pinecone/core-2020-05-10-deduplication huggingface dataset:
Predicting and forecasting flow discharge at sites receiving significant lateral inflow

Two models, one linear and one non-linear, were employed for the prediction of flow discharge hydrographs at sites receiving significant lateral inflow. The linear model is based on a rating curve and permits a quick estimation of flow at a downstream site. The non-linear model is based on a multilayer feed-forward back propagation (FFBP) artificial neural network (ANN) and uses flow-stage data measured at the upstream and downstream stations. ANN predicted the real-time storm hydrographs satisfactorily and better than did the linear model. The results of sensitivity analysis indicated that when the lateral inflow contribution to the channel reach was insignificant, ANN, using only the flow-stage data at the upstream station, satisfactorily predicted the hydrograph at the downstream station. The prediction error of ANN increases exponentially with the difference between the peak discharge used in training and that used in testing. ANN was also employed for flood forecasting and was compared with the modified Muskingum model (MMM). For a 4-h lead time, MMM forecasts the floods reliably but could not be applied to reaches for lead times greater than the wave travel time. Although ANN and MMM had comparable performances for an 8-h lead time, ANN is capable of forecasting floods with lead times longer than the wave travel time
Water uptake by trees in a riparian hardwood forest (Rhine floodplain, France)

Water flow in the soil–root–stem system was studied in a flooded riparian hardwood forest in the upper Rhine floodplain. The study was undertaken to identify the vertical distribution of water uptake by trees in a system where the groundwater is at a depth of less than 1 m. The three dominant ligneous species (Quercus robur, Fraxinus excelsior and Populus alba) were investigated for root structure (vertical extension of root systems), leaf and soil water potential (m), isotopic signal (18O) of soil water and xylem sap. The root density of oak and poplar was maximal at a depth of 20 to 60 cm, whereas the roots of the ash explored the surface horizon between 0 and 30 cm, which suggests a complementary tree root distribution in the hardwood forest. The flow density of oak and poplar was much lower than that of the ash. However, in the three cases the depth of soil explored by the roots reached 1Ð2 m, i.e. just above a bed of gravel. The oak roots had a large lateral distribution up to a distance of 15 m from the trunk. The water potential of the soil measured at 1 m from the trunk showed a zone of strong water potential between 20 and 60 cm deep. The vertical profile of soil water content varied from 0Ð40 to 0Ð50 cm3 cm3 close to the water table, and 0Ð20 to 0Ð30 cm3 cm3 in the rooting zone. The isotopic signal of stem water was constant over the whole 24-h cycle, which suggested that the uptake of water by trees occurred at a relatively constant depth. By comparing the isotopic composition of water between soil and plant, it was concluded that the water uptake occurred at a depth of 20 to 60 cm, which was in good agreement with the root and soil water potential distributions. The riparian forest therefore did not take water directly from the water table but from the unsaturated zone through the effect of capillarit
A mass-balance approach to estimate in-stream processes in a\ud
large river

A mass-balance approach was used to estimate in-stream processes related to inorganic nitrogen species (NH4 C, NO2  and NO3 ) in a large river characterized by highly variable hydrological conditions, the Garonne River (south-west France). Studies were conducted in two consecutive reaches of 30 km located downstream of the Toulouse agglomeration (population 760 000, seventh order), impacted by modification of discharge regime and high nitrogen concentrations. The mass-balance was calculated by two methods: the first is based on a variable residence time (VRT) simulated by a one-dimensional (1-D) hydraulic model; the second is a based on a calculation using constant residence time (CRT) evaluated according to hydrographic peaks. In the context of the study, removal of dissolved inorganic nitrogen (DIN) for a reach of 30 km is underestimated by 11% with the CRT method. In sub-reaches, the discrepancy between the two methods led to a 50% overestimation of DIN removal in the upper reach (13 km) and a 43% underestimation in the lower reach (17 km) using the CRT method. The study highlights the importance of residence time determination when using modelling approaches in the assessment of whole stream processes in short-duration mass-balance for a large river under variable hydrological conditions
Understanding hydrological processes with scarce data in a mountain environment

