bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Cumulants to Estimate Coefficients in Chow-Kulandaiswamy's GHS Model
Authors: Singh Vijay P. , McCann Roger C.
Published: May 2018

The coefficients in the General Hydrologic System (GHS) model of Chow and Kulandaiswamy (1971) are estimated using the method of cumulants. Based on this method a rational criterion is developed to determine the number of terms to be retained in the GHS Model. The least squares method used by Chow and Kulandaiswamy (1971) and the method of cumulants proposed here are compared and are found to yield comparable values of the model coefficients on an example watershed.
Development and Applications of a Runoff Model for Snowcovered and Glacierized Basins
Authors: Gottlieb Lars
Published: May 2018

A conceptual model has been developed for the prediction of runoff on a daily basis from snowcovered and glacierized basins. The basin is divided into an icefree area and an icecovered area, which are treated separately by the model in an attempt to account for the highly different physical conditions prevailing within these two types of areas. The heat exchange between the atmosphere and the snow- or icecover, which essentially controls the melt production, is calculated either by means of a modified degree-day approach or – if the necessary data are available – by means of the complete energy balance equation. The performance of the model has been tested on a glacierized basin in Western Canada – The Peyto Glacier Basin – from which eight years af basic meteorological observations exist for the melt period in addition to continuous discharge measurements.

Further, the model has been applied to a glacierized basin in Johan Dahl Land, Southern Greenland, which is of interest in relation to hydro power development. The purpose of this study has been to extend the existing 4 years series of discharge measurements on basis of long term meteorological observations from a station located appr. 17 km from the outlet of the basin.

The results of the two case studies are presented and discussed.
Discharge Measurements by a New-Formed Relative Salt-Dilution Method in Small Turbulent Streams
Authors: Bjerve L. , Grøterud O.
Published: May 2018

Water discharges in small turbulent streams are determined by injecting concentrated salt solutions at constant feed-rate and measuring the dilution level downstream by conductivity readings in situ. This new-formed method is comparable with the traditional relative salt-dilution method, as well as with other methods, with respect to accuracy. In small streams with complicated hydrodynamic structures the new-formed method seems to be most practical and reliable.
Groundwater Discharge through Springs with Well-Defined Outlets A Case Study from Jeløya – Moss, S. Norway
Authors: Englund Jens-Olaf , Meyer Knut-Fredrik
Published: May 2018

From the area of Jeløya - Moss, southern Norway, five springs draining fissured-rock aquifers, and one artesian well draining confined water from a sand and gravel aquifer were studied during the year period 7 June 1977 to 6 June 1978. This study has given valuable information about discharge variations, the amounts of water stored in the aquifers, as well as about the residence-time of the water in the aquifers. The springs are fed from groundwater bodies with chemical compositions close to that of deep circulating groundwaters, 30–100 m below land surface. Brackish water in the artesian well is mainly due to the dissolution of fossil sea salts.
Exceptional Groundwater Level Fluctuations at the Dutch Island of Schiermonnikoog
Authors: de Zanger F. A. P.
Published: May 2018

During a hydrological-meteorological investigation at a former beachplain at the Dutch island of Schiermonnikoog, groundwater fluctuations were recorded. Except for daily changes of the groundwater level there appeared to be exceptionally high fluctuations during rainfall. This phenomenon can be explained by the so-called »lisse-effect«.

This implies that the phreatic level can rise rapidly due to an increased pressure of the soilair above the capillary fringe. The increase of the pressure is caused here by the capillary infiltration of rainwater in the soil

At Schiermonnikoog it became obvious that the depth of infiltration and the extent of groundwater rise were determined by the thickness of a semipervious layer at the surface with strong capillary tension.
Application of Soil Water Flow Theory in Field Simulation
Authors: Høgh Jensen Karsten
Published: May 2018

A numerical model based on a finite difference approximation of the basic differential equation for soil water flow is described. The equation includes a sink term representing moisture extraction by root systems, and allowance for evaporation from the soil surface is made too. Estimation of these terms is based on a potential transpiration calculated from Penman-Monteith's equation, on a potential evaporation calculated from Ritchie's equation and in both cases on relations to soil moisture status over various soil depths. The model simulations are compared with field observations of moisture content and soil moisture tension. Further, the model has been applied in evaluating how irrigation treatment effects the increases in evapotranspiration and deep percolation.
Isotope Input into Runoff Systems from Melting Snow Covers
Authors: Herrmann A. , Lehrer M. , Stichler W.
Published: May 2018

Stable environmental isotope techniques contribute to reasonable separations of the direct runoff component in snowmelt hydrographs. For the separation procedure, the actual isotope input from snow cover outflows is required. In order to study the effects of isotope fractionation and exchange processes in the snow cover on the isotopic outflow concentrations several cold room experiments have been carried out with isotopically homogeneous and stratified snow columns. To simulate natural conditions the columns were treated with different heat supply and rainwater at the surface, and the outflows analysed for 2H and 18O contents. Some fundamental results are discussed with respect to the more complex natural situation. Finally, the hydrological application of such experience is demonstrated for a natural environment.
Sodium Mobility in a Mini-Catchment Studied with Radioactive Tracers and Artificial Precipitation
Authors: Christophersen N. , Seip H.M. , Qvenild C. , Tollan O.
Published: May 2018

