MESURE DE LA PERMÉABILITÉ DES SOLS EN PLACE: UN NOUVEL APPAREIL POUR LA MÉTHODE MUNTZ UNE EXTENSION DE LA MÉTHODE PORCHET AUX SOLS HÉTÉROGÈNES

ABSTRACT

The authors make a general survey of the methods of measuring soil permeability in the field, looking at them from the point of view of the hydrologist.

In the first part they describe new equipment built by the ORSTOM Centre in Lome, Togo, to apply the Muntz method of vertical infiltration under constant head, equipment using a double cylinder and semi-automatic regulation of the discharge.

In the second part, the authors make a mathematical analysis of the Porchet method of horizontal infiltration in a borehole full of water: they show that results may be interpreted even with heterogeneous (multi-layered) soils and that the calculations are simplified using a computer programme.

In conclusion they deal with some results of measurements obtained by the two methods, and examine their accuracy and their correlation with the physical and hydrodynamics characteristics of the soils.     

Multi-stage flood routing for gated reservoirs and conjunctive optimization of hydroelectricity income with flood losses

Abstract

A six-stage operation policy for routing of flood hydrographs of return periods from 1.01 year up to the Probable Maximum Flood (PMF) for any dam having a gated spillway is proposed. The gate opening rules are determined depending on the recent pool level. Regardless of the size and timing of any incoming floods, the fixed rules of the six-stage operation policy will provide optimum routing for all, which are classified into six different groups based on their return periods. 10-, 100-, 1000-, 10 000- 100 000-year floods, and PMF are the upper limits for the six groups. Next, an Incremental Dynamic Programming programme is developed to optimize both the firm and secondary energies of hydroelectric generation at monthly periods. First, the six-stage flood routing programme is applied sequentially to three dams, all on the Seyhan River in Turkey, for 18 combinations resulting from different active storages, and optimum flood operation policies for all three dams for all 18 combinations are determined. Second, the Dynamic Programming programme is applied to these three dams, and optimum hydroelectricity generation policies for all 18 combinations are computed. Finally, the optimum active and flood retention storages for the three dams are determined so as to maximize the net probability-weighted present worth of hydroelectricity benefits minus flood damage costs.     

THE STANFORD SEDIMENT MODEL I: TRANSLATION

SYNOPSIS

The simulation of sediment transport processes in a watershed by means of a mathematical model on a digital computer, as developed by Negev (¹) at Stanford University is considered, and the translation of this sediment model is presented in a commonly used, European computer programme language.     

MHD stability of a filament immersed in a solar bipolar magnetic region

Abstract

The stability properties of the filament model of Low (1981) are investigated. We use a two-dimensional formalism based on the magnetohydrodynamic energy principle of Bernstein et al. (1958). For the parameter range observed in quiescent prominences this model describes stable horizontal oscillations with periods of about 3–6 min. In other parameter ranges we find instability which is driven exclusively by compressional effects. The Lorentz force has a continuously stabilizing influence. In addition, it seems that gravity is practically unimportant for the stability state of the equilibrium.     

A BIVARIATE-REGRESSION MODEL FOR ESTIMATING CHEMICAL COMPOSITION OF STREAMFLOW OR GROUNDWATER / Modèle de régression bivarié pour l'évaluation de la composition chimique de l'écoulement total ou des eaux souterraines

Abstract

Regressions between concentrations of major inorganic constituents and either specific conductance or streamflow discharge characterize chemical-quality conditions at a sampling site or of an area and can be used to estimate streamflow chemical-quality composition over time and in space where information is lacking or deficient. In this manner, less costly water quality network operations may be achieved for a given programme, enabling available resources to be reallocated to the collection and analysis of data where information is deficient.

The SYSLAB system is a sequential set of documented special-purpose computer programs for statistically and graphically analysing historical water-quality records and deriving relevant regression relationships based upon this analysis. These computer programs have been applied under a variety of hydrological conditions to characterize regional chemical-quality patterns across the United States and in Pakistan. Case-study results using the proposed methodology are presented for Nigeria, Japan, and Pakistan.     

