bluuebunny/crossref_metadata_2025 huggingface dataset:
Derechos en jóvenes que viven en condiciones de pobreza en la ciudad de Medellín
Authors: Morales Mesa Santiago Alberto , Aguilar Quintana Alejandra , Solís Rodríguez María Alejandra , Múnera Muñoz Claudia Daniela
Published: May 2018

Objetivo: Éste artículo pretende dar a conocer el análisis de la vulneración y protección de los derechos fundamentales, acordes con la Constitución Política Colombiana de 1991, en grupos de jóvenes en situación de pobreza que habitan diversos sectores de la ciudad de Medellín, tales como Altos de la Torre, Moravia, Esfuerzos de Paz y un grupo de la Universitaria Católica Luis Amigó, pertenecientes a los estratos 1, 2 y 3, entre los años 2013 y 2016. Lo anterior, se logra a partir de la caracterización sociodemográfica de la población, la identificación de derechos fundamentales, que de acuerdo con los jóvenes le son vulnerados, y la descripción de situaciones de vulnerabilidad. Método: se abordó desde un enfoque cualitativo de corte descriptivo y para la generación de la información con los actores sociales, se utilizaron las técnicas interactivas, cumpliendo con el consentimiento informado. Resultados y Conclusiones: Finalmente, se evidenció que en la Ciudad de Medellín los derechos son vulnerados sin importar si son niños, jóvenes o adultos, lo cual los pone en condición de vulnerabilidad, en el ejercicio pleno de sus derechos, y como consecuencia de ello la dignidad humana se ve transgredida, lo que impide el desarrollo familiar, social y personal.
Hydroinformatics in 1999: what is to be done?
Authors: Cunge Jean A. , Erlich Marc
Published: May 2018

Some possible directions of future evolution of hydroinformatics as seen from the recently observed social demand point of view are indicated. Among key issues concerning water resources management, hydroinformatics can contribute by defining a coherent methodological approach for negotiation of the most relevant water-related conflicts. The latter require however equitable access of all stakeholders and parties in conflicting situations to reliable information and objective tools allowing assessment and evaluation of a family of feasible solutions. Rapidly changing Information and Communications Technologies (in particular Internet applications) will have also their impact on the way water-related industry will use the modelling software and an appropriate experience.
Integrated simulation of physical, chemical and ecological processes for river management
Authors: Goodwin Peter , Hardy Thomas B.
Published: May 2018

River management is a rapidly evolving science and recent major floods have prompted a re-examination of traditional approaches such as channelization, levees, flood walls and dams. These flood control measures are capital intensive, require significant maintenance costs, only protect local regions, and often require a tradeoff with ecological resources. Further, recent analyses have shown that the intended benefits and hydraulic performances are not achieved. A new paradigm in river management is evolving, which requires a broad range of design objectives to be met that include reduction in flood risks, ecological enhancement, recreation and aesthetics, as well as complying with strict environmental protection legislation. These more complex projects require extensive data and simulation tools to assist decision makers and communities in selecting management strategies which offer the maximum benefits, whilst preserving and enhancing the ecological integrity of the river system. A framework for the systematic analysis of the river ecosystem is outlined and illustrated by examples from the Western U S A.
Distributed environmental impact assessment using Internet
Authors: Yan Huang , Solomatine Dimitri P. , Velickov Slavco , Abbott Michael B.
Published: May 2018

The ever more widespread use of the Internet now makes it possible to bring many more persons than hitherto into environmental impact assessment and resulting decision-making processes. Because most at these persons are non-experts, however, it is necessary to provide them with tools that will support their assessments and decision-making efforts. When these tools are directed primarily to the making of judgements they may be described as judgement engines. The need to promote cooperative attitudes among participants in the assessment and judgemental/decision-making process, requires that these tools should promote transparency. Judgemental processes are introduced and related to evaluation processes so as to provide a characterisation of transparency.

This paper gives an overview of the relevant Internet technologies and then takes the reader through the conception and realisation of one client–server component of an Internet-distributed judgement engine for environmental impact assessment. Because this is built upon the MikeImpact judgement engine of the Danish Hydraulic Institute, it is called a Web-MikeImpact. Although possibly of interest to specialists in information and control technologies, this paper is primarily intended as a background for potential users of Web-MikeImpact. It should be used alongside the use of the artefact that it describes, as this is available on http://www.hi.ihe.nl/hi/test/mikeimpact/mikeindex1.htm.
Method for the identification of explicit polynomial formulae for the friction in turbulent pipe flow
Authors: Davidson J. W. , Savic D. , Walters G. A.
Published: May 2018

The paper describes a new regression method for creating polynomial models. The method combines numerical and symbolic regression. Genetic programming finds the form of polynomial expressions, and least squares optimization finds the values for the constants in the expressions. The incorporation of least squares optimization within symbolic regression is made possible by a rule-based component that algebraically transforms expressions to equivalent forms that are suitable for least squares optimization. The paper describes new operators of crossover and mutation that improve performance, and a new method for creating starting solutions that avoids the problem of under-determined functions. An example application demonstrates the trade-off between model complexity and accuracy of a set of approximator functions created for the Colebrook–White formula.
Uncertainty and sensitivity analysis of water transport modelling in a layered soil profile using fuzzy set theory
Authors: Schulz Karsten , Huwe Bernd
Published: May 2018

