bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of seasonal variability of precipitation and vegetation cycle on enhanced weathering for carbon sequestration
Authors: Cipolla Giuseppe , Calabrese Salvatore , Porporato Amilcare , Noto Leonardo
Published: September 2022

Enhanced weathering (EW) is one of the most promising technologies for sequestering atmospheric carbon. It consists on accelerating the chemical weathering fluxes naturally occurring in soils, by means of the addition of silicate minerals (i.e., forsterite), used as amendments, to the soil. If crushed into micrometer-sized particles, these minerals are characterized by high dissolution rates, that may be further improved under high soil water content and low pH conditions. Before actually applying EW technique at the global scale for carbon sequestration, an in-depth characterization of weathering and carbon sequestration rates, under different environmental conditions, is needed, also looking at correlated beneficial/detrimental effects. In this context, modeling approaches may play a pivotal role, since they allow to achieve this goal without affording costs required by laboratory and field experiments. The present study describes the application of a dynamic mass balance model connecting ecohydrological, biogeochemical and olivine dissolution dynamics. The model is composed of four connected components and is solved through an explicit system of eight mass balance total differential equations and an implicit one having 22 algebraic equations.

In this study, the model is applied to two sites in Italy (i.e., Sicily, in the south and the Padan plain, in the north) and two in the USA (i.e., California, in the south-west and Iowa, in the north-central area). The most common crops for the case studies, i.e., wheat for Sicily and California and corn for the Padan plain and Iowa are here considered, along with the most frequent soil types, namely the clay loam for Sicily and California and the silty clay loam for the Padan plain and Iowa. Maps of lithological composition of bedrocks and spatial distributions of soil pH have been also used to calibrate the background weathering flux, responsible of the H+ consume from all the minerals naturally present in the soil. Apart from deriving the most suitable locations, among those presented, providing the highest weathering and carbon sequestration rates, these simulations allow to assess the role of different climate, crop and soil types on EW dynamics, in perspective to find the combination that maximizes the CO2 sequestration.
Optical techniques: non-intrusive river monitoring approach
Authors: Alongi Francesco , Pumo Dario , Nasello Carmelo , Nizza Salvatore , Ciraolo Giuseppe , Noto Leonardo Valerio
Published: September 2022

Technological advances over last decades gave an innovative impulse to development of new streamflow measurements techniques, making possible to implement remote flow monitoring methods that allow for non-intrusive measurements. Here, we focus on image-based techniques that involve the use of digital camera, either installed on a bridge or equipped by a drone (UAVs – Unmanned Aerial Vehicles). The most widely known and used optical techniques are the Large-Scale Particle Image Velocimetry and the Large-Scale Particle Tracking Velocimetry. Optical techniques are based on four main steps: (i) seeding and recording, (ii) images pre-processing, (iii) images processing, and (iv) images post-processing. Tracer, naturally present on the water surface or artificially introduced, is assumed to move jointly with the surface liquid particles. Tracer dynamic is recorded and the resulting videos are processed by specific software, applying a statistical cross-correlation analysis to detect the most probable frame-by-frame tracer displacements. To obtain river discharge, it is then necessary to combine the geometry of the river cross-section with the assessed surface velocity field, often adopting simplified assumptions about the vertical velocity profiles.
The accuracy of these techniques depends on several factors, such as the size of the interrogation area, the seeding density, the video length, and many other aspects related to environmental and hydraulic conditions, that are less investigated in the scientific literature. The aim of this work is to exploit the results of an extensive field measurement campaign on several Sicilian rivers (Italy) to infer useful insights for the parametric setting of the two most popular open-source processing LS-PIV software (i.e, PIVlab and FUDAA-LSPIV). The field campaign includes discharge measures carried out at different sites, taking into account different roughness conditions and cross-sections, and, for each site, in different seasons, accounting then for different environmental and hydraulic conditions. Topographical surveys were preliminary performed on each site to obtain detailed DEMs, which are used in the pre-processing phase for image stabilization and orthorectification. Video sequences were acquired from both bridge and drone, using wood chips as tracer. Benchmark measures were also retrieved by ADCP.
Uncertainty analysis of moving-boat ADCP discharge measurements 
Authors: Calmel Blaise , Le Coz Jérôme , Despax Aurélien , Hauet Alexandre
Published: September 2022

The moving-boat Acoustic Doppler Current Profiler (ADCP) gauging method has been extensively used to measure the discharge of rivers and canals. To assess the quality of the data produced for all gauging situations, it is necessary to conduct an uncertainty analysis. It indicates to the operator the sources of error which contribute the most to the final uncertainty, in order to optimize the measurement process. To quantify measurement uncertainties in hydrometry, two approaches can be considered: the analytical propagation method of uncertainties, which makes it possible to "calculate" the uncertainty of a measurement result, and the inter-laboratory experiment method, which makes it possible to “measure” the uncertainty of a measurement method in the conditions of the experiment. The evaluation of the uncertainty is however a difficult task because of the complexity of the ADCP data workflow and the lack of discharge reference in rivers.

