bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal design of storm water inlets for highway drainage
Authors: Nicklow John W. , Hellman Anders P.
Published: May 2018

A new methodology and computational model are developed for direct evaluation of an optimal storm water inlet design. The optimal design is defined as the least-cost combination of inlet types, sizes and locations that effectively drain a length of pavement. Costs associated with inlets are user-defined and can include those associated with materials, installation and maintenance, as well as other project-related expenses. Effective drainage is defined here as maintaining a spatial distribution of roadway spread, or top width of gutter flow, that is less than the allowable width of spread. The solution methodology is based on the coupling of a genetic algorithm and a hydraulic simulation model. The simulation model follows design guidelines established by the Federal Highway Administration and is used to implicitly solve governing hydraulic constraints that yield gutter discharge, inlet interception capacity and spread according to a design storm. The genetic algorithm is used to select the best combination of design parameters and thus solves the overall optimization problem. Capabilities of the model are successfully demonstrated through application to a hypothetical, yet realistic, highway drainage system. The example reveals that genetic algorithms and the optimal control methodology comprise a comprehensive decision-making mechanism that can be used for cost-effective design of storm water inlets and may lead to a reduced overall cost for highway drainage.
Development of a discharge equation for side weirs using artificial neural networks
Authors: Khorchani Mohamed , Blanpain Olivier
Published: May 2018

Flow over a side weir is one of the more complex flows to simulate in one-dimensional unsteady flow analysis. Various experiments have been applied, but no agreement is apparent in the literature about the best method. In this study, an Artificial Neural Network model has been used to extract a discharge equation for side weirs which accurately estimates overflow discharges. The proposed methodology gives the advantage of accounting for both the geometric and hydraulic characteristics of the overflow structure. The developed model is calibrated and validated using experimental data. Model calibration is achieved by using a Multi-Layer Perceptron (MLP), trained with the back-propagation algorithm. In order to highlight the advantage of the developed model over an existing model widely in use, the model's performance is evaluated according to three comparison criteria. The provided results clearly reflect the ability of the developed model to overcome the weakness of conventional models.
Web-based GIS and spatial decision support system for watershed management
Authors: Choi Jin-Yong , Engel Bernard A. , Farnsworth Richard L.
Published: May 2018

Geographic Information Systems (GIS) have been widely used for spatial data manipulation for hydrologic model operations and as a supporting tool to develop spatial decision support systems (SDSS). Information technologies, including GIS and the Internet, have provided opportunities to overcome many of the limitations of computer-based models in terms of data preparation and visualisation, and provide the possibility to create integrated SDSS. This paper examines the relationship between changes in GIS technology and watershed management SDSS. It also describes a conceptual web-based SDSS framework in terms of system components and data flow. A prototype watershed management web-based SDSS that utilises the conceptual framework is examined (URL: http://pasture.ecn.purdue.edu/~watergen/owls). The SDSS uses web-GIS for watershed delineation, map interfaces and data preparation routines, a hydrologic model for hydrologic/water quality impact analysis and web communication programs for Internet-based system operation. The web-based SDSS can be helpful for watershed management decision-makers and interested stakeholders. The watershed management SDSS also provides insight into the role of GIS and information technologies in creating readily accessible and useable SDSS capabilities.
Integrated use of GIS-based field sampling and modeling for hydrologic and water quality studies
Authors: Vivoni Enrique R. , Richards Kevin T.
Published: May 2018

Enhancements to traditional catchment-scale water quality assessments can be realized by leveraging geographical information systems (GIS) for both field data collection and hydrologic and water quality (H/WQ) modeling. In this study, we describe a GIS-based data collection system for geo-referenced environmental sampling utilizing mobile, wireless and Internet technologies. Furthermore, sampled field data is combined with historical measurements within a GIS-based semi-distributed watershed model for simulating water quantity and quality in a large regional catchment. The GIS-based sampling and modeling system is intended to streamline water quality assessments as compared to current practices. We describe an application and field study in the Williams River, New South Wales, Australia designed to assess the impacts of point and non-point source pollution on water quality. Historical data were utilized for calibrating and validating the Hydrologic Simulation Program – Fortran (HSPF) with the BASINS GIS interface over the 1988–2000 period. Results from the study indicate that short-duration, spatially extensive field campaigns provide useful data for enhancing modeling studies based on historical measurements at sparse sites. In addition, the study suggests that the conjunctive use of data collection and modeling is a step towards real-time integration of field data in hydrologic and water quality modeling efforts.
DEPTH INTERVALS AND TOPSOIL MOISTURE MEASUREMENT WITH THE NEUTRON DEPTH PROBE
Authors: KRISTENSEN K. J.
Published: May 2018

From measurements and calculations using a depth probe, the relative response is estimated for soil layers of different thicknesses. For a 10 cm thick layer of soil with the instrument centre in the middle, about 40 to 70 per cent of the response is caused by this particular layer at a water content of 8 to 40 per cent by volume. For a 20 cm layer the response for similar conditions is about 65 to 85 per cent.

