bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbulence in Titan's Planetary Boundary Layer explored by Large-Eddy Simulations with realistic physics
Authors: Spiga Aymeric , Lefèvre Maxence , Lebonnois Sébastien
Published: September 2022

Titan, the largest satellite of Saturn, is known to host a rich and active meteorology, by all standards more dynamic than previously thought before the Cassini-Huygens mission. One key element of the dynamic Titan's atmosphere is the Planetary Boundary Layer (PBL), defined as the lowermost part of the atmosphere directly influenced by the presence of a surface below it. Turbulence in the PBL is a controlling factor for exchanges of momentum, heat, chemical species and aerosols between surface and atmosphere.

Following observations by the Cassini-Huygens mission, a debate has arisen on the vertical extent of the PBL mixing on Titan in daytime conditions. Radio-occultations by Voyager and Cassini, as well as insights from dune spacing, indicate that a mixed layer, following the dry adiabatic lapse rate, extends 2 to 4 km above the surface. Conversely, in situ mid-morning measurements on board the equatorial Huygens descent probe suggests a more complex structure, with a clear-cut mixed layer only found to extend 300 m from the surface of Titan, with slope breaks between 2 and 4 km in the vertical temperature profile being related to PBL processes by some studies but not by others.

The turbulent dynamics of Titan's PBL have been studied thus far either by Global Climate Models where mixing dynamics is parameterized rather than resolved, or by idealized Large-Eddy Simulations not coupled to realistic Titan physics and limited to the first hundreds meters above the surface. Here, to broaden the knowledge of Titan PBL processes, we present turbulent-resolving Large Eddy Simulations coupled with a realistic Titan radiative transfer and soil model, extended several kilometers above the surface and ran for the full daytime cycle of Titan environmental conditions. Using those new simulations, we are able to reconcile all existing observations in a single scenario of Titan PBL growth in daytime, from a couple hundreds of meters in mid-morning conditions to a 3 km fully-developed mixing layer in early afternoon conditions. We also explored turbulent statistics for Titan's PBL: sensible heat flux, updraft and downdraft intensity, wind gustiness. We also note the spontaneous occurrence of convective vortices (dustless devils) in our Titan Large-Eddy Simulations.

Our new simulations for Titan PBL bears the potential to help rethink Titan weather processes close to the surface -- and their link to the aerosol / volatile cycles. Furthermore, basic knowledge on PBL turbulence on Titan is needed in the perspective of the Dragonfly spacecraft which will be directly flying within Titan's PBL, thereby experiencing its turbulent dynamics and carrying out in situ measurements of this turbulence.
Geological History of Lava flows and Graben Systems (Dyke Swarms) Of The Mbokomu Mons Region, Along Parga Chasmata, 2400 Km SE Of Atla Regio, Venus.
Authors: Hannour Naima , El Bilali Hafida , Ernst Richard .E , Head James .W , Youbi Nasseriddine
Published: September 2022

Introduction:

The relationship between coronae and chasmata has been extensively discussed but is still enigmatic (e.g. [1-6]). One such relevant region is along the 10,000 km long Parga Chasmata which connects Atla Regio with Themis Regio. On the basis of detailed mapping of graben fissure systems and interpreted rift faults along a 1500 km long segment of Parga Chasmata, [6] recognized that many coronae represent the locus of local triple junction rift centres; extrapolating this observation to the entire length of Parga Chasmata (and also Hecate Chasmata), and then compared it to the Atlantic rift system of Earth.

To explore these relations more fully, we have selected a region along Parga Chasmata for detailed study. The general area is about 2000 km SE of the centre of Atla Regio and we focus on Mbokomu Mons. The goal of the present research is to provide detailed mapping (1:500,000 scale) of the graben fissure systems, lava flows associated with Mbokomu Mons (and in the surrounding area), in order to provide insights into the setting of coronae within the broad Parga Chasmata rift system. Our mapping builds on the previous reconnaissance mapping (1:5,000,000 scale) of Taussig Quadrangle (V–39) [7].

Initial mapping of the graben associated with Mbokomu Mons are provisionally grouped into distinct sets, which we provisionally interpret to mainly represent dyke swarms of both radiating, circumferential and linear geometry, on the basis of previously established criteria [e.g. 8,9]. We are attempting to identify potential magmatic centres as sources for these swarms. Flow systems to the east, and north and west of Mbokomu Mons are visible and mapped. Topographic profiles are provide for Mbokomu  Mons.

Upon completion, this detailed mapping will provide significant insight into the relationship between chasmata and associated coronae, of relevance to chasmata across Venus. 