Seasalts in the precipitation may lead to a short-term acidification of the runoff from natural catchments due to ion-exchange reactions. It was decided to investigate this effect in the Storgama area which has acidic streamwater and lies in Telemark county, southern Norway. The mobility of 24Na as compared to that of tritiated water (HTO) was studied in a natural mini-catchment (98 m2, 61% barren granitic bedrock) using artificial precipitation with an intensity of about 5 mmh−1. The tracers were delivered as a pulse, and after 6 days (4 days with watering) an estimated 84% of the HTO reaching the plot was recovered in the outlets compared to 45% for 24Na. Sodium is therefore fairly mobile in the mini-catchment, but the results show that the positively charged sodium ions are delayed compared to the water movement as traced by HTO.

From the observed sodium mobility and the [Na] values commonly occurring in natural precipitation in this area (average 15 μeql−1), it is estimated that the short-term acidification of the runoff due to seasalts is of minor importance in the mini-catcment which typically has [H+] ≈ 50 μeql−1 in runoff. This is probably also the case for the Storgama area as a whole.
Acidification of Groundwater in Norway
Authors: Henriksen A. , Kirkhusmo L. A.
Published: May 2018

The chemistry of ground- and surface-water in areas of similar geologic settings are compared by plotting the equivalent concentrations of each component in an XY-diagram. The deviations of each chemical component from the line through origin and the plot of the two ionic sums (line of proportional composition) give information about the differences in composition of the two types of water.

If we assume that the geologic conditions of the ground- and surface-water are similar when the plots of calcium and magnesium will fall close to the ionic sum line, then we find that the alkalinity is relatively higher and the sulphate concentration is relatively lower in groundwater than in surface-water. These observations indicate that in areas influenced by acid precipitation the groundwater is acidified less than the surface water.

The groundwater stations studied so far show a regional tendency to lower pH-values in areas where regional lake surveys show low pH in surface waters, these areas include southernmost Norway and parts of eastern Norway.
A Distributed Groundwater/Surface Water Model for the Suså-Catchment
Authors: Refsgaard Jens Chr , Hansen Eggert
Published: May 2018

A distributed hydrological model has been developed for the Suså catchment, covering about 1,000 km2 of Zealand, Denmark. Being a physically based description of the entire land phase of the hydrological cycle, the model is the result of an integration of an integrated finite difference groundwater model, an aquitard model, a model for unconfined phreatic aquifers and a root zone model. The main objective of the model has been to make possible predictions of the hydrological consequences of groundwater abstraction on the river discharges and on the hydraulic heads of the aquifers. Therefore special attention is given to the interaction between the streams and the aquifers. The model was tested against field data of streamflow, actual evapotranspiration, soil moisture deficit, drain water discharges and hydraulic heads of the confined aquifer. A model description and some results from the calibration and tests are given.
A Growth Model for Black Ice, Snow Ice and Snow Thickness in Subarctic Basins
Authors: Leppäranta Matti
Published: May 2018

A model for the growth of ice thickness in autumn and winter is presented. Temperature of the upper surface of the ice sheet, snowfall and heat flux from the water are external input variables, and the thickness of black ice, snow ice and snow and the density of snow are predicted through the model. Thermal inertia is neglected. The results are sensitive to the assumed density of freshly fallen snow and the formulation of snow metamorphism. Comparisons between observations and model calculations are given. The agreement is moderate and the need for field work on snow on ice is recognized. A discussion is given on the maximum annual ice thickness under varying external conditions.
Snowpack Liquid Water Determinations Using Freezing Calorimetry
Authors: Jones E. B. , Rango A. , Howell S. M.
Published: May 2018

Liquid water in a snowpack has been recognized for some time as a quantifiable variable of hydrologic significance. It is also important in the interpretation of snowpack microwave remote sensing data. One effective method for measuring the liquid water content of snow is freezing calorimetry. This technique is presented from theory through application including formulations for calculating the percent of liquid water in the snowpack. Silicone oil has been used successfully as the freezing agent. Consistent results can be obtained with the method, even when using newly-trained operators. Liquid water content data can be obtained approximately every 15 minutes when using two calorimeters and three operators. The freezing calorimetric approach was found to be accurate in determining the liquid water content of the snow to within ± 1.0-2.0 percent by weight.
Stochastic Simulation of Evaporation Data for Australia
Authors: Srikanthan R. , McMahon T. A.
Published: May 2018

Stochastic models are developed to simulate annual, monthly and daily evaporation data for Australia. For annual and monthly synthesis, the evaporation values are generated independently and dependently of rainfall; on the other hand, generation of daily evaporation is based on the knowledge of occurrence of daily rainfall. Data from nine Australian stations are used to illustrate applications of the models.
Evaluating a Model of Snow Cover Area versus Runoff against a Concurrent Flow Correlation Model in the Western Himalayas
Authors: Dey B. , Goswami D. C.
Published: May 2018