The OURSIN method has been developed according to the GUM framework. The uncertainty of discharges extrapolated in unmeasured areas is estimated from sensitivity calculations. The uncertainty due to transect-to-transect flow variability is computed from the coefficient of variation of single-transect discharges. This coefficient of variation is estimated through Bayesian inference to supplement the limited observational information with prior information. To evaluate and validate the OURSIN method, two inter-laboratory experiments were conducted in the Rhône River at Génissiat (2010) and the Taurion River at Chauvan (2016). These experiments, consisting of 634 and 574 ADCP gaugings respectively, cover different measuring conditions in terms of sites and flow ranges (from approximately 14 to 440 m3/s).

For each experiment, uncertainty results using the OURSIN method were compared to the empirical uncertainty estimates obtained using the inter-laboratory method, ranging from 4% to 13%, at the 95% probability level. The comparison shows that the OURSIN uncertainty estimates are similar to the empirical uncertainty results. The decomposition of uncertainty sources is relevant to the conditions observed on site. The OURSIN uncertainty calculation is now implemented in the QRevInt quality assurance software. This allows a wider use of this method while continuing the research on the quantification of the most complex uncertainty components.
The impact of climate change on hydrology and glaciation of the Zeravshan, Vakhsh and Pyanj river basin
Authors: Normatov Parviz
Published: September 2022

The results of observations of temperature changes in the Zeravshan River basin show that for the period 1940-2020, the temperature increase was 0.11 oC/10 yr and by 2050, the temperature increase is expected to be 3.1-3.4 oC. The amount of precipitation in the Zeravshan River basin by 2050 is increasing by an average of 21-24% compared to the period 1940-2020. There is an increase in the flow of the Zeravshan River by 2050. If the flow volume of the Zeravshan River in 1950 was 1.29 km3, then in 2020 and 2050 the flow volume increased to 2.05 km3 and 2.38 km3, respectively. According to forecast data, by 2050 to the reference period, the glaciation area is decreasing from 50% in the Zeravshan River basin to 62% in the Fondarya River basin. Based on the calculated forecasts, an increase in temperature in the upper reaches of the Vakhsh River by 2050 is expected to be 0.4 - 0.7 oC compared to the period 1950-2020 and by 2050 the reduction in the flow of the Vakhsh River will be 7% relative to the period 1960-1990. By 2050, the temperature in the Panj River basin is expected to increase by 0.31-0.54 °C compared to the period 1950-2020. On average, by 2050, an increase in atmospheric precipitation by 0.9% is predicted in the Pyanj River basin compared to the period 1950-2020. By 2050, the volume of glaciers in the basins of the Vakhsh and Pyanj Rivers will decrease by 55-56% and 79-80%, respectively, in relation to 1950. At the same time, the glaciation areas in the basins of the Vakhsh and Pyanj rivers, respectively, will be reduced by 48% and 73%.
The Applicability of Optical Satellite Photogrammetry for Snow Depth Derivation and Streamflow Estimates
Authors: McPhee James , Shaw Thomas , Gascoin Simon , Deschamps-Berger César , Mendoza Pablo , Ayala Álvaro , Pellicciotti Francesca
Published: September 2022

