Showing papers in "Hydrological Sciences Journal-journal Des Sciences Hydrologiques in 1987"
TL;DR: In this article, the power of parametric procedures is low, and their results may be in error when applied to non-normal data, and five important advantages of nonparametric methods over commonly used parametric procedure are illustrated.
Abstract: Water quality data are usually analysed with parametric statistical procedures requiring the normality assumption for accuracy of their attained significance levels. However, these data are typically non-normally distributed. When applied to non-normal data, the power of parametric procedures is low, and their results may be in error. Three typical case studies are discussed: differentiation of water quality in streams using analysis of variance; discernment of water quality types using discriminant analysis; and t-tests on differences between two groups which include data below the detection limit. Five important advantages of nonparametric methods over commonly used parametric procedures are illustrated.
89 citations
TL;DR: The water balance of the Sudd is represented by a hydrological model which uses measured inflows and outflows and estimates of rainfall and evaporation to reproduce volumes and areas of flooding over the historical period 1905-1980.
Abstract: The water balance of the Sudd is represented by a hydrological model which uses measured inflows and outflows and estimates of rainfall and evaporation to reproduce volumes and areas of flooding over the historical period 1905–1980. Predicted outflows based on inflows are then substituted for measured outflows so that the proposed diversions through the Jonglei Canal can be incorporated in the model in order to predict the effects of the canal on areas of flooding.
63 citations
TL;DR: In this article, the authors used the compounded Gumbel distribution to represent the return periods of low flows for the rivers studied, showing noticeable spatial trends both in terms of the seasonal mean and the standard deviation of the low flows.
Abstract: In areas where the annual low flow series is generated by more than one distinct hydrological process, a compounded Gumbel distribution can provide a satisfactory fit to the empirical data. The annual low flows of rivers in Northern Ontario are the result of storage depletion following either long periods of below freezing temperatures at the end of winter or early spring (spring low flows), or high evaporation in late summer and early fall (fall low flows). Use of the compounded Gumbel distribution adequately represents the return periods of low flows for the rivers studied. Parameters estimated for the distribution show noticeable spatial trends both in terms of the seasonal mean and the standard deviation of the low flows.
28 citations
TL;DR: A conceptual model for the simultaneous computation of runoff and inorganic nitrogen leaching is described in this paper, where the model is semi-empirical with coefficients that are calibrated against observed data.
Abstract: A conceptual model for the simultaneous computation of runoff and inorganic nitrogen leaching is described. The model is semi-empirical with coefficients that are calibrated against observed data. Two applications of the model, using well-controlled data from small fields of arable land in southern Sweden, are demonstrated. These show that a major part of the variations of concentrations of inorganic nitrogen in runoff water can be explained by this model approach. Finally, the sensitivity and limitations of this type of model are discussed.
28 citations
TL;DR: In this paper, the authors used the natural isotope oxygen-18 and artificially injected tritium to study the percolation of soil water and found that the groundwater recharge is distributed rather uniformly over the year, although high soil moisture flux near the ground surface is caused by single episodes.
Abstract: The natural isotope oxygen-18 and artificially injected tritium are used for studying the percolation of soil water. Particle velocity, progression rate and soil moisture flux are distinguished from each other. Water particle velocities and seasonal groundwater recharge are determined in glacio-fluvial deposits and in till soils. In the glacio-fluvial deposits of the Uppsala Esker it is found that the groundwater recharge is distributed rather uniformly over the year, although high soil moisture flux near the ground surface is caused by single episodes. The travel time of a water particle from the ground surface to the groundwater level at about 4 m depth is two to three years. In the more heterogeneous moraine areas, the dispersion of the marked water is considerable. However, the origin of water recharging the groundwater can be determined. The vertical distance travelled by the fastest moving water particles in one year does not exceed 10 m.
28 citations
TL;DR: The infiltration equations according to Horton and Philip are applied to 52 double-ring infiltrometer tests performed in a small semi-arid catchment in northern Tunisia as discussed by the authors.
