pinecone/core-2020-05-10-deduplication huggingface dataset:
Simulation of the spatio-temporal extent of groundwater flooding using statistical methods of hydrograph classification and lumped parameter models

This article presents the development of a relatively low cost and rapidly applicable methodology to simulate the spatio-temporal occurrence of groundwater flooding in chalk catchments. In winter 2000/2001 extreme rainfall resulted in anomalously high groundwater levels and groundwater flooding in many chalk catchments of northern Europe and the southern United Kingdom. Groundwater flooding was extensive and prolonged, occurring in areas where it had not been recently observed and, in places, lasting for 6 months. In many of these catchments, the prediction of groundwater flooding is hindered by the lack of an appropriate tool, such as a distributed groundwater model, or the inability of models to simulate extremes adequately. A set of groundwater hydrographs is simulated using a simple lumped parameter groundwater model. The number of models required is minimized through the classification and grouping of groundwater level time-series using principal component analysis and cluster analysis. One representative hydrograph is modelled then transposed to other observed hydrographs in the same group by the process of quantile mapping. Time-variant groundwater level surfaces, generated using the discrete set of modelled hydrographs and river elevation data, are overlain on a digital terrain model to predict the spatial extent of groundwater flooding. The methodology is applied to the Pang and Lambourn catchments in southern England for which monthly groundwater level time-series exist for 52 observation boreholes covering the period 1975–2004. The results are validated against observed groundwater flood extent data obtained from aerial surveys and field mapping. The method is shown to simulate the spatial and temporal occurrence of flooding during the 2000/2001 flood event accurately
Fluvial transport of suspended sediment and organic carbon during flood events in a large agricultural catchment in southwest France

Water draining from a large agricultural catchment of 1 110 km2 in southwest France was sampled over an 18-month period to determine the temporal variability in suspended sediment (SS) and dissolved (DOC) and particulate organic carbon (POC) transport during flood events, with quantification of fluxes and controlling factors, and to analyze the relationships between discharge and SS, DOC and POC. A total of 15 flood events were analyzed, providing extensive data on SS, POC and DOC during floods. There was high variability in SS, POC and DOC transport during different seasonal floods, with SS varying by event from 513 to 41 750 t; POC from 12 to 748 t and DOC from 9 to 218 t. Overall, 76 and 62% of total fluxes of POC and DOC occurred within 22% of the study period. POC and DOC export from the Save catchment amounted to 3090 t and 1240 t, equivalent to 1·8 t km−2 y−1 and 0·7 t km−2 y−1, respectively. Statistical analyses showed that total precipitation, flood discharge and total water yield were the major factors controlling SS, POC and DOC transport from the catchment. The relationships between SS, POC and DOC and discharge over temporal flood events resulted in different hysteresis patterns, which were used to deduce dissolved and particulate origins. In both clockwise and anticlockwise hysteresis, POC mainly followed the same patterns as discharge and SS. The DOC-discharge relationship was mainly characterized by alternating clockwise and anticlockwise hysteresis due to dilution effects of water originating from different sources in the whole catchment
Some relationships between lithology, basin form and hydrology : a case study from the Thames Basin, UK

The role of lithology in influencing basin form and function is explored empirically by investigating correlations between a range of catchment variables, where the spatial unit of analysis is not surface catchments but lithologically coherent groundwater units. Using the Thames basin, UK, as a case study, nine groundwater units have been identified. Values for 11 hydrological and geomorphological variables, including rainfall, drainage density, Baseflow Index, aquifer porosity, storage coefficient and log-hydraulic conductivity, aquifer and drainage elevation, river incision, and hypsometric integral have been estimated for each of the groundwater units in the basin, and Pearson correlation coefficients calculated for all pairs of variables. Seven of the correlation coefficients are found to be significant at a confidence level of > 99%. Negative correlations between drainage density and log aquifer hydraulic conductivity, and between drainage density and river incision, and positive correlations between log-hydraulic conductivity and river incision, log-hydraulic conductivity and Baseflow Index, and between Baseflow Index and river incision are inferred to have consistent causal explanations. For example, incision of rivers into aquifers leads to relative increases in hydraulic gradients in the vicinity of rivers which, in turn, promotes the development of secondary porosity increasing both aquifer hydraulic conductivity and, hence, Baseflow Index. The implication of this interpretation is that the geomorphological evolution of basins is intimately linked to the evolution of hydraulic conductivity of the underlying aquifers. This is consistent with, and supports the notion of a coupled complexly evolving surface water-groundwater system
RAPID applied to the SIM-France model

