bluuebunny/crossref_metadata_2025 huggingface dataset:
Cat scratch disease as zoonosis: Pathogenesis, clinical symptoms, diagnosis.
Authors: MAZUREK ŁUKASZ , WINIARCZYK STANISŁAW , ADASZEK ŁUKASZ
Published: May 2018

The cat scratch disease in humans is caused by the bacteria Bartonella henselae. The disease can take many different forms: from asymptomatic cases, cases of skin lesions, fever of unknown origin, enlargement of lymph nodes, ophthalmologic disorders, to severe cases involving inflammation of the brain and spinal cord or endocarditis. The reservoir of B. henselae for humans are domestic animals, especially cats. The diagnosis of the disease is based on data from the anamnesis, the patient’s confirmed exposure to cats, and the results of serological tests showing an increase in antibody titres for B. henselae. The disease can also be confirmed by positive results of the polymerase chain reaction (PCR). No vaccines against bartonellosis are available. The most important in preventing the disease is to maintain appropriate hygiene in contact with cats and dogs, and to eradicate the vectors of Bartonella, such as fleas..
An optimal design of water distribution networks with hydraulic-connectivity
Authors: Shin Hyun-Gon , Park Heekyung
Published: May 2018

In designing water distribution networks (WDN) against emergency situations, efforts must be made to achieve two objectives: maximizing reliability and minimizing cost. For such optimization, it is necessary first to quantify the reliability of WDN using a surrogate measure. Hydraulic-connectivity is selected as a surrogate measure in this study, which indicates a probability that every demand node in a network is connected to at least one supply source with required flow at adequate pressure. An optimization model using hydraulic-connectivity and the genetic algorithm (GA) is formulated. For illustration, the optimization model is applied to the New York City water supply tunnel. This tunnel cannot satisfy the minimum pressure with existing diameters. The new optimal design with required flow at adequate pressure is found to be lower than the existing tunnel cost by US$25.252 million when the hydraulic-connectivity is 0.9778. It is also noted that this approach allows the exploration of the trade-off between cost and reliability directly. This permits designers to design WDN based on more quantitative information regarding cost and reliability.
Genetic programming as a model induction engine
Authors: Babovic Vladan , Keijzer Maarten
Published: May 2018

Present day instrumentation networks already provide immense quantities of data, very little of which provides any insights into the basic physical processes that are occurring in the measured medium. This is to say that the data by itself contributes little to the knowledge of such processes. Data mining and knowledge discovery aim to change this situation by providing technologies that will greatly facilitate the mining of data for knowledge. In this new setting the role of a human expert is to provide domain knowledge, interpret models suggested by the computer and devise further experiments that will provide even better data coverage. Clearly, there is an enormous amount of knowledge and understanding of physical processes that should not be just thrown away. Consequently, we strongly believe that the most appropriate way forward is to combine the best of the two approaches: theory-driven, understanding-rich with data-driven discovery process. This paper describes a particular knowledge discovery algorithm—Genetic Programming (GP). Additionally, an augmented version of GP—dimensionally aware GP—which is arguably more useful in the process of scientific discovery is described in great detail. Finally, the paper concludes with an application of dimensionally aware GP to a problem of induction of an empirical relationship describing the additional resistance to flow induced by flexible vegetation.
Hydroinformatics and urban drainage: an agenda for the beginning of the 21st century
Authors: Price Roland K.
Published: May 2018

The developing insights of hydroinformatics have much to offer the water industry, and particularly urban storm and wastewater drainage. This paper reviews aspects of data mining and knowledge discovery of large asset databases, the complementary nature of both physically based and data-driven modelling of drainage network performance, and the roles of decision support systems and knowledge management. It concludes with the presentation of ten agenda items that would benefit research and practice at the beginning of the 21st century.
Design of two-storey final settling tanks using mathematical models
Authors: Stamou A. I. , Latsa M. , Assimacopoulos D.
Published: May 2018

A mathematical model is applied to the design of two-storey final settling tanks. Computations show that the flow and suspended solids (SS) concentration fields for the upper and bottom tanks are similar. The flow field has the ‘two-layer’ structure, observed in real and laboratory settling tanks, consisting of a bottom current and a free surface return current with approximately equal heights. The SS concentration field is governed by the flow field (and vice versa). The SS concentration profiles are uniform in the major part of the tanks. The hydraulic and SS removal efficiencies improve with decreasing flow rate. In both tanks the outlet SS concentrations are lower than the maximum permissible value (20 mg l−1), with the upper tank showing a better performance than the bottom tank.
On definitions
Authors: Abbott Michael B.
Published: May 2018

Originating from a concern about the use of terms in hydroinformatics, this paper takes up the question of the nature of a definition and its consequences in a technical, and increasingly sociotechnical field like hydroinformatics. It is explained that the way things are defined is not so simple and so obvious as might at first appear, but is in fact an essentially ideological matter, having consequences not only within an individual discipline, but also for the applications of that discipline within a wider context. A mode of definition that satisfies the needs and expectations of hydroinformatics is then advanced.