References:

[1] Hamilton, V.E., Stofan, E.R. (1996) Icarus, 121, 171–194. [2] Martin, P., Stofan, E.R. (2004). 35th LPSC, Abstract 1576. [3] Martin, P., et al. (2007) JGR, 112, E04S03. [4] Smrekar, S.E., et al. (2010). JGR, 115, No. E07010. [5] Ivanov, M.A., Head, J.W. (2015). Planet. Space Sci., 113-114, 10-32. [6] Graff, J.R., et al. (2018). Icarus, 306, 122-138. [7] Brian, A.W., et al. (2005). USGS SIM 2813. [8] Grosfils, E.B. Head, J.W. (1994) GRL, 21: 701–704. [9] Buchan, K.B and Ernst, R.E. 2021 Gond. Res., 100, 25–43.
Hydrological behaviour of mediterranean salt marshes and implications for vegetal cover
Authors: Berteloot Victor , Crabit Armand , Barkaoui Karim , Kazakou Elena , Colin François
Published: September 2022

Salinization is a worldwide issue particularly threatening arid and semi-arid soils. Primary salinization is due to unbalanced flows between upward water and solute flows leading to salts accumulation and downward flows which allow the leaching of salts. Soil salinity affects vegetation by causing osmotic and toxic stress. In return, soil water transfers are impacted since water extraction by plants is limited. Salinity leads also to a decrease of soil hydraulic conductivity.

Salinisation is often described as a threat to agriculture, but less as a driver of specific ecosystem functioning, such as salt marshes. These interfaces between land and sea are very present in the Mediterranean deltas and lagoon complexes, and provide several ecosystem services, (e.g. being the natural areas among with the highest carbon storage rate). Salinity in these ecosystems is highly dependent on freshwater inputs from precipitation, natural or anthropic flooding, making them vulnerable to global changes. Nevertheless, the effects of flooding on hydrological dynamics and solute transfers in salt marshes are not well known.

We choose a study site in the lowlands of the Aude river (the Castelou site, Narbonne, France) to address the question of the hydrological behavior of a salt marsh managed by different flooding intensities in relation to plant communities. Soil moisture, saturated zone depth, and salinity dynamics are monitored by a set of continuous and point measurements at 12 sites distributed along a flood management gradient and a natural salt pressure gradient. Based on these observations, time continuous data series have been built by a physics-based modeling. The analysis provides a better understanding of the effects of flooding on soil water and solute stocks and fluxes, and relates them to the specific composition of plant communities.

We show that flooding has varying effects on water storage in unsaturated and saturated zones. Soil water recharge has a small effect on soil salt content on an annual scale but limits the level of osmotic stress. In the absence of flooding, osmotic stress is more pronounced, altering the specific composition of plant communities, suggesting changes in their functional properties.
Bayesian model calibration in ungauged catchments via satellite data
Authors: Yoon Hae Na , Marshall Lucy , Sharma Ashish , Kim Seokhyeon
Published: September 2022

We launch a novel approach for hydrologic modeling in ungauged basins using satellite data. Due to universal availability, satellite data is an attractive option to fill the absence of in-situ data to calibrate a hydrologic model in ungauged or poorly gauged basins. The one specific satellite-derived calibration-measurement ratio (C/M ratio) is useful because of its physical property to indicate the water extent and its demonstrated correlation with observed streamflow. However, there are challenges in calibrating a hydrologic model using the C/M ratio because it has a different dimension to streamflow. Therefore, a new approach is required to use the modeled surrogate streamflow instead of the raw C/M ratio in place of streamflow. A new Bayesian approach is introduced here to identify parameters of surrogate streamflow in the absence of a time series of streamflow. This approach calibrates the conjugated probability of the parameter set of a hydrologic model and a surrogate streamflow model. Specifically, the proposed likelihood includes supplementary information, such as an estimated mean value of streamflow, to join the information of streamflow volume and dynamics of the modeled flow. Our new approach is assessed for multiple Australian Hydrologic Stations with distinct attributes. The strength in the new method is demonstrated with high Nash-Sutcliffe Efficiency values (0.535 ~ 0.781), and the uncertainties in the new model calibration are quantified via Markov Chain Monte Carlo sampling. The errors of the surrogate streamflow model and the hydrologic model are analyzed, and the predictive intervals are assessed with the benchmark model derived from the in-situ streamflow. Overall, our work improves previous studies on the hydrological predictions using the C/M ratio. Furthermore, it enables surrogate data to be highly correlated to the actual data, regardless of their dimensions.
A novel streamflow estimation using L-band passive microwave
Authors: Yoon Hae Na , Marshall Lucy , Sharma Ashish , Kim Seokhyeon
Published: September 2022