Modelling of water quality processes in rivers and estuaries. I

Abstract

A numerical method for evaluating the possibilities of the extreme wet and the extreme dry periods of a hydrological sequence is presented on the basis of stationary independent and Markovian processes that are currently employed in the planning and operation of water resources systems. The validity of the formula has been checked against the Monte Carlo simulation results obtained on a digital computer. Recurrence relationships for the probability distribution functions of the longest wet and dry periods have been derived by direct enumeration and the statistical properties of these extremes are presented.     

Real-time flood forecasting with the use of inadequate data

Abstract

A modelling scheme is developed for real-time flood forecasting. It is composed of (a) a rainfall forecasting model, (b) a conceptual rainfall-runoff model, and (c) a stochastic error model of the ARMA family for forecast error correction. Initialization of the rainfall-runoff model is based on running this model on a daily basis for a certain period prior to the flood onset while parameters of the error model are updated through the Recursive Least Squares algorithm. The scheme is suitable for the early stages of operation of flood forecasting systems in the presence of inadequate historical data. A validation framework is set up which simulates real-time flood forecasting conditions. Thus, the effects of the procedures for rainfall-runoff model initialization, forecast error correction and rainfall forecasting are assessed. Two well-known conceptual rainfall-runoff models (the Soil Moisture Accounting model of the US National Weather Service River Forecast Service—SMA-NWSRFS and TANK) together with data from a Greek basin are used for illustration purposes.     

Multi-objective optimization for free-phase LNAPL recovery using evolutionary computation algorithms

Abstract

A nonlinear, multi-objective optimization methodology is presented that seeks to maximize free product recovery of light non-aqueous phase liquids (LNAPLs) while minimizing operation cost, by introducing the novel concept of optimal alternating pumping and resting periods. This process allows more oil to flow towards the extraction wells, ensuring maximum free product removal at the end of the remediation period with minimum groundwater extraction. The methodology presented here combines FEHM (Finite Element Heat and Mass transfer code), a multiphase groundwater model that simulates LNAPL transport, with three evolutionary algorithms: the genetic algorithm (GA), the differential evolution (DE) algorithm and the particle swarm optimization (PSO) algorithm. The proposed optimal free-phase recovery strategy was tested using data from a field site, located near Athens, Greece. The PSO and DE solutions were very similar, while that provided by the GA was inferior, although the computation time was roughly the same for all algorithms. One of the most efficient algorithms (PSO) was chosen to approximate the optimal Pareto front, a method that provides multiple options to decision makers. When the optimal strategy is implemented, although a significant amount of LNAPL free product is captured, a spreading of the LNAPL plume occurs.

Editor Z.W. Kundzewicz; Associate editor L. See

Citation Dokou, Z. and Karatzas, G.P., 2013. Multi-objective optimization for free-phase LNAPL recovery using evolutionary computation algorithms. Hydrological Sciences Journal, 58 (3), 671–685.     

Calibration of conceptual models for rainfall-runoff simulation

Abstract

Conceptual mathematical models are a useful tool for rainfallrunoff modelling of a basin. The calibration of such models has attracted the attention of a number of hydrologists since unique and optimal parameters are difficult to obtain. The calibration of a conceptual model is discussed through a simple conceptual model whose parameters are determined using a search technique. It is shown that the optimization algorithm converges to a global optimum even when the errors in the initial parameters are quite significant and the input environment is noisy.     