The notion of a defining self is introduced in order to explain how the influences of the mode of definition attains to a greater influence in social and ecological applications. This influence is exerted through communication, which is necessarily realised through the use of tokens. The four classes of tokens necessary for all processes of communication are introduced, delineated and defined.

The way in which such broad concepts as ‘reality’ and ‘truth’ are defined is then seen to influence the definition of a model in the widest sense. Further definitions that are of central concern in hydroinformatics are developed accordingly. The paper concludes with a description of a phenomenon known only by its German name, as Gerede, that is at the root of much current confusion of terms in hydroinformatics, as in so many other places, and how its malign influences can be opposed.
Application of genetic algorithms for optimal seasonal furrow irrigation
Authors: Montesinos Pilar , Camacho Emilio , Alvarez Serafin
Published: May 2018

A quasi-optimum irrigation season calendar based on economic profit maximization for sloping and runoff-free furrows can be obtained by OPTIMEC (EConomic OPTIMization, in Spanish), a seasonal furrow irrigation model based on the concept of comprehensive irrigation. The model features four components: a soil moisture model, an irrigation hydraulic model, a crop yield model and an economic optimization module. This module uses a Genetic Algorithm (GA), a heuristic technique based on the laws of natural selection, to maximize farmer profit. The GA is a suitable technique to solve the problem of profit maximization due to the difficulties inherent in traditional optimization procedures, which require an explicit function relating flow rate, water depth and profit. For its practical application the model has been implemented in a Visual Basic program. A real case is analysed to compare the irrigation season scheduling using traditional criteria (event by event scheduling) and optimization-based criteria.
Design and development of a planning support system for policy formulation in water resources rehabilitation: the case of Alcázar De San Juan District in Aquifer 23, La Mancha, Spain
Authors: Sharifi Mohammad Ali , Rodriguez Erasmo
Published: May 2018

To support policy formulation for rehabilitation of the natural environment in the Western Mancha region in Spain, a planning support system was developed and applied. The system is based on a framework developed for planning and decision making, and includes three main components, namely, a water balance model of the groundwater basin, a planning model and an evaluation model. The water balance model, which makes use of GIS and remote sensing, simulates the average yearly recharge of the aquifer system in relation to the land use changes for average meteorological conditions, to help understand the current situation; the planning model, which makes use of mixed integer programming, simulates the reaction of farmers towards the changes in the present subsidy schemes and helps formulate a proper policy instruments; and finally the evaluation model, which makes use of multicriteria decision analysis to support the evaluation of developed policies and selection of attractive scenarios based on the identified criteria and the preferences/opinion of various decision makers.
An adaptive neuro-fuzzy inference system for the post-calibration of weather radar rainfall estimation
Authors: Hessami Masoud , Anctil François , Viau Alain A.
Published: May 2018

An Adaptive Neuro-Fuzzy Inference System, based on a jack-knife approach, is proposed for the post-calibration of weather radar rainfall estimation exploiting available raingauge observations. The methodology relies on the construction of a fuzzy inference system with three inputs (radar x coordinate, y coordinate and rainfall estimation at raingauge locations) and one output (raingauge observations). Subtractive clustering is used to generate the initial fuzzy inference system. Artificial neural network learning provides a fast way to automatically generate additional fuzzy rules and membership functions for the fuzzy inference system. Fuzzy logic enhances the generalisation of the artificial neural network system. In order to demonstrate the steps of the radar rainfall post-calibration using the Adaptive Neuro-Fuzzy Inference System, CAPPIs of one-hour rainfall accumulation and corresponding raingauge observations have been selected. Results show that the proposed approach looks for a response that is a compromise between radar rainfall estimations and raingauge observations and does not necessarily consider the raingauge observations as ground truth. The algorithm is very fast and can be implemented for real time post-calibration. This algorithm makes use of all available data—raingauge observations are usually scarce—for training and checking the neuro-fuzzy inference system. It also provides a degree of reliability of the post-calibration.
Handling uncertainty in the hydroinformatic process
Authors: Hall Jim W.
Published: May 2018

Hydroinformatics combines topics of modelling and decision-making, both of which have attracted a great deal of attention outside hydroinformatics from the point of view of uncertainty. Epistemic uncertainties are due to the inevitably incomplete evidence about the dependability of a model or set of competing models. Inherent uncertainties are due to the varying information content inherent in measurements or model predictions, be they probabilistic or fuzzy. Decision-making in management of the aquatic environment is, more often than not, a complex, discursive, multi-player process. The requirement for hydroinformatics systems is to support rather than replace human judgment in this process, a requirement that has significant bearing on the treatment of uncertainty. Furthermore, a formal language is required to encode uncertainty in computer systems. We therefore review the modern mathematics of uncertainty, starting first with probability theory and then extending to fuzzy set theory and possibility theory, the theory of evidence (and its random set counterpart), which generalises probability and possibility theory, and higher-order generalisations. A simple example from coastal hydraulics illustrates how a range of types of uncertain information (including probability distributions, interval measurements and fuzzy sets) can be handled in the types of algebraic or numerical functions that form the kernel of most hydroinformatic systems.
Calibration of physically based models: back to basics?
Authors: Guinot Vincent , Gourbesville Philippe
Published: May 2018

