pinecone/core-2020-05-10-deduplication huggingface dataset:
Hydraulic visibility: Using satellite altimetry to parameterize a hydraulic model of an ungauged reach of a braided river

What hydraulic information can be gained from remotely sensed observations of a river’s surface? In this study,we analyze the relationship between river bed undulations and water surfaces for an ungauged reach of the Xingu River, a first-order tributary of the Amazon river. This braided reach is crosscut more than 10 times by a ENVISAT (ENVironmental SATellite) track that extends over 100 km. Rating curves based on a modeled discharge series and altimetric measurements are used, including the zero-flow depth Z0 parameter, which describes river’s bathymetry. River widths are determined from JERS (Japanese Earth Ressources Satellite) images. Hydrodynamic laws predict that irregularities in the geometry of a river bed produce spatial and temporal variations in the water level, as well as in its slope. Observation of these changes is a goal of the Surface Water and Ocean Topography satellite mission, which has a final objective of determining river discharge. First, the concept of hydraulic visibility is introduced, and the seasonality of water surface slope is highlighted along with different flow regimes and reach behaviors. Then, we propose a new single-thread effective hydraulic approach for modeling braided rivers flows, based on the observation scales of current satellite altimetry. The effective hydraulic model is able to reproduce water surface elevations derived by satellite altimetry, and it shows that hydrodynamical signatures are more visible in areas where the river bed morphology varies significantly and for reaches with strong downstream control. The results of this study suggest that longitudinal variations of the slope might be an interesting criteria for the analysis of river segmentation into elementary reaches for the Surface Water Ocean Topography mission that will provide continuous measurements of the water surface elevations, the slopes, and the reach widths
Using land cover changes and demographic data to improve hydrological modeling in the Sahel

At the beginning of the drought in the Sahel in the 1970s and 1980s, rainfall decreased markedly, but runoff coefficients and in some cases, absolute runoff increased. This situation was due to the conversion of the land cover from natural vegetation with a low annual runoff coefficient, to cropland and bare soils, whose runoff coefficients are higher. Unless they are adapted, hydrological conceptual models, such as GR2M, are unable to reproduce this increase in runoff. Despite the varying environmental and climatic conditions of the West African Sahel, we show that it is possible to increase the performance of the GR2M model simulations by elaborating a time-varying soil water holding capacity and to incorporate this value in the annual maximum amount of water to be stored in reservoir A of the model. We looked for interactions between climate, rural society, and the environment. These interactions drive land-cover changes in the Sahel, which in turn drive the distribution of rainfall between infiltration, evaporation, and runoff and hence the water resources, which are vital in this region. We elaborated several time series of key indicators linked to these interactions. We then integrated these changes in the runoff conditions of the GR2M model through the maximum value of the reservoir capacity. We calculated annual values of water holding capacity using the annual values of four classes of land cover, natural vegetation, cultivated area, bare soil, and surface water. We then used the hydrological model with and without this time-varying soil value of A and compared the performances of the model under the two scenarios. Whatever the calibration period used, the Nash–Sutcliffe index was always greater in the case of the time-varying A time series. (Résumé d'auteur
Quantification of peatland water storage capacity using the water table fluctuation method

