pinecone/core-2020-05-10-deduplication huggingface dataset:
Continuous measurement of nitrate concentration in a highly\ud
event-responsive agricultural catchment in south-west of\ud
France: is the gain of information useful?

A nitrate sensor has been set up to measure every 10 min the nitrate signal in a stream draining a small agricultural catchment dominated by fertilized crops during a 2-year study period (2006–2008) in the south-west of France. An in situ sampling protocol using automatic sampler to monitor flood events have been used to assume a point-to-point calibration of the sensor values. The nitrate concentration exhibits nonsystematic concentration and dilution effects during flood events. We demonstrate that the calibrated nitrate sensor signal gathered from the outlet is considered to be a continuous signal using the Nyquist–Shannon sampling theorem. The objectives of this study are to quantify the errors generated by a typical infrequent sampling protocol and to design appropriate sampling strategy according to the sampling objectives. Nitrate concentration signal and flow data are numerically sampled to simulate common sampling frequencies. The total fluxes calculated from the simulated samples are compared with the reference value computed on the continuous signal. Uncertainties are increasing as sampling intervals increase; the method that is not using continuous discharge to compute nitrate fluxes bring larger uncertainty. The dispersion and bias computed for each sampling interval are used to evaluate the uncertainty during each hydrological period. High underestimation is made during flood periods when high-concentration period is overlooked. On the contrary, high sampling frequencies (from 3 h to 1 day) lead to a systematic overestimation (bias around 3%): highest concentrations are overweighted by the interpolation of the concentration in such case. The in situ sampling protocol generates less than 1% of load estimation error and sample highest concentration peaks. We consider useful such newly emerging field technologies to assess short-term variations of water quality parameters, to minimize the number of samples to be analysed and to assess the quality state of the stream at any time
Estimation of diffuse pollution loads in Europe for continental scale modelling of loads and in-stream river water quality

An export coefficient model of diffuse pollution at large scales has been developed as part of a larger study investigating and mapping the present and future patterns of the quantity and quality of European water resources. The model was developed to provide reasonable estimates across the whole of Europe based on readily accessible datasets, and that would be amenable to application within a gridded model of water quality loadings to surface waters. The export coefficient models for biochemical oxygen demand (BOD), total nitrogen (TN) and total phosphors (TP) were fitted to data from European Union European Environment Agency databases of 79–106 selected river basins around Europe depending on the variable in question. Estimated export coefficients were on a reasonable level with estimates made by other methods within Europe. Firstly, it was shown that runoff, number of livestock and point load were common factors for BOD, TP and TN loads with runoff as the most important factor. Secondly, cropland area also contributed to diffuse TN load. Thirdly, average slope steepness and runoff, as a combined factor, had a negative effect on diffuse TP load. Fourthly, lake area reduced diffuse loads because of retention mechanisms in lakes. A larger set of data with higher spatial and temporal resolution and partitioning of the data based on, e.g. climate or spatial patterns would further improve the precision of the export coefficient estimates. When applied at the catchment scale, the parameters should be updated with local data. In the long run, adaptive modelling should be applied in order to fit the model to continuously accumulating data and experience, although the study showed that the export coefficients derived were stable over time. It is also advisable to integrate the administrative monitoring, modelling and management of river basins more closely to improve data availability, model predictions and cost efficiency of management measures and policies
Unravelling changing sediment sources in a Mediterranean mountain catchment: a Bayesian fingerprinting approach

To determine the provenance of Holocene floodplain deposits of the Bügdüz catchment in southwest Turkey a Bayesian fingerprinting approach was used. An important requirement for any provenance study is that the potential sediment sources show sufficient spatial and compositional heterogeneity. The spatial distribution of potential sources, in this case the various lithologies present within the catchment, was mapped using field observations and ASTER and Quickbird satellite images. To distinguish the source lithologies a set of geochemical tracers was identified with the use of a Linear Discriminant Analysis. This optimum fingerprint was then used in the mixing model to determine the sediment provenance. The Bayesian mixing model uses Markov chain Monte Carlo random walks to determine the most probable source composition and mixing proportions. The uncertainty associated with the input data can be incorporated into the model through the prior probability distributions. The spread of the posterior probability distributions represents the uncertainty associated with the mixing proportion calculation.  The main contrasts in provenance of the floodplain deposits reflect the spatial distribution of potential sediment sources throughout the catchment. There are, however, also important temporal variations in sediment provenance and lateral differences due to the nature of floodplain build-up. The observed spatial and temporal variability of sediment provenance gives a first indication that hill slope-channel and within-channel coupling relations are not uniform through the catchment and that different locations showed a distinct response to disturbances.status: publishe
Assessment of current water pollution loads in Europe: estimation of gridded loads for use in global water quality models