Performance of process-based hydrological models is usually assessed through comparison between simulated and measured streamflow. Although necessary, this analysis is not sufficient to estimate the quality and realism of the modelling since streamflow integrates all processes of the water cycle, including intermediate production or redistribution processes such as snowmelt or groundwater flow. Assessing the performance of hydrological models in simulating accurately intermediate processes is often difficult and requires heavy experimental investments. In this study, conceptual hydrological modelling (using SWAT) of a semi-arid mountainous watershed in the High Atlas in Morocco is attempted. Our objective is to analyse whether good intermediate processes simulation is reached when global-satisfying streamflow simulation is possible. First, parameters presenting intercorrelation issues are identified: from the soil, the groundwater and, to a lesser extent, from the snow. Second, methodologies are developed to retrieve information from accessible intermediate hydrological processes. A geochemical method is used to quantify the contribution of a superficial and a deep reservoir to streamflow. It is shown that, for this specific process, the model formalism is not adapted to our study area and thus leads to poor simulation results. A remote-sensing methodology is proposed to retrieve the snow surfaces. Comparison with the simulation shows that this process can be satisfyingly simulated by the model. The multidisciplinary approach adopted in this study, although supported by the hydrological community, is still uncommon
The influence of resolution and topographic uncertainty on melt modelling using hypsometric sub-grid parameterization

Modelling of physical processes such as ablation or runoff at continental or global scales provides a key challenge: a high degree of abstraction is required in order to minimize computational demands, while spatial and temporal variability of key processes, often at the sub-scale level, need to be adequately captured and reproduced within a lower resolution model. For some approaches, such as temperature index models, downscaling to lower resolutions is straightforward. However a key issue when using these downscaled models is to assess the impact of scaling on model behaviour and results, including the associated uncertainties. We assess the impact of scaling on both a simple and an enhanced temperature index melt model from 100 m to 1, 5 and 10 km resolutions. Different sub-grid parameterization approaches are applied to both models across all resolutions and tested for their suitability against high-resolution reference data, with the aim of developing a robust, scalable and computationally undemanding parameterization. Results show patterns of over- and underestimation of potential melt rates for both models, with clear dependencies on scale, terrain roughness and variations of temperature thresholds, among other quantities. The sub-grid parameterizations tested in this article are found to effectively compensate these effects at little additional computational cost
Shuffled Complex Evolution Model Calibrating Algorithm: Enhancing its Robustness and Efficiency

Shuffled Complex Evolution—University of Arizona (SCE-UA) has been used extensively and proved to be a robust and\ud
efficient global optimization method for the calibration of conceptual models. In this paper, two enhancements to the SCEUA\ud
algorithm are proposed, one to improve its exploration and another to improve its exploitation of the search space.\ud
A strategically located initial population is used to improve the exploration capability and a modification to the downhill\ud
simplex search method enhances its exploitation capability. This enhanced version of SCE-UA is tested, first on a suite of test\ud
functions and then on a conceptual rainfall-runoff model using synthetically generated runoff values. It is observed that the\ud
strategically located initial population drastically reduces the number of failures and the modified simplex search also leads to\ud
a significant reduction in the number of function evaluations to reach the global optimum, when compared with the original\ud
SCE-UA. Thus, the two enhancements significantly improve the robustness and efficiency of the SCE-UA model calibrating\ud
algorithm
Low flow controls on benthic and hyporheic macroinvertebrate assemblages during supra-seasonal drought

This paper was submitted for publication in the journal, Hydrological Processes [© John Wiley & Sons, Ltd.] and the definitive version is available at: http://dx.doi.org/10.1002/hyp.7290Despite the widely accepted importance of the hyporheic zone as a habitat for stream macroinvertebrates during floods, few data exist regarding community composition and distribution during periods of low flow or drought in perennial streams. Integrating research on hyporheic invertebrates with results from a long-term study of a UK river provided the opportunity to examine how benthic and hyporheic macroinvertebrate communities respond to inter-annual variability in river flow and periods of groundwater drought. Changes in the riverine macroinvertebrate community associated with low flow included a reduction in species richness and the number of individuals per sample, particularly aquatic insects. The hyporheic community was characterized by a relatively homogeneous composition during a period of severe low flow, punctuated by short-term changes associated with variation in water temperature rather than changes in discharge. We present a conceptual model of the processes influencing benthic and hyporheic invertebrates under low-flow conditions. Previous studies have seldom integrated these two assemblages and their interactions. The model presented highlights the potential importance of surface water and hyporheic zone linkages for riverine invertebrate communities under a range of flow conditions
Influence of the hyporheic zone on the phosphorus dynamics of a large gravel-bed river, Garonne River, France