Peat specific yield (Sy) is an important parameter involved in many peatland hydrological functions such as flood attenuation, baseflow contribution to rivers, and maintaining groundwater levels in surficial aquifers. However, general knowledge on peatland water storage capacity is still very limited, due in part to the technical difficulties related to in situ measurements. The objectives of this study were to quantify vertical Sy variations of water tables in peatlands using the water table fluctuation (WTF) method and to better understand the factors controlling peatland water storage capacity. The method was tested in five ombrotrophic peatlands located in the St. Lawrence Lowlands (southern Québec, Canada). In each peatland, water table wells were installed at three locations (up-gradient, mid-gradient, and down-gradient). Near each well, a 1-m long peat core (8 cm × 8 cm) was sampled, and subsamples were used to determine SY with standard gravitational drainage method. A larger peat sample (25 cm × 60 cm × 40 cm) was also collected in one peatland to estimate Sy using a laboratory drainage method. In all sites, the mean water table depth ranged from 9 to 49 cm below the peat surface, with annual fluctuations varying between 15 and 29 cm for all locations. The WTF method produced similar results to the gravitational drainage experiments, with values ranging between 0.13 and 0.99 for the WTF method and between 0.01 and 0.95 for the gravitational drainage experiments. Sy was found to rapidly decrease with depth within 20 cm, independently of the within-site location and the mean annual water table depth. Dominant factors explaining Sy variations were identified using analysis of variance. The most important factor was peatland site, followed by peat depth and seasonality. Variations in storage capacity considering site and seasonality followed regional effective growing degree days and evapotranspiration patterns. This work provides new data on spatial variations of peatland water storage capacity using an easily implemented method that requires only water table measurements and precipitation data
Linking inter-annual river flow river variability across New Zealand to the Southern Annular Mode, 1979-2011.

River flow constitutes an important element of the terrestrial branch of the hydrological cycle, yet knowledge regarding the extent to which its variability, at a range of time scales, is linked to a number of modes of atmospheric circulation is meagre. This is especially so in the Southern Hemisphere where strong candidates, such as El Niño Southern Oscillation (ENSO) and the Southern Annular Mode (SAM), for influencing climate and thus river flow variability can be found. This paper presents the results of an analysis of the impact of the SAM on winter and summer river flow variability across New Zealand, purposefully controlling for the influence of ENSO and the tendency for the SAM to adopt a positive phase over the last 10 – 20 years. Study results, based on identifying hydrological regions and applying circulation-to-environment and environment-to-circulation approaches commonly used in synoptic climatology, reveal a seasonal asymmetry of the response of river flow variability to the SAM; winter flows demonstrate a higher degree of statistical association with the SAM compared to summer flows. Further, because of the complex orography of New Zealand and its general disposition normal to zonal flows of moisture bearing winds, there are intra-seasonal spatial variations in river flow SAM associations with clear rain shadow effects playing out in resultant river flow volumes. The complexity of SAM river flow associations found in this study warns against using indices of large scale modes of atmospheric circulation as blunt tools for hydroclimatological prediction at scales beyond hydroclimatological regions or areas with internal hydrological consistency
The fate of suspended sediment and particulate organic carbon in transit through the channels of a river catchment.

Particulate organic matter (POM) transiting through rivers could be lost to overbank storage, stored in‐channel, added to by erosion or autochthonous production, or turned over to release greenhouse gases to the atmosphere (either while in the water column or while stored in the channel). In the UK, a net loss of POM across catchments has been recorded, and the aim here was to investigate the balances of processes acting on the POM. This study considered records of suspended sediment and POM flux in comparison to stream flow, velocity, stream power, and residence time for the River Trent (English Midlands, 8,231 km2). We show that for the lower two thirds (106 km) of the River Trent, 2% is lost to overbank storage; 10% is lost to the atmosphere in the water column; and 31% is turned over while in temporary storage. Permanent in‐channel storage is negligible, and for the lower course of the river, material stored in‐channel will have a residence time of the order of hundreds of days between the last flood hydrograph of one winter and the first winter storm of the next winter (usually in the same calendar year).When considered at the scale of the UK, 1% POM in transit would be lost to overbank sedimentation; 5% turned over in the water column, and 14% turned over while in temporary storage. In the upper third of the study river channel, there is insufficient stream power to transport sediment and so in‐channel storage or in‐channel turnover over to the atmosphere dominate. The in‐channel processes of the River Trent do not conform to that expected for river channels as the headwaters are not eroding or transporting sediment. Therefore, the source of sediment must be lower down the channel network
Isotope mixing models require individual isotopic tracer content for correct quantification of sediment source contributions