We present a new basis for measuring river discharge in ungauged catchments worldwide, which is a prerequisite for any flood or drought mitigation system to be effective. Surrogate runoff (SR) is created from remotely sensed data to make up for the absence of in-situ streamflow. Because of its widespread availability and global coverage, SR derived from remotely sensed data offers an attractive streamflow alternative.
Specifically, the satellite-derived measurement-calibration ratio (MC ratio, also known as C/M ratio) is an appealing option because of its positive correlation with the observed streamflow and its physical property to detect floods. However, challenges in using the C/M ratio to predict streamflow dynamics have been identified because of its limited penetration skill and assumptions in the SR calculation. A signal with a longer wavelength is a possible alternative with better penetration, but the key assumptions for deriving SR are hard to satisfy with a coarser signal. Thus, a new approach to making an SR is required to use a longer wavelength sensor, such as the L-band microwave, which allows advanced data quality. The proposed SR formulation in our study alternates or reduces assumptions in SR calculation to use a coarse grid. The improved performance of the new SR is presented for 467 Australian Hydrologic Reference Stations, which can be considered free from anthropogenic effects and have distinct attributes. Results show significant enhancements in the Pearson linear correlation (R) between SR and in-situ streamflow: 44% of the study areas show R higher than 0.4 with the new approach, whereas only 13% of the study areas show R higher than 0.4 with the previous approach (C/M ratio). Overall, SR is dramatically improved by using the newly designed SR with the L-band microwave signal.
Exp’Eau, a hybrid serious game to explore pathways towards better water quality in rural catchments
Authors: Barreteau Olivier , Charpentier Isabelle , Elouati Hossam , Kelhetter Hugo , Kudriashov Daniil , Blanchoud Hélène , Bonnefond Mathieu , Dousset Sylvie , Gouy Véronique , Piscart Christophe , Pons Marie-Noëlle , Ragueneau Olivier , Salvador-Blanes Sébastien
Published: September 2022

Agriculture is considered today as having major impacts on water quality in river basins. Transition from this situation to a better integration of agricultural practices in their environment is sought by many stakeholders and policy makers, from water, land development and also agriculture sectors. This appears costly when incorporating their various constraints. With the on-going research project ExpEau, the LTSER-FR network aims at (1) raising awareness on the opportunities to handle agricultural sources of water pollution collectively, and (2) comparing them in various watersheds. 
To that end, we are developing a hybrid serious game featuring activities and relations between farmers, municipalities and river basin organization on a virtual river basin, generated from actual datasets for topography, soil properties, and climate. For comparison sake, the game features a framed number of entities and possibilities of action, and the process of transforming actual datasets is standardized. We consider representative small basins (ca. 100 km2) that we discretize into three sub-basins, each of them representing a municipality as the first level for collaboration. Each sub basin counts about 30 hexagons elementary tiles with a single land use for each.
In practice, the game is made of a physical board and playing action cards, as well as a twin on-line version. Farmer players access to the information on their environment and choose cultural practices thanks to a smartphone. Municipality and river basin organisation roles use their time and budget to facilitate collaboration and support more virtuous practices as well as infrastructures to decrease pollution. A local server computes the impacts of these actions in terms of production, collective well-being and contamination, and updates the players’ data. 
During the game session, players can see the virtual watershed, the land use and the infrastructures on the physical board. According to their role, they receive situated information on production, on territorial well-being and water quality and quantity.
Involving students or local stakeholders, each session is followed by a debriefing that could produce (1) a local understanding on the interactions between agriculture and water quality, and (2) socio-ecosystem data to feed a cross LTSER analysis of these interactions.
Algeria case study: Re-inventing the circular irrigation system in the semi-desert Mzab valley
Authors: Hamamouche Meriem Farah , Saidani Amine , Fantini Emanuele , Kuper Marcel
Published: September 2022

Perhaps one of the most elaborate community initiatives in managing groundwater consists of reinforcing the natural cycle of aquifer recharge, which can then be used for irrigation. Artificial groundwater recharge and use systems often deal with difficult waters that come suddenly (e.g flash floods). Operating such systems over the long run requires robust collective action and carefully balancing the available water resources and their use. These are exactly the two dimensions that have been challenged in past decades by the development of individual pumps entailing the possibility of intensive, often unsustainable, groundwater mining for entrepreneurial agricultures. In the oasis context, this new form of agriculture is developed, most often, without the local people and in contradiction with the principle of oasis agriculture. ​ The ancient oases in the M’zab valley in Algeria’s Sahara are the result of several centuries of hard work while respecting the fragile balance between resources and their needs. For instance, the community-managed circular irrigation system of the M'zab valley aims to capture water from the natural hydrological cycle and insert it into local use loops, complementing the natural recharge. This respect for balance was done also for energy and waste.

Regardless of entrepreneurial agriculture, the oasis communities of the M’zab valley developed another agricultural model on the lands surrounding the ancient oases. The farmers were inspired by the secular oasis repertoire, based on circularity while combining them with contemporary practices farming practices and techniques in order to produce a healthier and more sustainable market agriculture.