This study evaluates the estimates of seasonal snowmelt runoff in the Sutlej, Indus, Kabul and Chenab rivers derived from the model of snow cover area vs. runoff against those obtained from cross correlation of concurrent flows in the rivers. The concurrent flow correlation model explains more than 90 percent of the variability in flow of these rivers. Compared to this model, the model of snow-cover area vs. runoff explains less of the variability in flow. However, unlike the snow-cover model, the concurrent flow correlation model cannot be used for operational forecasting procedures. Where the strength of correlation is high, the concurrent flow correlation model has potential for use in retrospective analysis of flow for estimating missing data, extending time series and for evaluating estimates derived from other models. In the Himalayan basins under study and at least for the period under observation, the concurrent flow correlation model provides a set of results with which to compare the estimates from the snow cover model.
Experimental Estimation of the Current Field of a Complex Lake
Authors: Virta J.
Published: May 2018

The purpose of this study is to construct an experimental model to determine the dependence of lake-current velocity on the preceding wind velocity. The parameters of the model are determined by linear programming, using measured wind velocity data. The model is usable in studies, in which current field of a complex lake is estimated, for example in water quality studies. With the method it may be possible to compute current velocity in sounds directly from wind velocity, and then use numerical methods for each open area of the lake.
The Role of Soil Moisture in the Water-Balance of a Small-Clay Catchment, 1967-75
Authors: Pegg R. K.
Published: May 2018

An eight year run of detailed soil moisture data has been incorporated into simple water balance calculations in an attempt to estimate actual evapotranspiration. The value of this data is shown when compared with estimates using only groundwater storage and its role during the autumn is particularly evident.
Estimation of Canopy Reservoir Capacity and Oxygen-18 Fractionation in Throughfall in a Pine Forest
Authors: Saxena R. K.
Published: May 2018

Amount and oxygen-18 content of rainfall and throughfall have been monitored in a pine forest in Uppsala during summer 1983. It is found that the free throughfall coefficient, C, the canopy reservoir capacity, S, and the critical value of rain, R0, are ≈ 0.5, 2.1 mm and 4.1 mm respectively. The average value of throughfall is about 60% of rainfall. Generally, the throughfall is enriched in oxygen-18 with respect to rainfall, but in very few cases depletion has been observed. The enrichment or depletion in throughfall have been graphically predicted and agree fairly well with the observations. Oxygen-18 values of throughfall have been simulated by a model describing isotopic fractionation in throughfall. Using estimated relative humidity and temperature during the rainfall, the simulations describe quite closely the observed fractionation. It is felt that more accurate estimates of C, S and fractionation in throughfall can be obtained by monitoring rain and throughfall in small fractions of about 0.2 mm or even less.
Profiles of Nitrogen Species in a Sand-Silt Aquifer at Haslemoen, Solør, South Norway
Authors: Englund J.-O. , Haldorsen S.
Published: May 2018

Chemical profiles of water in the vadose zone and in the upper part of the groundwater from a water-table sand-silt aquifer at Haslemoen, South Norway, have been studied. Filter tips attached to steel pipes (BAT monitoring system) have been installed to different depths at two localities. The system makes it possible to measure pore pressures and hydraulic conductivities and to take samples under controlled conditions both above and below the groundwater level. One locality is characterized by forest, groundwater level at about 7 m below surface, and filter tips down to 13.2 m. Agricultural land surrounds the field installations at the other locality, the groundwater level is here about 4.5 m below surface, and filter tips are down to 10.4 m.

The chemical data demonstrate a) Higher concentrations of both total nitrogen and nitrate below agricultural land b) Decreasing concentrations downwards of both total nitrogen and nitrate in both profiles c) Iron and/or organic carbon seems to take part in the reduction of nitrate, probably to free nitrogen.
Stochastic Modelling of a Contaminated Aquifer
Authors: Van Rooy Dirk
Published: May 2018

A stochastic solute transport model is applied to a groundwater contamination case. The contamination is caused by leachate from an unprotected landfill situated in a highly-permeable unconfined aquifer.

The stochastic model combines the geostatistical techniques of semivariogram analysis and kriging with a numerical solute transport model. A Monte Carlo approach that utilizes the turning bands technique to genereate transmissivity fields is used. Here some preliminary results of the unconditional stochastic simulations are presented.