A special calibration function for the upper (0–20 cm) soil layer is demonstrated for the neutron depth probe. It is found that the water content in this soil layer can be estimated in this way with about the same degree of accuracy as can be expected by conventional methods.
The Prediction of Waste Water Dilution by a Long-Term Tracer Experiment
Authors: Kuoppamäki Risto , Muurinen Arto
Published: May 2018

In general tracer experiments made for the evaluation of waste water dilution in recipients have been of short-term type, with the tracer having an injection time that is markedly less than the time scale of flowpattern changing. In typical Finnish lakes and coastal waters, with complicated topography and frequently varying winds, the results from short term experiments have proved to be of rather limited value. In view of this, a study has been made of the possibility of measuring the dilution under such circumstances, by means of a long-term experiment with a tracer injection time extending over several weeks. Indium was considered to be the most suitable tracer for such an experiment; the complex form of indium is preferable to ionic solution to ensure reliability in the results.

The applicability of the method in the fields is illustrated by an example of a waste-water dilution study made for a pulp mill under construction. Two subsequent long-term experiments were conducted for measurement of the dilution of waste water from two alternative discharge points. The results obtained gave a very clear illustration of the local average dilution ratios, and allowed a reliable comparison being made between the two alternative discharge points.
Return Periods of Hydrological Events
Authors: Rosbjerg Dan
Published: May 2018

A relation between return periods of hydrological events in annual maxima and partial duration series respectively is shown to be exactly fulfilled when the events take place according to a Poisson process. Furthermore it is shown that the relation can be used as a good approximation when dealing with more regular processes than the Poissonian. Finally a record of rainfall depths is analysed.
Hot Groundwater Systems in Iceland Traced by Deuterium
Authors: Arnason Bragi
Published: May 2018

This paper summarizes the result obtained for hydrothermal systems in Iceland, by using deuterium and oxygen-18 as natural tracers.

The deuterium content of a single sample of a local cold spring or river, except those rivers fed by considerable amount of glacier melt water, can be used to estimate the mean deuterium concentration of precipitation in the corresponding locality. Furthermore the deuterium content of the last winter layer, collected on Icelandic glaciers in spring before the melting season, is practically identical to the mean value of the corresponding annual precipitation. These facts have been used to draw a detailed map showing the amount of deuterium in precipitation over the whole country. Deep ice core studies show that the deuterium content of precipitation in each place has remained more or less unchanged during the last 8000 years.

Measurements of both deuterium and oxygen-18 in the groundwater have confirmed that all groundwater in Iceland is originally meteoric and that the deuterium content of the thermal water does not change on its way through the bed-rock.

The deuterium content of water discharging from hot springs or drill holes is often very different from the deuterium content of local precipitation. On the other hand, by comparing results obtained with the deuterium map, it is often possible to find where this water has fallen as rain and to trace its underground flow path. Deuterium measurements have been made on water from nearly all geothermal areas in the country. The results are drawn up together in one picture, which shows the origin and flow paths of most of the hot groundwater systems in Iceland.

Finally it has been possible to give som idea of the age of the thermal groundwater, i.e. the time past since precipitation. The thermal water is obviously of varying ages. The »youngest« water seems only to be a few decades old, whereas the »oldest« appears to be from the last glaciations.
Optimal Scheduling of Water Supply Projects
Authors: Knudsen Jesper , Rosbjerg Dan
Published: May 2018

Some capacity expansion problems encountered in water resources development are studied. Models yielding least-cost shedules (i.e. optimal selection and sequencing of potential projects) in order to meet a stipulated increase in water demand are first discussed. However, recognizing uncertainties in the future demand, these ought to be taken into account. In order to do this, a new general dynamic programming algorithm has been developed. Depending on how detailed we are able to state the preferences against shortage, chance-constraints or penalty functions are included in the optimization. The use of the algorithm, as an aid in the current planning, is illustrated by solving an example under deterministic as well as stochastic assumptions about the future demand.
Estimation of Parameters of Converging Overland Flow Model
Authors: Singh Vijay P. , Shelburne Kevin L.
Published: May 2018

The converging overland flow model contains five parameters, three geometric and two kinematic. An attempt is made in this study to estimate these parameters utilizing watershed topographic characteristics. By applying the model, with parameters estimated in the proposed fashion, to natural agricultural watersheds, its potential in the prediction of surface runoff is indicated.
The Groundwater Runoff of Polish Rivers
Authors: Gutry-Korycka Malgorzata
Published: May 2018

The groundwater runoff of Polish rivers displays considerable regional variations which are also manifested in the time distribution. The spatial distribution depends upon geological structure of the area. Its characteristic features together with precipitation account for conditions of groundwater runoff based on permeability and natural drainage. The time and spatial variability of groundwater runoff is due to a joint effect of environmental and hydroclimatologic factors such as rainfall, snowmelting, evaporation.
Estimating Lake Evaporation with Floating Evaporimeters and with Water Budget
Authors: Järvinen Jukka
Published: May 2018