A methodology based on fuzzy set theory is presented to express imprecision of input data in a non-probabilitic sense. Imprecision may originate from indirect measurements, estimation routines, subjective interpretation, and expert judgement of available information. A numerical finite difference solution scheme was chosen to solve one-dimensional steady-state water flow in the unsaturated zone of a layered soil profile. To extend the solution algorithm to operate with fuzzy soil-hydraulic properties and boundary conditions, it is necessary to incorporate the scheme into a nonlinear optimisation routine from where resulting membership functions of soil water pressures with depths can be calculated. By subsequently considering the different imprecise parameters in the calculations and analysing their impact, it is concluded that resulting imprecision not only depends on the degree of imprecision and the number of uncertain parameters but also very much on the system context (e.g. boundary conditions and spatial distribution). The comparison with a closed form solution to solve the fuzzy water flow problem show the potential of that method to be extended towards transient, two- and three-dimensional process descriptions.
Specialist knowledge and its management
Authors: Ahmad K. , Miles L. A.
Published: May 2018

A method for systematically analysing text is outlined for use in the acquisition of specialist knowledge. Such knowledge can typically be engineered in the knowledge bases of hydroinformatic systems. A synthesis of work in the corpus-based studies of language and in the literature on Language for Special Purposes is presented. This synthesis forms the basis of semi-automatic analysis of texts for extracting terms, elaborating terms and identifying heuristics.
Fuzzy rules based model for solute dispersion in an open channel dead zone
Authors: Kettle Helen , Beven Keith , Hankin Barry
Published: May 2018

A method has been developed to estimate turbulent dispersion based on fuzzy rules that use local transverse velocity shears to predict turbulent velocity fluctuations. Turbulence measurements of flow around a rectangular dead zone in an open channel laboratory flume were conducted using an acoustic Doppler velocimeter (ADV) probe. The mean velocity and turbulence characteristics in and around the shear zone were analysed for different flows and geometries. Relationships between the mean transverse velocity shear and the turbulent velocity fluctuations are encapsulated in a simple set of fuzzy rules. The rules are included in a steady-state hybrid finite-volume advection–diffusion scheme to simulate the mixing of hot water in an open-channel dead zone. The fuzzy rules produce a fuzzy number for the magnitude of the average velocity fluctuation at each cell boundary. These are then combined within the finite-volume model using the single-value simulation method to give a fuzzy number for the temperature in each cell. The results are compared with laboratory flume data and a computational fluid dynamics (CFD) simulation from PHOENICS. The fuzzy model compares favourably with the experiment data and offers an alternative to traditional CFD models.
Development of a model for the characterization of fluid dispersion in electrochemical reactors
Authors: González-García Jose , Frías-Ferrer Angel , Montiel Vicente , Aldaz Antonio , Conesa Juan A.
Published: May 2018

This paper analyses the hydrodynamic behaviour of electrochemical reactors by simulating stimulus–response experiments. The experiments were performed with a simple experimental arrangement to generate data (Residence Time Distribution (RTD) curves) from electrolytic conductivity measurements. The multiparametric model proposed and the Matlab program developed allow the study of electrochemical reactors using three-dimensional electrodes, providing values of characteristic parameters of the materials, such as porosity and compressibility. The study of the reactor also permits modelling of the electrochemical reactions that will be produced inside it.
Optimal sampling in a noisy genetic algorithm for risk-based remediation design
Authors: Gopalakrishnan Gayathri , Minsker Barbara S. , Goldberg David E.
Published: May 2018

A groundwater management model has been developed that predicts human health risks and uses a noisy genetic algorithm to identify promising risk-based corrective action (RBCA) designs. Noisy genetic algorithms are simple genetic algorithms that operate in noisy environments. The noisy genetic algorithm uses a type of noisy fitness function (objective function) called the sampling fitness function, which utilises Monte-Carlo-type sampling to find robust designs. Unlike Monte Carlo simulation modelling, however, the noisy genetic algorithm is highly efficient and can identify robust designs with only a few samples per design. For hydroinformatic problems with complex fitness functions, however, it is important that the sampling be as efficient as possible. In this paper, methods for identifying efficient sampling strategies are investigated and their performance evaluated using a case study of a RBCA design problem. Guidelines for setting the parameter values used in these methods are also developed. Applying these guidelines to the case study resulted in highly efficient sampling strategies that found RBCA designs with 98% reliability using as few as 4 samples per design. Moreover, these designs were identified with fewer simulation runs than would likely be required to identify designs using trial-and-error Monte Carlo simulation. These findings show considerable promise for applying these methods to complex hydroinformatic problems where substantial uncertainty exists but extensive sampling cannot feasibly be done.
Neural network rainfall-runoff forecasting based on continuous resampling
Authors: Abrahart Robert J.
Published: May 2018