The contaminant plume is characterized by expected concentrations of chloride and standard deviations.
A Dimensionless Solution of Lag Time for Diverging Surface
Authors: Ağiralioğlu Necati
Published: May 2018

Using the kinematic wave theory, a dimensionless expression is obtained, and solved numerically in order to estimate the lag time for diverging surfaces. The findings show that the dimensionless lag time, which is the ratio of lag time for diverging surface to that of plane surface, ranges from 1 to 0.5 depending on the degree of divergence and friction formula used. The results can be used easily and reliably for all ranges of the geometric parameter for urban and rural catchments.
Joint Probability Distribution of Streamflows and Tides in Estuaries
Authors: Loganathan G. V. , Kuo C. Y. , Yannaccone J.
Published: May 2018

A procedure for estimating the joint probability of occurrence of correlated extreme tides and corresponding freshwater flows in estuaries is presented. The method uses the Box-Cox transformation to transform the original data to near normality, and therefore the search for a parent distribution is avoided. It is also shown that the traditional assumption of statistical independence for the jointly distributed random variables may lead to the underestimation of flows and tidal heights. The methodology is applied to the Rappahannock River in Virginia which flows into the Chesapeake Bay.
Environmental Impacts of an Old Mine Tailings Deposit – Modelling of Water Balance, Alkalinity and pH
Authors: Brandt M. , Bergström S. , Sandén P.
Published: May 2018

A diversity of hydrological and hydrochemical data is the foundation for an integrated modelling study of a leaching tailing deposit at Bersbo in southern Sweden. A distributed conceptual water balance model system combined with empirical hydrochemical subroutines are used to describe the variation pattern in runoff, alkalinity and pH of the outlet of the drainage basin. Examples of the sensitivity of the model output to perturbations of some of the model parameters are shown.
The Rational Formula Interpreted Using a Physically-Based Mathematical Model
Authors: Akan A. Osman , Al-Turbak Abdulaziz A.
Published: May 2018

A new interpretation is given for the rational formula in view of a mathematical model founded on the kinematic overland flow and Green and Ampt infiltration equations. The potential variability of the runoff coefficient with various rainfall and basin characteristics is demonstrated. However, using the concept of hydrologic similarity, it is possible to predict the runoff coefficient in terms of several physically-based non dimensional parameters for homogeneous planar, rectangular basins.
Acidification of Shallow Groundwaters During the Spring Melt Period
Authors: Craig D. , Johnston L. M.
Published: May 2018

During the spring of 1985 shallow recharge area groundwaters at depths less than one metre in the Turkey Lakes watershed were observed to undergo short term (1 to 10 days) pH and alkalinity depressions associated with both rain and snow melt events. At the same time the concentrations of K+ in the groundwater increased. Observations suggest that, if, during an individual loading event, the loading rate of Hydrogen ions (H+) exceeds the rate at which alkalinity is made available through carbonate weathering reactions, increased alumino-silicate alteration can occur. Thus alumino-silicate alteration may occur in groundwater systems with measurable carbonate alkalinity.
The Hydrology of Bayelva, Spitsbergen
Authors: Repp Kjell
Published: May 2018

The hydrology of Bayelva, which is located to the northwestern part of Spitsbergen, was investigated during the period 1974-78. The river drains a catchment of 31.5 km2, out of which 54% are covered by glaciers. Additional studies were carried out on erosion and transport of suspended solids in the river. The major part of the runoff occurs during the months June to August. The snow melting usually starts in late May or early June, when air temperature rises above o°C. Mean annual runoff during the period was measured to 31.8 × 106m3, which during an average runoff period of 109 days/year gives 3.4 m3/sec. Highest daily flood was measured to 32.2 m3/sec. Annual sediment transport (suspended load) varies from 6,646 to 16,558 t, while highest observed concentration was 3,830 mg/l. The high variations may be explained by annual runoff volume, frequency of floods, amount of rainfall and rainfall intensity.
On the Generation of Stream Runoff in Till Soils
Authors: Rodhe Allan
Published: May 2018

Isotope studies in Swedish till basins indicate that stream stormflow is normally dominated by pre-event water. The rapid response of the groundwater outflow to infiltration may be explained by a large increase in the hydraulic conductivity of the soil towards the ground surface. In homogeneous soils the effect of the capillary fringe may be important in building up large total head gradients towards the stream. In generating runoff peaks in the streams, the saturated discharge area contributes 100 %, by saturation overland flow. Various parts of the recharge area contribute less than 100 %, and less effectively the longer the distance to the recharge area is. The areal extent of the contributing recharge area is considerably larger than the discharge area.
Finite Element Analysis of Controlled Saltwater Intrusion in Heterogeneous Reservoirs
Authors: Refsgaard Anders , Christensen Steen , Reffstrup Jan
Published: May 2018

Environmental cleaning operations in coastal areas by pumping are complicated by the presence of both fresh water and salt water. The density difference makes the flow conditions very complicated to predict especially if the situation is further complicated by highly heterogeneous formations. The present paper gives results from a computer simulation of saltwater movements during pumping in a heterogeneous coastal reservoir. The example problem discussed in the paper is based on data from a polluted area in the north west of Denmark. A chemical plant situated on a small peninsular has caused serious groundwater pollution. Several measures have been taken to contain the pollution including draining and extra pumping.
Soil Moisture Deficits in South-Central Sweden
Authors: Andersson Lotta
Published: May 2018