Phosphorus (P) concentrations in sediments and in surface and interstitial water from three gravel bars in a large river (Garonne River, southern France) were measured daily, downstream of a wastewater treatment plant for a city of 740 000 inhabitants (Toulouse). Measurements were made of vertical hydraulic gradient (VHG), total dissolved phosphorus (TDP), soluble reactive phosphorus (SRP) and total phosphorus (TP) in water and of three extractable forms of phosphorus (water extractable, NaOH extractable and H2SO4 extractable) in hyporheic sediments from the gravel bars. Dissolved phosphorus was the major contributor to TP (74–79%) in both interstitial and surface waters on all sampling dates, and in most cases surface water P concentrations were significantly higher than interstitial concentrations. Hyporheic sediment TP concentrations ranged between 269 and 465 μg g -1 and were highest in fine sediment fractions. Acid-extractable P, a non-bioavailable form, represented at least 95% of sediment TP. A positive relationship was observed between VHG and TP in two of the gravel bars, with wells that were strongly downwelling having lower TP concentrations. These results suggest that in downwelling zones, hyporheic sediments can trap surface-derived dissolved P, and that much of this P becomes stored in refractory particulate forms. Bioavailable P is mainly present in dissolved form and only occupies a small fraction of total P, with particulate P comprising the majority of total P
Linking North Atlantic ocean-atmosphere teleconnection patterns and hydrogeological responses in temperate groundwater systems

Climate signals exhibit periodicity over a range of frequencies (e.g. diurnal, seasonal, annual and longer term climate phenomena) that are modified as they propagate through the terrestrial water cycle. Much of both our present understanding and modelling of temperate hydrological and hydrogeological systems relies on the preservation of high-frequency signals (e.g. diurnal and seasonal cycles: Holman et al., 2009; Alley et al., 2002). However, there is evidence to suggest that low-frequency oscillations in rainfall, temperature and evapotranspiration are linked to the El Ni ˜no Southern Oscillation (Jones and Banner, 2003), Pacific Decadal Oscillation (Gurdak et al., 2007), North Atlantic Oscillation (NAO) (Schroder and Rosbjerg, 2004; Qian and Saunders, 2003) and other ocean–climate cycles
Large-Scale Hydrology in Europe : Observed Patterns and Model Performance

In a changing climate, terrestrial water storages are of great interest as water availability impacts key aspects of ecosystem functioning. Thus, a better understanding of the variations of wet and dry periods will contribute to fully grasp processes of the earth system such as nutrient cycling and vegetation dynamics. Currently, river runoff from small, nearly natural, catchments is one of the few variables of the terrestrial water balance that is regularly monitored with detailed spatial and temporal coverage on large scales. River runoff, therefore, provides a foundation to approach European hydrology with respect to observed patterns on large scales, with regard to the ability of models to capture these.<br>
The analysis of observed river flow from small catchments, focused on the identification and description of spatial patterns of simultaneous temporal variations of runoff. These are dominated by large-scale variations of climatic variables but also altered by catchment processes. It was shown that time series of annual low, mean and high flows follow the same atmospheric drivers. The observation that high flows are more closely coupled to large scale atmospheric drivers than low flows, indicates the increasing influence of catchment properties on runoff under dry conditions. Further, it was shown that the low-frequency variability of European runoff is dominated by two opposing centres of simultaneous variations, such that dry years in the north are accompanied by wet years in the south.<br>
Large-scale hydrological models are simplified representations of our current perception of the terrestrial water balance on large scales. Quantification of the models strengths and weaknesses is the prerequisite for a reliable interpretation of simulation results. Model evaluations may also enable to detect shortcomings with model assumptions and thus enable a refinement of the current perception of hydrological systems. The ability of a multi model ensemble of nine large-scale hydrological models and the land surface scheme of a high resolution regional climate model to capture various aspects of runoff were assessed. In general high and mean flows were better captured than low flows, pointing toward deficiencies with the models representation of storage processes. The analysis of the multi model ensemble also showed that the mean of all model simulations generally provided a more robust and accurate estimator of continental scale variations of catchment runoff than any individual model
Interactions between subgrid-scale resolution, feature representation and grid-scale resolution in flood inundation modelling

This is the pre-peer reviewed version of the article which has been published in final form at: http://dx.doi.org/10.1002/hyp.7813Numerical modelling of flood inundation over large and complex floodplains often requires mesh\ud
resolutions coarser than the structural features (e.g. buildings) that are known to influence the\ud
inundation process. Recent research has shown that this mismatch is not well represented by\ud
conventional roughness treatments but that finer scale features can be represented through porositybased\ud
sub grid scale treatments. This paper develops this work by testing the interactions between\ud
feature representation, sub grid scale resolution and mesh resolution. It uses as the basis for this\ud
testing a 2D diffusion-based flood inundation model which is applied to a 2004 flood event in a\ud
topologically-complex upland floodplain in northern England. Results showed serious degradation of\ud
model predictions without explicit representation of features like walls. Inclusion of such features\ud
through raising mesh cell elevations where intersected by a feature resulted in a major improvement in\ud
model predictions in terms of reduced inundation extent. To make such treatments physically realistic,\ud
and notably so that the full potential for floodplain storage is included, it was shown that a sub grid\ud
scale treatment also needed to be included. The effects of this combined treatment was the recovery of\ud
more plausible floodplain friction values as well as a sensitivity to friction that allows for more\ud
effective representation of floodplain friction effects such as vegetation
Changes of flow regimes and precipitation in Huai River Basin in the last half century