Abstract: The infiltration equations according to Horton and Philip are applied to 52 double-ring infiltrometer tests performed in a small semiarid catchment in northern Tunisia. Spatial variability in infiltration properties is analysed as regards the coefficients of the two equations. Different geomorphological zones display different infiltration characteristics even if there is large variability within each zone and no clear statistical difference between the zones. Statistical properties of the coefficients of Horton's and Philip's equations describing cumulative infiltration are presented and discussed. The statistical distribution of the coefficients seems to be well approximated by an exponential function.
23 citations
TL;DR: In this paper, scale effects in computing sheet and rill erosion losses from large basins have been studied for grid sizes ranging from 0.03 to 42 km over drainage areas up to 3000 km2.
Abstract: Scale effects in computing sheet and rill erosion losses from large basins have been studied for grid sizes ranging from 0.03 to 42 km over drainage areas up to 3000 km2, As a result of the analysis conducted on the Chaudiere basin (5830 km2), the mean characteristics of the basin can be used to estimate the mean annual upland erosion losses after a correction factor for the influence of grid size is introduced into the calculation, The use of fine-meshed grids can be justified when information on the areal distribution of soil erosion is desired.
20 citations
TL;DR: A series of synthetic five-year return period storms having rectangular, triangular and bimodal (triangular) temporal profiles was compiled from depthduration-frequency (D-D-F) relationships based on (a) standard sorted clock time depths and (b) complete storms only.
Abstract: A series of synthetic five-year return period storms having rectangular, triangular and bimodal (triangular) temporal profiles was compiled from depthduration-frequency (D-D-F) relationships based on (a) standard sorted clock time depths and (b) complete storms only. These were used as inputs to a catchment runoff model to simulate the peaks and volumes of runoff from an actual and a hypothetical catchment respectively. The hypothetical catchment was used to prove the adequacy of the simplified hyetographs and the real catchment to demonstrate the difference in runoff hydrographs for the various hyetographs. The results were compared to establish the effect of storm profiles on peak and volume of runoff as well as to indicate the shortcomings of D-D-F relationships derived by conventional methods. In general, on the assumption that the model correctly converts storm input to runoff, triangular, and in particular bimodal, profiles were shown to reproduce adequately runoff peaks and volumes.
18 citations
TL;DR: In this paper, an expression for the confidence in the accuracy of a flow record is derived which depends on the time interval between gauging stations where rating changes are frequent, and the analysis can be used to estimate probable errors in existing records and to control future gauging operations.
Abstract: For gauging stations where rating changes are frequent, errors in streamflow estimation can occur from using out-of-date stage-discharge ratings. The chance of such errors occurring can be reduced by increasing the frequency of flow gaugings. An expression for the confidence in the accuracy of a flow record is derived which depends on the time interval between gaugin The information provided by the analysis can be used to estimate probable errors in existing records and to control future gauging operations. Application of the analysis is illustrated by a comparison of records from seven stations in New Zealand with mean flows from 2 to 200 m3 s−1, and for those records, missed rating changes are the only significant contribution to the probable error of annual flows.
15 citations
TL;DR: In this article, the main loss from rainfall is considered to be infiltration which is represented by an extended formulation of a point approach utilizing a two-branched scheme for time to ponding and soil infiltration capacity.
Abstract: Eight different versions of a simple rainfallrunoff adaptive model for on-line flood forecasting are formulated in a framework characterized by an ensemble of spatially uniform units. The main loss from rainfall is considered to be infiltration which is represented by an extended formulation of a point approach utilizing a two-branched scheme for time to ponding and soil infiltration capacity. The differences among the model versions are due to the computation of effective rainfall, the treatment of the transformation process from effective rainfall to direct runoff, and the estimation of surface retention. The various model versions were tested by their application to events observed on a large Italian basin. By a comparison of their forecasts with those of a no-model approach and the estimation of errors in peak runoff, it was found that two of the models were more appropriate and provided flow forecasts sufficiently accurate for forecast lead times up to 6 h.