Soil moisture fluxes in forest and grassland soils were analyzed for a rather dry region in south-central Sweden in order to assess climatologically induced dryness variability. Time series were constructed, using a conceptual soil moisture model, optimised against neutron probe measurements. Data in a 105 yrs climatic record were used as driving variables. A method to deal with the inhomogeneity of the long precipitation record was developed. It was shown that large variations existed, not only between the median values, but even more for the range of the quartiles, depending on the choice of time period. The statistical distribution varied significantly even between the two 50 yrs series, where the latter showed larger fluctuations around the median caused by a trend towards increased amount of high summer soil moisture deficits. Estimates of the interannual variations of possible water deficit stress on vegetation were made. The only time (1883-1987) when there was a calculated risk for drought stress on the forest during four consecutive years was during 1973-1976. This might have increased the vulnerability to the threats of acidification. It was concluded that the use of standard- and return periods can hardly be justified as no sets of average conditions exists.
Uncertainty in Dam Break Flow Simulation
Authors: Kung Chen Shan
Published: May 2018

The flow caused by a dam breaking across its entire length can be approximated by a one-dimensional, unsteady flow model in form of the St. Venant equations. In this model, the flow is governed by the river geometry and the river roughness, which is quantified by Manning's coefficient. The roughness characteristics are generally difficult to estimate under natural conditions. Thus, the estimates of the Manning's coefficient will in general be subject to uncertainty. In this paper, the uncertainty in the discharge and depth hydrographs due to the uncertainty in estimating the roughness characteristics of a river, is investigated. A specific case of the Noppikoski dam in Sweden that failed in 1985 is used to illustrate the sensitivity of the flow simulation on the roughness coefficient. The analysis shows that the uncertainty in the dam break flow simulation due to the uncertainty in estimating Manning's coefficient, is significant. The uncertainty is larger at greater distances from the dam, and is greater for the discharge hydrograph than for the depth hydrograph.
Saturated Hydraulic Conductivity of Clayey Tills and the Role of Fractures
Authors: Fredericia Johnny
Published: May 2018

The background for the present knowledge about hydraulic conductivity of clayey till in Denmark is summarized. The data show a difference of 1-2 orders of magnitude in the vertical hydraulic conductivity between values from laboratory measurements and field measurements. This difference is discussed and based on new data, field observations and comparison with North American studies, it is concluded to be primarily due to fractures in the till.
Unsaturated Hydraulic Conductivity Determined by the Hot Air Method for Some Danish Till Soils
Authors: Jacobsen O. H. , Jensen H.E.
Published: May 2018

Unsaturated hydraulic conductivity relations for topsoil and subsoil in 12 Danish till soils were obtained from measurements by the hot air method. In the range of pressure potentials (pF-values from 1.7 to 3.0) within which the method is most suitable the hydraulic conductivities were found to be within the range of 10-10-10-7 m s-1 for topsoils and 10-11-10-8 m s-1 for subsoils. The hydraulic conductivity relations obtained were briefly discussed in relation to the corresponding pF-curves. At any pF-value the subsoils differed more than the topsoils in hydraulic conductivity.
Effect of Climate Variability and Change in Groundwater in Europe
Authors: Thomsen Richard
Published: May 2018

Public water supply in Europe relies very heavily on groundwater. Recharge of groundwater takes place mainly in the winter months. An analysis of winter rainfall data shows that current recharge rates are abnormally high, and that during several periods in the past the rate has been less than half the current value. A return to such low values could have catastrophic consequences, but even more modest drops would be serious. Useful predictions must be based on climatic models and the full use of climatic, paleohydrological and historical data.
Climate, Hydrology and Vegetation Patterns Hot Weather Creek, Ellesmere Island, Arctic Canada
Authors: Edlund Sylvia A. , Woo Ming-ko , Young Kathy L.
Published: May 2018

Recent studies at Hot Weather Creek, Ellesmere Island document the climate and vegetation of a major part of the intermontane zone of Ellesmere Island. Summer temperatures in this region are much higher than would be expected for its 80° N location. This enables a variety of arctic species with more moderate temperature tolerances to thrive. The dense and diverse tundra and wetland vegetation in parts of the region, however, does not conform to polar desert or semidesert vegetation expected from the meager amount of precipitation (< 70 mm per year) recorded there. Comparisons between differing biological and geomorphological responses to the summer climatic regimes of 1988 and 1989 suggest a two source supply of moisture to the active layer in summer. Supplementary source of water, from the melting of massive ground ice bodies provides water from the base of the active layer, during the hot, dry summer of 1988. During the wet summer of 1989, a more conventional nival regime was in operation. These two potential sources of moisture in summer provide a fail-safe delivery system to vegetation in areas underlain by massive ground ice, and permit a richer vegetation growth than climate alone could.
Sulphur and Oxygen Isotopes Behaviour in Sulphates of Atmospheric Ground water System Observations and Model
Authors: Trembàczowski Andrzej
Published: May 2018

