Model Work in Greenland
Authors: Thomsen Th. , Jørgensen G.H.
Published: May 2018

The hydrological studies of the Greenland technical Organization in Greenland are being followed up at Copenhagen by hydrological data work as well as hydrological model-simulation.

The hydrological regions vary greatly in Greenland, depending on whether the drainage basin is influenced by ablation runoff. To describe a runoff time series from these areas, a hydrological model calibration is made, followed by a simulation. In drainage basins influenced by rain and snow only, a slightly modified version of the precipitation runoff model (NAM) is applied. The parameter transfer for the determination of model input is found by intensive data analysis work here between Nuuk and Kangerluarsunnguup Tasersua (KANG) for temperature and precipitation along with detailed investigations in the basin. This is to ensure that a too short calibration period in connection with the adaption of a hydrological model to the basin data is balanced in the manner that these adapt the hydrological model, and not vice versa.

In drainage basins also influenced by ablation runoff it is not possible to use a traditional precipitation runoff model but a hydrological ablation model has been developed in cooperation with The Geological Survey of Greenland. The hydrological ablation model describes the transfer of the temperature after heating and cooling factors as well as snow mobility on the ice, melting density criteria, refreezing etc. The model has been applied to the hydrological basin of Paakitsup Akuliarusersua (PAKI) at Ilulissat where 90% of the drainage basin is covered by the Ice cap.

Data evaluation work prior to hydrological model calibration thus allows for a higher degree of simulation reliability.
Nitrogen Balance in Fertilizer Application and Plant Production
Authors: Aslyng H.C.
Published: May 2018

The investigation comprises several agricultural crops, a Karup locality (56°16' N, 9°9' E) with an average annual precipitation of 775 mm and coarse sand (soil 1), and a Tåstrup locality (55°40' N, 12°18' E) with an average precipitation of 600 mm and clay with fine sand (soil 6). Soils 1 and 6 have 5 and 8 t N/ha in organic matter, respectively, to 50 cm soil depth and an average effective root zone capacity for available water of 60 and 170 mm.

Data for soils 1 and 6 in kg N/ha as average (with great annual variation) were for spring barley found to be around the following: mineralization 75 and 135, denitrification 5 and 20, uptake in harvest 105 and 155, leaching 65 and 40, and spring storage 10 and 60, respectively. Wintering and late growing crops reduce the leaching by around 20 kg N/ha. The nitrogen leaching from sandy soil is clearly influenced by variation in fertilization whereas the leaching from clay soil is only a little affected.
An Attempt to Reduce Nitrate Content in Ground Water Used for Municipal Water Supply by Changing Agricultural Practices
Authors: Andersson Rune , Kindt Torsten , Johansson Per-Olof , Maxe Lena
Published: May 2018

The heavy use of manure and fertilizers has in some parts of Sweden resulted in unacceptable concentrations of nitrate in ground water used for private and municipal water supply. In Halland for example, several of the municipal water supplies have nitrate concentrations close to 50 mg/I. Either anionic exchange or mixing with water with less nitrate are used to reduce the nitrate content in the distributed water. However, some wells have been abandoned because of high nitrate concentrations. In this study an attempt is made to reduce the nitrogen contamination of the ground water at the source. In well recharge areas the agricultural practices are investigated and, if necessary, alterations are proposed to the farmer in order to decrease the nitrogen leaching from the soil profile. The effect of these improvements is continuously studied in soil and ground water. An action plan is proposed for water supplies with dominating arable land in the recharge area.
Seasonal Variations of Oxygen-18 in Soil Moisture and Estimation of Recharge in Esker and Moraine Formations
Authors: Saxena R.K.
Published: May 2018

The use of Oxygen-18 as a natural tracer of soil moisture and estimation of recharge in different types of soils is presented and discussed. The 8 values of 18O in summer and winter precipitation in southern Sweden differ by about 6-8‰ SMOW, giving the soil moisture a distinct isotopic profile. For instance, meltwater having low δ18O labels the upper soil horizon with isotopically light water and pushes down the isotopically heavy old moisture contributed by the preceding summer precipitation. The soil moisture thus exhibits a cyclic pattern having low and high 18O contents. The temporal displacements of soil moisture layers depleted or enriched in 18O have been used to calculate seasonal and annual recharge in esker and moraine formations. In Uppsala region the annual recharge varies from 230-300 mm. These estimates are reliable since 18O depleted soil moisture layers contributed by two years consecutive meltperiods have been observed in the soil profile.
Infiltration in Unsaturated Frozen Soil
Authors: Engelmark Helén
Published: May 2018

A one-dimensional mathematical model is used to simulate the process of snow-melt infiltration in unsaturated frozen silt. Hydraulic and thermal parameters are mainly based on data given in the literature.

