A new approach to master recession curve analysis

Abstract

The analysis of drought discharge is of utmost relevance in the design of water intake structures, management of water resources, and in coping with environmental issues. In this context, the master recession curve represents a tool in hydrological analysis, giving integrated information on long period drought flow rates. In this paper, a technique is developed for deriving a master recession curve directly from daily discharge series that takes into account the high variability in the behaviour of individual recession segments. The statistical framework developed allows us to explicitly represent uncertainty, and hence a novel interpretation of the master recession curve is derived. The method is successfully applied to three important Italian basins draining the southern slopes of the eastern Alps.

Citation Fiorotto, V. and Caroni, E., 2013. A new approach to master recession curve analysis. Hydrological Sciences Journal, 58 (5), 966–975.     

Evaluation of basin storage–discharge sensitivity in Taiwan using low‐flow recession analysis

Sensitivity analysis of the hydrological behaviour of basins has mainly focused on the correlation between streamflow and climate, ignoring the uncertainty of future climate and not utilizing complex hydrological models. However, groundwater storage is affected by climatic change and human activities. The streamflow of many basins is primarily sourced from the natural discharge of aquifers in upstream regions. The correlation between streamflow and groundwater storage has not been thoroughly discussed. In this study, the storage–discharge sensitivity of 22 basins in Taiwan was investigated by means of daily streamflow and rainfall data obtained over more than 30 years. The relationship between storage and discharge variance was evaluated using low‐flow recession analysis and a water balance equation that ignores the influence of rainfall and evapotranspiration. Based on the obtained storage–discharge sensitivity, this study explored whether the water storage and discharge behaviour of the studied basins is susceptible to climate change or human activities and discusses the regional differences in storage–discharge sensitivity. The results showed that the average storage–discharge sensitivities were 0.056 and 0.162 mm^?1 in the northern and southern regions of Taiwan, respectively. In the central and eastern regions, the values were both 0.020 mm^?1. The storage–discharge sensitivity was very high in the southern region. The regional differences in storage–discharge sensitivity with similar climate conditions are primarily due to differences in aquifer properties. Based on the recession curve, other factors responsible for these differences include land utilization, land coverage, and rainfall patterns during dry and wet seasons. These factors lead to differences in groundwater recharge and thus to regional differences in storage–discharge sensitivity.     

Regional variation of recession flow power‐law exponent

Recession flows of a basin provide valuable information about its storage–discharge relationship as during recession periods discharge occurs due to depletion of storage. Storage–discharge analysis is generally performed by plotting ?dQ/dt against Q , where Q is discharge at time t . For most real world catchments, ?dQ/dt versus Q show a power‐law relationship of the type: ?dQ/dt = kQ^α . Because the coefficient k varies across recession events significantly, the exponent α needs to be computed separately for individual recession events. The median α can then be considered as the representative α for the basin. The question that arises here is what are the basin characteristics that influence the value of α ? Studies based on a small number of basins (up to 50 basins) reveal that α has good relationship with several basin characteristics. However, whether such a relationship is universal remains an important question, because a universal relationship would allow prediction of the value of α for any ungauged basin. To test this hypothesis, here, we study data collected from a relatively large number of basins (358 basins) in USA and examine the influence of 35 different physio‐climatic characteristics on α . We divide the basins into 2 groups based on their longitudes and test the relationship between α and basin characteristics separately for the two groups. The results indicate that α is not identically influenced by different basin characteristics for the two datasets. This may suggest that the power‐law exponent α of a region is determined by the way local physio‐climatic forces have shaped the landscape.     

Effects of temporal resolution on hydrological model parameters and its impact on prediction of river discharge / Effets de la résolution temporelle sur les paramètres d'un modèle hydrologique et impact sur la prévision de l'écoulement en rivière

Abstract

Temporal resolution of rainfall plays an important role in determining the hydrological response of river basins. Rainfall temporal variability can be considered as one of the most critical elements when dealing with input data of rainfall—runoff models. In this paper, a typical lumped rainfall—runoff model is applied to long- and short-term runoff prediction using rainfall data sets with different temporal resolution, including daily, hourly and 10-min interval data, and the dependency of model performance on the time interval of the rainfall data is discussed. Furthermore, the effect of temporal resolution on model parameter values is analysed. As results, rainfall data with shorter temporal resolution provide better performance in short-term river discharge estimation, especially for storm discharge estimation. The most accurate results are obtained on the peak discharge and recession part of the hydrograph by using 10-min interval rainfall data. It is concluded that model parameter values are influenced not only by the temporal resolution of calculation but also by the rainfall intensity—duration relationship. This study provides useful information about determination of hydrological model parameters using data of different temporal resolutions.     