Most neural network hydrological modelling has used split-sample validation to ensure good out-of-sample generalisation and thus safeguard each potential solution against the danger of overfitting. However, given that each sub-set is required to provide a comprehensive and sufficient representation of both environmental inputs and hydrological processes, then to partition the data could create limited individual representations that are, in some manner or other, deficient with respect to fitness-for-purpose. To address this issue a comparison has been undertaken between neural network rainfall-runoff models developed using (a) conventional stopping conditions and (b) a continuous single-model bootstrap. The results exhibit marginal improvement in terms of greater accuracies and better global generalisations—but the operation itself demonstrates substantial benefits through the provision of additional diagnostic capabilities and increased automation with respect to certain problematic aspects of the model development process.
Application of a 3D numerical model to a river with vegetated floodplains
Authors: Stoesser T. , Wilson C. A. M. E. , Bates P. D. , Dittrich A.
Published: May 2018

This paper describes the application of a three-dimensional computational fluid dynamics code to a large-scale river scheme. One of the primary aims of this paper is to provide a tool, which utilises a roughness closure derived from physical processes, requiring minimal calibration. Accordingly, a roughness closure based on the traditional drag-force approach is implemented. Unlike other implementations of this approach, the drag force is only introduced in the momentum equations and not into the turbulence closure. This ensures that the coefficients of the turbulence closure model (in this case the k−ε scheme) do not require recalibration for each application. An existing vegetated floodplain is used as a reference site and parameters characterising the dimensions of riparian vegetation and its distribution are quantified. A 100 year flood event on a considerable reach length (3500 m) of the lower River Rhine in South-West Germany is then simulated. Mean floodplain velocities are measured using dilution gauging techniques and these are compared with the computed values. Given information such as plant distribution and geometric properties of the various plant populations, the proposed tool can predict floodplain velocities, water elevation and hydrodynamic features indicative of vegetated compound channel flow.
A GIS methodology for the analysis of weather radar precipitation data
Authors: Gad M. A. , Tsanis I. K.
Published: May 2018

A GIS multi-component module was developed within the ArcView GIS environment for processing and analysing weather radar precipitation data. The module is capable of: (a) reading geo-reference radar data and comparing it with rain-gauge network data, (b) estimating the kinematics of rainfall patterns, such as the storm speed and direction, and (c) accumulating radar-derived rainfall depths. By bringing the spatial capabilities of GIS to bear this module can accurately locate rainfall on the ground and can overlay the animated storm on different geographical features of the study area, making the exploration of the storm's kinematic characteristics obtained from radar data relatively simple. A case study in the City of Hamilton in Ontario, Canada is used to demonstrate the functionality of the module. Radar comparison with rain gauge data revealed an underestimation of the classical Marshal & Palmer Z–R relation to rainfall rate.
A simple 3D model for coastal and estuarial applications
Authors: Osment J.
Published: May 2018

This paper describes a 3D model that was constructed in response to the need for a simple model for use in coastal and estuarial applications where tidal range may be large in relation to water depth. The model was required to simulate density driven flows. The model configuration selected to meet these objectives is presented, together with the assumptions, formulation and solution techniques upon which the model is based. The validation of the model against analytical results, an empirical relationship and other model results are also described.
Automating CFD for non-experts
Authors: Morvan Hervé P.
Published: May 2018

The focus of the paper is on demonstrating how it is possible to automate complex CFD simulations using scripting language around and within the structure of the CFD command files. To illustrate this, the concept of an atmospheric pollution case is used and, more specifically, that of a water treatment plant. The code that is used is CFX-5 with PERL as a scripting ‘language’.

The simulation of the factory atmospheric environment and its fluctuating conditions are fully automated. The simulation is based on a pre-defined generic CFD model, for which initial conditions, boundary conditions and source terms of atmospheric pollutant release are written automatically by the scripts using data recorded by measuring devices and stored on computers every half an hour as the simulation runs. When the correct amount of time has elapsed, the simulation pauses and the script updates the set-up using the newly recorded data. It then proceeds further, restarting from the appropriate result files. At each pause, a HTML report is also produced, which contains pictures of the area and summary tables. If a suitable criterion is defined in the post-treatment algorithm, such as a critical concentration for example, an alarm bell can be started, so that the technician knows the simulation has found a potential problem within the large domain that is thus monitored.