This study analyses how the circular irrigation system was reinvented in the M’zab valley. We will mobilize the Quantitative Story-Telling approach since it enables allows: i) bridge different sources of knowledge, including local knowledge, ii) combine both qualitative and quantitative information regarding the sustainable use of local resources, and iii) co-create narratives on desirable and viable socio-technical pathways. Based on the analysis, we will reflect on how re-adapating the circular irrigation system in the new agricultural extensions can represent sources of inspiration for ecologically sustainable and socially equitable forms of groundwater governance, even in particularly challenging situations.
Use of trace elements to distinguish flows from different types of carbonated rocks
Authors: Serène Leïla , Batiot-Guilhe Christelle , Mazzilli Naomi , Léonide Philippe , Emblanch Christophe , Resongles Eléonore , Freydier Rémi , Causse Léa , Babic Milanka , Dupont Julien , Simler Roland , Blanc Matthieu , Massonnat Gérard
Published: September 2022

Chemistry of groundwater is heavily affected by water-rocks interactions. Major elements in groundwater provide valuable indications on main aquifer rock types but requires strong lithological contrasts. Carbonate rocks differ because of deposit conditions and diagenesis and it bears significant implications for groundwater flow. It is established that trace elements in carbonates depend on deposit environment and diagenesis (Gholami Zadeh et al., 2019; Hood et al., 2018; Li et al., 2020). In waters from carbonate aquifers, variation of trace elements contents is observed at different spatial and temporal scales (Dematteis, 1995; Morgantini et al., 2010; Schürch et al., 2004). While some of this variability is due to recharge characteristics, in the absence of anthropic contamination the main process affecting trace elements contents is water-rock interactions. This leads to the potential for trace elements to be a natural tracer of limestone rock types.

This work aims to develop a natural tracer of limestone rock types that could distinguish the fingerprints of the different sub-reservoirs of carbonate aquifers.

To this purpose, we studied the Fontaine de Vaucluse karst system (southern France). It has a large recharge area (~ 1160km2; Ollivier, 2020) composed of Upper Barremian limestones of inner/outer platform, slope and basinal environnements (Masse and Fenerci-Masse, 2011; Léonide et al., 2012). We analysed major and trace elements of a set of 107 rock samples representative of the complete lithologie, facies and rock type properties of these carbonates. We also performed a one-year sampling campaign on 17 flow points: 12 in unsaturated zone from the LSBB gallery (lsbb.cnrs.fr), 3 springs, 1 stream losses, and at the main outlet of the karst system. In addition to trace elements we also monitored major elements, stables isotopes, TOC and fluorescence of natural organic matter.

A hierarchical clustering was performed with trace element contents of rock samples. It splits data into four groups according to facies description (inner/outer platforms, slope, basin). In water, first results show temporal and spatial variation of trace elements of Fontaine de Vaucluse system.

These promising results hint that trace element seem to be relevant natural tracers of the path taken by water in different limestones.
Applicability of VIC model for hydrological simulations over Upper Ganga Basin, India
Authors: Dayal Deen , Pandey Ashish , Gupta Praveen , Mahanandaiah Yogesh
Published: September 2022

Efficient management of water resources is crucial for sustainable development, protection of the environment, and growth of the nation. However, this is quite challenging in developing countries like India, mostly due to the lack of watershed-wide hydrological data from in-situ platforms. Under such circumstances, hydrologic models forced with widely available satellite-based datasets can be very useful. Keeping this in view, Variable Infiltration Capacity (VIC), a physically-based distributed model is set up over the Upper Ganga Basin up to Garhmukteshwar gauging site. Daily calibration and validation of the VIC model were carried out for the years 2009 and 2010. The streamflow simulation was sensitive to mainly two parameters i.e., infiltration parameter and soil layer depth when evaluated with different objective functions. Model performance in the terms of coefficient of determination (R2) and Nash-Sutcliffe Efficiency (NSE) during calibration was found to be 0.76 and 0.65, respectively, while for the validation period, they were 0.78 and 0.73, respectively. A good agreement between the simulated and observed hydrographs for discharge justifies the performance and utility of the VIC model. The spatial distribution of the simulated water balance components (i.e., runoff, ET, and soil moisture) generated from the successfully validated model are presented. The study reveals that the VIC model is capable of simulating hydrological fluxes for the Upper Ganga Basin.
Estimation of the  sediment yield from the drainage basin of the Lena River
Authors: Maltsev Kirill
Published: September 2022

The assessment of sediment runoff from the territory of two key catchments located in the Lena River basin was carried out within the framework of this study. The Lena River basin is located within the Russian Federation and belongs to the Arctic catchment. The study sites are located within very different natural conditions. The first section of the Chara river is located within the mountainous part of the catchment with coordinates of the section are 57° n.l, 118° e.l. The second site is located in the area of ​​Yakutsk, in the flat part of the Lena river basin with coordinates of the site are 62° n.l., 131° e.l.

The assessment of sediment yield from the catchment area was performed using the WaTEM / Sedem. The following values ​​of sediment runoff entering the catchment of the Chara and rivers in the area of ​​Yakutsk were obtained. The catchment area of ​​the Chara River is characterized by an average long-term modulus of sediment equal to 149 t / km2 per year (1961-1984), 172 t / km2 per year (1985-2020). The obtained values ​​do not agree with the data on sediment runoff measured in the river at the hydrographic station in the village of Chara. The sediment runoff measured in the river decreased from 28 to 15 t / km2 per year (Magritsky, Banshchikov, 2021). Comparison of data from modeling sediment runoff from the catchment area and measured data at Tabaga station in the area of Yakutsk indicates a greater consistency of the results. The modeling data give an estimate of 3.5 t / km2 per year, and the measurement data - 5 t / km2 1980-x (1961 - 1984) and 9 t / km2 per year (1956-2019).