Information about end-of-winter spatial distribution of snow depth is important for seasonal forecasts of spring/summer streamflow in high-mountain regions. However, obtaining detailed information about high mountain snowpacks is often limited by insufficient ground-based observations and uncertainty in the (re)distribution of solid precipitation. We utilize high-resolution optical images from Pléiades satellites to generate a 4 m snow depth map for a high mountain catchment of central Chile and test the potential of this high-resolution information for improving the representation of snow depth initial conditions (SDICs) in a glacio-hydrological model (TOPKAPI-ETH). We calibrate model parameters controlling glacier mass balance and snow cover evolution using ground-based and satellite observations, and consider the relative importance of SDICs compared to model parameters and forcings. Satellite-based estimates are negatively biased (median difference of −0.22 m) when compared against subdomain observations from a terrestrial LiDAR scan, though they replicate general snow depth variability well. However, the Pléiades dataset is subject to data gaps (17% of total pixels), negative values for shallow snow (12%), and noise on slopes >40–50° (2%). Snow depths (with an estimated error of ~0.36 m) relate well to topographical parameters such as elevation and northness in a similar way to previous studies. However, estimations of snow depth based upon topographic characteristics, physically based modeling or model spin-up cannot resolve localized processes (i.e., avalanching or wind scouring) that are detected by Pléiades, even when forced with locally calibrated data. We find that Pléiades SDICs improve the simulation of snow-covered area, glacier mass balance, and monthly streamflow compared to alternative SDICs for our glacio-hydrological model. Model simulations are found to be sensitive to SDICs in the early spring (up to 48% variability in modeled streamflow compared to the best estimate model), and to temperature gradients in all months due to its control on albedo and melt rates over a large elevation range (>2,400 m). Therefore, optical stereo-photogrammetry offers an advantage for obtaining SDICs that aid both the timing and magnitude of streamflow simulations, process representation (e.g., snow cover evolution) and has the potential for upscaling to larger spatial domains.
How well can citizens observe water levels and other hydrological variables using a smartphone app?
Authors: Seibert Jan , Blanco Sara , Scheller Mirjam , Schwarzenbach Franziska , Wang Ze , van Meerveld Ilja
Published: September 2022

Hydrology is chronically data limited, especially when it comes to spatially distributed observations. In this respect, citizen science observations can potentially complement existing monitoring networks. Engaging the public can help to overcome the lack of data in hydrology. So far, most hydrological citizen science projects have used different instruments or installations. Here, we present an evaluation of the CrowdWater smartphone app that allows hydrological data collection without any physical installation or specialized instruments. With the help of the free app, citizens can report the stream level, soil moisture conditions, the presence of water in temporary streams, plastic pollution in streams and on streambanks, as well as general information on streams. The approach is similar to geocaching, except that instead of finding treasures, hydrological measurement sites are set up. The initiator or other citizen scientists can find these sites on a map in the smartphone app at a later time and take additional measurements. A virtual staff gauge approach is used for the water level measurements instead of a physical staff gauge. A picture of a staff gauge is digitally inserted into a photo of a stream bank or a bridge pillar when the site is set up and serves as a reference. At the later visits to the site, the stream level is compared to the virtual staff gauge on the first picture to determine the new water level class. In this presentation, we discuss experiences from the CrowdWater project with regard to the app-based data collection and evaluate these data. We also highlight methods to ensure data quality and illustrate how these water level data can be used in hydrological model calibration. Additionally, we will give an update on new activities in the CrowdWater project.
Rainfall model comparison for continuous modelling for small and ungauged basins
Authors: Grimaldi Salvatore , Volpi Elena , Langousis Andreas , Papalexiou Simon Michael , De Luca Davide Luciano , Piscopia Rodolfo , Nerantzaki Sofia D. , Papacharalampous Georgia , Petroselli Andrea
Published: September 2022

The benefit of continuous modelling in hydrological studies is widely recognized since it provides the practitioner with effective hydrological outputs for risk assessment. However, this approach is still not common mainly because it needs as input simulated rainfall time series. Many rainfall generation methods exist yet there are still two main challenges: (i) many rainfall models are available without a clear suggestion on which is the most appropriate to use, (ii) most rainfall models are not user-friendly and require significant theoretical background to successfully be applied.

In this contribution, we test eight rainfall models by evaluating the performances of the simulated rainfall time series when used as input for a specific continuous rainfall-runoff model, named COSMO4SUB (COntinuous Simulation MOdel For Small and Ungauged Basin), particularly designed for small and ungauged basins. The rainfall models selected here are: two versions of the Complete Stochastic Modelling Solution (CoSMoS-1s and 2s); three versions of Bootstrap-based models; the classical Bartlett Lewis and Neymann-Scott rectangular pulses models; and a mixed method based on monthly simulation and multifractal cascade disaggregation.

The comparison was performed by analyzing runoff time series obtained with the COSMO4SUB model and using as input the rainfall time series simulated by the eight models and the observed one. We selected and investigated several general properties, such as the average number of flood events, the marginal distribution of peak, volume, duration and antecedent dry period before the flood, and their dependence structure.