International audienceSIM-France is a large connected atmosphere/land surface/river/groundwater modelling system that simulates the water cycle throughout metropolitan France. The work presented in this study investigates the replacement of the river routing scheme in SIM-France by a river network model called RAPID to enhance the capacity to relate simulated ﬂows to river gauges and to take advantage of the automated parameter estimation procedure of RAPID. RAPID was run with SIM-France over a 10-year period and results compared with those of the previous river routing scheme. We found that while the formulation of RAPID enhanced the functionality of SIM-France, the ﬂow simulations are comparable in accuracy to those previously obtained by SIM-France. Sub-basin optimization of RAPID parameters was found to increase model efﬁciency. A single criterion for quantifying the quality of river ﬂow simulations using several river gauges globally in a river network is developed that normalizes the square error of modelled ﬂow to allow equal treatment of all gauging stations regardless of the magnitude of ﬂow. The use of this criterion as the cost function for parameter estimation in RAPID allows better results than by increasing the degree of spatial variability in optimization of model parameters. Likewise, increased spatial variability of RAPID parameters through accounting for topography is shown to enhance model performance
Assessing impacts of agricultural water interventions in the Kothapally watershed, Southern India

The paper describes a hydrological model for agricultural water intervention in a community watershed at Kothapally in India,\ud
developed through integrated management and a consortium approach. The impacts of various soil and water management\ud
interventions in the watershed are compared to no-intervention during a 30-year simulation period by application of the\ud
calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Kothapally receives, on average, 800 mm rainfall\ud
in the monsoon period. 72% of total rainfall is converted as evaporation and transpiration (ET), 20% is stored by groundwater\ud
aquifer, and 8% exported as outflow from the watershed boundary in current water interventions. ET, groundwater recharge\ud
and outflow under no-intervention conditions are found to be 64, 9, and 19%, respectively. Check dams helped in storing water\ud
for groundwater recharge, which can be used for irrigation, as well minimising soil loss. In situ water management practices\ud
improved the infiltration capacity and water holding capacity of the soil, which resulted in increased water availability by\ud
10–30% and better crop yields compared to no-intervention. Water outflows from the developed watershed were more than\ud
halved compared to no-intervention, indicating potentially large negative downstream impacts if these systems were to be\ud
implemented on a larger scale. On the other hand, in the watershed development program, sediment loads to the streams\ud
were less than one-tenth. It can be concluded that the hydrological impacts of large-scale implementation of agricultural water\ud
interventions are significant. They result in improved rain-fed agriculture and improved productivity and livelihood of farmers\ud
in upland areas while also addressing the issues of poverty, equity, and gender in watersheds. There is a need for case-specific\ud
studies of such hydrological impacts along with other impacts in terms of equity, gender, sustainability, and development at\ud
the mesoscale
Prediction of the arrival of peak nitrate concentrations at the water table at the regional scale in Great Britain

