bluuebunny/crossref_metadata_2025 huggingface dataset:
The Combination of Simulated Discharges of Hydrological Models
Authors: Cavadias G. , Morin G.
Published: May 2018

Hydrological models are frequently used to simulate streamflow. A method for improving performance is to combine the simulated discharges of two or more models. Three different methods are given in detail for the calculation of the weights used in the combination. This paper applies the methods of Granger and Newbold (1977) to the combination of simulated discharges of conceptual deterministic models which participated in the recent WMO intercomparison of models of snowmelt runoff WMO (1985). The numerical criteria adopted in the above study were used to evaluate the performance of the combined simulated discharges. The results of this study show that the combination of discharges results in improved performance in 80 % of the cases and that in cases where there is no improvement, the losses in the values of the criteria are small.
Spatial Variability of Soil Water and Evapotranspiration
Authors: Hansen S. , Jensen H. E.
Published: May 2018

Spatial variability in evapotranspiration from a crop covered field exposed to homogeneous climatic conditions is partly caused by field variability in soil physical properties and partly by field variability in pertinent crop properties. The present paper presents an analysis of the spatial variability in soil water content and evapotranspiration for two 0.5 ha grass fields of different soil texture, viz. a coarse sand and a sandy loam. Soil physical properties and soil water profiles were determined 1 m apart at 16 points systematically located in each field. The analysis of soil water profiles in relation to soil physical properties indicates an appreciable variability within a range of 1 m. For this reason a relatively simple model was used to simulate the variability pattern of the evapotranspiration, taking into account the variability in plant available water content. The results of the simulations are compared with the evapotranspiration patterns determined on the basis of a short term water balance.
Transport and Chemodynamics of Organic Micropollutants and Ions during Snowmelt
Authors: Schöndorf Thomas , Herrmann Reimer
Published: May 2018

By means of laboratory experiments and field measurements we investigated the chemodynamics and transport behaviour of organic micropollutants and inorganic ions in melting snowpacks. Dissolved substances (e.g. ions) were released from the snowpack by convection and diffusion within the melt water. Substances which were adsorbed onto particles (e.g. PAH) were not desorbed to a significant degree. Moving particles were generally filtered out within the snowpack and, therefore, adsorbed substances were hardly leached by this way of transport. Frequent melt-freeze cycles and a deep snowpack lead to an enrichment of dissolved substances in the first melt water fractions and of substances adsorbed onto particles in the final fractions. A different macroscopic and microscopic spatial variation of ions within the snowpack results in different elution patterns during the snow melt. Since the PAH are predominantly adsorbed onto particles, approximately 90% of all PAH of a snow column were eluted with the last 20% of water during the snow melt. PAH with a high partition coefficient kow (e.g. benzo(a) pyrene, benzo(ghi)perylene) exhibited a stronger enrichment than fluoranthene with comparatively lower kow. Since the HCH isomers occur in dissolved as well as in adsorbed phase because of their low kow in melting snow, we observe an enrichment of the dissolved phase within the first fractions of melt water and of the adsorbed phase within the final fractions of melt water.
Environmental Impacts of an Old Mine Tailings Deposit – Hydrochemical and Hydrological Background
Authors: Allard B. , Karlsson S. , Lohm U. , Sandén P. , Bergström S. , Brandt M.
Published: May 2018

The release and distribution of metals as well as acid from a mine tailings deposit into a stream have been studied, particularly the distribution and neutralization of acids, the distribution and chemical speciation of metals and metal adsorption and precipitation phenomena. The Bersbo mine, some 250 km SSW of Stockholm, was selected for the study. An over-view is given of the local geology, hydrology and hydrochemistry as well as the research program (field measurements, sampling, analytical procedures and modelling). The databases (chemical and hydrological) generated within the project are outlined. The paper serves as an introduction to a series of three papers based on field data from the same area.
Progress in Developing an Operational Snowmelt-Runoff Forecast Model with Remote Sensing Input
Authors: Rango A.
Published: May 2018

In order to apply the snowmelt-runoff model (SRM) or any snowmelt model operationally, a logical progression is required from utilization in the pure simulation mode when all data are known to the pure forecasting mode when no future data are known. Significant progress has been made and results are presented which include pure simulation, simulation when the actual output data are unknown, simulation when estimated or forecasted snow cover input data are employed, simulations or forecasts with updating using observed streamflow, and first attempts at true forecasts. Based on these results, an objective method for forecasting with SRM is being developed.
A Review of Chemical Solute Transport Models
Authors: Engesgaard P. , Christensen Th. H.
Published: May 2018

This paper presents a review of groundwater models capable of simulating solute transport (i.e. advection-dispersion) and equilibrium chemistry processes.

Introductory, basic model components are discussed including a physical and a chemical model component and the coupling between the two components. However, emphasis is placed on the chemical model component, since this represents the recent addition to solute transport modeling.