The comparison confirms the capability of all models to provide realistic flood events and allows identifying the models to be further improved and tailored for data scarce hydrological risk applications.
Impact of changing climatic conditions and permafrost degradation on discharge in southern Siberian catchments
Authors: Menzel Lucas , Han Li
Published: September 2022

Inspired by own field studies on permafrost and hydrological variability, a study was launched to investigate changes in runoff in southern Siberian catchments on the large scale. Until now, the reasons for the sometimes-drastic changes in river discharge remained more or less unanswered or were speculative. We combined data assimilation techniques, statistical analysis and hydrological simulation to investigate in detail the different climatic and physiographic impacts on the runoff behaviour of the Selenga (northern Mongolia / southern Siberia), the upper Lena and the Aldan (tributary to the Lena). Through this selection, we have included two different climatic and vegetation zones (semi-arid, transition zone between steppe and boreal forest, and humid, with exclusively boreal forest) as well as three areas with different permafrost extension (sporadic, discontinuous, continuous) in our investigations. We have selected a period of maximum data availability covering the years 1954-2013.

First, we were able to establish that due to the oscillating, large-scale atmospheric circulation over Siberia, precipitation and runoff are subject to periodic natural changes between rather dry and wet conditions. In addition to these oscillations, precipitation in all catchments shows negligible long-term trends over the 60 years period. Thus, we associate the long-term trends in runoff with the impacts of permafrost degradation. In the predominantly semi-arid Selenga catchment, lateral permafrost degradation prevails, i.e. decreasing permafrost extent. We found that there is a strong loss of water due to increased infiltration and seepage, resulting in drier conditions and ultimately lower runoff. In the boreal Lena and Aldan catchments, on the other hand, vertical permafrost degradation is prevalent. However, a frozen and thus impermeable layer remains below the growing active layer, which leads to overall wetter conditions and increased runoff. This contrasting behaviour mirrors the "dry becomes drier, wet becomes wetter" phenomenon described in earlier research. We also found that the warming-induced increases in permafrost thaw have led to major changes in the hydrological regimes of the three investigated basins. This integrated approach enabled new insights into the complex and highly dynamic hydrological changes that will provide impetus for subsequent studies. 
Prediction in quantitative hydrological modelling: a small step away from uncertainty
Authors: Badou Djigbo Félicien , Yira Yacouba , Hounkpè Jean
Published: September 2022

Water use planning is vital, making hydrological modelling crucial for the development of human society. This role of hydrological modelling is rendered even more prominent given current population growth and global warming resulting in more pressure on water resources. Nonetheless, most quantitative hydrological predictions remain fundamentally uncertain leading to uncertain water availability assessment. This is so, partly, because streamflow continues to be used as the main dependent variable, calibration and validation data length and content are arbitrarily selected, and water balance components taken individually are not quantified with the best prediction models. This paper discusses three ideas for stepping further away from uncertainty in quantitative hydrological predictions. Less uncertain hydrological predictions can be achieved through (i) blue water and green water-based hydrological models validation, (ii) blue water and green water-based multi-model evaluation of water resources, and (iii) a conditioned selection of calibration and validation data.
Assessment of the long term change in the extreme hydrological events across the West African basins
Authors: Hounkpè Jean , Badou Djigbo Félicien
Published: September 2022

Understanding the variability in extreme hydrological events is the first step toward the reduction of its impacts on livelihoods. This work aims to identify possible changes in the hydrological regime of the West African basins which could explain the recent flooding observed across the region. For that purpose, 56 discharge stations were selected with the data ranging between 1922 and 2017. Multiple trend patterns on moving time slots of 20 years for stations having at least 40 years of data were performed using the modified Mann Kendall test and the strength of the trend computed using the Sen’s slope. Statistically significant trends in annual maximal discharge (AMD) have been found for many stations and distinct periods with different change directions. While a decreasing tendency was found for the AMD between the 1950 and 1970s, an increasing frequency was depicted from the 1980s to recently (2017) for most of the stations. The magnitude of change per year in AMD as depicted from Sen’s slope is substantially variable ranging from -14 to 12% relative to the mean discharge of the considered period. The highest increases in AMD were found for the stations located toward the Gulf of Guinea. The temporal variation in AMD is in line with the interdecadal rainfall variability in West Africa. 
Climate change and deforestation in Haiti: are historical hydro-meteorological observations relevant to describe present catchment hydrological characteristics?  
Authors: Bathelemy Ralph , Brigode Pierre , Boisson Dominique , Tric Emmanuel , Andréassian Vazken
Published: September 2022

Recent floods have highlighted the high vulnerability of Haitian territories to hydro-meteorological hazards. For example, the coastal city of Cayes (southern Haiti) has been heavily impacted by the torrential rainfall of October 5 to 6, 2018, with numerous damaged buildings. In Haiti, the only time period of continuous observations of both rainfall and streamflow lasts from 1920 to 1940. The concomitance of rainfall and streamflow observations at daily timestep enable the characterization of Haitian catchment hydrological response over that 20-year period. However, Haiti has experienced massive deforestation over the last century, and the Caribbean is a hotspot of climate change impacts such as warmer air and sea surface temperatures, leading to stronger hurricanes. Hence, the relevance of the characteristics estimated over the 1920-1940 period is questionable for present-time studies.