The modelling of extreme hydrological events often suffers from a lack of available data. Physically based models are the best available modelling option in such situations, as they can in principle provide answers about the behaviour of ungauged catchments provided that the geometry and the forcings are known with sufficient accuracy. The need for calibration is therefore limited. In some situations, calibration (seen as adjusting the model parameters so that they fit the calculation as closely to the measurements as possible) is impossible. This paper presents such a situation. The MIKE SHE physically based hydrological model is used to model a flash flood over a medium-sized catchment of the Mediterranean Alps (2820 km2). An examination of a number of modelling alternatives shows that the main factor of uncertainty in the model response is the model structure (what are the dominant processes). The second most important factor is the accuracy with which the catchment geometry is represented in the model. The model results exhibit very little sensitivity to the model parameters, and therefore calibration of these parameters is found to be useless.
Data transformation for neural network models in water resources applications
Authors: Bowden Gavin J. , Dandy Graeme C. , Maier Holger R.
Published: May 2018

A step that should be considered when developing artificial neural network (ANN) models for water resources applications is the selection of an appropriate transformation of the data. In general, the primary motivations for data transformation are: (1) to scale the data so as to be commensurate with the transfer function in the output layer; (2) to standardise each of the variables; (3) to provide a suitable initialization of the ANN; and (4) to modify the distribution of the input variables to provide a better mapping to the outputs. In this paper, five different transformations are investigated in an attempt to improve the ANN's forecasting ability. These are: linear transformation, logarithmic transformation, histogram equalization, seasonal transformation and a transformation to normality. A case study is presented in which each of the ANN models developed using the different transformation techniques is used to forecast salinity in the River Murray at Murray Bridge (South Australia) 14 days in advance. When tested on a validation set from July 1992 to March 1998, the model developed using the linear transformation resulted in the lowest root mean squared forecasting error. This finding further strengthens the claim that the probability distribution of the data does not need to be known to develop effective ANN models. No improvement in the ANN model's forecasting ability was made using the logarithmic, seasonal and normality transformations. The model developed using histogram equalization produced good results for data within the training domain but was not robust on new patterns outside of the calibration range.
Sensitivity and uncertainty analysis for river quality modelling
Authors: Radwan Mona , Willems Patrick , Berlamont Jean
Published: May 2018

Uncertainty analysis for model simulation is of growing importance in the field of water quality management. The importance of this concern is provided by recent public awareness over health risks from improper disposal of toxic wastes as well as by the continuing emphasis on risk assessment. The first step in the chain of risk assessment is the quantification of the error in predicting water quality.

In each mathematical modelling application, different uncertainties are involved. The uncertainty sources can be classified into different categories (in this study, as model-input uncertainty, model-structure uncertainty, model-parameter uncertainty and measurement errors). These different types of uncertainty sources determine collectively the total uncertainty in the model results. In this paper, the relative contributions of uncertainties associated with each source are studied for the physico-chemical water quality modelling of a river in Belgium. This provides information as to where available modelling resources should be focused.
Using genetic programming to determine Chèzy resistance coefficient in corrugated channels
Authors: Giustolisi Orazio
Published: May 2018

Genetic Programming has been used to determine Chèzy resistance coefficient for full circular corrugated channels. Three corrugated plastic pipes have been experimentally studied in order to generate data. The tests aim at measuring hydraulic parameters of the open-channel flow for some slopes, from 3.49–17.37% (2–10°), in order to discover the dependence of the channel resistance coefficient when wake-interference flow occurs. The monomial formula for the Chèzy resistance coefficient performs well on experimental data, both from measurement errors and from a technical point of view. In this paper, we present some very parsimonious formulae that have been created by Genetic Programming with few constants and which fit the data better than the monomial formula. Moreover, two of the Genetic Programming formulae, after ‘physical post-refinement’, seem to better explain the role of the roughness in the Chèzy resistance coefficient for corrugated channels with respect to its traditional expression for rough channels. This fact suggests that at least the structure of those formulae can be extrapolated to other types of corrugated channels. Finally, the work stresses the fact that the Genetic Programming hypothesis can be easily manipulated by means of ‘human’ physical insight. Therefore, Genetic Programming should be considered more than a simple data-driven technique, especially when it is used to perform scientific discovery.
Integrated application of cluster and multicriterion analysis for ranking water resources planning strategies: a case study in Spain
Authors: Raju K. Srinivasa , Duckstein Lucien
Published: May 2018