Several ways exist of formulating either model component. For the physical model component this may include a continous description based on the governing mass balance equations or a discontinous description by a mixing cell approach. For the chemical model component, i.e. processes such as ion exchange, adsorption, complexation, precipitation/dissolution and open/closed carbonate system reactions, local equilibrium is usually assumed. The assumption of local equilibrium is investigated. The relation between the continuous formulation and a coupling/decoupling of the physical and chemical components and the resulting nature of the mathematical problem and its numerical strategy is briefly discussed.

In all, 27 models have been surveyed in terms of their physical and chemical model components, their verification and applicability to field scale problems. Due to a lack of actual field applications it has not been possible to evaluate all models in natural settings and hence, each model will, in theory, be valid when the constraints given by the assumptions and limitations taken in developing the model are met.

The models show great diversity with respect to complexity and general applicability to field scale problems. Most of the models were developed for specific purposes and it is difficult to point out one or more »general« models. However, it may be concluded that there exist many ways of formulating a model both with respect to transport and chemical calculations, but also to numerical techniques.

Many of the models are very complex and future research should be directed towards validation studies of these models on a field scale, rather than developing still more complex models.
Hydrological Background of a Glacier-Influenced Hydropower Station in Greenland
Authors: Kern-Hansen Claus
Published: May 2018

For planning a hydropower station at Paakitsup Akuliarusersua in West Greenland, some unusual hydrological studies were required. The basin is situated about 45 km north-east of Ilulissat/Jakobshavn (69° 30'N latitude) at the Greenland Inland Ice and is hence strongly ablation-influenced. As only sparse hydrological measurements had been obtained from the actual basin, it was necessary to base the calculations on historical data from Ilulissat/Jakobshavn. This work included among other things preparation of a suitable hydrological ablation model, detailed analyses of data to establish time series for the simulation work, sensitivity analyses of the hydro-glaciological prerequisites, and analysis and evaluation of periodic elements in the time series.
Simulation of Soil Frost Depth and Effect on Runoff
Authors: Vehviläinen Bertel , Motovilov Yuri
Published: May 2018

A physically based soil frost depth model usable with air temperature data and precipitation data, is presented. Snow depth is calculated from precipitation data using a physical snow cover model. The soil frost depth model is tested in one small basin, with a five-year calibration and verification period. Results from snow depth and soil frost depth simulation were satisfactory also in the verification period.

In the second stage simulated frost depth information was used to develop an HBV-runoff model version, attempting to simulate the possible effect of soil frost on runoff. The simulation results are presented. These results suggest that soil frost does not have a very important effect on runoff in this forested basin.
The Effect of Heterogeneity on Large Scale Solute Transport in the Unsaturated Zone
Authors: Destouni Georgia , Cvetkovic Vladimir
Published: May 2018

The effect of natural heterogeneity on large scale solute transport in the unsaturated zone is investigated using stochastic methods. Several of the physical parameters that control flow and solute transport in the unsaturated zone are regarded as random fields. Specifically, the influence of spatial variability in recharge applied on the surface, saturated hydraulic conductivity, water content at saturation and depth to the groundwater table, on solute flux into the groundwater, is illustrated. It is shown that the prediction of solute penetration into the groundwater through the unsaturated zone is significantly affected by the natural variability in the physical parameters. A simple stochastic model for the estimation of large scale solute flux through the unsaturated zone, is provided.
Snow Cover of the Upper Colorado River Basin from Satellite Passive Microwave and Visual Imagery
Authors: Josberger Edward G. , Beauvillain Edouard
Published: May 2018

A comparison of passive microwave images from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and visual images from the Defense Meteorological Satellite Program (DMSP) of the Upper Colorado River Basin shows that passive microwave satellite imagery can be used to determine the extent of the snow cover. Eight cloud-free DMSP images throughout the winter of 1985-1986 show the extent of the snowpack, which, when compared to the corresponding SMMR images, determine the threshold microwave characteristics for snow-covered pixels. With these characteristics, the 27 sequential SMMR images give a unique view of the temporal history of the snow cover extent through the first half of the water year. Beginning mid-November, the snow-covered area rapidly increases from near zero to 80 percent by the middle of January. During late February the snow-covered area decreases as a result of basin-wide warming. The microwave determinations initially overestimate the decrease in snow cover, as a result of liquid water in the snowpack, but the return of cooler temperatures restores the veracity of the passive microwave determinations.
A Test of Snowmelt-Runoff Model for a Major River Basin in Western Himalayas
Authors: Dey B. , Sharma V. K. , Rango A.
Published: May 2018