The objectives of this work are firstly to estimate flow characteristics of gauged Haitian catchments considering 1920-1940 temporal series, and secondly to use this historical information to estimate present-time hydrological characteristics. After digitalization and quality control tests of daily rainfall and streamflow temporal series, two types of hydrological characteristics were estimated on each gauged Haitian catchment. First, the catchment annual water balance was described by calculating the ratio between mean annual precipitation, evapotranspiration and runoff (using Turc-Budyko representation). Then, daily flood characteristics were estimated with a rainfall-runoff event-based study, focused on rainfall event duration and amount, peak streamflows and runoff ratio. Finally, present-time flow characteristics were estimated using a global rainfall-runoff model (GR4J) calibrated on the digitalized series, and then fed by the MSWEP dataset. This global database is available at the daily time step from 1979 to 2017, and merges gauge, satellite, and reanalysis data. The uncertainties related to the temporal stability of the rainfall-runoff model parameters and the potential impact of the deforestation on flow characteristics were then discussed.
Petrophysical characterisation of a karstic carbonate aquifer, with implications for saltwater and brine intrusion into hydrothermal resources. The DEM'EAUX THAU project, Balaruc, France. 
Authors: Pezard Philippe , Henry Gilles , Brun Laurent , Le Ber Erwan , Raad Fadl , Séranne Michel , Widhen Florian , Schleifer Andrea , Bellezza Cinzia , Meneghini Fabio , Brillouet Nicolas , Neyens Denis , Lamotte Claudine
Published: September 2022

The Balaruc hydrothermal system is fed both from surrounding karstic carbonates with fresh water outpouring in the nearby Thau lagoon with the Vise source, and at depth along deep regional faults with local springs up to 50°C. This hydrothermal system was cored and logged in 2020-2021 down to 765m depth at Balaruc-les-Bains, 200m to the NE of the Vise source. During the project, the Vise source underwent a reversal in November 2020, with the Thau lagoon salty water being drained deep into the subsurface, shedding light into the complex processes affecting the Balaruc hydrothermal system. The DEM’EAUX THAU project is aiming at a better understanding of this complex geological and hydrological system for a more sustainable use of this resource.

A set of downhole geophysical data and borehole wall images was recorded from near surface to 756m depth in 4 vertical holes, only a few meters apart at surface. While mm-scale images reveal the detailed geological structure, petrophysical data (acoustic velocities, electrical resistivity and natural gamma) contribute to better define the penetrated structure, yielding porosity and permeability. Acoustic velocities provide a base to analyze the vertical (VSP) and walk-away seismic profiles shot to replace these holes in the regional geological structure. In turn, core petrophysical measurements are being made to support these analyses and, in particular, to provide a dm-scale description of the subsurface pore fluid salinity.

In addition, the physical and chemical properties of the borehole fluid were characterized with an Idronaute probe, showing the impact of the Vise source reversal from measurements before and after. Similarly, electrical resistivity profiles were recorded over time and during downhole pumping tests, emphasizing the hydraulic vertical connectivity. On that basis, pore fluids dynamics are being described from time-lapse downhole logging measurements and the emplacement of permanent downhole geophysical observatories consisting in (i) an optical fiber for temperature and (ii) a flute for electrical resistivity of the formation. In the future, a second optical fiber already in place will be used for acoustic probing of subsurface fluid flow from Digital Acoustic Scanning (DAS).
Spatial assessment of surface-atmosphere fluxes in the Mediterranean region: synergy between satellite estimates and local observations
Authors: Prévot Laurent , Mateo-Herrera Blanca , Jacob Frédéric , Demarty Jérôme , Limousin Jean-Marc , Ourcival Jean-Marc , Champollion Cédric , Olioso Albert
Published: September 2022