A methodology for estimating the loading of pollutants to water courses across all of pan-Europe, an area reaching to the River Don in the east and including some Mediterranean rim countries in the near east and North Africa is presented. Loadings come from point (domestic effluent, manufacturing discharge and urban runoff) and diffuse (scattered settlements and land use) sources. The loads have been calculated on a countrywide basis using readily available data held by national and international bodies. These loads are downscaled to the grid cells (5 × 5′) used in the model. The paper illustrates the general framework for making these calculations using biochemical oxygen demand (BOD) and total dissolved solids (TDS), and estimated loads for periods representing 1990, 1995, 2000 and 2005 are presented as maps.\ud
\ud
According to the model, in 2005, annual BOD loads came mostly from domestic effluent (3 Mt) and diffuse sources (5 Mt, mainly attributed to livestock). Manufacturing, urban runoff and scattered settlements contributed annual loads of 0.33, 0.15 and 1.2 Mt, respectively. For TDS, annual manufacturing loads were 65 Mt and annual domestic loads 28 Mt. Diffuse loadings (36 Mt) came from irrigated land and therefore showed a different spatial pattern from BOD. The total annual diffuse load of TDS was 56 Mt. Scattered settlements contributed only 9.6 Mt to the total pan-European load. Some limited comparison of the loads estimated in this study for BOD with those estimated by others for countries and large catchments in the area has been carried out.\u
Continental scale modelling of in-stream river water quality: a report on methodology, test runs, and scenario application

To address the continental and large-scale aspects of water quality assessments, new modelling approaches are required. This paper describes the development of a continental-scale model of river water quality – WorldQual. Simple equations, consistent with the availability of data on the continental-scale, are used to simulate the response of biochemical oxygen demand (BOD5) and total dissolved solids (TDS) to anthropogenic loadings and flow dilution. A methodology is developed that is appropriate for scenario analysis on the continental and global scale. Average monthly river water quality is modelled on a 5 arcmin grid covering all Europe. Loadings are derived from assumptions about water use, return flows and other variables. The model WorldQual is tested against measured longitudinal gradients and time series data at specific river locations. The model performance on European scale shows that a good fit can be reached when using concentration classifications as a measure: For BOD5, 51% of the simulated data is in the same quality class as the measurements and 30% differ only by one water-quality class; for TDS, the respective values are 35% and 41%. WorldQual was applied to investigate the impact of climate change on resulting changes of in-stream concentrations. The results for Europe show that future climate changes only have a small impact on European in-stream concentration levels of BOD5, except for the Eastern part and the Black Sea region. This effect is stronger for the IPCM4-A2 scenario than for the MIMR-A2 scenario
Effects of managed burning in comparison with vegetation cutting on dissolved organic carbon concentrations in peat soils.

Given the continuing concern about rising concentrations of dissolved organic carbon (DOC) in stream water leaving peat-covered catchments, this study has considered the impact of managed burning or cutting of Calluna vulgaris, a dominant vegetation cover in many UK peatlands. Pristine mature Calluna stands were compared with those that had been subject to cutting and or managed burning up to 5 years after intervention. The study measured the DOC concentration of both soil and surface runoff water over a period of 12 months in comparison with water table depth, conductivity, and pH. The results show the following: * The depth to the water table decreases upon both burnt and cut sites relative to controls in line with a change in evapotranspiration due to loss of vegetation. * The DOC concentration of surface runoff water was not significantly different (P < 0.05) between any of the treatments and the control. * The DOC concentration in soil water significantly (P < 0.05) decreased with both burning and cutting, but these differences could be explained by differences in water table and changes in flowpath through the soil profile. The study suggests that declines in soil water DOC concentration are brought about as different levels in the peat profile become the dominant source of water due to changes in the depth to water table. Changes in the depth to water table were brought about by changes in evapotranspiration that result from the loss of vegetation. The changes in water table mean that this mechanism may explain other observations of DOC concentration change with management. Cutting and burning may represent a management intervention that could be effective at reversing the current trends in DOC transfers from peat-covered catchments
Up-scaling potential impacts on water flows from agricultural water interventions: opportunities and trade-offs in the Osman Sagar catchment, Musi sub-basin, India