 Funding: The work was supported by the Russian Science Foundation (project № 21-17-00181)
Increasing rainfall data density in Northern Italy through daily extremes and the Hershfield factor
Authors: Mazzoglio Paola , Butera Ilaria , Claps Pierluigi
Published: September 2022

The majority of rainfall measurements in the world is at the daily scale, i.e. expressed over fixed 24-hours. It is then evident that the 24-hour annual maximum rainfall depths, which refer to a period starting at any instant, must not be less than the daily extremes, and are generally higher. The ratio between these extremes, called Hershfield factor (HF), has been studied to correct the errors between fixed time interval and sliding maxima, allowing to take advantage of the relevant amount of information included in historical records of daily extremes. For instance, before 1980, in the Italian Hydrological Yearbooks only a subset (< 50%) of the rain gauges was equipped with a recording device, from which annual maxima over 1, 3, 6, 12 and 24 consecutive hours can be derived.
In our study we investigated the possibility of using the daily data to enrich the availability of sliding maxima rainfall measurements included in the Improved Italian – Rainfall Extreme dataset (I2-RED), by selecting the Po river basin (North of Italy) as a case study. We retrieved from SCIA (http://www.scia.isprambiente.it/wwwrootscia/Home_new.html) and then we quality-controlled all the daily rainfall measurements available over this area from early 1900 until today. We computed the annual HF for all the stations and all the years where both the daily and the hourly extremes were available, to obtain data that can be analyzed in their interannual and spatial variability. 
Analyzing the HF spatial distribution within the Po basin we found values similar to the ones suggested in the literature. Hershfield himself originally estimated a mean value of about 1.13 for the United States, while further studies suggested values in the range of 1-1.2. The spatial distribution of the average HF values turns out to be related to the geographic position of the stations and entails the possibility to identify some distinct areas with a positive or negative anomaly. This map allowed us to reconstruct the missing 24-hour extremes in stations with only daily data, and improve the knowledge of the spatial variability of sub-daily rainfall extremes.
Seeking best streamflow assimilation scheme in a semi-distributed hydrological model for flood forecasting
Authors: Royer-Gaspard Paul , Bourgin François , de Lavenne Alban , Perrin Charles , Thirel Guillaume
Published: September 2022

Semi-distributed hydrological models have the potential to improve the efficiency of flood forecasting chains. Such models take into account the spatial distribution of both meteorological forcings and soil moisture states to predict streamflow along the river network and allow the assimilation of streamflow observations on multiple internal flow gauges. How to update the model states on ungauged upstream sub-catchments remains however a challenge. Indeed, the actual relative contribution of each upstream sub-catchment to the observed streamflow at the outlet cannot be observed but simply estimated by the hydrological model from the simulated upstream streamflow and routing-lag. In this work, we test the following hypotheses:

the simultaneous assimilation of streamflow observations at internal gauges should improve streamflow predictions at the main downstream outlet

accounting for time lags between flow gauges is needed to efficiently update model states in cases where no streamflow observations are available at internal gauges

The analysis is performed with a semi-distributed version of the hourly GR5H model (de Lavenne et al., 2019; Peredo-Ramirez et al., 2021) on a large dataset of French gauged catchments, each one having at least one internal gauged station. Several experiments were set up in gauged and pseudo-ungauged contexts to test both hypotheses. Two updating schemes were used: a particle filter (Piazzi et al., 2021) and a direct insertion method used in the operational flood forecasting model GRP (Furusho et al., 2016).

 

References

de Lavenne, A., Andréassian, V., Thirel, G., Ramos, M.-H., & Perrin, C. (2019). A regularization approach to improve the sequential calibration of a semidistributed hydrological model. Water Resources Research, 55, 8821–8839, 2018WR024266.

Furusho, C., Perrin, C., Viatgé, J., Lamblin, R., and Andréassian, V. (2016). Collaborative work between operational forecasters and scientists for better flood forecasts, La Houille Blanche, 102:4, 5-10.

Peredo-Ramirez, D., Ramos, M.-H., Andréassian, V., and Oudin, L. (2021). Investigating hydrological model versatility to simulate extreme flood events. Hydrological Sciences Journal, in review.