13 citations
TL;DR: In this paper, the spatial variability patterns of field-measured infiltration rates on a semiarid seeded rangeland near Eureka, Utah, USA were determined using two kinds of instruments, namely a double-ring infiltrometer and a modular type rainfall simulator.
Abstract: Field studies determined the spatial variability patterns of field-measured infiltration rates on a semiarid seeded rangeland near Eureka, Utah, USA. Two kinds of instruments, namely a double-ring infiltrometer and a modular type rainfall simulator, were used in both a moderately grazed pasture and an ungrazed exclosure (protected for over 20 years) to measure infiltration rates at 10 and 30 minutes. There were 104 grid points per instrument on a 24 m x 24 m grid (2 m spacing) at each site, with a total of 416 infiltrometer plots. Dependency of specific infiltration rate measurements on nearby measurements, as determined from autocorrelograms and semivariograms, was nonexistent. Percent cover (vegetation plus litter) explained from 18 to 36% of the variance associated with measured infiltration rates.
TL;DR: The tritium-tagging technique for estimating groundwater recharge has been used in the arid region of the Thar desert, western Rajasthan as mentioned in this paper, revealing considerable spatial variability of groundwater recharge in the areas investigated, between 6 and 14% of the rainfall input.
Abstract: A proper understanding of soil moisture movement in the unsaturated zone is of considerable importance in understanding and estimating groundwater recharge. Conventional methods, e.g. inventory, storage, lysimetric methods etc., require the availability of a long-term hydrometeorological data base for the area under consideration. Because of this constraint, there has been, in recent years, an increasing emphasis on the use of isotopic techniques, involving environmental and artificial tritium, for estimating groundwater recharge. The tritium-tagging technique for estimating groundwater recharge has been used in the arid region of the Thar desert, western Rajasthan. The study reveals considerable spatial variability of groundwater recharge in the areas investigated, between 6 and 14% of the rainfall input. The technique has yielded some insight into the variability of groundwater recharge in the arid region of the Thar desert. A simplified evapotranspiration-runoff model has also been developed t...
TL;DR: In this article, the mixing process in rivers is represented by the advection-dispersion equation, and a method of solution of the dispersion equation is presented for a special curvilinear coordinate system.
Abstract: The problem under consideration is the mixing of conservative, nonbuoyant pollutants released into a river. Such pollutants are mixed with the water of a river by different mechanisms, i.e. molecular diffusion, turbulent diffusion, advection and dispersion. These mechanisms are explained. One of the most important is dispersion, which is derived and described in the paper. The mixing process in rivers is represented by the advection-dispersion equation. Analysing this process in irregular rivers is usually impossible because of the lateral advection term in the dispersion equation. However, this term disappears in a special curvilinear coordinate system. Such a system is introduced and a method of solution of the dispersion equation is presented. Two examples of the simulation of a mixing process in curvilinear channels are given.
TL;DR: This keynote paper addresses four rhetorical questions regarding water quality monitoring which are paramount in formulating network-design strategies and some recommended guidelines for setting of goals and objectives, specifying network- design functions, identifying information users, and anticipating future monitoring perspectives.
Abstract: This keynote paper addresses four rhetorical questions regarding water quality monitoring which are paramount in formulating network-design strategies. These consist of (1) why, (2) how, and (3) for whom do we collect monitoring data, and (4) how do we evaluate monitoring-programme effectiveness in considering future information needs? Aspects of these rhetorical issues are discussed in this keynote paper, along with some recommended guidelines for setting of goals and objectives, specifying network-design functions, identifying information users, and anticipating future monitoring perspectives. The paper's intent is to focus on topics relevant to deliberations resulting from technical papers presented at the Symposium on Monitoring to Detect Changes in Water Quality Series, Budapest, July 1986.
TL;DR: In this paper, the authors present a calcule, en periode d'eau libre, the temperature journaliere de l'Eau en riviere a n'importe quel point d'un bassin versant, en utilisant les composantes d'Un modele hydrologique conceptuel.