In the Snowmelt-Runoff Model (SRM), the estimate of discharge volume is based on temperature condition in the form of degree days which are used to melt the snowpack in the area of the basin covered by snow as observed from satellites. Precipitation input is used to add any rainfall runoff to the snowmelt component. When SRM was applied to the large, international Kabul River basin, initial simulations were much above the observed stream flow values. Close inspection revealed several problems in the application of SRM to the Kabul Basin that were easily corrected. Foremost among the corrections were determination of an appropriate lapse rate, substitution of a more representative mean elevation for extrapolation of temperature data, and use of an automatic streamflow updating procedure. These improvements led to a simulation for 1976 that was comparable to other simulations on large, inaccessible basins. As SRM is applied to more basins similar to the Kabul River, the determination of suitable parameters for new basin will be enhanced. Additional improvements in simulations would result from installation of climate stations at the mean elevation of basins and work to assure delivery of timely and reliable satellite snow cover data.
Reliability Concepts in Reservoir Design
Authors: Plate Erich J.
Published: May 2018

The case of a dam for an irrigation reservoir is used as an example to illustrate the different modes of failure of a water resources system. The types of failure to which a dam can be subjected are described in the first section of the paper, in terms of a framework of general reliability analysis. Two applications are considered: the case of operational failure, illustrated by means of an irrigation reservoir for arid countries, and the case of dam failure due to overtopping. Conceptual models are given which permit the inclusion of reliability and other figures of merit into both operation and safety analysis.
Till Genesis and Hydrogeological Properties
Authors: Haldorsen Sylvi , Krüger Johannes
Published: May 2018

Hydrogeological properties of tills are highly dependent upon factors as grain-size distribution, compaction, orientation of particles, presence of fractures and occurrence of sorted sediments. These factors are again dependent upon the till forming processes. Lodgement tills formed under active, temperate sliding glaciers are usually compact, rather homogeneous and in many cases they are fractured. Melt-out tills deposited in connection with stagnant ice are in most cases less dense, have a lower content of fine-grained particles and a higher abundance of sorted sediment lenses. Flow tills which are mainly formed by a secondary flow of supraglacial debris are commonly very variable, they may have a low content of fine-grained components, a low degree of compaction and they are often closely connected with sorted glaciofluvial sediments. Till genesis is in many cases difficult to interpret, and an objective description of all main characteristics of the till is important in hydrogeological studies. The lodgement till has a lower effective porosity than the melt-out and flow tills due to its finer grain-sizes and higher compactness. The saturated hydraulic conductivity is lower, and dependent upon the fracture pattern. In melt-out tills and flow tills the occurrence of well sorted sediments will in many cases control the hydraulic conductivity. In all till types the structural properties are most important for the saturated water flow.
Rain-Runoff Parameters for Six Small Gauged Urban Catchments
Authors: Jensen Mogens
Published: May 2018

The interpretation of rain-runoff measurements from 6 small (less than 17 ha) urban catchments is described. The recording period covers mostly 1979-1983. Relations between rain- and runoff depths were developed using the traditional linear regression model as well as a new continuous model. Both models compute runoff from impervious surfaces in the same way. Calculation of runoff from semipervious surfaces accounts for infiltration through cracks, percolation from a sublayer and evaporation during dry weather. These phenomena are related to water content of the sublayer. The 10 parameters in the continuous model are calibrated and show values in good agreement with data from the literature. The continuous model fits the measured runoff depths somewhat better for the largest runoff events. For more frequent events, however, the two models are equally good.

Rain intensity – duration – frequency curves have been computed. Variations of up to 20 %, for return periods 1/5 and 1/2 yr., are seen for catchments with distances approximately 5 km from each other.

Peak flow statistics are compared with rain intensity. The peak runoff coefficient (cf. rational method) is mostly constant or slightly increasing with the return period.
The Solubility and Hydrolysis of Aqueous Aluminium Hydroxides in Dilute Fresh Waters at Different Temperatures
Authors: Lydersen Espen
Published: May 2018

This study is mainly focusing on the effect of temperature and pH on the chemistry of Al(OH)3(s) using available thermodynamic data.

The calculations show that a doubling of the [H+] or a decrease in temperature by 15°C, approximately yields the same solubility increase of the various Al(OH)3(s) presented.

The relative concentration of aqueous aluminium hydrolysis complexes is also highly temperature dependent. At 25°C and pH 5, the calculated distribution of dissolved, inorganic aluminium hydroxides corresponds to about 36% of Al3+, 37 % of Al(OH)2+, 26 % of Al(OH)2+ and 1 % of Al(OH)30. At the same pH but at 0°C, about 84%, 13%, 2% and 0% are present as Al3+, Al(OH)2+, Al(OH)2+ and Al(OH)30, respectively. This temperature effect is of major importance as the hydroxide species are supposed to be the most toxic species to aquatic biota.

Literature reports on the equilibrium constants Al(OH)3(s), log*Ks, vary from about 8 to 11, a variation in the product by a factor of 1000. In natural soil/water systems the solubility products of crystalline and amorphous solid aluminium sources are unknown and the solubility may also be coupled to combined weathering/ion exchange processes. In addition substantial amount of aluminium may be present as organic complexes where aluminium by cation exchange reactions may enter the solution as monomeric inorganic species. Thus, if a low value for the equilibrium constants of Al(OH)3(s) is used as reference when calculating the degree of aluminium saturation, an apparent oversaturation will often be demonstrated. To estimate the degree of aluminium saturation in natural waters whould therefore only be of theoretical interest.
Electromagnetic Profiling for Groundwater in Precambrian Basement Complex Areas of Nigeria
Authors: Olayinka A. Idowu
Published: May 2018

Ground electromagnetic profiling, using a Geonics EM34-3 instrument, has been employed to identify areas of high conductivity in a Precambrian basement complex terrain of Nigeria.