A short review of the four lake evaporation research projects in Finland is given. Three of the lakes studied are situated in southern Finland and one in the north. One of the lakes is deep in Finnish terms and the rest are shallow. The methods used and the results obtained in 1971–1974 are also discussed in this paper. The results are compared with those of a Class A pan station. Two of the research projects have already been reported in more detail in IAHS publication No. 109.
A Finite Element Aquifer Model which takes into Account Elevation Changes of the Aquifer
Authors: Aalto Jukka
Published: May 2018

A finite element formulation for confined aquifer flow, which takes into account elevation changes of the aquifer is presented. The middle surface of the aquifer is assumed not as a horizontal plane but as a curved surface. The theory of isoparametric finite elements is applied to develop a general isoparametric surface element for the problem. The presented technique can, with little additional programming effort, be incorporated into any standard finite element computer program for solving the two-dimensional quasi-harmonic differential equation (i.e. equation governing heat conduction, electric potential, seepage through porous media etc.) A computer program using a four node quadrilateral surface element has been developed. Some results of two examples analyzed using this program are finally established.
Geohydrological Properties of Tectonic Zones in Hard Rocks Obtained from Artificial Recharge Tests and Numerical Modeling
Authors: Carlsson L. , Ejdeling G.
Published: May 2018

Results from artificial recharge tests through wells in Angered, Gothenburg have made studies on geohydrological properties of tectonic zones possible. Measurements of piezometric head in bore holes were used to evaluate the transmissivity and storage coefficient of the zones by using a finite element model. The zones were considered to act as separate confined aquifers, and the values obtained were T ≡ 3-4 · 10−6 m2/s and S ≡ 4-6 · 10−5.. The hydraulic conductivity of the rock mass was then found to be greater than 2-5 · 10−8 m/s, which is in agreement with values of fractured, crystalline rock in Sweden obtained in other investigations.
Redox Reactions in Soils Sequence of Redox Reactions in a Waterlogged Soil
Authors: Ohlsson Thord
Published: May 2018

An apparatus is described which under laboratory conditions permits sampling of water and gases from a waterlogged soil throughout the experimental period. A cultivated soil supplied with 6% straw is waterlogged during 97 days and the sequence of some redox reactions is shown. After one day of waterlogging the redox potential declines and reaches negative values after six days. pH declines from 7.5 to 6.5 after 17 days of waterlogging and then slowly increases to about neutral again. NO3−− is the first compound to be reduced and within two days all NO3− has disappeared. NO2− is only detected during the first two days. After NO3− has been reduced Mn2+ increases, followed by a large increase of Fe2+. S042−- has totally disappeared within the first three weeks of waterlogging. CO2 is produced during the whole experimental period. A large production of CH4 begins after three weeks of waterlogging. N2O was not detected.
Snowmelt Prediction in a Subarctic Drainage Area
Authors: Fitzgibbon J.E. , Dunne T.
Published: May 2018

Three prediction methods were tested against observed melt for their ability to predict snowmelt in a variety of subarctic environments. Four melt environments were defined according to vegetation cover. They are: Closed Lichen Woodland, Open Lichen Woodland, Regenerating Burn and Burn. The three methods tested are the physical energy balance method (with some data approximations), the U.S. Army Corps of Engineers method (empirical energy balance) and the temperature index method (using mean daily air temperature). It was found that the physical energy balance is most applicable in the Burn and Regenerating Burn while the U.S. Army Corps of Engineers and temperature index methods provide adequate prediction in all four melt environments.
Monitoring Glacier Outburst Floods
Authors: Young G.J.
Published: May 2018

A review is given of the phenomenon of glacier outburst floods. Geographical distribution, modes of occurrence of glacier-dammed lakes and modes of lake-emptying are discussed. Techniques of monitoring the filling and emptying of glacier-dammed lakes are evaluated and procedures for forecasting the magnitude and frequency of floods are analyzed. The histories of floods on the Salmon River (British Columbia/Alaska) and the Donjek River (Yukon) are given as examples.
Inadequacies in theTechnique of Resistivity Method for Location of Waterwell Sites in Hard Rock Areas
Authors: Ballukraya P.N. , Sakthivadivel R. , Baratan R.
Published: May 2018

Large scale exploratory work for groundwater in hard rock region of South India has been carried out by the authors during the last ten years, using electrical resistivity method. The standard methods of data interpretation were found to be inadequate in locating water well sites and determining the existence and depth of occurrence of water bearing fractures and joints. Wenner and Schlumberger type vertical electrical sounding (VES) curves were interpreted by matching against theoretical model curves and also by inverse slope method. The interpreted results were correlated with the actual driller's logs. No satisfactory correlation could be observed either between the geoelectrical interpreted layer boundaries and the layer boundaries from the wells or between the resistivity in the hard rock and the water yield. A more pragmatic approach to the problem is desirable to minimize the failures of wells in hard rock terrain.
Evapotranspiration at Two Mountain Sites During the Vegetation Period
Authors: Staudinger M. , Rott H.
Published: May 2018