Abstract: RESUME Le modele presente calcule, en periode d'eau libre, la temperature journaliere de l'eau en riviere a n'importe quel point d'un bassin versant, en utilisant les composantes d'un modele hydrologique conceptuel. A cette fin, le bassin est divise en parcelles sur lesquelles on etablit un bilan d'energie journalier. Ce bilan considere, d'une part, les echanges d'energie a la surface de l'eau, soit le rayonnement solaire, le rayonnement infrarouge, l'evaporation et la convection et, d'autre part, les echanges d'energie associes aux trois formes d'ecoulement prises en compte par le modele hydrologique, a savoir le ruissellement, l'ecoulement hypodermique et l'ecoulement de base. Le modele a ete applique au bassin versant de la riviere Sainte-Anne (Quebec, Canada) pour quatre annees differentes.
TL;DR: In this paper, two rainfall modelling techniques are assessed on their ability to reproduce the necessary historic rainfall statistics and, when routed through a deterministic catchment model, to produce the correct runoff characteristics.
Abstract: Efficient irrigation scheduling requires information on future reservoir inflows and field irrigation requirements. Where rainfall plays a significant part in determining these variables it is important to be able to forecast that rainfall accurately. Two rainfall modelling techniques are assessed on their ability to reproduce the necessary historic rainfall statistics and, when routed through a deterministic catchment model, to produce the correct runoff characteristics. For the data studied, a Markov chain—gamma distribution model is the more promising but there is an evident need for improvements in the technique.
TL;DR: A survey of the mathematical (quantitative) modelling of the interaction between surface water and groundwater is given in this article, where the authors present a brief review of the principal works on the subject under consideration including Soviet ones.
Abstract: The objective of the paper is to give a survey of the mathematical (quantitative) modelling of the interaction between surface water and groundwater. Besides describing the existing approach to such modelling and the main difficulties in its realization, the paper presents a brief review of the principal works on the subject under consideration including Soviet ones. The construction of such coupled models requires the development of methods of conjunction between models which represent surface and subsurface flows, which describe the different processes of water transfer and transformation, constituting the hydrological cycle, and which include the different components of hydrological, hydrogeological and water management systems (water bodies, streams, aquifers, etc.). Such models are of different complexities and have different dimensionality in space variables. The characteristic time-scales of transient processes for surface water and groundwater differ greatly, and this is of profound impor...
TL;DR: The extreme value type III distribution was derived by using the principle of maximum entropy as discussed by the authors, which required only two constraints to be determined from data, and yielded a procedure for estimation of distribution parameters.
Abstract: The extreme value type III distribution was derived by using the principle of maximum entropy. The derivation required only two constraints to be determined from data, and yielded a procedure for estimation of distribution parameters. This method of parameter estimation was comparable to the methods of moments (MOM) and maximum likelihood estimation (MLE) for the low flow data used.
TL;DR: In this paper, the authors described model studies for homogeneous and layered aquifers using finite difference numerical solutions and compared the flow conditions at the phreatic surface and the approach velocities to the well face.
Abstract: The presence of layers of different hydraulic conductivity can significantly affect the flow to a well in an unconfined aquifer. Model studies are described for homogeneous and layered aquifers using finite difference numerical solutions. The flow conditions at the phreatic surface and the approach velocities to the well face are calculated and compared for the different cases. The effect of the well penetration on the discharge is also observed. The adequacy of representing a layered aquifer as an equivalent anisotropic aquifer is discussed.
TL;DR: In this article, a Cryospheric Data Management System (CDSS) is developed which will enable snow cover maps to be constructed, for example, using passive microwave data from the US DMSP satellite.
Abstract: Up to now the study of snow cover conditions has been carried out on a local or regional scale. Research is hindered because the data are not even homogeneous in different countries. As a contribution to the assembly of such data, WDC-A for Glaciology has initiated an inventory of the observational methods and variables measured. Further, a Cryospheric Data Management System is being developed which will enable snow cover maps to be constructed, for example, using passive microwave data from the US DMSP satellite.