Comparison of sulphate concentrations in groundwaters and atmospheric precipitation suggests that about 30 % of groundwater sulphate may be of atmospheric origin. Another source of sulphate ion is the oxidation of sulphur compounds by microorganisms in the soil or in the aquifer. The sulphates of atmospheric and biogenic origin are mixed in the soil and subsequently the mixture gets into the groundwater. The ð34S data suggest, that ð34S of biogenic sulphates is the same as that of atmospheric sulphates. Processes such as: the assimilation of sulphates by plants, their decay and oxidation of organic compounds do not change the ð34S significantly. Significant differences between ð18O values of sulphates of atmospheric and biogenic origin, which are created by microbiological sulphur-oxidizing processes, may be useful for interpretation of the processes in the groundwater system.
Experiments of Conceptual Mathematical Groundwater Dynamics and Runoff Modelling in Latvia
Authors: Krams M. , Ziverts A.
Published: May 2018

A mathematical model METUL for estimating the daily groundwater level and drainage, surface and subsurface runoff in small areas is described. Input data for the model are daily mean values of air temperature, precipitation and vapour pressure deficit, as well as the occurrence and disappearance of snow cover. Questions about the determination of the model's parameters are discussed, and the results of the model's application to experimental areas in two drainages are analyzed. The model's usefulness in objectively determining the soil water regime of small areas after only short-term groundwater level observations is shown.
Runoff Generation in a High Boreal Wetland in Northern Canada
Authors: Gibson J. J. , Edwards T. W. D. , Prowse T. D.
Published: May 2018

The stable isotope composition of water and major-ion concentrations were measured in a small catchment tributary to Manners Creek, situated in the zone of discontinuous permafrost near Fort Simpson, Northwest Territories. Hydrograph separation calculations based on δ18O and δ2 H values of snow, active-layer water, and streamflow reveal that snowmelt contributions were secondary to active-layer storage contributions throughout the spring freshet period of 1990. At the time of peak spring runoff an estimated 40 to 50 % of streamflow was contributed by snowmelt, while over the entire spring period only 25 to 30 % of streamflow was contributed by snowmelt. Overland and pipe flow are shown to be important mechanisms of rapid snowmelt runoff from permafrost slopes.
Adapting the CREAMS Model for Finnish Conditions
Authors: Rekolainen Seppo , Posch Maximilian
Published: May 2018

The CREAMS model, a management model for predicting field-scale runoff and erosion, has been modified and adapted for Finnish conditions: The most important changes are the implementation of a new snow accumulation and snow melt model, a simple soil frost model, the use of an adjustable albedo for evapotranspiration calculations, the implementation of a plant growth model for calculating leaf area index and soil loss ratio, and allowing for a variation in the rainfall erosivity parameters. The modified model has been compared to the original model and observed data from an experimental field in southwestern Finland. In most cases the modified model predicted surface runoff and soil loss better than the original model. Although there remain discrepancies between model simulations and observations, the modified model seems to perform better and allows an easier comparison of management practices.
Field Investigation of the Thermal Bar in Lake Ladoga, Spring 1991
Authors: Malm Joakim , Grahn Lennart , Mironov Dmitry , Terzhevik Arkady
Published: May 2018

The thermal bar in Lake Ladoga was studied during one week in May 1991. Temperature and current velocity distributions were measured. The movement of the thermal bar and the horizontal heat transport were examined.

The temperature off-shore the thermal bar was found to be constant within a vertical. The velocity distributions were complex and dependent on wind conditions. Calculations of changes in heat content showed that there was a horizontal heat transport from the near-shore warm zone towards the thermal bar. The observed off-shore progression of the thermal bar was compared with analytically computed progression rates. The progression rate is underestimated if it is assumed that surface heating and vertical mixing are the only mechanisms contributing to the thermal bar progression. Better agreement is obtained if mixing of warm and cold water near the thermal bar zone is considered.
Hydrology of a Patterned Bog-Fen Complex in Southeastern Labrador, Canada
Authors: Price J. S. , Maloney D. A.
Published: May 2018

A 0.05 km2 patterned bog and a 0.29 km2 ribbed fen were compared to determine the influence of their morphometry on runoff and evapotranspiration. The bog hydrology was dominated by irregularly located and poorly linked pools ≤1.0 m deep, separated by prominent ridges containing local water-table maxima. This small basin had an appreciable lag-to-peak time (e.g. 6 h), and a low runoff ratio (0.1 to 0.2), because of the large depression storage of the pools, and a long detention storage caused by the weak pool-to-pool linkage. The ribbed fen was dominated by a 1.3 km water track, which consisted of shallow pools (≤0.25 m deep), separated by low ridges that did not produce local water table maxima. The pools were well linked, but their sequential arrangement resulted in a very large detention storage which trimmed the runoff ratio to only 0.003 to 0.07. The lag-to-peak time was relatively short (approx. 3 h), because of sheet flow in the lower water track, just above the weir. The large depression and detention storage of both systems enhanced evapotranspiration losses. Between July 5 and August 14, 1990, evapotranspiration from the bog was 97 mm, compared to 126 mm from the fen, while runoff was only 12 and 28 mm for the bog and fen, respectively. Evapotranspiration from ridges was 67 and 84% of pool evaporation, in the bog and fen respectively.
Long-Term Records of Snow Cover Water Equivalent in the Swiss Alps
Authors: Rohrer M.B. , Braun L.N.
Published: May 2018