Agricultural water management (AWM) has been shown to improve and secure yields in the\ud
tropics and has been suggested as an important way to combat poverty in the region. In this\ud
paper we describe potential impacts on upstream and downstream flows of extensive AWM\ud
interventions, using the watershed development programme of the Osman Sagar catchment of\ud
Musi sub-basin, Andhra Pradesh semi-arid India, as an example. Various AWM interventions\ud
are compared with a non-intervention state and the current state of the study area, using 31-\ud
years of data by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a)\ud
modelling tool. Different AWM interventions contribute to improved livelihoods of upstream\ud
smallholder farmers by increasing soil moisture availability and groundwater recharge, which\ud
can subsequently be used for irrigation. The result is higher crop production and hence larger\ud
incomes. Moreover, lower flow intensities and sediment losses reduced by 30-50 %, reduce\ud
the risk of flooding and sediment accumulation in the Osman Sagar drinking water reservoir.\ud
On the other hand, AWM interventions are predicted to result in reduced total water inflows\ud
to the Osman Sagar reservoir from 11 % of the total annual rainfall (754 mm) recorded at\ud
present, to 8 % if AWM interventions were implemented at large scale throughout the\ud
catchment. A cost-benefit analysis of AWM interventions showed that the highest net\ud
economic returns were achieved at intermediate intervention levels (only in-situ AWM)
Reconstruction and Analysis of the Po River Inundation of 1951

Flood inundation models have become essential tools in flood risk management, being used also in the analysis of historical flood events, which is often needed for a reliable assessment of the potential flood hazard. This study aims at reconstructing the 1951 inundation of the Polesine Region, Italy. The 1951 flooding was a mayor natural catastrophe that caused a large inundated area (1080 km2) and produced devastating social consequences. The reconstruction of the 1951 hydraulic conditions is based on partial knowledge of discharges and water stages at the Pontelagoscuro gauging station (downstream of the 1951 levee breach) using extrapolation of the rating curves beyond the measurement range. This is, even today, something open to uncertainty. We applied a decoupled hybrid approach to the hydraulic modeling: a 1D model is used to simulate the flow into the river and to compute the flow through the levee breach; this result is then adopted as the inflow condition for a 2D model application on the inundated area. A good agreement between the patterns of the observed and reconstructed inundation areas was found, and the timing of the inundation was also found to be close to the information derived from the historical chronicles. The results of the flood inundation modelling exercise provide two practical insight: (i) obstacles in the floodplains increased the flooded area by 40% and prolonged the time to reach the sea from 5 to 15 days, (ii) the peak discharge of the event was overestimated by up to 20
Factors controlling the temporal variability in dissolved oxygen regime of salmon spawning gravels

This article was published in the journal Hydrological Processes [© John Wiley & Sons, Ltd.]. The definitive version is available at: http://dx.doi.org/10.1002/hyp.9565Dissolved oxygen (DO) plays a critical role in the development of the juvenile stages of benthic spawning fish and salmonids in particular. Factors influencing the DO regime within spawning gravels include the accumulation of fine sediment, penetration of groundwater or surface water into the gravels, thermal regime, and the consumption of oxygen by sediment and its associated organic fractions. In this field study, we quantify the DO regime within an artificial salmon redd at high temporal resolution. The environment within the redd is shown to be complex, with large variations in DO. Application of a numerical model (SIDO-UK) enables for the first time, the quantification of the relative contributions to DO consumption from thermal regime, sediment accumulation and sediment oxygen demand. Sediment accumulation is shown to have a minor impact on DO in the redd whereas upwelling groundwater is identified as the most likely cause of the major changes in DO. Bed mobility has a minor impact on DO regime of the redd. The effects of fine sediment and oxygen supply on salmon embryo survival are estimated. Implications for river catchment management and prospects for future research are discussed. © 2012 John Wiley & Sons, Ltd
A shrub bending model to calculate the albedo of shrub-tundra

At high latitudes, the albedo and energy budget of shrub-tundra landscapes is determined by the relationship between the fractional snow cover and the fraction of vegetation protruding above the snowpack. The exposed vegetation fraction is affected by the bending and/or burial of shrubs in winter and their spring-up during melt. Little is known about the meteorological conditions and snowpack and shrub properties required to cause bending, and few quantitative measurements of bending processes exist. Here, a model combining the few, mostly qualitative, observations available with a biomechanical model representing branches as cantilevers is proposed to provide a first approximation of bending mechanisms. The exposed vegetation fraction is then calculated using structural parameters of shrubs measured at two sites in Canada: the Granger Basin in the Yukon Territory and Trail Valley Creek in the Northwest Territories. The exposed vegetation fraction is in turn used to calculate albedo, which is evaluated against measurements at the two sites. The model considerably improves modelled albedo compared to a model which only buries but does not bend shrubs at TVC, where shrubs become completely buried. However, the model overestimates albedo at GB where only a few shrubs get buried. The bending model is then used to calculate a compression factor for use in a simple parameterization of the exposed vegetation fraction proposed by previous investigators. The parameterization, which is simpler and computationally less expensive than the full model, is evaluated and found to perform well. Despite the need for further developments, the model provides a first approximation of bending processes and contributes to the identification of measurements that are needed in order to improve the model and our understanding of the bending of shrubs
Long-term monitoring of a mercury contaminated estuary (Ria de Aveiro, Portugal): the effect of weather events and management in mercury transport