Hourly values of evapotranspiration (ET) for the months July to September 1976 and 1977 were calculated from energy balance measurements at two test sites near the village of Obergurgl in the Austrian Alps. One test site was situated at 1,960 m a.s.l. on a cultivated meadow near the timberline, the other test site at 2,580 m a.s.l. was covered with alpine sedges and grasses. Examples of the daily variations and daily sums of the energy fluxes are presented for clear and cloudy days. The mean daily courses of ET at the two test sites are shown for every month of the measurement periods; differences in ET between the two test sites are related to the decrease of transpirating leaf areas with altitude. Monthly sums of ET are presented in relation to net radiation and precipitation; on the average ET was about 30% lower at the higher elevated site. High correlations were found between the daily sums of net radiation and of ET at both sites. This relation can be used for calculating ET from radiation measurements.
Meltwater Hydrology and Hydrochemistry in Snow- and Ice-Covered Mountain Catchments
Authors: Collins David N. , Young Gordon J.
Published: May 2018

Electrical conductivity, a surrogate measure of total dissolved solids content, and discharge of meltwaters draining from two adjacent contrasting watersheds in the Rocky Mountains, Canada, were recorded continuously from mid-May – August 1979, throughout the ablation season, in order to investigate the influence of snow- and ice-melt on alpine hydrochemistry. Solute concentration varied inversely diurnally with discharge in both nival and glacial meltwaters. Solute content and discharge of the snowmelt-fed Amiskwi River declined with decreasing availability of snowcover through July, followed by increased solute content during low flows in August. In the glacially-fed Peyto Creek, conductivity decreased with increasing flow during spring snow-melt, but during ice-melt domination of flow from mid-July oscillated daily through a limited range. Snow- and ice-melt are shown to have contrasting roles in determining distinctive patterns of diurnal and seasonal temporal variations of discharge and hydrochemistry in mountain basins. Continuous monitoring of water quality is essential in characterising the hydrochemistry of alpine environments.
Glacial-Hydrological Investigations at the Vernagtferner Glacier as a Basis for a Discharge Model
Authors: Oerter H. , Baker D. , Moser H. , Reinwarth O.
Published: May 2018

The report gives a review on the glacial-hydrological work carried out since 1974 in the project “Runoff within and from glaciers” of Sonderforschungs-bereich 81 of the Technical University Munich with the aim of creating a deterministic discharge model. Since 1974 the runoff of Vernagtferner glacier has been recorded at the gauge station “Pegelstation Vernagtbach” (catchment area 11.44 km2, mean altitude 3,125 m a.s.l., 81% glaciated). The discharge hydrographs for the years 1974-1980 are discussed and characteristic time intervals with characteristic discharge components are pointed out. Using the different discharge patterns exhibited by different parts of the glacier, a spatial classification for the discharge formation is given, and the different hydraulic conditions are described. The mathematical model which is proposed uses four parallel linear reservoirs for which the storage constants were determined by former experiments. For a fortnight period with dry and sunny weather the discharge is calculated with the energy balance on the glacier surface as input data.
Lag Time for Diverging Overland Flow
Authors: Singh V.P. , Agiralioglu N.
Published: May 2018

This paper presents kinematic solutions, both analytically and nomographically, of surface water lag time for diverging overland flow. These solutions can be utilized to estimate lag time from physically measurable watershed characteristics.
Statistical Flood Flow Estimation
Authors: Reinius Erling
Published: May 2018

The frequency analysis of flood flows recommended in textbooks yields different results by the graphical method of plotting on probability paper using e.g. the Weibull plotting position formula and the analytical method assuming e.g. log-normal or log Pearson type III distributions. If both methods were correct, the results of the two methods should be identical.

The plotting position formulas assume that the plotting position should coincide with the mean (or median) of the probabilities which the observation of a rank m has in a great number of samples, each of the same size N. A study of the problem by using synthetic samples shows that these positions do not coincide with the line of the population.

A further study shows, however, that the positions of the probabilities of the expected – mean – values of the largest, next largest etc. observation coincide with the line of the population. Thus, it is not the mean value of p of a rank m, but the value of p of the mean value of log q of the rank m, which agrees with the line of population. Therefore, the author finds it essential that the logarithm of the annual peak flows obtain a plotting probability equal to the probability of the expected value of the logarithm of the observations. A new plotting position formula which corresponds to the probability of the expected values of log q is derived.
Measurement and Modeling of Microwave Emission from Forested Snowfields in Michigan
Authors: Hall D. K. , Foster J. L. , Chang A. T. C.
Published: May 2018