TL;DR: In this article, the authors describe some of the more recent work in the United Kingdom on the utilization of quantitative weather radar data in hydrological modelling and discuss several projects presently underway in the area of real-time flood forecasting and flood producing storm analysis.
Abstract: This paper describes some of the more recent work in the United Kingdom on the utilization of quantitative weather radar data in hydrological modelling. The historical background to weather radar developments is briefly discussed and several projects presently underway in the area of real-time flood forecasting and flood producing storm analysis are outlined.
TL;DR: In this paper, the authors derived the speed and direction of movement of rainfall patterns from data sets comprised of the coordinates (x,y) of a number of rainfall recording stations and the times of arrival (T) of some prominent feature of the recorded hyetographs.
Abstract: The speed and direction of movement of rainfall patterns can be derived from data sets comprised of the coordinates (x,y) of a number of rainfall recording stations and the times of arrival (T) of some prominent feature of the recorded hyetographs. The problem may be interpreted geometrically as the determination of the equation of an inclined plane in the x,y,t space, so that it best represents the set of data points. The speed of movement is given by the inverse of the maximum slope of the plane and its direction is parallel to that of the maximum slope. The proposed method is based on minimizing the sum of the squared deviations between the observed arrival times (T) and values (t) computed by the equation of the inclined plane.
TL;DR: In this article, apercu de la qualite de la phase solide (suspension and sediments de fond) des eaux du systeme Saint-Laurent (fleuve, estuaire et golfe) is presented.
Abstract: RESUME Le bassin hydrographique du fleuve Saint-Laurent, le siege de nombreuses activites humaines, engender habituellement une deterioration de la qualite du milieu et une contamination des eaux par les rejets industriels et municipaux et par des apports de ruissellement de surface Cet article presente un apercu de la qualite de la phase solide (suspension et sediments de fond) des eaux du systeme Saint-Laurent (fleuve, estuaire et golfe) Dans les eaux du fleuve Saint-Laurent, la concentration des solides en suspension varie de 4 a 10 mg 1−1 pour la partie en amont du lac Saint-Pierre et de 30 a 50 mg 1−1 dans la partie aval jusqu'a la ville de Quebec A l'exception du delta de Sorel, cette section du systeme Saint-Laurent ne constitue pas de fosses a sediments importantes La composition moyenne des sediments de fond en SiO2, Al2O3, Fe2O3, CaO et MgO est sensiblement la meme dans la region d'etude Cependant, l'enrichissement des sediments de fond en phosphore, en biphenyls polychlores, cuivre et plom
TL;DR: In this article, a partially-ducing well is modeled and the proportion of aquifer water in well discharge is numerically evaluated, tabulated as a function of time and compared with results for a fully penetrating well.
Abstract: A borehole partially penetrating a confined aquifer and pumped at a constant rate is modelled, taking account of water stored within the casing of the borehole. A solution for drawdown in the Laplace transform domain is obtained. The proportion of aquifer water in well discharge is numerically evaluated, tabulated as a function of time and compared with results for a fully penetrating well. Modification of the fully penetrating well theory, for application to partially penetrating wells, was found to give comparable results to the more complete analysis for a partially penetrating well both at early and late times. A previous estimate of the time of pumping before sampling (ts) to minimize casing storage effects, based on the fully penetrating well theory, was confirmed by the partially penetrating well analysis and in fact was shown to be a conservative estimate (or overestimate) of the pumping time required when sampling from a partially penetrating well.
TL;DR: In this article, it is shown that the Muskingum method is an approximate solution of the instantaneous unit hydrograph (IUH) of the lag and route flood routing method.