Analysing individual recession events: sensitivity of parameter determination to the calculation procedure

ABSTRACT

This study assesses the sensitivity to model fitting methods and segment selection of the estimated parameters A and B of the model dQ/dt = ?AQ^B for individual events. We investigated about 750 recession events observed at 25 US Geological Survey gauges in the Iowa and Cedar river basins in the United States, with drainage areas ranging from 7 to 17 000 km². The parameters of these recession events were estimated using three commonly adopted methods and recession segments with different extraction criteria. The results showed that the variations of the parameter estimates for the same recession event were comparable to the variations of parameters between different events due to using different model fitting methods and recession segments. This raises cautions for comparative analysis of individual recessions. The result also implies that the nonlinear direct fitting method is the most robust among the three model fitting methods compared.

EDITOR Z.W. Kundzewicz ASSOCIATE EDITOR T. Okruszko     

Robustness of flood-model calibration using single and multiple events

ABSTRACT

Lack of discharge data for model calibration is challenging for flood prediction in ungauged basins. Since establishment and maintenance of a permanent discharge station is resource demanding, a possible remedy could be to measure discharge only for a few events. We tested the hypothesis that a few flood-event hydrographs in a tropical basin would be sufficient to calibrate a bucket-type rainfall–runoff model, namely the HBV model, and proposed a new event-based calibration method to adequately predict floods. Parameter sets were chosen based on calibration of different scenarios of data availability, and their ability to predict floods was assessed. Compared to not having any discharge data, flood predictions improved already when one event was used for calibration. The results further suggest that two to four events for calibration may considerably improve flood predictions with regard to accuracy and uncertainty reduction, whereas adding more events beyond this resulted in small performance gains.     

THE EFFECT OF EVAPOTRANSPIRATION ON STREAMFLOW RECESSION / L'effet de l'évapotranspiration sur l'écoulement en décrue

Abstract

The effect that evapotranspiration has on recession curves during low flow periods is explored. Recession constants are obtained from flow data and plotted against the average daily pan evaporation occurring during the recession. The results for the three study basins are similar, showing a decrease in recession constant with an increase in average daily pan evaporation. For low values of average daily pan evaporation, the recession constant approaches a constant value.     

Experimental methods for river discharge measurements: comparison among tracers and current meter

Abstract

Discharge measurements in natural watercourses are performed in order to determine the value of the surface outflow of a basin, its temporal variability, and the outflow characteristics. The methods conventionally used for these measurements utilize an immersed current meter in different points of a river section, which acquires the mean flow velocity. Using this measurement, the discharge can be calculated. Some experimental problems arise, however, when there is a very high discharge. An important method, valid in such cases, is the artificial tracing method. In particular, the use of chemical tracers for small watercourses is very convenient because they are low cost, easily handled, low impact and provide satisfactory results. In the past, radioactive tracers such as tritium have been used in large rivers, while fluorescent tracers have been commonly exploited in the USA and now elsewhere. However, if the water is turbid, the suspended sediments may easily absorb some tracers. In this paper, the preliminary results of a comparison between current meter and artificial tracer measurements are reported. In particular, field tests in a small tributary have been performed, in order to investigate the behaviour of different tracers.

Citation Tazioli, A. (2011) Experimental methods for river discharge measurements: comparison among tracers and current meter. Hydrol. Sci. J. 56(7), 1314–1324.     

Estimation of river discharge from non-trapezoidal open channel using QuickBird-2 satellite imagery/Utilisation des images satellites de Quickbird-2 pour le calcul des débits fluviaux en chenaux ouverts non-trapézoïdaux

Abstract

Abstract River discharge is traditionally acquired by measuring water stage and then converting the water stage to discharge by using a stage–discharge rating curve. The possibility of monitoring river discharge by satellite has not been adequately studied hitherto, because of the difficulty in making sufficiently precise measurements of the water surface. Since the successful launch of commercial satellites with very-high-resolution sensors, it has become possible to derive ground information from satellite data. To determine river discharge in a non-trapezoidal open channel, an efficient approach has been developed that uses mainly satellite data. The method, which focuses on the measurement of surface water width coupled with river width–stage and ?remote? stage–discharge rating curves, was applied to the Yangtze River (Changjiang) and an accurate estimate of river discharge was obtained. The method can be regarded as ancillary to traditional field measurement methods or other remote sensing methods.     