Integrated application of cluster analysis and Multicriterion Decision-Making (MCDM) is employed for the case study of the Flumen Monegros irrigation area in the Huesca province of Spain. Economic, environmental and social criteria are used to rank alternative strategies. Alternative strategies are formulated by mixing factors such as irrigation systems, water pricing, water allocation, crop distribution, fertiliser use and subsidies received. Cluster analysis is employed to reduce the large size payoff matrix to a manageable subset for further use of the MCDM technique. ELECTRE-3, an MCDM technique of outranking nature, is employed to rank the alternative strategies. The Kendall rank correlation coefficient is employed here to analyse the correlation between the ranking patterns obtained from various scenarios. Results indicate that three representative strategies are to be preferred based on this analysis.
Using Bayesian networks to model watershed management decisions: an East Canyon Creek case study
Authors: Ames Daniel P. , Neilson Bethany T. , Stevens David K. , Lall Upmanu
Published: May 2018

An approach to developing and using Bayesian networks to model watershed management decisions is presented with a case study application to phosphorus management in the East Canyon watershed in Northern Utah, USA. The Bayesian network analysis includes a graphical model of the key variables in the system and conditional and marginal probability distributions derived from a variety of data and information sources. The resulting model is used to 1) estimate the probability of meeting legal water quality requirements for phosphorus in East Canyon Creek under several management scenarios and 2) estimate the probability of increased recreational use of East Canyon Reservoir and subsequent revenue under these scenarios.
MECHANISM OF GROUND WATER RESERVOIRS
Authors: ELIASSON JONAS
Published: May 2018

The article deals with unsteady ground water flow in an aquifer of limited horizontal extent. The changes in storage are taken to be dependent on a storage coefficient S, and flow rates are taken to be dependent on the coefficient of transmissibility T. Here the relation to Darcy's constant k is that T ≿ kD, where D is the aquifer thickness. The equilibrium ground water surface is found and further calculations are based on the departure of the ground water level from this equilibrium value.

An expression of the impulse response function (the instantaneous unit hydrograph or IUH) is found, and its use demonstrated.

Finally, it is shown how such calculations have been used to analyse the inflow into a water reservoir in Iceland, serving as guidelines in the planning of field investigations of a major ground water reservoir in a nearby lava field.
CHECKS ON THE WATER BALANCE OF A SMALL CATCHMENT
Authors: WARD R. C.
Published: May 2018

The paper discusses water balance data for a small (16 km2) boulder clay catchment. In order to check the accuracy of the calculations, water balances are cast for different, overlapping periods of time within the same run of data (e.g. three-year, annual, seasonal, monthly, ten-day and storm-period). For each period the residual values are satisfactorily low (cf. 12 mm for the three-year balance and zero for the storm-period balance). A further series of checks is provided by rewriting the water equation in a number of different ways to enable estimated and measured values of certain water balance components to be compared. It is concluded that the measured values seem to be accurate and that the catchment appears to be watertight.
NUMERICAL SIMULATION OF THE RAINFALL-RUNOFF PROCESS ON A DAILY BASIS
Authors: NIELSEN STEEN ASGER , HANSEN EGGERT
Published: May 2018

A digital model has been developed for the simulation of the rainfall-runoff process of rural watersheds. Input data are daily values of precipitation and temperature together with mean monthly potential evapotranspiration. The model produces daily values of streamflow as well as information on the time variation of the soil moisture content. In all, ten model parameters have to be identified, seven of which have a major influence on the performance of the model.

The model operates by accounting continuously for the moisture content in four different and mutually interrelated storages representing physical elements in the watershed.

It has been applied to three different Danish watersheds. Several statistical measures of accuracy have been utilized for a quantitative evaluation of the simulation results. The simulations demonstrate that the main shortcomings of the model are due to the lack of a procedure accounting for frozen ground during extended periods of frost, which could improve some of the simulation results during winter and spring.
GROUND WATER COMPUTATIONS IN NEW JERSEY, U.S.A.
Authors: HALASI-KUN GEORGE J.
Published: May 2018

In rural areas the 100-year flood of smaller watersheds has a strong dependence on the permeability of the geologic subsurface of the watershed and on the point rainfall intensity.

Based on 70 000 well record files in the state of New Jersey, U.S.A. the ground water availability in the rock formations have been estimated.
SNOWMELT - RUNOFF MODEL FOR STREAM FLOW FORECASTS
Authors: MARTINEC J.
Published: May 2018

Following the development of rainfall-runoff models the attention of the international hydrologic program is now increasingly focused on the snowmelt-runoff. The present simple model is based on taking into account the variability of the degree-day factor, recession coefficient and snow coverage. It can be adapted to heterogenous conditions of snow accumulation and temperature in mountainous basins.
Wind-Tilted Pebbles in Sand - Some Field Observations and Simple Experiments
Authors: Mattsson Jan O.
Published: May 2018