The implications of this work are numerous. Firstly, non-CFD experts can run and use results from a CFD simulation without having to implement the models, run the simulation or fully understand the intricacy of the physics and mathematics that it contains. Going further, it is even possible to parametrize the generic model set-up, e.g. the domain dimensions or the location of emission sources, to make the case more flexible. Running the application remotely is also possible, using a web browser to submit the necessary input to the CFD code. Secondly, a very wide area can be monitored numerically, which would not be commercially viable with physical devices and field monitoring campaigns. Thirdly, such a simulation can be used to learn the general behaviour of, and the potential problems associated with, the region of interest and eventually set up a response plan to any given situation known to cause discomfort or form a health hazard to the neighbourhood. This feedback can be used to improve the operation of the plant and its safety, but also to enhance the model set-up for future simulations.
Integration of an analytic element model in a stochastic analysis of infiltration into a complex unconfined aquifer system
Authors: Paleologos E. K. , Sarris T. S. , Tolika M.
Published: May 2018

A hydrologic model based on the Analytic Elements Method (AEM) has been developed for a phreatic aquifer in the General Separations Area (GSA), of the Savannah River Site (SRS), South Carolina, USA. The AEM is a semi-analytical method that relies on the superposition of individual closed-form solutions of elements representing the main hydrologic features of a site. Our study adopts techniques from the stochastic subsurface hydrology to assess the impact of precipitation (and consequently infiltration) variations on the flow field. The precipitation was considered as a random variable following a statistical model that was obtained from a record of the past 112 years. A measure of the variability of the hydraulic head field is obtained through Monte Carlo simulations and a discussion on the uncertainty in different regions of the model is provided. The ease of model development and the small processing power required by AEM models, make the method applicable not only to initial investigations for the identification of test parameters and boundary conditions but also as a tool that in a stochastic framework can provide initial estimations of uncertainty associated with certain model assumptions.
Efficient implementation of inverse approach for forecasting hydrological time series using micro GA
Authors: Liong S. Y. , Phoon K. K. , Pasha M. F. K. , Doan C. D.
Published: May 2018

This paper implements the inverse approach for forecasting hydrological time series in an efficient way using a micro-GA (mGA) search engine. The inverse approach is based on chaos theory and it involves: (1) calibrating the delay time ((), embedding dimension (m) and number of nearest neighbors (k) simultaneously using a single definite criterion, namely optimum prediction accuracy, (2) verifying that the optimal parameters have wider applicability outside the scope of calibration, and (3) demonstrating that chaotic behaviour is present when optimal parameters are used in conjunction with existing system characterization tools. The first stage is conducted efficiently by coupling the Nonlinear Prediction (NLP) method with mGA using a lookup facility to eliminate costly duplicate NLP evaluations. The mGA-NLP algorithm is applied to a theoretical chaotic time series (Mackey–Glass) and a real hydrological time series (Mississippi river flow at Vicksburg) to examine its efficiency. Results show that: (1) mGA is capable of producing comparable or superior triplets using only up to 5% of the computational effort of all possible points in the search space, (2) the lookup facility is very cost-effective because only about 50% of the triplets generated by mGA are distinct, (3) mGA seems to produce more robust solutions in the sense that the record length required to achieve a stable optimum triplet is much shorter, and (4) the prediction accuracy is not sensitive to the parameter k. It is sufficient to use k = 10 in future studies. In this way, the 3D search space could be reduced to a much smaller 2D search space of m and τ.
The extrapolation of artificial neural networks for the modelling of rainfall—runoff relationships
Authors: Hettiarachchi P. , Hall M. J. , Minns A. W.
Published: May 2018

The last decade has seen increasing interest in the application of Artificial Neural Networks (ANNs) for the modelling of the relationship between rainfall and streamflow. Since multi-layer, feed-forward ANNs have the property of being universal approximators, they are able to capture the essence of most input–output relationships, provided that an underlying deterministic relationship exists. Unfortunately, owing to the standardisation of inputs and outputs that is required to run ANNs, a problem arises in extrapolation: if the training data set does not contain the maximum possible output value, an unmodified network will be unable to synthesise this peak value. The occurrence of high magnitude, low frequency events within short periods of record is largely fortuitous. Therefore, the confidence in the neural network model can be greatly enhanced if some methodology can be found for incorporating domain knowledge about such events into the calibration and verification procedure in addition to the available measured data sets. One possible form of additional domain knowledge is the Estimated Maximum Flood (EMF), a notional event with a small but non-negligible probability of exceedence. This study investigates the suitability of including an EMF estimate in the training set of a rainfall–runoff ANN in order to improve the extrapolation characteristics of the network. A study has been carried out in which EMFs have been included, along with recorded flood events, in the training of ANN models for six catchments in the south west of England. The results demonstrate that, with prior transformation of the runoff data to logarithms of flows, the inclusion of domain knowledge in the form of such extreme synthetic events improves the generalisation capabilities of the ANN model and does not disrupt the training process. Where guidelines are available for EMF estimation, the application of this approach is recommended as an alternative means of overcoming the inherent extrapolation problems of multi-layer, feed-forward ANNs.
THE EARTH'S GASEOUS HYDROSPHERE AS A NATURAL RESOURCE
Authors: STARR VICTOR P. , ANATI DAVID A.
Published: May 2018