Forest cover was found to confuse the normally inverse relationship between microwave brightness temperature (TB) and snow depth in dry snowpacks in the lower peninsula of Michigan during February of 1979 and 1980. However, even in the presence of forest cover, consisting of a mixture of hardwoods and softwoods, the average Nimbus-7 SMMR 37 GHz vertically and horizontally polarized TBs were 11° and 19° K lower during the study period in February of 1979 versus February of 1980. This is attributed to deeper average snowcover for the study period in 1979 (43.8 cm) as compared to 1980 (9.9 cm) since lower TBs accompany deeper snow under dry snowpack conditions. 37 GHz brightness temperature was correlated with snow depth for the study periods in 1979 and 1980, resulting in positive relationships instead of the expected inverse relationships. Because the snow depth increased with increasing forest cover in the lower peninsula of Michigan, it was assumed that the emissivity of the forest cover overwhelmed that of the snow - both in 1979 and 1980 causing higher TBs in more heavily forested areas. Using a simple model, we removed the effects of the trees from the TB/snow depth relationship. A new value, TBR, residual brightness temperature, derived from the 37 GHz data, was correlated with snow depth for selected time periods in February 1979 and 1980 resulting in inverse relationships of R ≡ .82 and .77 respectively. In addition, SMMR data of August 1979 were correlated with percent forest cover to determine the TB of the study area in the absence of snow. The lower SMMR frequencies (10.69 and 6.6 GHz) showed statistically significant inverse relationships with forest cover during the August study period. These inverse relationships were probably due to increased soil moisture in the more heavily forested areas in the northern half of lower peninsula of Michigan thus causing lower TBs.
The Effect on Storm Runoff Response of Seasonal Variations in Contributing Zones in Small Watersheds
Authors: Taylor Colin H.
Published: May 2018

Storm runoff production by saturation overland flow has been studied in two small watersheds in south-central Ontario. One is in rural land use and contains a wetland. The total saturated zone is at its maximum extent during spring snowmelt, when the overwhelming majority of total runoff and quickflow is produced. The stream seldom flows during the summer and winter seasons but does so occasionally in the fall if the wetland is recharged sufficiently. Simple calculations show that storm-to-storm variations in quickflow response are controlled by the extent of surface soil saturation (measured by field mapping and correlated with antecedent wetness variables) and precipitation amount. The other watershed has been undergoing suburban development since 1973. Quickflow response during summer and fall seasons has not changed noticeably since then, although 30% of the watershed surface has been disturbed. This is because in those seasons quickflow is still produced as saturation overland flow from the original contributing zones alongside the stream. In contrast, during spring snowmelt the very wet soil conditions and a high water table allow the disturbed surfaces with low infiltration capacities to be integrated into the contributing area via normally dry drainage lines. As a result spring quickflow has increased by three to four times over the original values.
Development and Application of a Storage Model for River Flow Forecasting
Authors: Hata Takeshi , Anderson Malcolm G.
Published: May 2018

A lumped sequential river flow forecasting model is outlined. It is shown to be flexible in both temporal and spatial scales, thereby allowing simulations to be undertaken for a wide range of practical purposes. In addition, the required data input is very low, and is restricted to topographic data for only small segments of the entire catchment. The model is successfully applied to the River Avon in England and the River Kako in Japan.
Estimation of Potential and Actual Evapotranspiration
Authors: Hansen Søren
Published: May 2018

A model for determining the potential and actual evapotranspiration from agricultural crops is presented. The model requires only a limited number of meteorological variables, i.e. global radiation, air temperature and precipitation. The vegetation is characterized by the crop surface area and the efficient root depth. The soil is characterized by the root zone capacity. The model simulates evaporation of intercepted water, evaporation from the soil surface and transpiration from plants. The evapotranspiration pressure (potential evapotranspiration) is divided between crop and soil by use of Beer's law.
The Movement of a Continuously Growing Body of Oil on the Ground Water Table
Authors: Greulich Rudolf , Kærgaard Henrik
Published: May 2018

Approximative formulas for the movement of a continuously growing body of oil on the ground-water table are presented and illustrated. The approxima­ions are many, but the formulas are believed to produce realistic results for a major flow of crude oil from a leaking pipeline. The main objective is a simple hydraulic flow description, where also capillary forces at the rim are considered.
A Mathematical Modelling System for Flood Forecasting
Authors: Jønch-Clausen T. , Chr. Refsgaard J.
Published: May 2018

In this paper comprehensive simulation models are presented which can forecast the streamflow in real time at various points in river systems and provide a tool for identifying improvements of the reservoir operations during flood situations while taking into consideration the conditions downstream. The mathematical modelling has involved rainfall-runoff predictions as well as flood routing. The application of the modelling system to a part of the 22,000 square kilometres Damodar River Catchment located in Bihar and West Bengal in India, is described.
A Comparison of Some Methods of Deriving the Instantaneous Unit Hydrograph
Authors: Singh V. P. , Corradini C. , Melone F.
Published: May 2018

The geomorphological instantaneous unit hydrograph (IUH) proposed by Gupta et al. (1980) was compared with the IUH derived by commonly used time-area and Nash methods. This comparison was performed by analyzing the effective rainfall-direct runoff relationship for four large basins in Central Italy ranging in area from 934 to 4,147 km2.