Field examples, conducted as part of a rural water supply programme, are presented. They indicate that the apparent conductivities are generally lower than about 60 mmho m−1. Subsequent borehole drilling suggests a good correlation between high EM34 anomalies, deep weathering and high well yield (> 1 1 s−1). On the other hand, boreholes sited on conductivity lows penetrated a thinner regolith with relatively lower yields.
Response of Soil Moisture Change to Hydrological Processes in a Continuous Permafrost Environment
Authors: Woo Ming-ko , Marsh Philip
Published: May 2018

The moisture content of the active layer at three sites in a continuous permafrost area was measured using a twin-probe gamma density meter. The moisture storage status at these sites were related to various hydrological processes. Moisture was gained by meltwater and rainfall infiltration, but lost to evaporation in summer. Lateral inflow maintained a thick saturated zone at the fen (wetland) site. At the gravel site, there was a net moisture loss due to evaporation and lateral outflow.

Moisture changes in the active layer during the summer were examined in terms of the water balance at the three sites. This established quantitative relationships between the moisture regime and the major hydrological processes in the permafrost environment.
Changes in the Flexural Strength of Ice under Radiation Decay
Authors: Prowse T. D. , Demuth M. N. , Chew H. A. M.
Published: May 2018

The strength of an ice cover significantly affects the timing and severity of breakup on northern rivers. During the pre-breakup period, thermal and radiative warming is known to significantly decrease such strength. Although reductions in strength with temperature are reasonably well known, there is a dearth of data concerning strength changes due to internal radiative melt. In the spring of 1989, near Floral, Saskatchewan, Canada, a detailed series of experiments were conducted to determine changes in flexural strength, porosity and optical properties of the ice cover. The test data strongly support existing theoretical models of strength reduction due to porosity development in columnar grained ice. Experimental methods and results with respect to flexural testing, porosity determinations and radiation energy balance are discussed.
Effect of Texture, Rainfall and Slope on Rainfall Interrill Sediment Transport
Authors: Agarwal Avinash , Dickinson W.T.
Published: May 2018

Experiments were conducted with rainfall intensities of 45.0 and 140.0 mm/hr at slopes of 2, 9 and 20 per cent to separate the dominant effect of rainfall intensity on sediment transport capacity. The effect of sediment size on rainintensity contribution to unit sediment transport capacity was also investigated. Regression models for rain-intensity contribution to unit sediment transport capacity Y were developed including median particle diameter X of sediment as an additional independent variable. The constants of power relationships of the form Y ≡ aXb were found to vary with the median particle diameter of the soil.
High Resolution Measurements of Pollution Wash-Off from an Asphalt Surface
Authors: Spångberg Å. , Niemczynowicz J.
Published: May 2018

The paper describes a measurement project aiming at delivering water quality data with the very fine time resolution necessary to discover deterministic elements of the complex process of pollution wash-off from an urban surface. Measurements of rainfall, runoff, turbidity, pH, conductivity and temperature with 10 sec time resolution were performed on a simple urban catchment, i.e. a single impermeable 270 m2 surface drained by one inlet. The paper presents data collection and some preliminary results.
Evaluation of Geological and Recharge Parameters for an Aquifer in Southern Sweden
Authors: Olin Malin H. E. , Svensson Chester
Published: May 2018

Groundwater levels fluctuate as a result of changes in the relation between inflow and outflow to the aquifer, and the magnitude of the fluctuations are also depending on the geologic conditions in the aquifer. Of special interest when studying groundwater is to estimate the inflow to the aquifer, the recharge, as it is the renewable part of a water resource. Here a simple method for modelling the relation between inflow and outflow from groundwater level variations is described, a method that also relates to the geologic features of the aquifer. Input data are groundwater level observations from several years, data that are often readily available. From these data longer periods of decreasing groundwater levels are chosen, during which the recharge is assumed to be zero. An exponential recession curve is established by a least-square fitting to all the chosen periods, and from this curve a base level for zero groundwater runoff is evaluated, together with a geologic reservoir parameter that consists of the storage coefficient, the area of the aquifer, and a groundwater runoff coefficient. A recharge parameter that is proportional to the recharge is then evaluated.
Suspended Sediment Yield in the Baltic Drainage Basin
Authors: Lajczak Adam , Jansson Margareta B.
Published: May 2018