The main aim of this research was to assess the mercury transport from an estuarine basin with a background of anthropogenic
contamination during a spring tidal cycle (year 2009) and compare it with two previous tidal cycles (years 1994 and 1999), as
part of a long-term monitoring program.
Results showed that effective mercury transport occurs both in the dissolved and particulate fractions (0.18 and 0.20 kg per tidal
cycle, respectively), and despite an overall decrease in environmental contamination, results more than double previous findings
on particulate transport in the system. These findings result essentially from changes in the tidal prism (net export of 2 million m3
of water), given that both dissolved and particulate concentrations did not increase over time. Hydrodynamic simulations were
performed to evaluate the effect of physical disturbance (dredging) and weather events (increased freshwater flow) in these
processes, and results suggest the increased freshwater flow into the system as the main forcing function for the mercury transport
increment. These results highlight the importance of long-term monitoring programs, since despite an overall improvement in
local contamination levels, the enhancement of transport processes through hydrological changes increases environmental
pressure away from the contamination source.This work was financed by the Portuguese Foundation for
Science and Technology (FCT) through a Post-Doc grant
to J.P. Coelho (SFRH/BPD/48449/2008) and P. Pato
(SFRH/BPD/35068/2007)
Smiling in the rain: Seven reasons to be positive about uncertainty in hydrological modelling

Artículo científico -- Universidad de Costa Rica. Centro de Investigaciones Geofísicas, 2012Over 20 years ago, the notion of ‘positive uncertainty’ was introduced in the field of psychology (Gelatt, 1989). This was coincident to some developments in the hydrological sciences (e.g. Beven and Binley, 1992; Grayson et al., 1992) which laid the foundation for today’s continued efforts to explicitly acknowledge and quantify uncertainties inherent in our modelling efforts. ‘Positive uncertainty’ urges moving beyond deterministic frameworks of the past, but doing so not just by regrettably accepting that uncertainties are inevitable, but by positively thriving in the new perspectives that accompany this recognition (Gelatt, 1989). During a recent small workshop in Sweden – while the rain was pouring down – we discussed some of the positive developments in recent years that have resulted directly from explicit recognitions of uncertainty in hydrological modelling.With the earlier paper of Pappenberger and Beven (2006) in mind, we here summarise that workshop and elaborate seven reasons to be positive about uncertainty in hydrological modelling. How have the hydrological sciences benefitted in the last 20 years from the increased recognition of uncertainties, particularly in the modelling of time series data? In our view, uncertainty estimation is a means to address hydrologic research questions in an honest and robust way. There have also been (and will continue to be) new research questions and opportunities initiated by the recognition of what needs to be done to quantify and then constrain uncertainties. This notion fits intrinsically with the view of modelling as a learning process (Box, 1976), learning about the nature of the uncertainties involved and the possibility of reducing them by improving our models or our data.Universidad de Costa Rica. Centro de Investigaciones Geofísicas.UCR::Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigaciones Geofísicas (CIGEFI
Carbon loss by water erosion in drylands: Implications from a study of vegetation change in the south-west USA

Journal ArticleSoil organic carbon (SOC) is an important component of the global carbon cycle yet is rarely quantified adequately in terms of its spatial variability resulting from losses of SOC due to erosion by water. Furthermore, in drylands, little is known about the effect of widespread vegetation change on changes in SOC stores and the potential for water erosion to redistribute SOC around the landscape especially during high-magnitude run-off events (flash floods). This study assesses the change in SOC stores across a shrub-encroachment gradient in the Chihuahuan Desert of the south-west USA. A robust estimate of SOC storage in surface soils is presented, indicating that more SOC is stored beneath vegetation than in bare soil areas. In addition, the change in SOC storage over a shrub-encroachment gradient is shown to be nonlinear and highly variable within each vegetation type. Over the gradient of vegetation change, the heterogeneity of SOC increases, and newer carbon from C3 plants becomes dominant. This increase in the heterogeneity of SOC is related to an increase in water erosion and SOC loss from inter-shrub areas, which is self-reinforcing. Shrub-dominated drylands lose more than three times as much SOC as their grass counterparts. The implications of this study are twofold: (1) quantifying the effects of vegetation change on carbon loss via water erosion and the highly variable effects of land degradation on soil carbon stocks is critical. (2) If landscape-scale understanding of carbon loss by water erosion in drylands is required, studies must characterize the heterogeneity of ecosystem structure and its effects on ecosystem function across ecotones subject to vegetation change. © 2013 John Wiley & Sons, Ltd.NS