The Nash method was found to be the most accurate of the three methods. The geomorphological method, with only one parameter estimated in advance from the observed data, was found to be little less accurate than the Nash method which has two parameters determined from observations. Furthermore, if the geomorphological and Nash methods employed the same information represented by basin lag, then they produced similar accuracy provided the other Nash parameter, expressed by the product of peak flow and time to peak, was empirically assessed within a wide range of values. It was concluded that it was more appropriate to use the geomorphological method for ungaged basins and the Nash method for gaged basins.
Effects of Excess Rainfall Time Distribution on Catchment Area Hydrograph
Authors: Hager Willi H.
Published: May 2018

The effect of triangular excess hyetographs on catchment area runoff process is investigated, thereby fixing the precipitation time. The approach accounts for the kinematic wave theory and allows a discussion of arbitrary hyetograph shapes. The results are compared with these originating from a uniform excess rainfall and underline the importance of proper account for the hyetograph shape.
Unsteady Flow to a Non-Penetrating Well in Extensive Aquifers
Authors: Şen Zekâi
Published: May 2018

The unsteady drawdown distribution around a non-penetrating well discharging from an extensively thick confined aquifer has been obtained. The solution is expressed in terms of dimensionless time factor and well function similar to the Theis method. However, the basic parameters are the hydraulic conductivity and specific storage coefficient. It is found that the type curves for non-penetrating wells is identical to the Theis type curve. Classical matching procedure leads to the determination of the specific storage and hydraulic conductivity coefficients.
Modeling the Hydrologic Cycle: The MC Model
Authors: Deschesnes J. , Villeneuve J.-P. , Ledoux E. , Girard G.
Published: May 2018

This article discusses the joint modeling of surface and groundwater flows by presenting and describing the MC model. The purpose of this deterministic physically based model is to simulate the behavior of available water resources for one or many watersheds. The model integrates surface flow, streamflow, flow in the non-saturated zone, groundwater flow and the interactions between rivers and water tables. Its formulation and its structure, especially its nested square meshes of variable sizes, confer a great deal of flexibility to the model; this facilitates adaptation to variable modeling scales and to a wide range of geological, geographical and climatological conditions.
Extrapolating Snow Measurements on the Marmot Creek Experimental Basin
Authors: Bernier Pierre Y.
Published: May 2018

From 1969 to 1980, each March, snow depth and water equivalent were sampled around 249 pins of a grid covering the forested portion of Marmot Creek basin. Continuous record from four snow pillows and monthly data from six snow courses were used to extrapolate the spatially intensive grid data to other winter months. Snow courses were better estimators of grid data than snow pillows. Readings from about 80 % of the pins were correlated to the data from one or the other snow pillows with r2 above 0.70. The ability of a snow course to track the year-to-year variations in the March data of individual pins of the grid was not related to similarities in elevation or aspects between the course and the pins.
Modelling Water Exchange and Transit Times in Till Basins Using Oxygen-18
Authors: Lindström Göran , Rodhe Allan
Published: May 2018

The application of hydrological models to data on conservative tracers can yield information about transit times and storage volumes and may provide an independent test of the model structure.

In this study, the PULSE-model has been modified to simulate conservative tracers. Attempts have been made to describe both short-term and long-term variations in oxygen-18 concentration in three small forested basins.

The performance of the model was considerably increased, when additional storage was introduced in the model. The turnover times were estimated to approximately 7 and 12 months for two of the basins.
Storage Coefficient Determination from Quasi-Steady State Flow
Authors: Şen Zekâi
Published: May 2018

A method has been proposed for determining a unique storage coefficient value for confined and unconfined aquifers tapped by a large diameter well. The prerequisites for the application of this method are estimation of the transmissivity value and the field measurements of well radius, pumping discharge and time-drawdown measurements at large times, or preferably at the steady or quasi-steady state flow conditions. The application of the method does not require any complicated mathematical procedure of the classical type curve matching procedures. It is recommended especially as a supplementary method to the existing techniques in determining the storage coefficient.
Modelling the Effects of Acid Deposition: Estimation of Long-Term Water Quality Responses in Forested Catchments in Finland
Authors: Lepistö A. , Whitehead P. G. , Neal C. , Cosby B. J.
Published: May 2018