The knowledge of the temporary snow-water equivalent storage term (SWE) is an important prerequisite for the assessment of short- and long-term runoff volumes and water quality aspects. Since SWE measurements are frequently not available, this varilable is modelled on the basis of operationally measured meteorological data. For model verification fortnightly measured SWE values are used. The choice of the proper model depends on the aim of the simulation and the input data available: if SWE is the only variable to be modelled and time-series of daily total and new snow depths values are available, then a simple model based on Martinec (1977) employing settling curves for each snowfall event is suggested. If apart from SWE values other variables such as liquid water storage, snow albedo, etc. are to be modelled, and hourly input data are available, the conceptual energy and mass balance approach as presented here is suggested. The following variables, measured in hourly intervals, are used as input: air temperature, precipitation, wind speed, water vapour pressure, global radiation and cloud cover (term readings). This model was originally developed at a research-type station but can now be applied at up to 70 stations of the automatic network (ANETZ) of the Swiss Meteorological Institute (SMI). The modelled values are good estimates of the measured ones in the accumulation as well as in the ablation season.
An Operational Forecasting Snowmelt Model with Objective Calibration
Authors: Rodríguez J. Y.
Published: May 2018

After a review of existing operational models for daily snowmelt forecasting, an operational oriented one has been developed in order to provide a simple tool for one-to-three-day ahead flow management. The main advantage of this lumped degree-day model lies in the algorithmic development which allows a quick and objective parameter calibration. The proposed iterative algorithm is able to furnish a reduction of the number of parameters and an error criteria plotting which allows to choose an adequate set of them. A case study – La Durance at la Clapière station (2,170 km2) – illustrates the use of this proposed methodology. The case study is not limited to a classical fitting on calibration data and testing on a validation set, but also shows the actual day-to-day one-to-three-day ahead forecast made during spring 1993. The forecasting model capabilities as well as its limits are then discussed.
Prediction of Log-Transmissivity
Authors: Christensen Steen
Published: May 2018

The log-transmissivity may in many cases be predicted from the log-transformed specific capacity of wells by applying a linear statistical model. The coefficients of the linear equation can be estimated by the least-square method. It is shown that if the estimated slope of the line differs from unity then it may indicate that the specific capacity is correlated with the well efficiency.

The above prediction method is applied to case studies of aquifers in three different formations: the prediction should not be used for a homogeneous fluvioglacial formation because the variance of the well efficiency dominates the variance of the transmissivity; the prediction is fair for a heterogeneous fluvioglacial formation; and the prediction is poor for a homogeneous limnic formation. In the study of the first formation a correlation between specific capacity and well efficiency can be identified directly from the slope of the regression line.

If the predictor values are taken from the drillers log then the standard error of prediction in all the cases is 0.35. This seems to be unacceptable in most practical applications. However, if one needs to predict the mean of a domain and the domain contains a number of observations of the predictor, then the averaging will reduce the prediction error. The averaging procedure ought to take the covariance structure of the variables into consideration.
Frost Heave due to Ice Lens Formation in Freezing Soils
Authors: Sheng D. , Axelsson K. , Knutsson S.
Published: May 2018

An operational model for estimation of frost heave in field where stratified soil profile appears is presented. The model is developed from the research model described in part B. Soil layers are first classified into frost-susceptible layers (FSL) or non-frost-susceptible layers (NFSL). In an FSL, both heat flow and water flow are considered and ice lensing can occur. In a NFSL, only heat flow is possible and no ice lensing is allowed. The governing equations for heat and mass transfer are established for the time period when the frost front is moving within FSL. Capillarity and unsaturation are also considered. The operational model is verified by field measurements of heave amounts. Examples of application are given.
Topographical Influence on Precipitation Distribution in Different Ranges of Western Himalayas
Authors: Singh Pratap , Ramasastri K. S. , Kumar Naresh
Published: May 2018

Seasonal and annual distribution of rainfall and snowfall with elevation has been studied for outer, middle and greater Himalayan ranges of Chenab basin in the western Himalayas. Rainfall and snowfall exhibited different trends with elevation on the windward and leeward slopes of the three ranges of Himalayas. Seasonal characteristics of rainfall have shown a spill over effect on leeward side during winter, pre-monsoon, and post-monsoon seasons in the outer Himalayas. The role of orography in the middle Himalayas was found to be more pronounced for both rainfall and snowfall in comparison to other ranges of Himalayas. Variation of snowfall with elevation was more prominent in comparison to variation of rainfall. In the greater Himalayan range it is found that rainfall descreases exponentially with elevation and snowfall increases linearly. Rainfall becomes negligible at elevations beyond 4,000 m on the windward side of the greater Himalayan range. Efforts have also been made to explain whether variation in precipitation is due to changes in precipitation intensity or number of precipitation days or a combination of both.
Spring Circulation Associated with the Thermal Bar in Large Temperate Lakes
Authors: Malm Joakim
Published: May 2018

The overall circulation pattern in spring is rather specific as density-induced currents may be of significance. The density-driven circulation perpendicular to the shore can be described as consisting of two circulation cells, with a zone of convergence, referred to as thermal bar, in between. The thermal bar, which coincides with the 4°C isotherm (the temperature of maximum density), inhibits horizontal water exchange, implying its practical importance. In this paper, a hydrodynamic numerical model is used to study the relative influence of wind- and density-driven currents in a large temperate lake during spring.