Piazzi, G., Thirel, G., Perrin, C., and Delaigue, O. (2021). Sequential data assimilation for streamflow forecasting: assessing the sensitivity to uncertainties and updated variables of a conceptual hydrological model at basin scale. Water Resources Research, 57(4), e2020WR028390.
Influence of initial glacier conditions to the future evolution of river runoff
Authors: Champollion Nicolas , Gimenes Lucille , Millan Romain
Published: September 2022

The effects of climate change on water resources are partly determined by the size and the spatial distribution of ice reservoirs around the world. While mountain glaciers represent only 1% of today’s global ice volume, they have contributed around 25% to sea-level rise during the last decades, and are expected to contribute within the same proportion during the rest of the 21st century [SROCC, 2019]. Mountain glaciers also represent sources of drinking water for millions of people. The glacierized drainage basins cover around 26% of the global land surface and are populated by more than two billions of people [Huss et Hock, 2018]. However, mountain glacier ice thickness estimates are largely uncertain due to the use of simplified retrieval approaches [Rabatel et al., 2018]. Furthermore, nearly 50% of the global glacier evolution uncertainty comes from the glacier model itself and the initial glacier representation in space [Marzeion et al., 2019]. The objective of this study is to understand the effects of initial glacier conditions, and specifically the ice thickness, on simulations of glacier evolution and their contribution to river runoff.

For that purpose, we used the Open Global Glacier Model [OGGM, Maussion et al., 2019], that simulates the surface mass balance and ice dynamics to estimate the evolution of any glacier in the world. We used three new different ice thickness dataset and proposed a framework to assimilate them within OGGM. We then focused on sensitivity analysis of future glacier evolution using different climate scenarios, initial conditions of ice thickness and internal model parameters such as the creep parameter, the spatial resolution, the spin-up initialization. These experiments were performed for different types of glaciers in terms of location, size and geometry. The results helped us to assess the importance of model initialization with respect to other model parameters, in the glacier evolution during the 21st century and specifically the changes in surface and volume. We also explored the differences induced in terms of glacier contribution to river runoff and peak water timing, which is of great importance for freshwater resources management.
Simulating catchment scale river discharges and flood events from large scale atmospheric information: Example of the Upper Rhône River (European Alps)
Authors: Legrand Caroline , Wilhelm Bruno , Hingray Benoît
Published: September 2022

Floods are highly destructive natural hazards causing widespread impacts on socio-ecosystems. This hazard could be further amplified with the ongoing climate change, which will likely alter magnitude and frequency of floods. Estimating how flood-rich periods could change in the future is however challenging (UPH 9). The classical approach is to estimate future changes in floods from hydrological simulations forced by time series scenarii of weather variables for different future climate scenarii. The development of relevant weather scenarii for this is often critical. To be adapted to the critical space and time scales of the considered basins, weather scenarii are thus typically produced from climate models with downscaling models, either dynamic or statistical.

In this study, we aim to evaluate the capacity of such a simulation chain to reproduce changes in flood-rich periods of the upper Rhône River (10900 km², European Alps) over the last century (1902-2009). The modeling chain is made up of (i) the atmospheric reanalysis ERA-20C, (ii) either the statistical downscaling model SCAMP (Sequential Constructive Atmospheric Analogues for Multivariate weather Predictions; Raynaud et al., 2020) or the dynamical downscaling model MAR (Modèle Atmosphérique Régional; Ménégoz et al., 2020), and (iii) the glacio-hydrological model GSM-SOCONT (Glacier and Snowmelt SOil CONTribution model; Schaefli et al., 2005).

To assess the performance of each modeling chain, several hydro-meteorological variables are analysed. The simulated scenarii of mean areal precipitation and temperature are compared to the observed time series over the common period (1961-2009), whereas the discharge scenarii and the simulated flood-rich periods are compared to the reference ones (1920-2009). The flood-rich periods are derived from the discharge time series using the Peak Over Threshold (POT) method.

Preliminary results suggest that flood events are better reproduced with the statistical downscaling model. This may result from the biases in the MAR simulations for both the mean areal precipitation and the mean areal temperature. Further work will explore the interest for a quantile-quantile correction of MAR precipitation and temperature. The interest for a bias correction will be also explored for SCAMP temperature.

References:

Raynaud et al. (2020) HESS doi.org/10.5194/hess-24-4339-2020
Ménégoz et al. (2020) HESS doi.org/10.5194/hess-24-5355-2020
Schaefli et al. (2005) HESS doi.org/10.5194/hess-9-95-2005
How much value is in climate and geomorphological descriptors for distributed hydrological modelling? A decision tree based approach in North-Western Italy
Authors: Pesce Matteo , Viglione Alberto , Hardenberg Jost , Tarasova Larisa , Basso Stefano , Merz Ralf
Published: September 2022

Large scale modelling is becoming increasingly important in hydrology, particularly to characterize and quantify changes in the hydrological regime, whose drivers are typically large-scale phenomena, up to the global scale (e.g., climate change). This can be done with distributed models by estimating spatially consistent model parameters, that are parameters having a functional relationship with catchment characteristics. In this study we adopt the newly developed PArameter Set Shuffling (PASS) approach, based on a machine learning decision tree algorithm, for the regional calibration of the SALTO (SAme Like The Others) model. The method exploits observed patterns of locally calibrated parameters and catchment (climatic and geomorphological) descriptors, to derive functional relationships between the variables. The results, for around 100 catchments located in North-Western Italy, demonstrate that the use of regionally calibrated parameter sets results in similarly good performances as for local calibration. This suggests that the predicted parameter sets can be efficiently used for streamflow prediction in ungauged basins or under changing conditions.
Spatial characterization of drought through CHIRPS and a station-based dataset in the Eastern Mediterranean 
Authors: Orieschnig Christina Anna , Cavus Yonca
Published: September 2022