A modelling study has been undertaken to investigate long-term changes in surface water quality in two contrasting forested catchments; Yli-Knuutila, with high concentrations of base cations and sulphate, in southern Finland; and organically rich, acid Liuhapuro in eastern Finland. The MAGIC model is based on the assumption that certain chemical processes (anion retention, cation exchange, primary mineral weathering, aluminium dissolution and CO2 solubility) in catchment soils are likely keys to the responses of surface water quality to acidic deposition. The model was applied for the first time to an organically rich catchment with high quantities of humic substances. The historical reconstruction of water quality at Yli-Knuutila indicates that the catchment surface waters have lost about 90 μeq l−1 of alkalinity in 140 years, which is about 60% of their preacidification alkalinity. The model reproduces the declining pH levels of recent decades as indicated by paleoecological analysis. Stream acidity trends are investigated assuming two scenarios for future deposition. Assuming deposition rates are maintained in the future at 1984 levels, the model indicates that stream pH is likely to continue to decline below presently measured levels. A 50% reduction in deposition rates would likely result in an increase in pH and alkalinity of the stream, although not to estimated preacidification levels. Because of the high load of organic acids to the Liuhapuro stream it has been acid before atmospheric pollution; a decline of 0.2 pH-units was estimated with increasing leaching of base cations from the soil despite the partial pH buffering of the system by organic compounds.
Overland Flow on Pervious, Converging Surface
Authors: Osman Akan A.
Published: May 2018

A desk-top method based on kinematic overland flow and Green-and-Ampt infiltration models is developed to determine the time of concentration of and the peak runoff rate from a converging basin. The governing equations of the rainfall-infiltration-overland flow process are written in terms of various dimensionless parameters. Common values of these parameters indicate hydrologic similarity of an infinite number of different converging basins, and therefore the results obtained in terms of these physically-based parameters can be generalized. Using this similarity concept, two charts have been developed to determine the time of concentration of a basin and the peak runoff rate. As illustrated by a sample application, these charts can be used for quick estimates of the design discharge for storm drainage facilities.
Dynamic Ice Breakup Control for the Connecticut River near Windsor, Vermont
Authors: Ferrick M. G. , Lemieux G. E. , Weyrick P. B. , Demont W.
Published: May 2018

The Cornish-Windsor bridge is the longest covered bridge in the United States and has significant historical value. Dynamic ice breakup of the Connecticut River can threaten the bridge and cause flood damage in Windsor, Vermont. We monitored ice conditions throughout the 1985-86 winter, observed a mid­winter dynamic ice breakup, conducted controlled release tests during both open water and ice cover conditions, and analyzed more than 60 years of temperature and discharge records. River regulation presents alternatives for ice mangement that would minimize water levels during breakup. In this paper we develop the basis of a method to produce a controlled ice breakup at lower stage and discharge than occur during major natural events.
On the Physico-Chemical Basis for the Capillary Barrier Effect
Authors: Rasmuson Anders , Eriksson Jan-Christer
Published: May 2018

The capillary barrier concept, using fine and coarse soil layers to reduce water infiltration into piles of hazardous wastes, is investigated theoretically. A detailed account of the hydrological and physico-chemical basis for the phenomenon is given. It is established that the capillary barrier will, in practice, only function if the fine layer remains somewhat unsaturated, i.e. the upper menisci exist and no ponding over the fine layer occurs. Accordingly, water reaching the fine layer must be transported laterally within this layer. The pressure conditions are dependent on the length of the interface, the slope of the interface, the thickness of the fine layer, the type of soil in the fine layer, the water influx at the surface, and the total volume of water infiltrated during an infiltration event. A simple estimate shows that the capillary barrier concept is feasible only for small heaps with steep interfacial slopes.
A new Expression for the Uncertainty of a Current Meter Discharge Measurement
Authors: Lintrup Morten
Published: May 2018

A method for the conduction of routine current meter discharge measurements practised in Denmark and Norway is described. Contrary to traditional methods (ISO-recommendations) it incorporates information about the geometry of the stream profile in question into the choice of measurement layout. An associated method for calculation of the measurement uncertainty is developed. By tentative application to a testset of mesaurements it is rendered probable that the developed method will be able to provide satisfactory estimates of the uncertainty of current meter measurements while at the same time having a wider applicability and being easier to use than existing methods.
Methods for Measuring the Saturated Hydraulic Conductivity of Tills
Authors: Jenssen Petter D.
Published: May 2018

The texture of tills excludes many of the traditional methods for measurement of the saturated hydraulic conductivity. The hydraulic conductivity is scale dependent and for massive relatively homogeneous till a representative sample volume of 104-105 cm3 is suggested. There are no ideal methods for measuring the saturated hydraulic conductivity in till and type of method and equipment should be carefully selected. Studies comparing and evaluating different methods for use in till are few. Comparative studies should be carried out. In the unsaturated zone a variant of the inverse auger hole method using a constant head and a lined pit is recommended. In the saturated zone measurements in dug wells are considered as the most representative method. Correlative methods can only be used for very approximate predictions of the saturated hydraulic conductivity in till.
Saturated Hydraulic Conductivity of Scandinavian Tills
Authors: Lind Bo B. , Lundin Lars
Published: May 2018

There is a distinctive difference in hydraulic properties between the upper horizons of Scandinavian till soil and the deeper C-horizon. The hydraulic conductivity has been studied in different soil profile types, mainly Podzolic variants. In the topsoil there are correlations from grain size and porosity to hydraulic conductivity. Both porosity and hydraulic conductivity are stratified with depth. Often high conductivity appears in the upper soil horizons decreasing with depth to low values at about one metre. This pattern varies with soil type. The soils vary with topographic location as does the groundwater level.