Field observations in a watershed (of area 1.8 km2) are compared with simulated data and consequences on snow melt run-off are discussed.
Estimation of Combined Sewer Overflow Discharge From the City of Malmö
Authors: Hogland W. , Berndtsson R. , Larson M.
Published: May 2018

The function of combined sewer overflows (CSO) from both a quantitative and a qualitative point of view is often little known in the Nordic communities. Since large pollution loads are discharged from urban areas by CSO, it is important to consider this problem when rehabilitation plans are established.

A study aiming at the estimation of yearly volumes of CSO and yearly quantities of pollution load from CSO has been carried out in the city of Malmö, Sweden. The CSO discharges into four different types of receiving waters: the channel, the harbour, the Sege River and the Öresund. Registration of frequency, duration and water volume was made at about 30 weirs at different time periods.

Storm Water Management Model (SWMM) was used both to simulate single SCO events and for continuous simulation. The results from these simulations were compared with actual measurements.

The total pollution load was estimated from mean concentration of pollutants from more than 100 samples taken at different weirs and CSO events.

Through analysis of the occurrence of CSO in time and space, a program of priorities for the rehabilitation of the CSO-system was established.
Frequency Analysis of Low Flows
Authors: Loganathan G. V. , Kuo C. Y. , McCormick T. C.
Published: May 2018

The transformations (i) SMEMAX (ii) Modified SMEMAX (iii) Power and Probability Distributions (iv) Weibull (α,β,γ) or Extreme value type III (v) Weibull (α,β,0) (vi) Log Pearson Type III (vii) Log Boughton are considered for the low flow analysis. Also, different parameter estimating procedures are considered. Both the Weibull and log Pearson can have positive lower bounds and thus their use in fitting low flow probabilities may not be physically justifiable. A new derivation generalizing the SMEMAX transformation is proposed. A new estimator for the log Boughton distribution is presented. It is found that the Boughton distribution with Cunnane's plotting position provides a good fit to low flows for Virginia streams.
Characteristics of Snowmelt Induced Peak Flows in a Small Northern Basin
Authors: Bengtsson Lars
Published: May 2018

Six years' runoff data from Bensbyn Research Watershed (BRW) in northern Sweden is discussed. BRW is 1.6 km2, out of which 0.5 km2 is a large meadow and the remaining area consists of a dense coniferous forest. In the runoff analysis, runoff contribution from the meadow is separated from that from the forest. Peak flows are related to snowmelt from each separate area, and to rain events. The snowmelt generated runoff hydrographs are compared to those from rain events. The diurnal fluctuations of the snowmelt-induced runoff are analyzed in order to determine to what extent the stream flow originates from overland flow or subsurface flow. The highest flow recorded, 1.25 mm/h, was the result of a major rain storm of 60 mm occurring two weeks after all snow had disappeared. The peak runoff generated by snowmelt only was 0.78 mm/h. Overland flow is shown to take place from the meadow, but the runoff contribution from the forest is mainly due to subsurface flow. The peak flows from BRW are compared with observations reported in the recent literature.
Dispersion in Ice-Covered Lakes
Authors: Bengtsson Lars
Published: May 2018

Dispersion studies in three ice-covered lakes are presented. One of the lakes has a large river through-flow. In the other two lakes, small seiche-induced currents are generated through wind action on the ice cover. Dispersion coefficients are computed from five dye experiments lasting from ½ day to 16 days. These coefficients are related to measured current velocities. The turbulence in the river-flow dominated lake is found to be very low with disperision coefficients less than 1 cm2/s in directions transverse to the flow. In the lakes where the turbulence is generated by shear from the seiche-induced currents the horizontal dispersion coefficients are two orders of magnitude higher, being almost as high as in ice-free lakes.
Temperature and Flow Conditions in a Reservoir with a Submerged Outlet Tunnel During the Winter Period
Authors: Tvede Arve M.
Published: May 2018

The reservoir Sundsbarmvatn, in Southern Norway, is used for electricity production from November to May. Sundsbarmvatn has two main basins. Water from the upper basin, Mannerosfjorden, flows into the lower basin, Gullnesfjorden. The two basins are separated by a narrow sound with a sill. The regulation interval for Sundsbarmvatn is 612-574 m a.s.l., but the sill prevents Mannerosfjorden from being lowered below 580 m a.s.l. The water intake in Gullnesfjorden is 571 m a.s.l.