A simple process-based approach to predict regional-scale loading of nitrate at the water table was implemented in a GIS for Great Britain. This links a nitrate input function, unsaturated zone thickness and lithologically-dependent rate of nitrate unsaturated zone travel to estimate arrival time of nitrate at the water table. The nitrate input function is the loading at the base of the soil and has been validated using unsaturated zone pore-water profiles. The unsaturated zone thickness uses groundwater levels based on regional-scale observations infilled by interpolated river base levels. Estimates of the rate of unsaturated zone travel are attributed from regional-scale hydrogeological mapping. The results indicate that peak nitrate loading may have already arrived at the water table for many aquifers, but that it has not where the unsaturated zone is relatively thick There are contrasting outcomes for the two main aquifers which have similar unsaturated zone velocities, the predominantly low relief Permo-Triassic sandstones and the Chalk, which forms significant topographic features. For about 60% of the Chalk, the peak input has not yet reached the water table and will continue to arrive over the next 60 years.  The methodology is readily transferable and provides a robust method for estimating peak arrival time for any diffuse conservative pollutant where an input function can be defined at a regional scale and requires only depth to groundwater and a hydrogeological classification. The methodology is extendable in that if additional information is available this can easily be incorporated into the model scheme
An automated disc infiltrometer for infiltration rate measurements using a microflowmeter

19 Pag., 1 Tabl., 4 Figs. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-1085This work presents a new design of disc infiltrometer, which, associated with a microflowmeter (MF) and a solenoid valve set, makes it possible to automate the infiltration rate (Q) measurements at different soil pressure heads (ψ). The MF consists of a 13·8-cm long and 1·5 mm i.d. pipe, with a pressure transducer connecting the two ends of the MF, inserted in a water-flow pipe that connects the Mariotte tube and the water-supply reservoir of the disc infiltrometer. Water flow is calculated from the head losses in the MF. Changes in ψ in the bubble tower, automatically affected when the infiltration rate reaches steady state, are controlled by a datalogger connected to four solenoid valves. The new design was tested in laboratory and field conditions, and the results showed that the MF allows the soil water infiltration rates to be correctly estimated for different soil characteristics. The solenoid valve set plus datalogger system satisfactorily monitored the changes in ψ and allowed the measurement time to be optimized.This research was supported by the Ministerio de Ciencia e Innovación of Spain (grants AGL2007-66320-CO2-02/AGR; 200840I214).Peer reviewe
TDR pressure cell for monitoring water content retention and bulk electrical conductivity curves in undisturbed soil samples

30 Pags., 4 Tabls., 5 Figs.-- The .pdf file is the last author version.-- The definitive version is avalaible at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-1085The water retention curve (θ(ψ)), which defines the relationship between soil volumetric water content (θ) and matric potential (ψ), is of paramount importance in characterizing the hydraulic behaviour of soils. However, few methods are so far available for estimating θ(ψ) in undisturbed soil samples. We present a new design of TDR-pressure cell (TDR-Cell) for estimating θ(ψ) in undisturbed soil samples. The TDR-Cell consists of a 50-mm-long and 50-mm internal diameter stainless steel cylinder (which constitutes the outer frame of a coaxial line) attached to a porous ceramic disc and closed at the ends with two aluminium lids. A 49-mm-long and 3-mm-diameter stainless steel rod, which runs longitudinally through the centre of the cylinder, constitutes the inner rod of a coaxial TDR probe. The TDR-Cell was used to determine the θ(ψ) curves of a packed sand and seven undisturbed soil samples from three profiles of agricultural soils. These θ(ψ) curves were subsequently compared to those obtained from the corresponding 2-mm sieved soils using the pressure plate method. Measurements of bulk electrical conductivity, σa, as a function of the water content, σa(θ), of the undisturbed soil samples were also performed. An excellent correlation (R2 = 0·988) was found between the θ values measured by TDR on the different undisturbed soils and the corresponding θ obtained from the soil gravimetric water content. A typical bimodal θ(ψ) function was found for most of the undisturbed soil samples. Comparison between the θ(ψ) curves measured with the TDR-Cell and those obtained from the 2-mm sieved soils showed that the pressure plate method overestimates θ at low ψ values. The σa(θ) relationship was well described by a simple power expression (R2 > 0·95), in which the power factor, defined as tortuosity, ranged between 1·18 and 3·75.This research was supported by the Ministerio de Ciencia e Inovación (Grants: AGL2007-66320-CO2-02/AGR), CSIC (Grants: PIE-200840I214 and 2008401246) and DGA-Obra social La Caixa (Grants: GA-LC-010/2008; GA-LC-006-2008).Peer reviewe
Modelling wetland connectivity during overbank flooding in a tropical floodplain in north Queensland, Australia