Abstract: The Muskingum flood routing method is widely used by hydrologists and good results are frequently achieved. However, there is still some dispute about the Muskingum method. In this paper it is shown that the Muskingum method is an approximate solution of the instantaneous unit hydrograph (IUH) of the lag and route flood routing method. The integration solution of the Muskingum method for multiple river reaches is also derived. The negative response issue is discussed in relation to the basis of the linear theory of hydrological systems.
TL;DR: In tropical Colombia, where 75% of groundwater exploitation is concentrated in two limited areas, successful agricultural ventures proved its economic value as discussed by the authors, and it is therefore imperative to assess the development possibilities of this almost untouched resource to complement surface water in irrigation and water supply projects, and in some cases to replace contaminated sources.
Abstract: In tropical Colombia, where 75% of groundwater exploitation is concentrated in two limited areas, successful agricultural ventures proved its economic value. It is therefore imperative to assess the development possibilities of this almost untouched resource to complement surface water in irrigation and water supply projects, and in some cases to replace contaminated sources. The present paper introduces the major aquifer units of the country and discusses the state of exploitation and approximate recharge values.
TL;DR: In this paper, the long-term groundwater regime and stream discharge in the Wilson Creek basin, southwestern Manitoba, from 1965 to 1980 were analyzed using the groundwater rating curve, monthly values of groundwater runoff from May to August were determined and analyzed.
Abstract: Observations and measurements of both the long-term groundwater regime and stream discharge were carried out in the Wilson Creek basin, southwestern Manitoba, from 1965 to 1980. Using the groundwater rating curve, monthly values of groundwater runoff from May to August were determined and analysed. As a result of statistical analyses, probability equations which describe each monthly groundwater runoff over this period were obtained. Seasonal groundwater runoff from May to August was calculated using the groundwater rating curve as well as water balance calculations. With the exception of two years, both series of groundwater runoff values agree. During summer storm runoffs, the average groundwater contribution to stream discharge derived from groundwater depletion curves was equal to 30%, while both direct runoff and interflow accounted for 70% of stream discharge.
TL;DR: In this article, the present state of the operational handling of the real-time short-range forecasting is outlined, together with a description of the model structure and of the underlying networks.
Abstract: The discharge of the Rhine upstream of Basle has been subject to forecasting at the Swiss Federal Institute of Technology, Zurich, for more than 20 years. The present state of the operational handling of the real-time short-range forecasting is outlined, together with a description of the model structure and of the underlying networks. The problems of spatial and temporal variation of precipitation need particular consideration. Because of the short response times and in order to meet the requirements of a lead time of three days, quantitative forecasts of precipitation and temperature are employed, including their variation in time and their distribution within the river basin.
TL;DR: In this article, the development of a mathematical model to simulate supercritical flow with sediment transport in sandy rivers is described, based on a numerical scheme for the integral version of the full governing equations and taking into account bottom configurations.
Abstract: Supercritical flow with sediment transport is a common phenomenon in steep rivers. This kind of flow presents features not present in rivers flowing in subcritical conditions. The development of a mathematical model to simulate supercritical flow with sediment transport in sandy rivers is described. The model is based on a numerical scheme for the integral version of the full governing equations and takes into account bottom configurations.
TL;DR: A complex of hydrogeological, hydrochemical, and biochemical investigations aimed at developing methods for the quality control of irrigation return water and agricultural nonpoint discharge was conducted from 1981 to 1985 as discussed by the authors.
Abstract: A complex of hydrogeological, hydrochemical, and biochemical investigations aimed at developing methods for the quality control of irrigation return water and agricultural nonpoint discharge was conducted from 1981 to 1985. The chemical composition of drainage flow in the zone of transient humidification in the Ukraine has been investigated; some dependencies of salts and humidity transfer rates as a function of a range of irrigation and climatic factors have been established. A new so-called “bioengineering” type of water-protective structure based upon natural mechanisms of water purification has been developed. The efficiency of the bioengineering structure for the reduction of the content of nitrogen, phosphorus and some compounds has been determined as a function of temperature, duration of the flow contact with biogeocenosis, water column depth and other parameters.