The aim of this paper is to quantify the spatial distribution of suspended sediment yield in the Baltic Sea drainage basin, and to quantify the suspended sediment inflow to the Baltic. The sediment yield in the studied area varies in accordance with the potential erosion conditions in the morphological sub-units and reaches values from below 2 to almost 1,000 t/km2/yr. Topographical, pedological and climatic conditions are decisive for the sediment yield variations. The suspended sediment yield increases generally from north to south, and reaches maximum values in the lower parts of the Carpathians. In contrast, the Scandinavian mountains are characterized by low suspended sediment yield. The suspended sediment load derived from the source areas decreases during its transport to the Baltic as a result of sedimentation processes. In the largest rivers of the area no more than 20 to 30% of the sediment amount flowing from tributaries to the main rivers ends up in the Baltic Sea. The total mass of suspended material flowing to the Baltic Sea is 4,455,000 t/yr, 37% of which is carried into the Baltic proper. 20% of the total supply to the Baltic Sea comes from the Vistula river.
Tracer Test in Fractured Chalk
Authors: Jakobsen R. , Høgh Jensen K. , Brettmann K. L.
Published: May 2018

A two-well tracer test was conducted in eastern Denmark, in which a short duration pulse of lithium chloride was injected into a recharge well and made to flow through a fractured chalk aquifer to a discharge well. The wells were 25 m apart, and the concentration of lithium arriving at the discharge well was monitored at five vertical intervals in the well for a 21-day period. The observed breakthrough curves show a sharp breakthrough front, with an arrival time that is consistent with advective transport through the fractures in the chalk. The breakthrough curves also exhibit a long tail in the falling limb, suggesting the influence of a secondary transport mechanism of diffusion into the porous matrix.
Potential Evaporation – A Matter of Definition
Authors: Lindroth Anders
Published: May 2018

The aim of this paper is to discuss the concept of potential evaporation and its use in runoff models. The potential evaporation for forest is defined on basis of estimated minimum canopy resistances for a well-watered spruce forest. The difference between the Penman open water evaporation, commonly used as “potential” evaporation, and a more realistic estimate of the potential evaporation from a dry forest showed a large scatter and a systematic seasonal deviation. Part of the differences were explained by differences in vapour pressure deficit. It was also shown that the evaporation rate of a completely wet forest was typically four times higher than the rate predicted by the Penman equation. The conclusion was that Penman open water evaporation did not give a good representation of forest conditions.
Hydrogeophysical Concepts in Aquifer Test Analysis
Authors: Şen Zekâi
Published: May 2018

Aquifer test data analysis is an art leading to reliable hydraulic parameter identifications rather than a mechanical curve fitting. Most often aquifer test data processing is achieved by matching the data with suitable type curve without detailed interpretations of deviations from this curve. In fact, relevant interpretations might yield valuable qualitative and quantitative features about the subsurface geological composition of the aquifer domain at least in the well vicinity. The view taken in this paper is to obtain additional information from various data segments by considering two or more successive measurements. Such a detailed investigation of aquifer test data is referred to herein as the “hydrogeophysical” approach since it yields important clues about the geological set up as well as the groundwater flow regime in the well vicinity. Main features of hydrogeophysical investigation are given based on author's experience. It is hoped that additional points will be supplemented in future applications by other groundwater hydrologists. The application of hydrogeophysical concepts are exemplified for some field data available in the groundwater literature.
Metal Transport in Groundwater Contaminated by Acid Mine Drainage
Authors: Herbert Roger B.
Published: May 2018

Acid mine drainage from a rock dump at an abandoned mine in Dalarna, Sweden, has contaminated the groundwater and created a leachate plume characterized by low pH and high concentrations of Fe, SO4, and heavy metals. Groundwater samples have been collected in order to explain the observed spatial variations in groundwater chemistry. The mineralogy of soil samples collected at the water table has been identified by X-ray diffraction analysis In order to determine which processes may be controlling the evolution of the leachate plume, the geochemical mass-transfer model PHREEQE is used to evaluate a possible reaction pathway controlling the reaction of the leachate plume with uncontaminated groundwater and the till aquifer. The results suggest that silicate weathering and goethite precipitation are the processes primarily controlling observed pH, pe, and Fe concentrations in groundwater direct down-gradient of the rock dump. Increases in K, Na, and Al concentrations along the flow path can be attributed to the feldspar weathering while Al and SO4 concentrations further down-gradient can be controlled by the precipitation of AlOHSO4. The attenuation of heavy metal concentrations may be the result of adsorption and coprecipitation with goethite and other Fe xides.
Modelling the Effects of Acid Sulphate Soils on River Acidity in Finland
Authors: Palko Jukka , Weppling Kjell
Published: May 2018