Pebbles on a wind-exposed sand surface have a tendency to tilt forward in the direction against the wind. This paper describes field observations and basic experiments aimed at increasing the knowledge of wind-tilting processes. The tilting velocity was related among other factors to wind velocity, mass balance conditions, and the geometry and weight of the obstacles. In addition basic studies on the flow pattern and micro-morphology around the objects were performed. Two main types of tilting could be distinguished: cavity tilting and deflational tilting. The former type is characteristic of obstacles with a high front edge; the latter is typical of flat obstacles. By the cavity tilting a hollow is excavated in front of the obstacle. In due course the obstacle tilts down into this depression. By the deflational tilting the surrounding sand surface is subsequently lowered and the obstacle will rest on a »sand pillar«, which is successively weakened on the windward side. Consequently the object is turned over. A basic model of the wind-tilting processes in dry sand is found at the end of the paper.
Fluctuations in the Waterlevel in Wells Due to Variations in Atmospheric Pressure
Authors: Sørensen Tage , Kærgaard Henrik
Published: May 2018

Deviations from the classical theory of the barometric efficiency (Jacob 1940) is shown in some examples. A model with a semipermeable bed overlying the aquifer is proposed, and equations for the flow in this model, generated by changes in the total load, for instance changes in air pressure, are presented. Solutions are given for specified variations in the total load, and some data from nature are compared with one of these solutions. The data presented are from the archives of the Geological Survey of Denmark, Hydrogeological Department (DGU, HA).
Routing of Floods in River Channels
Authors: Gill Mohammad Akram
Published: May 2018

An objective method of determining the constants of the Muskingum type linear equation is described. In situations where the relationship between storage and the weighted flow is nonlinear, an approximate method of analysis is proposed. These methods are explained by solving typical examples.
On Dense Bottom Currents in the Baltic Deep Water
Authors: Pedersen Flemming Bo
Published: May 2018

A rational entrainment function for a subcritical dense bottom current is outlined. As an example the formula has been used to some orders of magnitude calculations of the deep water currents from the Darss Sill to the Stolpe Channel. It is shown that the salt and oxygen supply to the deep water of the Baltic Proper during a »normal« year stems from this bottom current and its entrained water. The renewal of the deep water in the Baltic Proper can be traced in the Bornholm Basin, and hence it is strongly recommended, that continous measurements of salinity, temperature, oxygen, phosphate etc. are performed in the Bornholm Basin, especially in the highly entraining area just north of Bornholm.
Studies of the Variations in Water Content in the Unsaturated Zone of an Esker
Authors: Aneblom Thomas , Persson Gösta
Published: May 2018

In this study the changes in water content in the unsaturated zone of a large esker at Tärnsjö have been measured with a combined gamma/neutron probe. Periods of heavy rainfall and intense snow-melting have resulted in infiltration events, which later have been traced as zones with high water content moving downwards in the unsaturated zone towards the groundwater table. The results indicate a velocity of the movement of such zones of about 1.5-3.0 m/month. These results are compared with those obtained by Andersen and Sevel (1974) from a study in Denmark, and with preliminary results from a study of the movement of tritiated water in the unsaturated zone of the Tärnsjö esker performed by Z. Dressie.
Pattern Recognition Analysis of Snowdrifts
Authors: Rawls W. J. , Jackson T. J.
Published: May 2018

Terrain features and prevailing wind patterns play a dominant role in how snow is accumulated. Research was conducted to determine the location of snowdrifts on a 0.41 km2 subbasin of the Reynolds Creek Experimental Watershed located in the Owyhee Mountains in southwestern Idaho. Snow depths at maximum accumulation were determined on a 7.6 m grid using aerial photography. The terrain variables used in the analysis were ground slope, ground aspect, elevation, distance from the top of the ridge, in the direction of the prevailing wind and the difference in elevation between the top of the ridge and the point. A pattern recognition technique called cluster analysis was used to determine the best terrain variables for locating snowdrifts. Our analysis indicated that slope and aspect were the best variables. Discriminant functions using these variables and the prevailing wind were developed to predict the location of snowdrifts. The functions were tested on a 16.7 km2 area.
Effects of Land Use on the Diffuse Load of Phosphorus and Nitrogen
Authors: Kauppi Lea
Published: May 2018

The diffuse load of phosphorus and nitrogen was studied in 23 small drainage basins in different parts of Finland between 1965 and 1974. Total phosphorus and total nitrogen concentrations were analyzed monthly and runoff measured continuously. Mean concentrations and loads for each basin are presented. The mean concentrations of phosphorus varied from 8.3 to 98 μg 1−1and of nitrogen from 190 to 2400 μg1−1. The dependence of concentrations on runoff was in most basins rather slight, but the highest concentrations were usually observed during the spring floods. The mean loads of phosphorus varied from 4.0 to 44 kgs km−2 a−1 and of nitrogen from 79 to 740 kgs km−2a−1.. The dependence of concentrations and loads on basin characteristics was studied by linear regression analysis. The percentage of cultivated land was found to be the most descriptive variable of the characteristics of the basin. The percentage of cultivated land also reflects the loading caused by sparse population and by domestic animal population because of the strong intercorrelations between these variables.
Chemical Budgets and Chemical Quality of Snow and Runoff During Spring Snowmelt
Authors: Skartveit Arvid , Gjessing Yngvar T.
Published: May 2018

In connection with water acidification and the subsequent disappearance of fish populations and also massive fish kills during spring floods, particular interest has been focused upon the fate and effects of ions released from the snowpack during melting.