Consideration is given to the desirability of regarding the water vapor of the atmosphere as a resource for the extraction of fresh liquid water by artificial means. One method for doing this, previously proposed by the writers, is analyzed from the standpoint of simple dynamic calculations, using actual meteorological data taken in the Middle East and the Gulf of Mexico. Various problems and design features of the scheme are discussed in the light of climatological factors and of meteorological physics. The necessity of much preliminary study is stressed, in order to increase the probability of success of an initial experimental unit. Due to the importance of cost considerations, ways of decreasing the minimum necessary size of the device proposed are considered for incorporation as design features. In effect the method may be looked upon as the generation by artificial means of a captive and controlled miniature rainstorm. In certain special arrangements it may also be regarded as a means for the desalinization of sea water.
LYSIMETERS WITH RAINFALL AND SOIL WATER CONTROL
Authors: KRISTENSEN K. J. , ASLYNG H. C.
Published: May 2018

The lysimeter installation described comprises 36 concrete tanks each with a soil surface of 4 m2. The installation is useful for plant growth experiments under natural conditions involving different treatment combined with various controlled water supplies. The ground installation is at least 20 cm below the soil surface and tillage can be done with field implements. The lysimeter tanks are provided with a drainage system which can drain the soil at the bottom (100 cm depth) to a tension of up to 100 cm. A constant ground-water table at less than 100 cm soil depth can also be maintained. The soil moisture content at different depths is determined from an underground tunnel by use of gamma radiation equipment in metal tubes horizontally installed in the soil.

Rainfall is prevented by a movable glass roof automatically operated and controlled by a special rain sensor. Water is applied to the soil surface with a special trickle irrigation system consisting of a set of plastic tubes for each lysimeter tank and controlled from the tunnel. Fertilizers in controlled amount can be applied with the irrigation water.
STOCHASTIC MODELLING OF STORM PRECIPITATION
Authors: RAMASESHAN S.
Published: May 2018

The distribution of precipitation in time during storms constitutes a complex stochastic process. Mathematical modelling of the process is quite difficult. The process is conceived as a finite-duration, quantitized-data, continuous-variable, stochastic process that can be represented as a finite time series.

Broad outlines of the procedure have been given in an earlier paper (Chow & Ramaseshan 1965). This paper deals with the details of formulating and fitting a suitable stochastic model for the process and the steps are illustrated with an example. The conclusions derived on the basis of the model are also discussed. The methods discussed in this paper may be useful for the study of transient stochastic processes such as floods, droughts, earthquakes, squalls, etc., and for the design of engineering systems to resist or control such processes.
VARIABILITY OF SEASONAL AND ANNUAL RUNOFF IN NORWAY
Authors: TOLLAN ARNE
Published: May 2018

A preliminary map of variability of annual runoff in Norway has been prepared based on estimates of the coefficient of variation cv for 56 non-regulated discharge stations having more than 35 years of continuous observations. The regional pattern of cv reflects the altitude and possibly also the different precipitation regimes of Norway; low variability characterizes the wet western part of the country where frontal precipitation dominates, and relatively high variability typifies the drier South-Eastern Norway where considerable amounts of convective precipitation are common. cv for annual runoff is slightly affected by catchment area. Variability of monthly runoff also shows a regional pattern which is interpreted in terms of runoff regime characteristics.
CHEMISTRY OF GROUNDWATER IN IGNEOUS ROCK AT ANGERED, GOTHENBURG
Authors: JACKS GUNNAR
Published: May 2018

Within an area of about 5 km2, 25 wells were drilled to depths of about 90 m for groundwater observation. The wells were sampled and analyzed, and from the results it could be concluded that the ionic composition is controlled by equilibrium between water and solids. The dominating weathering product is Ca-montmorillonite.

Establishing equilibrium takes approximately ten years. On higher grounds, equilibrium is far from being reached, and these waters are only a couple of years old. In lower positions of the terrain, sea water from glacial times is retained. Turn-over time of water is thus in the order of hundreds to thousands of years. The degree of washing out of the salt water is correlated to the transmissibility of the tectonic zones by which the water is found.
POTENTIAL EVAPOTRANSPIRATION AND WATER BALANCE IN ICELAND
Authors: EINARSSON MARKÚS Á.
Published: May 2018

The paper describes the results of estimations of potential evapotranspiration (Ep) in Iceland using Penman's equation. The calculations are based on distribution maps for global radiation for the period 1958-1967 previously developed by the author, and meteorological data from 28 weather stations for the same period. The distribution of Ep for the year and for the summer (April-September) are mapped. Further, the difference between precipitation and potential evapotranspiration (P-Ep) is calculated and mapped for the year as a whole and for the two periods April-September and May-August according to the values of Ep and precipitation normals (P) for the years 1931-1960.
SINGLE AND MULTI-SITE OPERATIONAL HYDROLOGY
Authors: McMAHON T. A. , CODNER G. P. , PHILIPS C.
Published: May 2018

This paper reviews several different single- and multi-site generation models to complement those papers in which the models are developed but not applied. Initially the historical time series is looked at using various time series techniques, including correlograms and spectral analyses, to determine whether a lag one Markov model will satisfactorily represent the historical data.