Acid sulphate (AS) soils cover extensive areas of the coastal plains in western Finland. These soils constitute an environmental hazard due to their ability to release acidity when exposed to atmospheric oxygen. Acidification of soil and water can be reduced or prevented if the factors influencing the release and transport of acidity in AS soils are known. The objective of this study was to develop mathematical models describing the acidity load from AS soils, thus providing tools for accurate soil and water management in the affected areas. The work resulted in a static and a dynamic model for predicting the runoff acidity from catchments containing AS soils. The main features of the models are described in the paper. Both models require significant catchment characteristics and hydrological monitoring results as input data, but no ion balance information is needed. Model applications showed that the static model is able to give good estimates of the mean acidity level to be expected during specific flood periods in the studied river, while the dynamic model, after calibration, is capable of predicting the daily acidity with appreciable accuracy. The information provided by the models can be used to assess adequate mitigration strategies for the watercourses affected by AS soils.
Correlations between Concentrations of Plant Nutrients in Runoff from Small Catchments in Norway
Authors: Haraldsen T. K. , Oygarden L. , Rognerud B. , Aastveit A. H.
Published: May 2018

Factor analysis investigated the relationship between different compounds of nitrogen, phosphorus, potassium and suspended dry matter in runoff from catchments in agricultural areas in southern and central Norway. The plant nutrients were grouped in three factors: phosphorus factor, nitrogen factor and erosion factor. In south-eastern Norway there was a significant correlation between runoff and concentration levels of phosphorus and suspended dry matter in winter and spring erosion periods. Climate, agricultural practices and soil conditions caused seasonal variation of the different factors. In the catchments in south-western Norway there was a decreasing trend in concentration level of nitrogen due to changed practice for slurry application. In the catchments in eastern and central Norway there was a decreasing concentration level of phosphorus. The reduction in applied phosphorus was 15-50% but the decrease in concentration level of phosphorus in runoff accounted for 5 to 15% of the variation.
Hydrology of a Polythermal Glacier, Erikbreen, Northern Spitsbergen
Authors: Vatne G. , Etzelmüller B. , Sollid J. L. , Ødegård R. Strand
Published: May 2018

Glacial and glaciohydrologic processes that control the glaciofluvial sediment delivery from Erikbreen, a polythermal glacier on the north coast of Spitsbergen (79°40'N, 12°30'E), were studied during the summer seasons of 1990,1991 and 1992. Erikbreen differs from most glaciers of similar size in Svalbard, by the high flow velocity and a heavily crevassed surface. Water tracing experiments were conducted to study the geometry and stability of subglacial conduits, and the influence of the drainage system on subglacial sediment withdrawal. The withdrawal of sediments was monitored in the proglacial stream. High concentrations of suspended sediments were found. The type of drainage system and the presence of unconsolidated sediments at the glacier bed exerts the main control on the glaciofluvial sediment delivery. Annual delivery of suspended sediments varies by a magnitude, runoff being the controlling variable.
Modeling the Effects of Rainfall Variability on Groundwater Recharge in Semi-Arid Tanzania
Authors: Sandström Klas
Published: May 2018

A conceptual model of the effects of rainfall variability on groundwater recharge was developed and applied to a small forested catchment in semi-arid Tanzania. The model simulated dual-domain recharge through the soil matrix and macropores, and was based on daily values of rainfall and potential evapotranspiration. Three different land-cover conditions (forested-nondegraded, deforested-nondegraded, and deforested-degraded) were included in the study in order to simulate the large-scale deforestation and land degradation process now occurring in Tanzania. In addition, the alternative land covers were also considered in combination with three different rainfall regimes.

The results indicate the importance of macropore flow, particularly during dry years. The lack of macropores under deforested-degraded conditions reduces the simulated groundwater recharge to such an extent that it is less than under forested conditions. Simulating a climate change scenario shows that a small change in rainfall (-15%) can cause a large change in recharge (-45%).
Release of Major Ions and Hydrogen Peroxide from Homogeneous, Melting Snow
Authors: Herrmann Reimer , Kranz Jutta
Published: May 2018

We undertook two laboratory experiments to study the change of concentrations and the preferential elution of major ions and hydrogen peroxide during melting of a homogeneous snow pack. The elution sequence was as follows: alkali metals, alkaline-earth metals and protons > anions > NH4+ > H2O2. We explain the late elution of Cl−, NH4+ and H2O2 by high ice/water partition coefficients and a more even distribution of the two ions as well as of H2O2 within the ice crystal due to formation processes of snow particles in the atmosphere.
Seasalt Effects on the Acid Neutralizing Capacity of Streamwaters in Southern Norway
Authors: Lydersen Espen , Henriksen Arne
Published: May 2018