Meltwater, enriched in ions, leaves the snowpack during melting episodes in winter. These (often small) amounts of water may via the ground-water reservoir have a long term influence upon the quality of winter runoff.

Data from catchments ranging from 0.04 to 232 km2 indicate that, during spring snowmelt in Tovdal, South Norway, the equivalent sum of ions in runoff is mainly governed by the release from the snowpack of sulphate and chloride, which move more or less directly into the watercourses, carrying with them cations directly from the snowpack or from biological and geological material within the catchment.

The concentrations in bulk snow decrease during melting and, therefore, during early snowmelt, the concentrations of sulphate and chloride are 2–5 times higher in the runoff than in the snowpack, well in accordance with polyethylene lysimeter experiments. The composition of the cationic counterparts of these anions in the runoff varies with the runoff rate, with high runoff rate yielding the most acid water.
Evaluation of a Precipitation Map Using a Smoothed Elevation-Precipitation Relationship and Optimal Estimates (Kriging)
Authors: de Montmollin F.A. , Olivier R.J. , Simard R. G. , Zwahlen F.
Published: May 2018

Using 45 rain gauges, located in the center of French-speaking Switzerland (approx. 1,600 sq. km), we evaluate an annual mean precipitation map for the years 1974, 1975 and 1976. This estimate is based mainly on the anomaly method. For the index elevation, we selected an average altitude over an area of optimized size. This was evaluated from the best linear regression between index elevation of different areas and the precipitations.

An anomaly map was estimated using universal kriging: the structural analysis of the anomaly values permitted the adjustment of a variogram which made it possible to evaluate the spatial dependence of the anomaly variable. In order to obtain the precipitation map, not only was an anomaly map used but also a smoothed altitude map. This was calculated with the aid of an altimetric data bank covering the west part of Switzerland
Aluminium in Groundwater Possible Solution Equilibria
Authors: Eriksson Erik
Published: May 2018

Recent investigations in the west coast region of Sweden has revealed the occurrence of groundwaters with a pH of around 4 and, further, alarmingly high concentrations of soluble aluminium. The reason for the occurrence of acid groundwater is, of course, the acid precipitation falling over this area of Sweden in combination with coarse soils on resistant types of granites and gneisses. The »resistance« against acidification of groundwater offered in the soil profile by aluminium and iron hydroxides must obviously have been partly broken. It seems therefore relevant to examine the solubility conditions of aluminium compounds in soils and rocks. From this we may reconstruct the process which led to the present state and we may also be able to tell what information on soils is needed in order to predict the future acidification of groundwater.
Acid Groundwater
Authors: Hultberg Hans , Johansson Sivert
Published: May 2018

Studies of the groundwater flow and quality around the lakes Bredvatten and Lysevatten have shown, that the increased concentrations of aluminum in acid lake water is caused by acid groundwater, and hence of leaching of aluminum into the groundwater. The increased aluminum concentration was later shown to be a major factor in the widespread ecosystem changes occurring in lakes and water systems.

When a similar, but even more pronounced soil- and groundwater acidification occurred via oxidation of accumulated sulfur to sulfuric acid and thereby releasing several soil minerals to the groundwater, a number of regional investigations were carried out on wells and groundwater systems in different provinces in southern Sweden.

The widespread problem with acid groundwater and thus acid tap water, made clear in these studies, shows that several thousand individual households have already acute problems with their drinking water and corroding metalpiping.

The acidification of the groundwater has caused health problems by elevated metal concentrations and economic problems for house owners in an even more pronounced way than acidification of the surface water systems (lakes and rivers). These effects also show how severely affected the lime poor natural ecosystem has become through our own and other countries' airborne acid pollutants.
Microwave Measurements of Snowpack Properties
Authors: Stiles W.H. , Ulaby F.T. , Rango A.
Published: May 2018

Prior microwave measurements of snow water equivalent and liquid water content and conceptualizations of emission and backscattering models are reviewed. The results of an experiment designed to collect simultaneous passive and active microwave data to be used in interpreting and analyzing the sensitivity of the microwave spectrum to changing snowpack properties are reported. Both the scattering coefficient, σ°, and the apparent radiometric temperature, Tap, were found to be sensitive to changes in snow water equivalent and liquid water content. The σ° data exhibit an exponential-like increase with increasing water equivalent, whereas, the Tap data exhibit an exponential-like decrease. For both the active and passive data, the snow water equivalent at which the microwave response begins to saturate decreases as the wavelength decreases. Increasing liquid water in the snowpack causes a decrease in σ° and an increase in the Tap. Diurnal data sets show the greatest σ° and Tap variation in response to snowmelt at 35 and 37 GHz with correspondingly less variation at the lower frequencies. Based on research results to date, immediate formulation of a comprehensive microwave and snow research program is recommended.
Rainfall-Runoff Characteristics for a Mountainous Watershed in the Northeast United States
Authors: Engman E.T.
Published: May 2018