Assessment of the MODIS global evapotranspiration algorithm using eddy covariance measurements and hydrological modelling in the Rio Grande basin

Abstract

Remote sensing is considered the most effective tool for estimating evapotranspiration (ET) over large spatial scales. Global terrestrial ET estimates over vegetated land surfaces are now operationally produced at 1-km spatial resolution using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the MOD16 algorithm. To evaluate the accuracy of this product, ground-based measurements of energy fluxes obtained from eddy covariance sites installed in tropical biomes and from a hydrological model (MGB-IPH) were used to validate MOD16 products at local and regional scales. We examined the accuracy of the MOD16 algorithm at two sites in the Rio Grande basin, Brazil, one characterized by a sugar-cane plantation (USE), the other covered by natural savannah vegetation (PDG) for the year 2001. Inter-comparison between 8-day average MOD16 ET estimates and flux tower measurements yielded correlations of 0.78 to 0.81, with root mean square errors (RMSE) of 0.78 and 0.46 mm d^-1, at PDG and USE, respectively. At the PDG site, the annual ET estimate derived by the MOD16 algorithm was 19% higher than the measured amount. For the average annual ET at the basin-wide scale (over an area of 145 000 km²), MOD16 estimates were 21% lower than those from the hydrological model MGB-IPH. Misclassification of land use and land cover was identified as the largest contributor to the error from the MOD16 algorithm. These estimates improve significantly when results are integrated into monthly or annual time intervals, suggesting that the algorithm has a potential for spatial and temporal monitoring of the ET process, continuously and systematically, through the use of remote sensing data.

Editor D. Koutsoyiannis; Associate editor T. Wagener

Citation Ruhoff, A.L., Paz, A.R., Aragao, L.E.O.C., Mu, Q., Malhi, Y., Collischonn, W., Rocha, H.R., and Running, S.W., 2013. Assessment of the MODIS global evapotranspiration algorithm using eddy covariance measurements and hydrological modelling in the Rio Grande basin. Hydrological Sciences Journal, 58 (8), 1658–1676.     

OPERATING A LIMESTONE AQUIFER AS A RESERVOIR FOR A WATER SUPPLY SYSTEM

Abstract

An aquifer can be used not only as water source but also as a regulating reservoir linked to a water supply system, planning the operation of such reservoirs calls for a good knowledge of the characteristics and limitations of the aquifer, an estimate of its natural replenishment and outflows, as weil as the determination of a programme for pumping and artificial recharge.

A limestone aquifer of karstic nature, heavily exploited and artificially recharged, has been studied recently with respect to its storage capacity and responses to a planned scheme of operations established for the national water supply systems.

The physical characteristics of this aquifer, its inflows, outflows and dynamic behaviour, were first determined by geological and hydrological investigations. The dynamic model obtained was then verified and improved by use of a resistor-capacitor electric analog constructed for this purpose. Later on, several operational alternatives were tested on the same analog. An optimization analysis was performed on a simplified single cell model representing the aquifer system. The methodology of such integrational operation is discussed in light of the results obtained.     

Calibration of a semi-distributed model for conjunctive simulation of surface and groundwater flows / Calage d’un modèle semi-distribué pour la simulation conjointe d’écoulements superficiels et souterrains

Abstract

Abstract A hydrological simulation model was developed for conjunctive representation of surface and groundwater processes. It comprises a conceptual soil moisture accounting module, based on an enhanced version of the Thornthwaite model for the soil moisture reservoir, a Darcian multi-cell groundwater flow module and a module for partitioning water abstractions among water resources. The resulting integrated scheme is highly flexible in the choice of time (i.e. monthly to daily) and space scales (catchment scale, aquifer scale). Model calibration involved successive phases of manual and automatic sessions. For the latter, an innovative optimization method called evolutionary annealing-simplex algorithm is devised. The objective function involves weighted goodness-of-fit criteria for multiple variables with different observation periods, as well as penalty terms for restricting unrealistic water storage trends and deviations from observed intermittency of spring flows. Checks of the unmeasured catchment responses through manually changing parameter bounds guided choosing final parameter sets. The model is applied to the particularly complex Boeoticos Kephisos basin, Greece, where it accurately reproduced the main basin response, i.e. the runoff at its outlet, and also other important components. Emphasis is put on the principle of parsimony which resulted in a computationally effective modelling. This is crucial since the model is to be integrated within a stochastic simulation framework.     