The water temperature conditions has been studied during two winters when the reservoir water was released. This study shows that a marked thermocline was gradually developed at the depth of withdrawal in Gullnesfjorden. In the epilimnion layer the temperature is gradually lowered through the winter, but in the hypolimnion layer the temperature seems to stay constant through the winter. In Mannerosfjorden, however, we find no clear thermocline at the end of the winter. The remaining water was relatively warm with temperatures mainly above 3 °C.

The sill between the two basins seems to have a strong influence on which depth the water is flowing out of Mannerosfjorden and hence on the temperature and circulation pattern in Gullnesfjorden. At the end of the winter season this flow is strengthening and initiates a homogeneous flow layer in Gullnesfjorden. This layer is dipping downwards towards the outlet tunnel. For this reason the temperature of the water leaving the power station is 0.4-1.2 °C colder than the hypolimnion temperature in the reservoir at the tunnel depth.
Microwave Remote Sensing of Snowpack Properties: Potential and Limitations
Authors: Bernier P. Y.
Published: May 2018

This review explores from a user's viewpoint the possibilities and limitations of microwave-based techniques for the remote sensing of snowpack properties. Mapping of dry snowpacks and detection of melt onset can be achieved with combinations of readings taken at different frequencies with passive microwave sensors. A combination of readings from both passive and active sensors coupled with ground truth data will be required to estimate snow water equivalent under most snow conditions. Snowpack structure and overlying vegetation still present major problems in the estimation of snowpack water equivalent from microwave remote sensing devices.
Variations of 87Sr/86Sr in Water from Streams Discharging into the Bothnian Bay, Baltic Sea
Authors: Åberg F. , Wickman F. E.
Published: May 2018

The 87Sr/86Sr ratio in 53 water samples were analysed, 26 from streams in Sweden, 22 from streams in Finland and 5 from the Bothnian Bay itself. The brackish seawater of the bay had the isotope ratio 0.7095, while the stream-water samples varied from 0.7177 to 0.7366. The weighted average isotope ratio with respect to discharges was 0.7313, this high ratio reflecting the dominance of granitic Proterozoic rocks in the region.

For streams with an average discharge between 1-40 m3/s the isotope ratio was within the interval 0.718-0.736, while those with discharges >150 m3/s defined an interval of 0.728-0.735. The variations in isotope ratios are discussed with respect to bedrock geology of drainage basins, possible effects of seawater inundations and Postglacial uplift combined with the complex history of the Baltic Sea.
The Peatland Hydrologic Impact Model: Development and Testing
Authors: Phillip Guertin D. , Barten Paul K. , Brooks Kenneth N.
Published: May 2018

Questions concerning the effects of drainage, peat mining and timber harvesting on streamflow response in the northern Lake States of the U.S.A. led to the development of the Peatland Hydrologic Impact Model (PHIM). PHIM is a generalized, deterministic, continuous simulation model, that is physically-based to the extent possible. Three independent landtype submodels represent watershed conditions common in the region. The appropriate land-type submodel(s), either natural peatland (NWATBAL), mined peatland (MWATBAL), or mineral soil upland (UWATBAL) are configured by the model user to represent the watershed. The submodels were applied to test the model on the streamflow response from three different peatland watersheds. Stormflow events were simulated for a 3,758 ha natural peatland and a 155 ha mined peatland. Annual water yield simulations for a 9.72 ha upland-peatland watershed produced a mean ratio of predicted/observed streamflow of 1.01 ± 0.08 for six test years. The model is generalized so that it should be adaptable to similar physiographic regions with minor modifications.
Sensitivity of the Groundwater Mound Model for Predicting Mire Topography
Authors: Kneale Pauline E.
Published: May 2018

The Dupuit-Forcheimer model for groundwater mounds has been proposed to explain the morphology of raised peat mires. This paper discusses the sensitivity of the model as a predictor for mire profiles using data from a raised Irish mire where an attempt was made to reconstruct the equilibrium profile. The most sensitive parameters are shown to be hydraulic counductivity and net recharge. Detailed measurements of saturated hydraulic conductivity show significant spatial variability, which is correlated with mire stratigraphy. Objective determination of an average value for modelling would have an error band of an order of magnitude which is unsatisfactory for prediction. Net recharge is calculated from the water balance but parameters like overlandflow must be estimated, usually from limited data, making the proposed value suspect. This model may be helpful for mire description but its variables cannot be specified accurately enough for predictive purposes.