A 112 square kilometer research watershed was instrumented to study basic hydrologic processes in the mountainous areas of the Northeastern United States. Within this area the rainfall-runoff relationships are characterized by fast response but relatively low volumes of runoff. There is very little evidence of surface runoff and the partial-area hydrology concept appears to describe the runoff process. A partial area storm runoff process has been described and experimentally verified for an extremely small area in this watershed. This process attributes storm runoff to channel and near channel areas where surface runoff is generated because the groundwater or perched water table has intersected the surface and there is no resulting infiltration. Storm data for nine watersheds have been analyzed and the results demonstrate that the partial area concept can be generalized to large areas. Other data relating to the general hydrology and water balance of this watershed are also described.
Environmental Isotope Studies of an Alpine Snowpack
Authors: Stichler W. , Rauert W. , Martinec J.
Published: May 2018

At the experimental plot of Weissfluhjoch in Switzerland, 2,540 m a.s.l., tritium, deuterium and oxygen-18 have been used to study exchange processes during the build-up and ablation of the snow cover as well as the hydrological balance. Selected results from the period 1971-1979 are presented. The varying isotope concentration of the respective snow layers reveal a mass exchange between the percolating melt water and the snowpack, influencing the isotope composition of the outflow from a snow lysimeter. A correlation between the isotope concentrations in the snow cover and meltwater has been established. The enrichment of meltwater in stable isotopes enables the evaporation to be calculated independently from the hydrological measurements. Parallel tritium data point to a surprisingly high exchange between the snow surface and air moisture.
The Step-Drawdown Test and Non-Darcian Flow: A Critical Review of Theory, Methods and Practice
Authors: Kærgaard Henrik
Published: May 2018

Step-drawdown tests are usually carried out with succeeding steps of increased pumping yield, each step of equal duration of 1 hour. The background for this procedure is reviewed, and it is shown, that very often much shorter duration of steps is adequate.

The analysis of step-tests is usually based on the formulas of Jacob or Rorabaugh. The physical background for these formulas is reviewed, and the latter is shown to be unsatisfactory. However, the formula is used in cases where the data do not fit the Jacob formula, some typical deviations are shown. Reasons for these problems, trivial and non-trivial, are discussed, and some reasonably sound pshysical explanations for the various systematic deviations from the Jacob formula are given.
Watershed Bounded Network Model (WBNM) for Runoff Prediction of Large Basins
Authors: Venugopal K. , Gopalakrishnan T. V. , Sakthivadivel R.
Published: May 2018

Applicability of a nonlinear version of the watershed bounded network model (WBNM) for large basins namely Shellbyville (1,246 km2), Columbia (3,129 km2), Centreville (5,304 km2) and Hurricane Mills (6,536 km2) of Duck River basin, to predict flood hydrograph based on rainfall excess hyetograph is investigated. Boyd et al. (1979) have applied this model for basins with areas ranging from 0.4 to 251 km2 and recommended a constant value for the model parameter namely, c. In this investigation, c is found to vary from basin to basin and in a given basin it varies with rainfall excess volume. The effect of subdividing the basin into a finer mesh on the reproduction of the observed flood hydrograph is also investigated and the results discussed.
Land Use Planning in Denmark:
Authors: Breuning Madsen H. , Platou S. W.
Published: May 2018

The present paper deals with a model developed and used at the Danish Ministry of Agriculture, Bureau of Land Data, for calculation of the amount of water needed for irrigation. The model incorporates information on soil types and their geographical distribution, soil water retention and root development in relation to soil types, and climatic conditions such as water deficits.
Application of a Cell Model to the Bellebeek Watershed
Authors: Diskin M.H. , Wyseure G. , Feyen J.
Published: May 2018

A new version of a semi-distributed routing model has been applied to the Bellebeek watershed in Belgium, where runoff data were available for a number of internal gauging stations in addition to the outlet runoff data. The new version has provisions for separately routing the rainfall excess input and the channel inflow input to each unit of area represented in the model by a cell. The cells are interconnected in a tree-like structure reflecting the main drainage pattern of the watershed. The semi-distributed nature of the model makes it possible to simulate spatially variable rainfalls or moving storms. The cell model was calibrated by adjusting its three parameters to reproduce, as nearly as possible, the outflow at the main gauging station of the watershed. The direct surface runoff hydrographs for internal points of the model were then compared to the measured runoff at the internal gauging stations.
Effect of Local Bottom Slope and Roughness Coefficient Variations in Overland Flows
Authors: Hager Willi H.
Published: May 2018