The interaction of topography and shear flow in a homogeneous rotating fluid

Abstract

Laboratory experiments are described in which a cylindrical obstacle is moved azimuthally through a rotating cylindrical tank of fluid in which a basic azimuthal flow inversely dependent upon the tank radius is generated by means of a source-sink arrangement. A technique is described whereby the flow can be adjusted until, relative to the obstacle, it is forward near the centre of the tank and reversed near the rim, with a monotonic variation between these extremes. The sense of this shear, relative to the obstacle, can be altered so that it either opposes or coincides with the sense of the basic rotation. Both cases are investigated in the experiments. The results of both qualitative and quantitative measurements are presented, and some comparison with related theoretical work is attempted.     

A SAMPLING SCHEME FOR SHALLOW SNOWPACKS

ABSTRACT

A hydrological sampling scheme should satisfy the purpose for which the samples are being collected, allowing for the variability of the samples in time and space. Snow measurements are commonly taken to provide estimates of the mean water equivalent over an area. A criterion for selecting a snow sampling scheme for shallow snowpacks is expressed in terms of the standard error of the mean water equivalent as a function of the means, variances, and sample sizes of snow depth and snow density. Analysis of data from the Blue Springs Representative Basin, Ontario, Canada, reveals relatively minor increases in the standard error term as the number of snow density samples is greatly reduced.     

New data for water losses from mature Sitka spruce plantations in temperate upland catchments / Nouvelles données pour les pertes d’eau de plantations adultes de sapins de Sitka en bassins versants tempérés d’altitude

Abstract

Abstract Accurate estimates of water losses from mature Sitka spruce (Picea sitchensis) plantations in the UK uplands are required to assess the sustainability of water supply in the event of land-use change. Many investigations have demonstrated that afforestation increases water losses from temperate upland catchments, to up to 40% of annual site rainfall. In a 0.86 km² upland water supply catchment in southwest Scotland, interception loss in a Sitka spruce-dominated 37-year old plantation, was 52% of annual precipitation (2912 mm), considerably higher than reported in previous studies of similar catchments. From direct measurements of rainfall, cloudwater, discharge and soil evaporation, the catchment water balance was 96–117% complete, within the limits of measurement error. The most probable explanation for the higher forest interception loss reported here is the inclusion of cloudwater measurements.     

Simulation and consequences of successive anthropogenic activity in the Agua Amarga coastal aquifer (southeast Spain)

Abstract

The Agua Amarga coastal aquifer has been the object of a succession of anthropogenic interventions over the last 90 years: (a) the operation of saltworks from 1925 to 1975; (b) the withdrawal, since 2003, of groundwater from the aquifer along the coast line; and (c) the programme of pouring seawater over the salt marsh, carried out since 2009, to recover the piezometric levels and the soil moisture conditions. For a better understanding of how these past and present human activities have affected the natural groundwater regime, and to validate certain hypotheses concerning the interpretation of experimental data on temperature depth profiles and piezometric and salinity changes, a numerical fluid flow and solute transport model was designed and applied to the period 1925–2010, using SEAWAT. This model reproduces, in a qualitative and quantitative way, the flow and transport processes that operated during this time, as well as the behaviour of the seawater wedge.

Citation Alhama Manteca, I., 2013. Simulation and consequences of successive anthropogenic activity in the Agua Amarga coastal aquifer (southeast Spain). Hydrological Sciences Journal, 58 (5), 1072–1087.

Editor D. Koutsoyiannis     

Environmental flow requirements assessment in the Halda River,Bangladesh

Abstract

Environmental flows have scarcely been considered in river water management in Bangladesh. This study attempts to assess the environmental flow requirements in the Halda River, Bangladesh. Thus, the objectives are to estimate the Halda River flow with different return periods/probabilities, which was done using the log-Pearson Type III distribution (LPIII), and to mitigate the environmental problems in the Halda River using the building block method. The LPIII distribution was used to estimate the expected extreme and satisfactory flows for fish habitat at Panchpukuria station and the expected extreme water levels at Panchpukuria, Narayanhat, Telpari and Enayethat stations. It was found that floods are likely to occur at least once in 2.1, 1.02, 1.75 and 1.25 years at Panchpukuria, Narayanhat, Telpari and Enayethat stations, respectively. The results of flow and water quality analyses suggest that environmental flow requirements cannot be achieved in this river throughout the year. The environmental flow requirements and conservation of fish resources can be achieved by implementing the suggestions provided in conjunction with a comprehensive awareness programme, investigations and trade-off analyses being among the suggestions.