The single site models which are examined include an empirical model using the historical probability distribution of the random component, the Thomas and Fiering model using both logarithms of the data and Matalas' log-normal transformation equations, and finally Moran's Gamma distribution. Matalas' Residual method with several probability distributions and Moran's Multivariate Gamma technique are used in the multi-site analysis. All models are applied to the streams of the Melbourne metropolitan water supply system.
RESERVOIR MECHANISM
Authors: ELIASSON JONAS , ARNALDS SIGURDUR ST. , JOHANNSSON SKULI , KJARAN SNORRI P.
Published: May 2018

The physical problem dealt with in this article is the unsteady ground-water flow in an aquifer of limited horizontal extent and arbitrary boundary shape.

The unsteady ground-water level is described by a differential equation, the solution of which includes the solution of an eigen-value problem by a numerical method.

Boundary conditions are provided by nature in the form of watertight rocks, rivers, lakes or any kind of constant water level in hydraulic contact with the aquifer.

The run-off is found to behave as a sum of flows through infinitely many linear reservoirs, corresponding to the eigen-functions.

The resulting equations for ground-water level and run-off discharge are sums of convolution integrals of the infiltration, an easy process to handle in a digital computer.

Finally, the mathematical model derived is used to analyse the inflow into a water reservoir in Iceland from a nearby lava field, and the runoff is compared with flow data.
A DETERMINISTIC PARAMETRIC WATER-BALANCE MODEL
Authors: GRIP HARALD
Published: May 2018

A simple deterministic model, that needs little input-data, is derived. It is based on an analysis of the recession curve, where new considerations are introduced. Input data consist of time-series of precipitation, initial values of storage in upper and lower soil-storages and in interception storage, and initial runoff. Output data are time-series of evapotranspiration, interception, upper and lower soil-storages and runoff, all given as 2-hour mean values.
CHEMISTRY OF SOME GROUND WATERS IN IGNEOUS ROCKS
Authors: JACKS GUNNAR
Published: May 2018

Chemical changes in water circulating deep in the fissures of the solid rock are studied. The ultimate chemical composition is determined by the conditions of percolation through the soil zone. For each liter of water 1 g of mineral will be destroyed. An alkaline environment favors an early formation of Na-montmorillonite. The turnover time varies from some years to thousands of years.
THE CONTENT OF SOME NATURAL RADIOACTIVE ELEMENTS, ESPECIALLY 222Rn, IN SOME POTABLE WATERS IN SWEDEN
Authors: SNIHS JAN OLOF
Published: May 2018

The content of 222Rn in drinking water from 118 wells in southeastern Sweden has been measured. The radiation dose from 222Rn is completely dominant in comparison with the dose from other nuclides examined. Only bored wells and especially those in granite bedrock have contents exceeding 20 nCi per 1. Dug wells usually have contents less than 2 nCi per 1.
EVAPORATION-CONDENSATION AND SNOWMELT MEASUREMENTS IN FINLAND
Authors: LEMMELÄ RISTO , KUUSISTO ESKO
Published: May 2018

Measurements on evaporation and the melting of snow cover are presented, followed by an explanation of how the measured values depend on meteorological factors and the structure of the snow. The observations were made during the period 1968–1973 on an experimental field situated in southern Finland. The regression analysis of the evaporation gave no motive for the use of a non-linear wind function. A theoretical model based on the energy balance has been sought with the aim of explaining snowmelt. However, a simple model containing certain basic parameters gave better results.
DEVELOPMENT OF A STORM RUN-OFF PREDICTION MODEL WITH SIMULATED TEMPORAL RAINFALL DISTRIBUTION
Authors: RAO D. V. L. N. , MANTAN D. C. , HASIJA S. C.
Published: May 2018

The Yamuna catchment up to Kalanur is studied. The representative character of limited pluviograph data was determined using the storm index concept. After establishing a relationship between the limited pluviograph data and areal rainfall data, the possible effects of areal rainfall variation on the use of limited data was studied. A simulated temporal rainfall pattern for the area was then worked out and applied in the unit graph analysis, which led to the development of interesting relationships between rainfall intensity, Antecedent Precipitation Index and Phi-Index on the one hand and the API-IL relationships on the other. These two put together have given rise to a reasonable peak trend prediction diagram for the Yamuna catchment up to Kalanur.
PROCEDURES FOR EVALUATING THE SURFACE WATER BALANCE OF GRAN CANARIA
Authors: AHLGREN LEIF E. , VAN DER ZEL HUBERTUS J.
Published: May 2018