The use of isotopic tracers for sediment source apportionment is gaining interest with recent introduction of compound-specific stable isotope tracers. The method relies on linear mixing of source isotopic tracers, and deconvolution of a sediment mixture initially quantifies the contribution of sources to the mixture's tracer signature. Therefore, a correction to obtain real sediment source proportions is subsequently required. As far as we are aware, all published studies to date have used total isotopic tracer content or a proxy (e.g., soil carbon content) for this post-unmixing correction. However, as the relationship between the isotopic tracer mixture and the source mixture is different for each isotopic tracer, post-unmixing corrections cannot be carried out with one single factor. This contribution presents an isotopic tracer model structurethe concentration-dependent isotope mixing model (CD-IMM)to overcome this limitation. Herein, we aim to clarify why the conventional approach to converting isotopic tracer proportions to source proportions using a single factor is wrong. In an initial mathematical assessment, error incurred by not using CD-IMM (NCD-IMM) in unmixing two sources with two isotopic tracers showed a complex relation as a function of relative tracer contents. Next, three artificial mixtures with different proportions of three soil sources were prepared and deconvoluted using C-13 of fatty acids using CD-IMM and NCD-IMM. Using NCD-IMM affected both accuracy (mean average error increased up to a threefold compared with the CD-IMM output) and precision (interquartile range was up to 2.5 times larger). Finally, as an illustrative example, the proportional source contribution reported in a published study was recalculated using CD-IMM. This resulted in changes in estimated source proportions and associated uncertainties. Content of isotopic tracers is seldom reported in published work concerning use of isotopic tracers for sediment source partitioning. The magnitude of errors made by miscalculation in former studies is therefore difficult to assess. With this contribution, we hope the community will acknowledge the limitations of prior approaches and use a CD-IMM in future studies
Spatial and temporal variability of 0-to 5-m soil-water storage at the watershed scale

Dynamic relationships among rainfall patterns, soil water distribution, and plant growth are crucial for sustainable conservation of soil and water resources in water-limited ecosystems. Spatial and temporal variation in deep soil water content at a watershed scale have not yet been characterized adequately due to the lack of deep soil water data. Deep soil-water storage (SWS) up to a depth of 5m (n=73) was measured at 19 sampling occasions at the LaoYeManQu watershed on the Chinese Loess Plateau (CLP). At a depth of 0-1.5m, the annual mean SWS was highly correlated with rain intensity, and the correlation decreased with depth, but within the layers at 1.5-5.0m, the changes in SWS indicated a lag between precipitation and the replenishment of soil water. Geostatistical parameters of SWS were also highly dependent on depth, and the mean SWS presented similar spatial structures in two adjacent layers. Temporal stability of SWS as indicated by mean relative difference, standard deviation of the relative difference (SDRD), and mean absolute bias error (MABE) was significantly weaker at the shallow than at deeper layers. Soil separates and organic carbon content controlled the spatial pattern of SWS at the watershed scale. One representative location (Site 57) was identified to estimate the mean SWS in the 1- to 5-m layer of the watershed. Semivariograms of the SDRD and MABE were best fitted by an isotropic spherical model, and their spatial distributions were depth-dependent. Both temporal stability and spatial variability of SWS increased over depth. This study is helpful for deep SWS estimation and sustainable management of soil and water on the CLP, and for other similar regions around the world
A method for uncertainty constraint of catchment discharge and phosphorus load estimates.

River discharge and nutrient measurements are subject to aleatory and epistemic uncertainties. In this study we present a novel method for estimating these uncertainties in co‐located discharge and phosphorus (P) measurements. The ‘voting point’ based method constrains the derived stage‐discharge rating curve both on the fit to available gaugings and to the catchment water balance. This helps reduce the uncertainty beyond the range of available gaugings and during out of bank situations. In the example presented here, for the top 5% of flows, uncertainties are shown to be 139% using a traditional power law fit, compared to 40% when using our updated ‘voting point’ method. Furthermore, the method is extended to in situ and lab analysed nutrient concentration data pairings, with lower uncertainties (81%) shown for high concentrations (top 5%) than when a traditional regression is applied (102%). Overall, for both discharge and nutrient data, the method presented goes some way to accounting for epistemic uncertainties associated with nonstationary physical characteristics of the monitoring site
Using source‐specific models to test the impact of sediment source classification on sediment fingerprinting