Hydrological connectivity between floodplain wetlands and rivers is one of the principal driving mechanisms for the diversity, productivity and interactions of the major biota in river-floodplain systems. This article describes a method of quantifying floodinduced overbank connectivity using a hydrodynamic model (MIKE 21) to calculate the timing, the duration and the spatial extent of the connections between several floodplain wetlands and rivers in the Tully-Murray catchment, north Queensland, Australia. Areal photogrammetry and field surveyed stream cross data were used to reproduce floodplain topography and rivers in the model. Laser altimetry (LiDAR)-derived fine resolution elevation data, for the central floodplain, were added to the topography model to improve the resolution of key features including wetlands, flow pathways and natural and artificial flow barriers. The hydrodynamic model was calibrated using a combination of in-stream and floodplain gauge records. A range of offstream wetlands including natural and artificial, small and large were investigated for their connectivity with two main rivers (Tully and Murray) flowing over the floodplain for flood events of 1-, 20- and 50-year recurrence intervals. The duration of the connection of individual wetlands varied from 1 to 12 days, depending on flood magnitude and location in the floodplain, with some wetlands only connected during large floods. All of the wetlands studied were connected to the Tully River for shorter periods than they were to the Murray River because of the higher bank heights and levees on the Tully River and wetland proximity to the Murray River. Other than hydrology, land relief, riverbank elevation and levee banks along the river were found key factors controlling the degree of connectivity. These variations in wetland connectivity could have important implications for aquatic biota that move between rivers and off-stream habitats during floods.Full Tex
Simulating the effects of spatial configurations of agricultural ditch drainage networks on surface runoff from agricultural catchments

The study of runoff is a crucial issue because it is closely related to flooding, water quality and erosion. In cultivated catchments, agricultural ditch drainage networks are known to influence runoff. As anthropogenic elements, agricultural ditch drainage networks can therefore be altered to better manage surface runoff in cultivated catchments. However, the relationship between the spatial configuration, i.e., the density and the topology, of agricultural ditch drainage networks and surface runoff in cultivated catchments is not understood. We studied this relationship by using a random network simulator that was coupled to a distributed hydrological model. The simulations explored a large variety of spatial configurations corresponding to a thousand stochastic agricultural ditch drainage networks on a 6.4 km2 Mediterranean cultivated catchment. Next, several distributed hydrological functions were used to compute water flow-paths and runoff for each simulation. The results showed that (i) denser networks increased the drained volume and the peak discharge and decreased hillslopes runoff, (ii) greater network density did not affect the surface runoff any further above a given network density, (iii) the correlation between network density and runoff was weaker for small subcatchments (< 2 km2) where the variability in the drained area that resulted from changes in agricultural ditch drainage networks increased the variability of runoff and (iv) the actual agricultural ditch drainage network appeared to be well optimized for managing runoff as compared with the simulated networks. Finally, our results highlighted the role of agricultural ditch drainage networks in intercepting and decreasing overland flow on hillslopes and increasing runoff in drainage networks
Malleable disc base for direct infiltration measurements using the tension infiltrometry technique