To evaluate the surface water balance in Gran Canaria, standard procedures were modified to fit local conditions, taking into account the availability and quality of data as well as the special features of the island. In a bookkeeping method the terms of the balance equation were calculated on a daily basis. The precipitation was based on data from a limited number of representative stations. Runoff data were extrapolated by quantifying the characteristics of the geological formations using the SCS curve number method. Potential evapotranspiration data based on Class A pan measurements or Penman calculations were extrapolated using the Blaney-Criddle method, and the real evapotranspiration was calculated using the Thornthwaite-Mather hypothesis. The results of this simplified procedure coincide well with results of an independent evaluation of the recharge.
THE BALTIC SEA - A SEMI-ENCLOSED SEA, AS SEEN BY THE HYDROLOGIST
Authors: FALKENMARK MALIN , MIKULSKI ZDZISLAW
Published: May 2018

The paper discusses water renewal of the Baltic Sea, a semi-enclosed basin, the general configuration of the water balance, the size and distribution of its individual elements and the interrelations between them. Connections between long-term variations in the water balance and certain ecological features are stressed. To make possible a deepened understanding of the water renewal, international cooperation has been organized between the seven riparian countries.
ESTIMATION OF THE STORAGE COEFFICIENT OF THE CAMBRIAN SANDSTONE IN THE BILLINGEN - FALBYGDEN AREA, VÄSTERGÖTLAND, SWEDEN
Authors: CARLSSON LEIF , CARLSTEDT ANDERS
Published: May 2018

The storage coefficient for a confined aquifer in lower Cambrian sandstone has been calculated, partly from pumping tests and partly from correlations of water-level fluctuations with changes in atmospheric pressure. The different methods of calculation were in close agreement, although the values differed slightly depending on drawdown or recovery and on the horizontal distance to the border of the confining bed. In the pumping tests, the aquifer was undergoing conversion from confined to unconfined condition, which made it possible to calculate the specific yield of the sandstone too.
Stochastic Modelling of Monthly Streamflow in the Federal Republic of Germany
Authors: Robinson S. A. , Rohde F. G.
Published: May 2018

Monthly streamflow series from five catchment areas, representative of some of the typical types encounted in Germany, are analysed. The time series structure of the streamflow can be described by a set of statistical parameters from which the catchment areas can be parametrically classified and regionalised according to the physical characteristics, local climate and geographical location. Simple stochastic models, with emphasis on the seasonal multiplicative model, are considered. These models describe the streamflow generating process and may be used for synthetic data generation for water resources planning and operational purposes. Their performance and limitations are discussed.
Water Availability to Some Arctic Ecosystems
Authors: Rydén B.E.
Published: May 2018

Water in permafrost areas is available to the organisms during a short time and in a restricted space. Models of soil water occurrence and flow are applicated as basis for analysis of moisture in the environment of organisms. Soil moisture, available for the transpiration process, has been calculated as to soil in permafrost. The seasonal variation of soil moisture is shown.
The Influence of Man's Activities in Rivers on Sediment Transport
Authors: Nilsson Bengt
Published: May 2018

An attempt to use old semicompiled data on turbidity, transport and deposition of suspended material is carried out. The influence of different activities is illustrated. The change of water chemistry during storage in new reservoirs, the influence of short periodic water release and the dam construction itself as a trap to the sediment transport are exemplified. The use of the Sundborg formula as an aid to predict the increased concentration of suspended material during dredgings is shown.
Effects of Acid Precipitation on a Small Acid Lake in Southern Norway
Authors: Henriksen Arne , Wright Richard F.
Published: May 2018

Langtjern is an acid lake situated in south-central Norway, 516 m above sea level. The watershed is underlain by biotite gneisses and granites. Coniferous forests cover 63% of the watershed, while 16% is covered by peaty areas. The lake has a relatively large watershed (4.8 km2) in relation to lake size (0. 23 km2), and most of the water and chemicals reach the lake via the watershed and inflowing streams. Direct precipitation on the lake surface is less important.

The two major inflowing streams show rapid responses to influxes of acid precipitation (weighted annull mean pH 4.3) and long recovery periods between episodes. The fall and spring acid episodes have different impacss on the lake-water chemistry. The spring episode during which large amounss of H+ are released in the first phases of the snow melt reduces the pH in only the surface layers of the still ice-eovered lake and much of the inflowing pollutants are promptly discharged. In the fall, however, the acid inputs are readily mixed through the entire water column during the autumnal circulation period.

Assuming chloride as a conservative parameter, mass-balance calculations show that there is a net loss of Ca, Mg and Al from the watershed while there is a net uptake of H+, NO3 and NH4. SO4 and Na budgets balance. The net uptake of H+ in the watershed is directly related to net losses of other cations. The net uptake of NO3 and NH4 is most likely due to biological uptake by the forest ecosystem.