Sediment fingerprinting estimates sediment source contributions directly from river sediment. Despite being fundamental to the interpretation of sediment fingerprinting results, the classification of sediment sources and its impact on the accuracy of source apportionment remain under‐investigated. This study assessed the impact of source classification on sediment fingerprinting based on Diffuse Reflectance Infrared Fourier Transform Spectrometry (DRIFTS), using individual, source‐specific partial least squares regression (PLSR) models. The objectives were to (i) perform a model sensitivity analysis through systematically omitting sediment sources; and (ii) investigate how sediment source group discrimination and the importance of the groups as actual sources relate to variations in results. Within the Aire catchment (UK), five sediment sources were classified and sampled (n = 117): grassland topsoil in three lithological areas (limestone, millstone grit and coal measures), riverbanks, and street dust. Experimental mixtures (n = 54) of the sources were used to develop PLSR models between known quantities of a single source and DRIFTS spectra of the mixtures, which were applied to estimate source contributions from DRIFTS spectra of suspended (n = 200) and bed (n = 5) sediment samples. Dominant sediment sources were limestone topsoil (45 ± 12 %) and street dust (43 ± 10 %). Millstone and coals topsoil contributed on average 19 ± 13 % and 14 ± 10 %, and riverbanks 16 ± 18%. Due to the use of individual PLSR models, the sum of all contributions can deviate from 100%, thus a model sensitivity analysis assessed the impact and accuracy of source classification. Omitting less important sources (e.g. coals topsoil) did not change contributions of other sources, while omitting important, poorly‐discriminated sources (e.g. riverbank), increased contributions of all sources. In other words, variation in source classification substantially alters source apportionment depending on source discrimination and source importance. These results will guide development of procedures for evaluating the appropriate type and number of sediment sources in DRIFTS‐PLSR sediment fingerprinting
Suspended solids discharge from a small forested basin in the humid tropics

Suspended solids (SS) discharge from a tropical rain forest was observed at the Bukit Tarek Experimental Watershed in Peninsular Malaysia in order to elucidate mechanisms of SS production and transport. Peaks of water discharge and electrical conductivity (EC)lagged further behind rainfall peaks than did dissolved oxygen (DO), indicating that the discharge in the early stage of a storm is mainly formed by rain water with high DO. Stream water showing a high value of EC originating from subsurface water formed the main storm flow and lagged behind the rainfall. SS concentrations rose to a peak quickly and, like DO, the peak preceded that of water discharge. A clockwise hysteresis loop in the relationship between SS and water discharge exists, and the magnitude of hysteresis loop is in proportion to storm size. The values of SS concentration correlate positively with the values of rainfall intensity on logarithmic axes. The time intervals between peaks of rainfall and SS concentrations are assumed to be a delivery term expressing distance from sediment source to measuring point. Immediate transport of SS from the source to the sampling site, the short time gap between the peaks of rainfall and SS concentrations, and the high rate of infiltration on the hillslope suggest that the sources of high SS concentrations are located close to the stream. The calculated source area is located at a gentler part of the stream, where wet riparian areas exist. The strong relationship between water discharge and SS concentration during the small storm proves that the source areas of SS and water were the same. In contrast, the source area of SS disappeared when rainfall ceased, whereas the source area of water discharge was still expanding in the larger storm. These phenomena may produce clockwise loops in the SS concentration-water discharge relationship
Hydrological Processes