A new fuzzy linear regression approach for dissolved oxygen prediction

Abstract

A new method for fuzzy linear regression is proposed to predict dissolved oxygen using abiotic factors in a riverine environment, in Calgary, Canada. The proposed method is designed to accommodate fuzzy regressors, regressand and coefficients, i.e. representing full system uncertainty. The regression equation is built to minimize the distance between fuzzy numbers, and generalizes to crisp regression when crisp parameters are used. The method is compared to two existing fuzzy linear regression techniques: the Tanaka method and the Diamond method. The proposed new method outperforms the existing methods with higher Nash-Sutcliffe efficiency, and lower RMSE, AIC and total fuzzy distance. The new method demonstrates that nonlinear membership functions are more suitable for representing uncertain environmental data than the typical triangular representations. A result of this research is that low DO prediction is improved and consequently the approach can be used for risk analysis by water resource managers.

Editor D. Koutsoyiannis; Associate editor T. Okruszko     

Hydrological variability of major French rivers over recent decades,assessed from gauging station and GRACE observations

Abstract

This study was carried out in the framework of the Surface Water and Ocean Topography (SWOT) programme of the French National Centre of Space Studies (CNES). Based on discharge measurements and Gravity Recovery and Climate Experiment (GRACE) determination of total water storage (TWS), we have investigated the hydrological variability of the main French drainage basins (Seine, Loire, Garonne and Rhône) using a wavelet approach (continuous wavelet analyses and wavelet coherence analyses). The results of this analysis have shown a coherence ranging between 82% and 90% for TWS and discharge, thus demonstrating the potential use of TWS for characterization of the hydrological variability of French rivers. Strong coherence between the four basin discharges (between 73% and 92%) and between their associated TWS data (from 82% to 98%) suggested a common external influence on hydrological variability. To determine this influence, we investigated the relationship between hydrological variability and the North Atlantic Oscillation (NAO), considered as an index of prevailing climate in Europe. Basin discharges show strong coherence with NAO, ranging between 64% and 72% over the period 1959–2010. The coherence between NAO and TWS was 62% to 67% for 2003–2009. This is similar to the coherence between NAO and basin discharges detected for the same period. According to these results, strong influence of the NAO was clearly observed on the TWS and discharges of the major French river basins.

Editor Z.W. Kundzewicz     

Estimation of peak streamflows through channel geometry / Estimation de pics de débit fluviatiles à l'aide de la géométrie des cours d'eau

Abstract

Knowledge of peak discharge is essential for safe and economical planning and design of hydraulic structures. In India, as in most developing countries, the majority of river basins are either sparsely gauged or not gauged at all. The gauged records are also of short length (generally 15–30 years), therefore development of robust models is necessary for estimation of streamflows. Various studies reveal that flood estimation through channel geometry is an alternative method for ungauged catchments. It is appropriate for use where flow characteristics are poorly related to catchment area and other catchment characteristics. In the present study, stream geometry parameters for 42 river sites in central-south India were used; calibration equations were developed with data for 35 stations and tested on data for the remaining seven stations. The relationships developed between mean discharge and channel geometry parameters provide an alternative technique for estimation of mean annual channel discharge.     

Simulating the daily discharge of the Mandovi River,west coast of India

Abstract

A hydrological modelling framework was assembled to simulate the daily discharge of the Mandovi River on the Indian west coast. Approximately 90% of the west-coast rainfall, and therefore discharge, occurs during the summer monsoon (June–September), with a peak during July–August. The modelling framework consisted of a digital elevation model (DEM) called GLOBE, a hydrological routing algorithm, the Terrestrial Hydrological Model with Biogeochemistry (THMB), an algorithm to map the rainfall recorded by sparse raingauges to the model grid, and a modified Soil Conservation Service Curve Number (SCS-CN) method. A series of discharge simulations (with and without the SCS method) was carried out. The best simulation was obtained after incorporating spatio-temporal variability in the SCS parameters, which was achieved by an objective division of the season into five regimes: the lean season, monsoon onset, peak monsoon, end-monsoon, and post-monsoon. A novel attempt was made to incorporate objectively the different regimes encountered before, during and after the Indian monsoon, into a hydrological modelling framework. The strength of our method lies in the low demand it makes on hydrological data. Apart from information on the average soil type in a region, the entire parameterization is built on the basis of the rainfall that is used to force the model. That the model does not need to be calibrated separately for each river is important, because most of the Indian west-coast basins are ungauged. Hence, even though the model has been validated only for the Mandovi basin, its potential region of application is considerable. In the context of the Prediction in Ungauged Basins (PUB) framework, the potential of the proposed approach is significant, because the discharge of these (ungauged) rivers into the eastern Arabian Sea is not small, making them an important element of the local climate system.