For the Langtjern itself the inputs of all major ions equal the outputs, except for H+ and NO3 which are retained by the lake. The neutralization of H+ in Langtjern varies seasonally, whereas only 10-20% is neutralized during spring, in the autumn 50-70% is neutralized.
A Method of Calculating the Hydraulic Properties of Leaky Aquifer Systems
Authors: Gustafson Gunnar
Published: May 2018

This paper describes a method for calculating the hydraulic properties of esker aquifers where a leakage to the aquifer is induced by pumping. The method is an extension of the channel method described in an earlier paper. As an example of the applicability of the method a short description of a performed pumptest is given.
The Physiographic Influence on Recession Runoff in Small Norwegian Rivers
Authors: Tjomsland Torulv , Ruud Erik , Nordseth Kjell
Published: May 2018

This paper presents a statistical correlation procedure to predict a master depletion curve by use of basin characteristics and the specific storage of water available for runoff at a particular recession discharge in small watersheds. Percentual lake area, drainage density and a weighted lake inflow area index are the most significant parameters to explain differences in specific storage among basins. The significance shows time-dependency. Percentual lake area has a decreasing contribution to a total explanation from high to low specific discharges, while drainage density increases its importance.
Eutrophication Models for Lakes
Authors: Simonsen Jørgen F. , Dahl-Madsen K.I.
Published: May 2018

In the years 1970-1977 eutrophication models have been developed and applied for about 15 shallow Danish lakes. The structure of these models are discussed. An example of the calibration of the model on data from Lake Gyrstinge in the Suså catchment area is shown, and the use of the model for calculating ecological consequences of changed hydraulic retention times is demonstrated. The dynamic eutrophication model is compared to the Dillon-Rigler version of the input-output model. Limitations of both types of models are discussed.
Spatial Correlation of Hydrologic and Physiographic Elements
Authors: Gottschalk Lars
Published: May 2018

In an earlier paper (Gottschalk 1977) analytical expressions were given for the time correlation of hydrologic processes from the linearized equations of motion for these processes. In this paper space correlation is similarly treated. Comparison is made with empirical space correlation functions of hydrologic and physiographic elements.
A Unified Approach to Watershed Modelling
Authors: Afouda A.
Published: May 2018

This paper summarizes the main points of a theoretical study of the general watershed behaviour, on the basis of the known deterministic physics-based approaches for overland flow, underground flow and unsaturated medium phýsics. A parameter z(θ) which describes the soil water movement in the unsaturated zone and accounts for evaporation is introduced. Thus, a differential equation which allows a state-space formulation of the processes in the watershed is obtained, and the solution of the state equation can be given the form of the Volterra Integral series. The obtained results are compared with those of previous studies.
Mass Balance of Dissolved Inorganic Substances in Three Representative Basins in Sweden
Authors: Andersson-Calles Ulla Maria , Eriksson Erik
Published: May 2018

During the International Hydrological Decade six representative basins were operated in Sweden. One of these represented an extensive raised bog area, Komosse, southwest of Lake Vättern. Another basin, Verka, north of Stockholm, represented a mixture of agricultural and forestry typical for this part of Sweden. A third covered an extensively glaciated area in the north of Sweden, well above the thimber line.

The typical forested areas in Sweden were represented by three basins, Velen between Lake Vänern and Lake Vättern; Kassjöån in the middle of Sweden and Lappträsket in the far north.

The research programs for all these basins included hydrochemistry mainly for the purpose of establishing balances of dissolved inorganic matter. The present paper discusses the results from the three forested basins, Velen, Kassjöån and Lappträsket.
The Sulphur Budget of Sweden During this Century
Authors: Odén Svante
Published: May 2018

Based on data from the Swedish water quality covering 78% of the Swedish area, the discharge of sulphur has been computed for the period 1969 to 1977. The trend for this period gives a figure for 1977 of 660,000 tons per year. This figure exceeds that of the atmospheric fallout by about 200,000 tons per year. The different items contributing to this difference are discussed.

The increase of the discharge of sulphur during the investigated period varies from 2 to 5% per year in the different regions of Sweden. Due to the storage characteristics of the soil-water reservoirs the increase of the input of sulphur must be larger than these figures.

The discharge of sulphur from different parts of Sweden during this century has been reconstructed. The total figure in excess of a geochemical reference amounts to about 60 million tons of sulphur. In parts of the South and West of Sweden the annual deposition of sulphur amounts to about 25 kgs per ha. Rough figures of the so-called biogenic sulphur can be given for Sweden along with a geochemical reference value.

The application of these figures to the increasing acidification of Sweden is obvious.
Acidification in 50 Norwegian Lakes
Authors: Økland Jan
Published: May 2018

In 50 lakes in south-eastern Norway hydrogen-ion concentration (pH) and total hardness (°dH) were measured in surface water in the 1950's and then once again 10 years later. Significant acidification was observed. In the total material average pH dropped from 7.0 to 6.8. The lakes were grouped into a low-total-hardness (0-l°dH) and a high-total-hardness group (>l°dH). [l°dH = 10 mg »CaO«/l]. In the low-total-hardness group average pH had dropped from 6.6 to 6.3 and the average H+ concentration increased with 4.33. 10−7 mol/1. In the high-total-hardness group significant acidification could hardly be traced. The data confirm previous observations that also lakes which in previous years had pH close to the neutral point have become acidified. Total hardness showed no significant change.

Acidification seems to occur most frequently in lakes with total hardness ⩽l°dH. Such lakes are present all over Norway and are dominant in many areas.