Published data on hydraulic conductivity in the C-horizon of sandy-silty tills in Scandinavia covers a wide range, from about 5 × 10−9 m/s to 5 × 10−4 m/s, with a mean of 3 × 10−6 m/s. The correlation between porosity and hydraulic conductivity, as well as between mean grain size and hydraulic conductivity, is weak in the C-horizon. It is concluded that the sediment structure has a decisive influence on the hydraulic conductivity of till. A model of the relationship between fabric (in relation to water flow direction), the porosity in the poresize interval 30-95 μm and the hydraulic conductivity is presented.
Evapotranspiration from a Small Alaskan Arctic Watershed
Authors: Kane D. L. , Gieck R. E. , Hinzman L. D.
Published: May 2018

Evapotranspiration (ET) vies with runoff as the primary mechanism for water loss from a watershed underlain by permafrost, yet past attempts to predict ET have proven to be less than completely successful in the Arctic. Imnavait Creek, a small 2.2 km2 watershed underlain by continuous permafrost has been studied for 4 years. Evapotranspiration on a watershed scale has been calculated from water balance studies. These results are compared with point measurements of pan evaporation and daily estimates of ET by the energy balance and Priestley-Taylor methods. Since it is difficult to determine the daily change in soil moisture, the energy balance approach appears to be the best method to determine daily ET. The water balance approach is the best method to determine total ET over the course of the summer because it is possible to delete the soil moisture term due to an insignificant change annually in this watershed. Priestley-Taylor gave adequate estimates of ET with only limited data. After a pan coefficient is determined, the evaporation pan functions well over extended time periods but is less accurate for shorter periods. Evapotranspiration is greatest in early summer, immediately following the spring snowmelt, during the period of maximum incoming radiation but not necessarily maximum air or soil temperatures. The cumulative potential evaporation is greater than the cumulative summer precipitation. The source of moisture for ET in early summer is from snowmelt or moisture stored in the active layer.
A Review of Techniques used by Canada and other Northern Countries for Measurement and Computation of Streamflow under Ice Conditions
Authors: Pelletier Patrice M.
Published: May 2018

In Canada, Water Survey of Canada, a division of the Water Resources Branch of Environment Canada, is responsible for the collection and processing of data from more than 3,300 active streamflow, water level and sediment data gauging stations. Because of the climatic conditions prevalent in Canada, an important part of the monitoring program is conducted under winter ice conditions. The determination of daily streamflow records during the winter period is important for several practical purposes, in particular for water power development. Essential to the computation of daily discharge records, are reliable streamflow measurements. However, discharge measurements under ice conditions are generally difficult to obtain because of severe weather conditions, hazardous field conditions, and ill-adapted field measurement techniques.

In this paper, the field methods and instruments, and computational methods used by Water Survey of Canada for streamflow measurement and computation under ice conditions are reviewed. Factors affecting the accuracy of discharge measurements performed under ice conditions are discussed. Newly developed instruments for use under ice conditions are described and their advantages discussed. A comparison between techniques used by Canada and other northern countries is also given. Areas of research and investigations for improvement in the overall quality of data are suggested.
The Influence of Uncertainty in Air Temperature and Albedo on Snowmelt
Authors: Blöschl G.
Published: May 2018

Extrapolating meteorological data to the basin scale represents a major problem of spatial snowmelt modelling in alpine terrain. Within this study errors in air temperature introduced by regionalization are analyzed for the Sellrain region in the Austrian Alps. Albedo is simulated using a range of model parameters representing different snow cover conditions. The influence on snowmelt is assessed by simulating water equivalent at the site scale using estimated air temperatures and albedoes. Simulation results indicate that a bias in measured temperatures as produced by local effects may be significantly more important than interpolation errors. Uncertainty in albedo appears to affect snowmelt to a higher degree than air temperature.
Spatial Variability of Physical Parameters and Processes in Two Field Soils
Authors: Høgh Jensen K. , Refsgaard J. C.
Published: May 2018

The horizontal variability of soil hydraulic parameters, water content and suction measured within two research fields in Denmark is analyzed and discussed.

A numerical analysis of the flow in the two spatially heterogeneous fields is carried out by assuming that the fields are composed of ensembles of one-dimensional non-interacting soil columns, each column representing a possible soil profile in statistical terms. Flow predictions based on the classical Richards' equation are carried out for all columns, and the mean and standard deviation of water content and suction in planes perpendicular to the flow direction is derived and compared to measurements. The analysis shows that the model to a reasonable degree is able to describe most of the variation in flow variables within the two fields.

The concept of equivalent soil properties is also investigated and applied to the two fields. Based on the average retention properties it is possible to predict the horizontal averages of flow variables within the fields.