The investigation analyses the effects of local bottom slope and roughness coefficient variations in overland flow over a plane by using the kinematic wave theory. Results are compared with the usual approach, and it is found that certain configurations of surface topography and roughness characteristics yield results, that deviate from the usual predictions.
Trends in Nitrate Pollution of Groundwater in Denmark
Authors: Overgaard Kurt
Published: May 2018

A nation-wide investigation of nitrate concentrations in groundwater in Denmark has been carried out. The investigation is based on analyses of groundwater samples from app. 11,000 wells and drinking water from 2,800 groundwaterworks spread equally all over the country, 43,000 km2. Furthermore the trends in nitrate concentrations have been investigated on the basis of time-series of nitrate concentrations for 184 waterworks.

The investigation shows that:

- the overall mean level of nitrate concentrations in the groundwaters has trebled within the last 20-30 years,

- there are pronounced regional differences in the nitrate concentrations of the groundwaters and in the trends of the nitrate concentrations,

- in the western parts of the country the groundwaters are more seriously affected than in the eastern parts and rising trends are significantly more pronounced,

- 36% of the investigated time-series of nitrate concentrations in drinking water from 184 groundwaterworks show a rising trend of 1 to 6 mg NO3/1 per year with a mean value of 3.3, and there is no sign of levelling off,

- drinking water from 8% of the waterworks exceed the EEC maximum admissible concentration for nitrate of 50 mg/1 and 18% EEC guide level of 25 mg/1.

The causes of the general rising trends in the nitrate concentrations in the groundwaters and the regional differences of the trends are discussed. In particular, the impact of agricultural activities and the role of the geological conditions are considered.
Experience with Field Testings of SHE on Research Catchments
Authors: Storm Børge , Høgh Jensen K.
Published: May 2018

The development of the European Hydrologic System (SHE) has now reached such a stage, that it is ready for practical applications. Extensive field testings and associated developments have been carried out in recent years. The testings have included the complete system as well as the individual components. Particular emphasis has been given to the development and testing of the soil water flow model.

The paper demonstrates results from a field testing of SHE on the Wye Catchment in Britain, as well as examples of applications on small experimental catchments in Germany and New Zealand.
Integrated Modelling of Runoff, Alkalinity, and pH on a Daily Basis
Authors: Bergström S. , Carlsson B. , Sandberg G. , Maxe L.
Published: May 2018

Based on the experience from runoff and groundwater recharge simulation a model system has been developed for terrestrial, hydrochemical, and hydrological simulations. The system emphasizes the role of temporary or long term storage in the aquifers of a basin and, separately, accounts for each rainfall or snowmelt event from its entrance into the ground until mixing in the river system. The model is primarily intended for simulation of natural short term variations in alkalinity and pH in running waters. The hydrochemical processes are modelled in a semi-empirical way without assumption of complete hydrochemichal mass-balance. In the paper a brief hydrochemical background is given, and a model with two alternative hydrochemical sub-structures is described. Examples of daily simulations of runoff alkalinity and pH from three different basins are given.
On Fitting Gamma Distrubution to Synthetic Runoff Hydrographs
Authors: Singh V. P. , Chowdhury P. K.
Published: May 2018

Twelve methods of fitting the two-parameter gamma distribution to unit hydrographs are evaluated using experimental data. Five of them are the methods of moments (MOM), cumulants (MOC), maximum likelihood estimation (MLE), least squares (MOLS), and principle of maximum entropy (POME). The remaining seven are based on specification of different point and planar boundary conditions. It is found that of the later seven methods, only one is satisfactory; the other six are inaccurate and should be abandoned for purposes of achieving a mathematical fit. The first five methods are reliable, easier and efficient, and should be preferred.
An Automatic Precipitation Gauge Based on Vibrating-Wire Strain Gauges
Authors: Bakkehøi S. , Øien K. , Førland E. J.
Published: May 2018

The Norwegian Geotechnical Institute, NGI, has recently developed and tested a new automatic precipitation gauge for rain and snow which can measure accumulated precipitation with a resolution better than 0.1 mm. The gauge, which is a direct weighing device, is based on the use of vibrating-wire strain gauges. NGI's prototype instrument has a capacity of up to 300 mm precipitation before the gauge must be emptied. A new improved version designed by Geonor has a capacity of 600 mm precipitation. A diagram showing the relationship between the automatic observations and the manual measurements is included.

In the NGI prototype the precipitation container is suspended from three small steel wires, each of which is in effect the sensing element in a vibrating-wire type strain gauge. When these gauge wires are set into vibration by an electromagnetic exciter, their resonant frequency of vibration is proportional to the square of the tension in the wire. Thus change in the frequency signals is a measure of the change in tension in the wires and correspondingly a measure of the accumulative weight of precipiation in the container.

The distance between the precipitaion gauge and the monitoring station can be up to one kilometre without any loss in performance.