The study shows that the general density-driven circulation is strongly dependent on the bottom topography, with a more pronounced circulation and considerable descending motions in the thermal bar zone in lakes with steep sloping bottoms. In shallow lakes, the wind-driven circulation dominates, and the effect of density-induced currents is marginal, except at locations with a drastic change in bottom depth.
A Simple Monthly Runoff Model for Snow Dominated Catchments in Western Himalayas
Authors: Rao S. V. N. , Ramasastri K. S. , Singh R. N. P.
Published: May 2018

The rivers originating from middle and greater Himalayas have a significant part of their catchments under permanent snow cover and glaciers. Modeling runoff becomes difficult with almost no data from these parts. Even in the seasonal snow covered zones, the network is generally inadequate. However precipitation characteristics show repetitiveness and snowline movement elevation wise by and large occurs the same pattern each year. The snowline movement is distinct on a monthly basis and the location of permanent snowline is also more or less constant at about 4,500 m.

A simple monthly snowmelt runoff model with relatively few parameters is proposed to take advantage of above mentioned characteristics, using the degree day method. The model uses monthly rain, snow (snow water equivalent), mean air temperature and snowline elevation as primary inputs. Model conceptualisation has been made in view of the data constraints. All parameters are estimated through few trial simulations, except the storage coefficient, which is optimised using Rosenbrock technique.

The model was applied on two sub-catchments of Chenab basin (of Indus river system) to evaluate the model capability. The results are encouraging. There is further scope for model improvement, generalisation and for application to other catchments in the Western Himalayas.
Open-Water and Ice-Jam Flooding of a Northern Delta
Authors: Prowse Terry D. , Lalonde V.
Published: May 2018

Flooding is critical to the ecosystem health of many river-delta environments, particularly to perched-ponds and lakes that are vertically separated from the open-water flow system. This is the case for the Peace-Athabasca Delta in northern Canada, one of the world's largest, freshwater deltas. Unfortunately, this delta has not experienced a major flood since 1974. As a result, significant drying has occurred in the higher-elevation portions of the Delta landscape. This has led to significant changes in, for example, the vegetation regime and the related small-mammal habitat. For almost two decades, popular belief was that drying of the Delta was due to a reduction in the size of open-water floods resulting from upstream flow regulation and/or changes in climate. Following a historically high flood in 1990, however, it was realized that open-water floods were relatively ineffective in flooding the perched bases. A historical analysis of hydrometric records revealed that the major peak-water levels have been produced at the time of break-up. The spring flow driving such events are more related to downstream tributary runoff than flow produced within the headwaters, above the point of regulation. Other ice factors, however, such as thickness, strength, and winter levels, may also have been important in controlling break-up severity.
Effects of Hydrology on the Thermal Conditions of the Active Layer
Authors: Woo Ming-ko , Xia Zhaojun
Published: May 2018

Ground thawing and soil warming are governed by ground heat flux, soil thermal properties and the ice content of the soil, all of which are directly or indirectly influenced by the soil moisture status. Ground temperature and moisture were measured at two Arctic sites: a wetland site of frequent saturation and an adjacent pebbly loam site which was much drier. Both thermal conductivity and heat capacity were strongly affected by the ice and water contents. At both sites, about half of the ground heat flux was consumed by latent heat for ground thawing and a large fraction of heat was also conducted from the seasonally thawed zone into the permafrost, leaving only a small amount of heat to warm the active layer. The wetland soil had a shallower maximum depth of thaw than the drier site and this was due to the large ice content in its active layer. Our results demonstrate the ground thaw response to the thermal properties of the soil and its ice content, both of which are influenced by the hydrological conditions of the active layer.
Temperature and Salt Content Regimes in Three Shallow Ice-Covered lakes
Authors: Malm J. , Terzhevik A. , Bengtsson L. , Boyarinov P. , Glinsky A. , Palshin N. , Petrov M.
Published: May 2018

A field study was carried out in three small shallow ice-covered lakes to study heat and mass fluxes and their spatial and temporal variability. During the main part of the winter, the heat flux at the ice-water interface, being of the order 0.5-1 W m−2, was dominated by conduction from water to ice and did not show any significant variations in time or space. The heat flux from sediments to water was the main source for the lake water heating during early and mid-winter, being depth-dependent and 1-4.5 W m−2 in early winter, and 0.5-3 W m−2 in late winter. A heat transport from shallow regions to deep parts was shown to occur during the winter, being of the same order as the vertical fluxes, and should thus be accounted for in any attempt to predict the temperature evolution in an ice covered lake.

The salt flux from sediments was found to be of the order 1-10 × 10−10 kg m−2 s-l. A comparison of this flux with salt content changes indicates that the former is of the same order as the horizontal salt flux which is directed from shallow regions to the deeper parts of a lake during winter.