19 Pags.  The definitive version, with 2 Tabls. and 6 Figs., is available at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-1085The correct use of the tension disc infiltrometer requires the membrane of the disc base to be completely in contact with the soil surface. To achieve this contact, a thick layer of sand is commonly placed between the soil surface and the disc base. This paper presents an alternative disc (MDB), which, by incorporating a malleable membrane, allows direct infiltration measurements without using a contact sand layer. Infiltration curves obtained with this new design in a soil under three different tillage management treatments were compared with the corresponding curves obtained with a conventional disc (CDB) that uses a contact sand layer. The cumulative infiltration curves measured with CDB were analysed by the differentiated linearization (DL) method, and the corresponding curves obtained with MDB were analysed using both the DL and the cumulative linearization (CL) models. The values of hydraulic conductivity (K0) and sorptivity (S0) estimated with CDB were also compared with those obtained with MDB. Finally, the cumulative infiltration curves measured with CDB and MDB were compared with the corresponding modelled function for the respective K0 and S0 values calculated with the CL and DL models. The results show that, compared with CDB without a contact sand layer, MDB allows complete soil surface wetting even when non-smoothed soil surfaces are used. The CDB, which yielded average K0 values 18% lower than those estimated with MDB, gave the highest values of standard error for the hydraulic parameters calculated. Furthermore, the subjective method employed in the CDB-DL technique, which requires the first points of the differential infiltration line corresponding to the sand layer to be manually removed, introduces additional uncertainties in estimating S0 and K0. Comparison between the modelled and measured infiltration curves demonstrates that the DL or CL methods applied to MDB gave excellent estimates of S0 and K0.This research was supported by the Ministerio de Ciencia e Innovación of Spain (grant AGL2010-22050-C03-02) and by the Aragón regional government and La Caixa (grant GA-LC020/2010).Peer reviewe
Impacts of upland open drains upon runoff generation : a numerical assessment of catchment-scale impacts.

Shallow upland drains, grips, have been hypothesized as responsible for increased downstream flow magnitudes. Observations provide counterfactual evidence, often relating to the difficulty of inferring conclusions from statistical correlation and paired catchment comparisons, and the complexity of designing field experiments to test grip impacts at the catchment scale. Drainage should provide drier antecedent moisture conditions, providing more storage at the start of an event; however, grips have higher flow velocities than overland flow, thus potentially delivering flow more rapidly to the drainage network. We develop and apply a model for assessing the impacts of grips on flow hydrographs. The model was calibrated on the gripped case, and then the gripped case was compared with the intact case by removing all grips. This comparison showed that even given parameter uncertainty, the intact case had significantly higher flood peaks and lower baseflows, mirroring field observations of the hydrological response of intact peat. The simulations suggest that this is because delivery effects may not translate into catchment-scale impacts for three reasons. First, in our case, the proportions of flow path lengths that were hillslope were not changed significantly by gripping. Second, the structure of the grip network as compared with the structure of the drainage basin mitigated against grip-related increases in the concentration of runoff in the drainage network, although it did marginally reduce the mean timing of that concentration at the catchment outlet. Third, the effect of the latter upon downstream flow magnitudes can only be assessed by reference to the peak timing of other tributary basins, emphasizing that drain effects are both relative and scale dependent. However, given the importance of hillslope flow paths, we show that if upland drainage causes significant changes in surface roughness on hillslopes, then critical and important feedbacks may impact upon the speed of hydrological response
Testing the influence of topography and material properties on catchment-scale soil moisture patterns using remotely sensed vegetation patterns in a humid temperate catchment, northern Britain.

In order to evaluate the relationship between the apparent complexity of hillslope soil moisture and the emergent patterns of catchment hydrological behaviour and water quality, we need fine-resolution catchment-wide data on soil moisture characteristics. This study proposes a methodology whereby vegetation patterns obtained from high-resolution orthorectified aerial photographs are used as an indicator of soil moisture characteristics. This enables us to examine a set of hypotheses regarding what drives the spatial patterns of soil moisture at the catchment scale (material properties or topography). We find that the pattern of Juncus effusus vegetation is controlled largely by topography and mediated by the catchment's material properties. Characterizing topography using the topographic index adds value to the soil moisture predictions relative to slope or upslope contributing area (UCA). However, these predictions depart from the observed soil moisture patterns at very steep slopes or low UCAs