Drought is a natural hazard which occurs in all climatic zones and affects different sectors such as irrigation, energy, water supply, and ecology. Monitoring and predicting drought are pressing challenges since drought is becoming more common and severe owing to the impacts of climate change and increased climatic variability. However, in many areas of the globe, the temporal and spatial characterization of droughts and trends in their frequency and severity is hindered by a lack of reliable, long-term locally measured data and unevenly distributed, erratic meteorological stations. In this situation, remote sensing datasets such as Climate Hazards Group InfraRed Precipitation with Station Data (CHIRPS) can offer valuable insights into long-term developments and the spatial characteristics of droughts. Nonetheless, it is often uncertain to which extent data such as CHIRPS succeeds in representing local dynamics and how this varies between geographical regions and climate zones. 

In this analysis, we aim to evaluate spatial drought conditions over the Seyhan River basin in Turkey in the Eastern Mediterranean. Using the Standardized Precipitation Index (SPI) as a drought index, the applicability of CHIRPS as a long-term satellite precipitation product for drought monitoring is investigated. We compare two spatial representations of the SPI: one derived on a per-pixel basis from CHIRPS data since 1981, the other based on data from 19 meteorological stations scattered across the basin which was spatialized using inverse distance weighted interpolation. Our results offer insights into the relative accuracy of CHIRPS data in the Eastern Mediterranean, and avenues towards optimizing the quality of spatial drought characterization approaches. 
Reanalysis of the October 1940 record flash flood in the Pyrenees 
Authors: Gaume Eric , Payrastre Olivier , Coeur Denis , Kovacs Yves
Published: September 2022

One of the most impressive flash floods of the 20th century in France as well as in Catalunia occurred in the Eastern part of the Pyrenees on October 1940. 47 people were killed in France during this extraordinary event and more than 100 in Spain. It caused tremendous damages to buildings and, in particular, destroyed the center of the resort town of Vernet-les-Bains on the slopes of the mount Canigou. The maximum observed 24-hour accumulated rainfall reached locally 1000 mm and this remains until a record value for the French European territory. The flood has been abundantly documented by the technical State services as well as some scientists of the time and a large part of this documentation has been archived.

At the light of the recent advances in flash flood studies, this data set has been unearthed and the past analyses of the event have been deeply revisited. This revealed, in particular, that the peak discharge values, on which local risk assessment studies are based, had been largely over-estimated. This led to several mis-interpretations of the processes occurred during this flood such inundation dynamics or the driving factors of the tremendous observed scour and erosion volumes. Some particular features of this event could also be confirmed or revealed: (1) an impressive wave propagation of about four million cubic meters due to the breach of a natural dam due to a massive landslide in the upper part of the Tech river which occurred during the night, affected already destroyed areas and got therefore almost unnoticed, (2) a local major amplification of the inundation induced by the breach of a railway embankment, (3) the dynamics of scour and erosion. Beyond the conclusions drawn on this specific extreme flash flood, this study illustrates that our knowledge about extreme flood events is still limited by their poor and often biased documentation. New and adapted observation and documentation strategies, based for instance on the systematic collation and analysis of opportunistic data such as amateur videos, have to be implemented to enable a real progress in the science of extreme flash floods.
Nivo-glaciological changes in Alpine catchments: impacts on hydrological regimes and aquatic ecosystems
Authors: Lemoine Anthony , Gouttevin Isabelle , Condom Thomas , Cauvy-Fraunié Sophie , Becquet Juliette , Bolibar Jordi , Rabatel Antoine
Published: September 2022

The rapid evolution of glaciers and snow cover in mountain areas reflects the impacts of climate change on these regions. The decrease of the water stock in solid form induces irreversible changes on the hydrological regimes of alpine rivers and affects their ecological functioning. In addition, there are numerous anthropogenic pressures, mainly due to the use of water in mountain areas (artificial snow, water supply, agriculture, hydropower production, tourism). To better understand the consequences of glacial retreat and snow cover changes on water resources and help decision makers, we have set up a modeling chain composed of a dynamic glacier module, based on the ALPGM glaciological model (Bolibar et al., 2020), as well as the J2000 semi-distributed hydrological model (Branger et al., 2016) running at daily time step. In the present contribution, this modelling chain is applied to 3 catchments of the French Northern Alps characterized by contrasting ranges of altitudes and glacier cover. The evolution of hydrological regimes over the last sixty years is first examined using meteorological reanalysis products adapted to the Alpine regions (SPAMZ; Gottardi, 2009 and S2M; Vernay et al., 2021). Then, we envisage hydrological projections until 2100 from regionalized climate projections (Verfaillie et al., 2017) according different greenhouse gas emission scenarios. We also study of the evolution of evapotranspiration as a function of altitude to characterize its impact on the catchment’s water balance. The ALPGM-J2000 modelling chain allows us to discriminate the contributions of different inputs to the riverflow (glacial melt, snow melt, precipitation runoff), highlighting the shift in time of the parts of the catchment under glacial or more nival influence. We illustrate the use of this modelling chain through the production of indicators to characterize the impacts of glacier melt on aquatic ecosystems at different temporal scales, with particular emphasis on the relationship between changes in hydrological conditions and changes in aquatic invertebrate habitat.