Input of neutral salt, primarily NaCl, from sea spray is an important factor for short-term acidification of surface water, primarily in already acidified areas, because Na may substitute for H+ and cationic aluminium by cation-exchange reactions in the soil. By evaluating the variation of non-marine sodium (Na*) separately it is possible to estimate the major effect of seasalt episodes on the neutralizing capacity (ANC) of stream water. At four long-term monitored Norwegian catchments, the Na* in stream water on average explained 28 ± 4% of the monthly variations of ANC in stream water at Birkenes, and 27 ± 3%, 20 ± 2% and 56 ± 5% of the correspondent variations at Storgama, Langtjern and Kaarvatn, during the respective monitoring periods. The remaining variations in acid neutralizing capacity are explained by the difference between non-marine base cations (ΣCa*,Mg*,K*) and non-marine sulphate (SO4*) and NO3. This paper also indicates that seasalt episodes are probably of greater importance for the periodic variations in ANC of stream water than commonly recognized. During the last years, extreme seasalt episodes have occurred in southern Norway, and more frequently at winter-time, which means that seasalt inputs have played a more important role for the short-term variations of ANC in stream water the last years. This tendency is also strengthened by the fact that there has been a significant decline in the input of acidic sulphur compounds and non-marine base cations in stream water during the last 10-15 years. Because the decline in soil-derived base cations in stream water is somewhat lower than the correspondent decline of sulphate, a slowly improving ANC of stream water should be expected on long-term basis. Seasalt episodes of the same magnitude as those present during the last years, will therefore most likely cause less extreme water-chemical conditions in the years to come. Because the seasalt effect seems to be a short-term effect, there is no reason to claim that these effects may cause long-term acidification, a conclusion earlier drawn from several correspondent studies.
Monitoring Soil Condition in the Northern Tibetan Plateau Using SSM/I Data
Authors: Chang A. T. C. , Cao M. S.
Published: May 2018

A combination of a low 37 GHz brightness temperature and a negative 19 and 37 GHz spectral gradient can be an effective discriminant for frozen and thawed soil. SSM/I data for 1988 are used to study the freeze/thaw of soil in the Northern Tibetan Plateau, China. In this study, a previously derived freeze/thaw classification scheme was tested for this unique geographic location. It was found that the 37 GHz threshold needed to be refined for this region. It was also found that the 37 GHz emission is sensitive to the scattering centers embedded in the soil, which may account for the observed low brightness temperature. The selection of the 37 GHz brightness temperature threshold depends on the atmospheric and soil conditions inherent in a particular region.
Subpermafrost Groundwater, Western Svalbard
Authors: Haldorsen S. , Heim M. , Lauritzen S. -E.
Published: May 2018

Subpermafrost groundwater aquifers are found in Ny-Ålesund, western Svalbard. Recharge of groundwater takes place along the base of the nearby glaciers, and groundwater flows in open bedrock fracture systems and porous sedimentary rocks. A subpermafrost sandstone with a primary porosity of more than 10% makes up a pore aquifer with a considerable storability. The water discharges into one of the old coal mines, with a flow rate of 11.5 1/s measured in the summer and fall of 1993 and 1994. There was a considerable discharge during the winters 1993 and 1994, a discharge making up nearly the whole annual water budget from the upper part of the Vestre Lovénbreen. Similar situations are found in other places on Svalbard and may have an important influence upon the glaciers' hydrological regime. The groundwater system in Ny-Ålesund is manipulated by human activity. Outflow channels in the old coal mines probably have increased discharge relative to an undisturbed system and may locally have melted the permafrost. The groundwater flow is an efficient mechanism for transferring geothermal heat, and may have an important influence locally upon the permafrost distribution on part of Svalbard.
Oxygen Isotope and Ionic Concentrations in Glacier River Water: Multi-Year Observations in the Austre Okstindbreen Basin, Norway
Authors: Theakstone Wilfred H. , Knudsen Niels Tvis
Published: May 2018

Austre Okstindbreen, the largest glacier of the Okstindan area, Norway, covers about 14 km2 within a drainage basin of 22.5 km2. Each year, about one third of the discharge of the glacier river results from snowmelt outside the glacier margins. Snow melting on the glacier contributes about twice as much water to the river as does glacier ice. Early in the melt season, the glacier river is supplied almost entirely by snow meltwater. Na+ ion concentrations in the snow are much higher than those of Ca2+; percolation of meltwater from the surface results in chemical changes. Water entering the body of the glacier from the melting snow cover is relatively depleted of 18O, whilst the residual snow is more enriched. As the ablation season proceeds and the transient equilibrium line rises up-glacier, an increasing amount of ice meltwater is mixed with snow meltwater, diluting the overall concentration of ions in the river. Ice meltwater is 18O-rich, and the δl8O value of glacier river water rises at times of high ice ablation. Water which percolates through the snow cover above the transient equilibrium line during the melt season may maintain river discharge in late summer. Mean concentrations of the principal cations in the river water vary between years; after winters with above-average snow accumulation, Na+ values tend to be high. Ca2+ concentrations are determined largely by subglacial conditions.
Preliminary Considerations for Runoff Modelling in GCMS
Authors: Verseghy Diana
Published: May 2018

Modelling of runoff in GCMs is a two-stage process: first, a residual water amount resulting from precipitation, evapotranspiration, snowmelt, infiltration and soil moisture movement at each time step must be generated for each grid cell; then a runoff routing model must be applied to this water excess to produce streamflow. Incorporation of the latter into GCMs is as yet in the most initial stages, and will not be reliably achieved for some years to come. However, before this can be accomplished, the water excess that is to be routed must be generated in a physically realistic fashion.