Editor D. Koutsoyiannis; Associate editor S. Grimaldi

Citation Suprit, K., Shankar, D., Venugopal, V. and Bhatkar, N.V., 2012. Simulating the daily discharge of the Mandovi River, west coast of India. Hydrological Sciences Journal, 57 (4), 686–704.     

Groundwater recharge assessment in a rural,arid, mid-mountain basin in North-Central Chile

ABSTRACT

A basic component of any hydrogeological study is the magnitude and temporal variation of groundwater recharge. This can be difficult to assess accurately, particularly in arid and semi-arid rainfed mid-mountain zones, as is the situation in the rural, low population density zones of North-Central Chile. In this study, recharge in the Punitaqui Basin, North-Central Chile, was characterized, contrasting the results of two methods: a modified Thornthwaite-Mather (MTM) and discharge recession analysis (DRA). We found a recharge rate of between 1 and 4% of average annual precipitation. Average recharge estimated by the MTM method is consistently higher than that estimated by DRA. Also, DRA tends to smooth the recharge values, resulting in a lower inter-annual variation coefficient. Both methods identified a threshold value of total annual precipitation, above which recharge can be expected to occur, of the order of 180 mm year^?1, consistent with values reported in similar areas.     

Changes in concentration–discharge regression parameters due to coal mining and reclamation activities / Changements dans les paramètres de régression entre concentration et débit,causés par l’exploitation minière de charbon et des activités de reconversion

Abstract

Abstract Assessment of the impacts of mining and reclamation, and design of management practices to reduce chemical loads in stream channels, require knowledge of changing hydrological conditions and of changing sources and rates of release of chemicals into stream waters. One simple method for evaluating these impacts is to combine flow duration curves with regression relations between surface-water chemical concentrations (C) and instantaneous discharge (Q). However, little is known regarding the drainage basin-scale effects of mining and reclaiming drainage basins on regression relations. These effects were assessed on three small experimental drainage basins in Ohio subjected to surface mining for coal. Comparisons were made between regression parameter changes for natural/undisturbed conditions, land disturbances caused by mining and reclamation, incomplete reclamation, and the final condition of the reclaimed drainage basins. Regression analysis used a total of 5047 laboratory analyses of 36 constituents. Of 429 regressions, 153 (36%) were statistically significant. Knowledge of changes in regression parameters is important because regressions supply information on the rate of release and supply of chemical constituents in mined and reclaimed drainage basins. Duration curves of concentration and loads can be constructed using these regressions with flow–duration curves to give estimates of the percentage of time that concentrations and loads are exceeded during different phases of disturbance. This study assessed the changes in regression relations due to mining coal seams and reclamation activities for 36 chemical constituents, two mining methods, three reclamation practices and three distinct geologic settings.     

Neural network model for discharge and water-level prediction for Ramganga River catchment of Ganga Basin,India

ABSTRACT

Discharges and water levels are essential components of river hydrodynamics. In unreachable terrains and ungauged locations, it is quite difficult to measure these parameters due to rugged topography. In the present study an artificial neural network model has been developed for the Ramganga River catchment of the Ganga Basin. The modelled network is trained, validated and tested using daily water flow and level data pertaining to 4 years (2010–2013). The network has been optimized using an enumeration technique and a network topology of 4-10-2 with a learning rate set at 0.06, which was found optimum for predicting discharge and water-level values for the considered river. The mean square error values obtained for discharge and water level for the tested data were found to be 0.046 and 0.012, respectively. Thus, monsoon flow patterns can be estimated with an accuracy of about 93.42%.