Huai River Basin, as the sixth largest river basin in China, has a high-regulated river system and has been facing severe water problems. In this article, the changing patterns of runoff and precipitation at 10 hydrological stations from 1956 to 2000 on the highly regulated river (Shaying River) and less-regulated river (Huai River) in the basin are evaluated at the monthly, seasonal and annual scales using the Mann-Kendall test and simple linear regression model. The results showed that: (1) No statistically significant trends of precipitation in the upper and middle Huai River Basins were detected at the annual scale, but the trend of annual runoff at Baiguishan, Zhoukou and Fuyang stations in Shaying River decreased significantly, whereas the others were not. Moreover, the decreasing trends of runoff for most months were significant in Shaying River, although the trend of monthly precipitation decreased significantly only in April in the whole research area and the number of months in the dry season having significantly decreasing trends in runoff was more than that in the wet season. (2) The rainfall-runoff relationship was significant in both highly regulated river and less-regulated river. In regulated river, the reservoirs have larger regulation capacity than the floodgates and thus have the smaller correlation coefficient and t-value. In Huai River, the correlation coefficients decreased from upper stream to downstream. (3) The regulation of dams and floodgates for flood control and water supply was the principal reason for the decreasing runoff in Huai River Basin, although the decreasing precipitation in April in this basin was statistically significant. The findings are useful for recognizing hydrology variation and will provide scientific foundation to integrated water resources management in Huai River Basin.Full Tex
Improvement of the solute transfer in a conceptual unsaturated zone scheme : a case study of the Seine River Basin

International audienceFor predicting the evolution of solute concentrations in groundwater and testing the impact of remediation policies, a coupling between the agronomical model STICS and the hydrogeological model MODCOU was implemented. Applied to the Seine river basin, this model represents accurately the temporal evolution of average nitrate concentrations in the aquifer, but with large local errors. We propose an improvement of the simple unsaturated zone scheme NonsatSW used in STICS-MODCOU. The modifications are based on a comparison with the mechanistic model Metis considered as a reference as it solves Richards'equation. A more realistic saturation profile and a varying percolation rate are integrated in NonsatSW. This new model, named NonsatVG, is assessed by a comparison with NonsatSW and Metis. In an ideal case, NonsatVG generates a solute transfer and a dispersion closer to that of Metis than NonsatSW. In real cases, without additional calibration, NonsatVG and Metis simulate better the average transfer velocities of the observed nitrate profiles. Furthermore, modifications in NonsatVG give a direct link between the water table depth and the saturation profile. We obtain therefore, as in Metis, an evolution of the solute transfer velocity depending on the piezometric level. These dynamics are not simulated in NonsatSW. Despite a modified water transfer through the unsaturated zone, NonsatVG is also as valid as NonsatSW in the modelling of water transfer to the saturated zone. Finally, an application on the Seine basin show that solute transfer velocities are lower with NonsatVG than with NonsatSW, but in better agreement with literature
Can atmospheric circulation be linked to flooding in Europe?

This is the peer reviewed version of the following article: PRUDHOMME, C. and GENEVIER, M., 2011. Can atmospheric circulation be linked to flooding in Europe? Hydrological Processes, DOI: 10.1002/hyp.7879, which has been published in final form at: http://dx.doi.org/10.1002/hyp.7879. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.This paper evaluates whether circulation type catalogues (CTCs) can inform on the occurrence of floods in Europe, and if the same few circulation types (CTs) are systematically associated with floods at the European scale. A measure of the spatial coherence of CT was introduced to compare the relative performance of CTCs in discriminating flood events, based on a local indicator measuring if a CT occurs more frequently than usual prior/during a flood. Antecedent conditions and time-lag of catchments were accounted for in calculating the indicators on a range of durations up to 30 days preceding a flood. Relationships between flood occurrence on 488 river basins and CTCs were explored using 73 catalogues developed within COST733 Action, all defined from automatic algorithms using ERA-40 data. Results showed that at the river basin scale, some CTs have significant, positive frequency anomalies with flood occurrence. At the scale of Europe, the same CTs showed the strongest links with flood occurrence. The number of classes of CTCs is of lesser importance than the algorithm used, and depending whether global frequency or persistence of CT was analysed could give contrasting results. Results obtained from an automatically derived Grosswetterlagen classification were consistent with previous research, but performance was lower than that of other automatic algorithms (e.g. WLKC and SANDRAS). Results showed seasonal variation, possibly highlighting the differences in flood generation mechanisms in different regions and seasonal CT frequency. © 2010 John Wiley & Sons, Ltd