Editor Z.W. Kundzewicz; Associate editor B. Sivakumar

Citation Akter, A. and Ali, Md. H., 2012. Environmental flow requirements assessment in the Halda River, Bangladesh. Hydrological Sciences Journal, 57 (2), 326–343.     

Direct relationships of discharges to the mean and standard deviation of the intervals between their exceedences

Abstract

This article paves a way for assessing flood risk by the use of two-parameter distributions, for the intervals between threshold exceedences rather than by the traditional exponential distribution. In a case study, the apparent properties of intervals between exceedences of runoff events differ from those anticipated for exponentially distributed series. A procedure is proposed to relate two statistical parameters of the intervals to threshold discharges. It considers partial duration series (PDS) with thresholds equal to all high enough observed discharges. To avoid unnecessary assumptions on the behaviour of those parameters and effects of dependence between parameters for different PDS, a non-parametric trend-free pre-whitened scheme is applied. It leads to power-law relationships between a discharge and the mean and standard deviation of the intervals between its exceedences. Predicted mean inter-exceedence intervals, for the highest observed discharges at the stations, are closer to the observational periods than those predicted by GEV distributions fitted to AMS, and by GP distributions to fitted PDS. In the present case, the latter predictions are longer than the observational periods whereas some of the predicted mean inter-exceedences are shorter than the corresponding observational periods and some others are longer.

Citation Ben-Zvi, A. & Azmon, B. (2010) Direct relationships of discharges to the mean and standard deviation of the intervals between their exceedences. Hydrol. Sci J. 55(4), 565–577.     

Un exemple de collaboration internationale en hydrologie

Summary

Forecasts of the discharge of the Rhine at Basel have been studied in Zurich since 1954.

In this programme have cooperated hydro-power companies of Switzerland, Germany and France, French shipping-firms, and the Dutch water management authorities. For the Netherlands the forecast of the summer yield of the Rhine is of great concern, since it is the main resource of fresh water.

The studies have resulted in:

— since 1955, annual forecasts of the yield from snowmelt for periods of one to eight months beginning with March, and monthly and bi-monthly forecasts in winter

— since 1960, forecasts issued 2 to 5 times per week for the next three days, from October to March.

The forecast method is the least squares multiple regression, based on the observations of more than 50 years.

For the short term forecasts, the significant predictors are discharge and rainfall, eventually the snow cover percentage on the Swiss midland plateau. The largest errors of forecast were encountered in thawing conditions. Meteorological forecasts are provided by the Swiss Meteorological Institute.

For the long range forecasts, the alpine snow pack (in practice represented by the cumulative winter precipitations) and the levels of the Swiss lakes play an important role.

The forecasts are used by the hydro-power plants in their operation programmes for maintenance planning, and for proper timing of construction work.

In the future, the probability graduation of these forecasts will also be introduced in the optimisation of power production according to the methods of operations research.     

Solar-activity cycle from observations of magnetic characteristics of prominences

According to measurements of the magnetic fields in quiescent prominences carried out by different teams in 1964–1989, the maximum values of the field correspond to the minimum values of the Wolf numbers averaged through the corresponding periods of observations. It has been shown that the synoptic noneclipse 2D linear polarimetry of quiescent Hα-prominences can be actually implemented; this method is based on the use of a coronagraph with a primary-optics diameter equal to or larger than 100 mm, a narrow-band filter with FWHM ≤ 0.4 nm, a standard linear polariod, and a high-precision linear polarimetric technique.