Editor M.C. Acreman; Associate editor E. Gargouri     

Water and nutrient predictions in ungauged basins: set-up and evaluation of a model at the national scale

Abstract

A dynamic water quality model, HYPE, was applied to a large, data-sparse region to study whether reliable information on water quantity and water quality could be obtained for both gauged and ungauged waterbodies. The model (called S-HYPE) was set up for all of Sweden (～450 000 km²), divided into sub-basins with an average area of 28 km². Readily available national databases were used for physiographic data, emissions and agricultural practices, fixed values for representative years were used. Daily precipitation and temperature were used as the dynamic forcing of the model. Model evaluation was based on data from several hundred monitoring sites, of which approximately 90% had not been used in calibration on a daily scale. Results were evaluated using the Nash-Sutcliffe efficiency (NSE), correlation and relative errors: 92% of the spatial variation was explained for specific water discharge, and 88% and 59% for total nitrogen and total phosphorus concentrations, respectively. Day-to-day variations were modelled with satisfactory results for water discharge and the seasonal variation of nitrogen concentrations was also generally well captured. In 20 large, unregulated rivers the median NSE for water discharge was 0.84, and the corresponding number for 76 partly-regulated river basins was 0.52. In small basins, the NSE was typically above 0.6. These major achievements relative to previous similar experiments were ascribed to the step-wise calibration process using representative gauged basins and the use of a modelling concept, whereby coefficients are linked to physiographic variables rather than to specific sites.

Editor D. Koutsoyiannis

Citation Strömqvist, J., Arheimer, B., Dahné, J., Donnelly, C. and Lindström, G., 2012. Water and nutrient predictions in ungauged basins: set-up and evaluation of a model at the national scale. Hydrological Sciences Journal, 57 (2), 229–247.     

On the evaluation of snow water equivalent estimates over the terrestrial Arctic drainage basin

Comparisons between snow water equivalent (SWE) and river discharge estimates are important in evaluating the SWE fields and to our understanding of linkages in the freshwater cycle. In this study, we compared SWE drawn from land surface models and remote sensing observations with measured river discharge (Q) across 179 Arctic river basins. Over the period 1988‐2000, basin‐averaged SWE prior to snowmelt explains a relatively small (yet statistically significant) fraction of interannual variability in spring (April–June) Q, as assessed using the coefficient of determination (R²). Averaged across all basins, mean R²s vary from 0·20 to 0·28, with the best agreement noted for SWE drawn from a simulation with the Pan‐Arctic Water Balance Model (PWBM) forced with data from the European Centre for Medium‐Range Weather‐Forecasts (ECMWF) Re‐analysis (ERA‐40). Variability and magnitude in SWE derived from Special Sensor Microwave Imager (SSM/I) data are considerably lower than the variability and magnitude in SWE drawn from the land surface models, and generally poor agreement is noted between SSM/I SWE and spring Q. We find that the SWE versus Q comparisons are no better when alternate temporal integrations–using an estimate of the timing in basin thaw–are used to define pre‐melt SWE and spring Q. Thus, a majority of the variability in spring discharge must arise from factors other than basin snowpack water storage. This study demonstrates how SWE estimated from remote sensing observations, or general circulation models (GCMs), can be evaluated effectively using monthly discharge data or SWE from a hydrological model. Copyright © 2007 John Wiley & Sons, Ltd.     

Incorporating groundwater recharge and discharge functions into an existing monthly rainfall–runoff model/Incorporation de fonctions de recharge et de vidange superficielle de nappes au sein d’un modèle pluie-débit mensuel existant

Abstract

Abstract There is an urgent need for an integrated surface water and groundwater modelling tool that is suitable for southern African conditions and can be applied at various basin scales for broad strategic water resource planning purposes. The paper describes two new components (recharge and groundwater discharge) that have been added to an existing monthly time-step rainfall–runoff model that is widely used in the southern African subcontinent. The new components are relatively simple, consistent with the existing model formulation, but based on accepted groundwater flow principles and well understood groundwater parameters. The application of the revised model on two basins in southern Africa with quite different baseflow characteristics has demonstrated that the new components have a great deal of potential, even if the improvement is only to be able to simulate the groundwater baseflow component of total runoff more explicitly. More comprehensive testing and comparison of the results with existing groundwater and geohydrological data is required, while some extensions to the new components need to be considered to ensure that the model can be considered applicable to a wide range of basin and climate types.