Two land-surface models of widely varying complexity are presently available as options in the Canadian GCM (developed at Atmospheric Environment Service, Canada). The old scheme is based on a bucket approach for soil moisture and on the force-restore method for soil temperature; a more recently developed scheme (“CLASS” – Canadian Land Surface Scheme) incorporates physical modelling of the heat and moisture budgets of three soil layers, the snow cover and the vegetation canopy. Based on comparisons of year-long runs of both models, it is postulated that reliable modelling of the surface water excess cannot be achieved using a “bucket” model. It is also shown that sub-grid scale variability of the precipitation rate must be taken into account, and that the land surface model must allow for surface water retention between timesteps.
Characterization of Flood Waves by Rating Curves
Authors: Mishra S.K. , Jain M.K. , Seth S.M.
Published: May 2018

The flood waves are characterized within the frame-work of loop (or hysteresis) of rating curves. The National Weather Service's Dam Break Flood Forecasting Model is used to generate the flood waves in the downstream valley of the Bargi dam located in Central India. The quantified hystereses, η, of non-dimensional rating curves are related with the corresponding flood wave characteristics, viz., speed of travel, wave number, phase difference, and attenuation. The analysis has led to the development of an exact relationship between η and phase difference. Using the concept of wave zoning, the better performance of the hysteresis based criteria compared with the available criteria is verified using Convex and Muskingum-Cunge routing in the wave zones. η limits are specified for the applicability of these simplified routing models. Furthermore, the envisaged applications of the based analysis are introduced.
A Simple Automatic Calibration Routine for the HBV Model
Authors: Lindström Göran
Published: May 2018

A simple, but efficient, method for automatic calibration of the conceptual HBV rainfall-runoff model was developed. A new criterion, which combines the commonly used efficienyy criterion R2 and the relative volume error was introduced. Optimising this combined criterion resulted in R2 values nearly as high as those for optimssing only R2, but with much smaller volume errors. An earlier automatic calibration method for the HBV model relied on the use of differett criteria for different parameters. With the simplification to one single criterion, the optimum search method could be made more efficient. The optimisation is made for one parameter at a time, while the others are kept constant. This one-dimensional optimisation is repeated in a loop for all parameters. A new loop is performed as long as there is a sufficiently large improvement since the last one. After each loop a search is made in the direction which is defined by the differences in parameter values between the two latest loops. The calibration routine was developed for, and tested with, the HBV model, but it should be general enough to be applicable to other modess as well.
Adaptive Use of a Conceptual Model for Real Time Flood Forecasting
Authors: Da Ros D. , Borga M.
Published: May 2018

This paper investigates the adaptive use of a simple conceptual lumped rainfall-runoff model based on a Probability Distributed Model complemented with a Geomorphological Unit Hydrograph. Three different approaches for updating the model and for its use for real time flood forecasting are compared: the first two are based on a parameter updating approach; in the third procedure the model is cast into a state-space form and an Extended Kalman Filter is applied for the on-line estimation of the state variables. The comparison shows that the procedure based on the filtering techniques provides more reliable results; acceptable results are also obtained by using a parameter updating approach based on the on-line adjustment of the initial conditions.
A Study of Sedimentation in Chenab Basin in Western Himalayas
Authors: Rao S. V. N. , Rao M. V. , Ramasastri K. S. , Singh R. N. P.
Published: May 2018

The young Himalayas have a serious problem of soil erosion and consequent sedimentation in river reaches downstream. The study revealed the high rates of sedimentation in Chenab basin and its effect on an existing reservoir. Correct estimation of sediment yield at any given point in space and time is of vital importance for water resources development and management. In the present study data of 17 to 27 years were used to develop statistically significant spatial models to estimate sediment yield in the Chenab basin (22,000 km2) using geomorphological, climatic and landuse parameters. The sediment yield was estimated for total and fine sediment for monsoon, premonsoon seasons and the year.
Changes of Ionic and Oxygen Isotopic Composition of the Snowpack at the Glacier Austre Okstindbreen, Norway, 1995
Authors: Raben Peter , Theakstone Wilfred H.
Published: May 2018

Marked vertical variations of ions and oxygen isotopes were present in the snowpack at the glacier Austre Okstindbreen during the pre-melting phase in 1995 at sites between 825 m and 1,470 m above sea level. As the first meltwater percolated from the top of the pack, ions were moved to a greater depth, but the isotopic composition remained relatively unchanged. Ions continued to move downwards through the pack during the melting phase, even when there was little surface melting and no addition of liquid precipitation. The at-a-depth correlation between ionic concentrations and isotopic ratios, strong in the pre-melting phase, weakened during melting. In August, concentrations of Na+ and Mg2+ ions in the residual pack were low and vertical variations were slight; 18O enrichment had occurred. The difference of the time at which melting of the snowpack starts at different altitudes influences the input of ions and isotopes to the underlying glacier.