References : https://cloud.univ-grenoble-alpes.fr/index.php/s/Gz9iLzd9ZRtrTjt
Qualitative analysis between increased demand for wells and changes in activities at the community scale, case study of the Forquilha and Algodão Creek, Banabuiú Basin – Ceará State 
Authors: Alves Rafaela , Linhares Samiramisthaís , Möbus Gilberto , Gasmi Hela , Martins Eduardo , Rocha Renan , Estácio Alyson
Published: September 2022

Climate change has modified global and local water cycle patterns inducing more intense and severe drought events. In the Ceará state (Northeast Brazil), a semiarid region very vulnerable to droughts, groundwater acts as a strategic reserve to ensure water security for small rural communities. Well drilling jointly with the building of dams and cisterns are the main policy performed by the public authority to cope with the droughts. This study performed a preliminary qualitative analysis to investigate the anthropogenic effect of the recent drought (2012-2016) in the local hydrogeological environment. The study area selected was the micro-basins of the Algodão and Forquilha creek, in which the alluvial aquifer has been monitored by Funceme since 2010. This aquifer has a great importance for local agricultural development and the water supply for domestic activities. A historical analysis of the evolution of well drilling was performed. In the physical context, the piezometric level of the wells monitored were evaluated. The well drilling was notably more intense between the years 2015 and 2018 and a continuous drawdown of the groundwater level was observed in response to the last drought event. Since 2017 the piezometric level started to rise, however, the monitoring reveals a different pattern of the piezometric levels after the latest drought, with sudden changes between the periods of recharge and drawdown of the aquifer. In the social context, field diagnostics with local stakeholders revealed how the wells installation changed the dynamics of the activities developed by the rural communities. Observed effects were the increase of the number of families and the development of local economics. The heterogeneity of this environment and of its water users requires efficient management policies adapted for the local physical and socioeconomic conditions to avoid overexploitation and maintain the recharge of the aquifers.
Improving hydrological modelling across West Africa with the HYPE model
Authors: Santos Léonard , Andersson Jafet , Arheimer Berit
Published: September 2022

Floods pose an increasing challenge for societies in West Africa; causing loss of lives, damaged infrastructure, and food insecurity. Improving flood management is hence an important development priority for the region, which several initiatives aim to contribute to. Hydrological forecasting systems can help, in which a core component is hydrological models. This research focus on the refinement of the hydrological model HYPE across West Africa within FANFAR (www.fanfar.eu).

The FANFAR domain stretches across West Africa (from Cap Verde to Chad), and hence the research focussed spatial hydrology, specifically finding suitable representations of runoff and key hydrological features across the domain. Our starting point was the World-Wide HYPE model (Arheimer et al. 2020). We analysed its performance in the region and found that runoff response was generally too fast, and not sufficiently differentiated between sub-regions (median daily KGE was -0.09 for 151 gauges). We setup an experiment to try four different approaches to regionalize runoff-regulating processes, namely Hydrobelts, Köppen, Soil capacity index, and Hydroclimatic regions. We divided representation of runoff-generating processes in HYPE (infiltration excess, saturation excess, soil storage, subsurface runoff) into regions linked to each regionalization scheme. We found that the Soil capacity index by Wang-Erlandsson et al. (2016) provided the most useful basis for regionalisation, giving the best and most balanced representation of discharge across the domain. However, we also noted that the added value of regionalisation compared to domain-wide calibration was rather limited, possibly due limited data availability. Another key adaptation was to calibrate regulation parameters of dams and floodplain dynamics of the Inland Niger Delta. All in all, this resulted in a much-improved West Africa HYPE model (for 151 daily streamflow gauges the median KGE was 0.36, reaching up to 0.9 at specific locations). This model was put into an operational forecasting chain within FANFAR, where West African hydrological services and disaster managers used it to disseminate alerts and reduce flood impacts.

Here we summarize this hydrological experiment, and how spatial hydrology, big and open data, participatory research, and capacity development can help reaching development priorities.

References

Arheimer et al. 2020, https://doi.org/10.5194/hess-24-535-2020

Wang-Erlandsson, et al. 2016, https://doi.org/10.5194/hess-20-1459-2016