The south Ecuadorian Andean mountain belt between 3500 and 4500 m altitude is covered by a highly endemic and fragile ecosystem called paramo. The Histic Andosols covering this regi ´ on have highly developed hydric properties and exert a key function in the hydrological regulation of the paramo ecosystem. Unlike most Andosols, their extreme ´water retention capacity is not due to the presence of typical minerals such as allophane or imogolite. Although these minerals are virtually absent, the large organic carbon content, due to organometallic complexation, gives rise to similar properties. The water content at 1500 kPa can exceed 2000 g kg 1, and the high hydraulic conductivity at saturation (about 15 mm h 1) drops sharply when low suction is applied. The three methods applied, i.e. the inverted auger hole, the tension infiltrometer and the constant-head permeameter method, give very similar results. The paramo ´is characterized by a slow hydrological response and a good water regulation, caused by the combination of a high water storage capacity and high conductivity. The wide pore size distribution of the organometallic complexes results in a water retention curve that differs significantly from the classic Mualem–Van Genuchten description, but can better be described with a simple linear or semilogarithmic model. The soils investigated are very prone to irreversible structural changes caused by land-use changes. The conversion of natural land for cultivation has a large impact on the hydrological function of the region. The water storage capacity increases by 5 to 30%, and the hydraulic conductivity
is 31% higher in cultivated catchments. These changes are related to a larger peak flow, a smaller base flow and generally a smaller discharge buffering capacity, despite the higher storage capacity. Copyright  2005 John Wiley & Sons, Ltdvol. 19; no. 2
d13C tracing of dissolved inorganic carbon sources in Patagonian rivers (Argentina)

The main Patagonian rivers (Colorado, Negro, Chubut, Deseado, Coyle, Chico, Santa Cruz and Gallegos) were sampled between September 1995 and November 1998 to determine their chemical and isotopic compositions, the origins of the suspended and dissolved river loads and their inputs to the South Atlantic Ocean. This paper focuses on the dissolved inorganic carbon (DIC) transport and its υ13C isotopic signature. The υ13CDIC values vary between 12Ð8 and 1Ð8‰ and allow one to distinguish two river groups: (i) the Colorado, Negro, Chubut and Santa Cruz, which display the highest values and the lowest seasonal variations; (ii) the Deseado, Coyle, Chico and Gallegos, which show the lowest values and the highest seasonal variations. For the first group, υ13CDIC is mainly controlled by important exchanges between the river waters and atmospheric CO2, due to the presence of lakes and dams. For the second group, υ13CDIC also appears to be controlled by the oxidation of organic carbon, showing a negative relationship between υ13CDIC and the dissolved organic carbon. These biogeochemical processes interfere with the contribution of carbonate and silicate weathering to the riverine DIC and do not allow use of υ13CDIC alone to distinguish these contributions. The annual DIC flux exported by Patagonian Rivers to the South Atlantic Ocean averages 621 ð 109 g. of C, i.e. a specific yield of 2Ð7 g m2 year1. The mean υ13CDIC can be estimated to 4Ð9‰, which is high compared with other rivers of the world
Boundary layer growth and advection of heat over snow and soil patches: Modelling and parametrization

Essery, RLH, RJ Granger and JW Pomeroy, 2006. Boundary layer growth and advection of heat over snow and soil patches: Modelling and parametrization. Hydrological Processes, 20, 953 - 967.Melting snow is generally patchy; upward sensible heat fluxes from patches of snow-free ground warm the air and contribute energy for snowmelt. A simple model is presented for advection of heat over partial snowcovers and compared with measurements of temperature profiles over snow and snow-free ground. Approximations for flux and temperature profiles in the internal boundary layers over snow patches are used to develop parametrizations for local and average surface fluxes into the snow. In comparison with results from the advection model for regular patterns of alternating snow patches and snow-free ground, a tile model is found to give a good parametrization for average heat fluxes over the whole surface but does not match the local fluxes into snow and snow-free ground separately; an extended tile model that gives better results is developed from the flux profile parametrization. For complex snowcover patterns with a fractal distribution of patch sizes, average fluxes are found to be close to those obtained for a regular pattern with an effective patch size linearly related to the average patch size of the complex pattern.Peer reviewe