Evapotranspiration (ET) is a major component of both the hydrological cycle and the surface energy balance. Furthermore, ET is strongly linked to the primary production of natural and cultivated vegetation covers. Therefore, obtaining spatialized estimates of ET is of paramount importance in Mediterranean areas, submitted to hot and dry summers, all the more so as climate change is expected to worsen the water deficit in this region. In the framework of the preparation of the TRISHNA satellite mission, the objective of this study was (1) to produce maps of ET over a small Mediterranean region from high resolution satellites, and (2) compare these satellite estimates with local measurements of ET from flux towers. The studied area was located in the Hérault river area, south of France. During the period 2013 - 2019, 63 clear sky Landsat 7 and 8 images were collected and processed, having spatial resolutions of 60 and 100 meters, respectively. Maps of ET were generated using the EVASPA processing tool (Gallego-Elvira, 2013), with various methods for estimating the soil heat flux and the evaporative fraction. These satellite estimates were compared to those measured by long term flux towers installed on three biomes representative of Mediterranean landscapes: Puechabon (Quercus ilex forest on a rocky soil), Larzac (grassland on a limestone plateau) and Roujan (vineyards in the plain). In the estimation of ET from satellite images, intermediate variables (albedo, net radiation, soil heat flux, surface temperature) were first compared to those measured locally, when available. Finally, instantaneous and daily satellite estimates of ET were compared to the local measurements. Depending on sites and EVAPSA methods, the RMSE of instantaneous estimates of ET ranged between 39 and 202 W.m-2. The RMSE of daily estimates of ET ranged between 0.96 and 1.82 mm.day-1. Future work will be conducted to analyze the effect of air temperature variations, induced by altitude variations, on ET satellite estimates. This will allow to extend this study to larger regions of southern France.
Impact of seasonal touristic activity on emerging contaminants of micro-estuaries and hydraulically connected water bodies in North-Western Corsica
Authors: Huneau Frédéric , Garel Emilie , Santoni Sébastien , Mattei Alexandra , Tafani Caroline , Pasqualini Vanina
Published: September 2022

Micro-estuaries are very common in the Mediterranean. Their ecological role is also of uppermost importance for the preservation of biodiversity as well as for the nutrient input towards the coastal marine environment. Strong seasonal contrasts are characteristic of the Mediterranean regions, for the hydrological behaviour of rivers but also for activities in relation with the tourism industry. Therefore, in coastal regions water bodies can be exposed to very strong impacts due to the very focused touristic activity especially along the most appreciated zones like beaches, sand dunes and sand bands where micro-estuaries are very frequently also located. Due to the very short duration of the highest touristic season and to the very frequently under-calibrated capacities of sanitation infrastructures, it is frequent to observe wastewaters releases towards the surface waters which can contaminate groundwaters and in the end micro-estuaries. It is then of major interest to evaluate what type of emerging contaminants can be found in these regions, and if a clear seasonality in the contaminant release can be observed.

The strategy is to investigate the emerging contaminant content in waters of micro-estuaries and other types of connected waters (river waters, groundwaters) from a coastal areas of North-Western Corsica characterized by a very dynamic seasonal touristic activity. Sampling were organized before the touristic period and after in order to appreciate the impact of the high season peak on the water quality. 102 molecules were analyses on 20 water samples from 4 different coastal watersheds.

Results show a clear impact of the increase in the population due to the touristic activity, but a baseline contamination is also observed for the winter season. 11 molecules are present for each sampling and mostly composed of pharmaceuticals, nicotine and caffeine metabolites as well as artificial sweeteners. A tendency towards the reduction of concentrations is observed in rivers along the flow due to dilution processes and degradation of contaminants. Groundwater contamination appear as really more stable and mostly in relation with the immediate vicinity of boreholes and wells. Micro-estuaries, which are the final collector all the watershed pollution sources, are the most contaminated water bodies of the survey.
Sediment transport and origin in Mediterranean semi-arid basins: Sediment dynamics assessment and quantification
Authors: Khettab Omar El Farrouk , Megnounif Abdeslam
Published: September 2022

Sediment transport is linked to socio-economic issues, including reservoir siltation, dam storage loss, arable soil loss, terrain quality deterioration, and land productivity decline. In semi-arid regions (e.g., north of Algeria), the climate often alternates between long periods of drought and sporadic floods. Sediment production steadily occurs during dry periods as a result of various processes that disturb the soil, and it is greatly increased during a rainfall episode, due to the rain-splash effect. During a flood, heavy sediment transport occurs because of sediments originating from both the basin and hydrographic network. Consequently, to prioritize management strategies, sediment dynamics and sources contribution assessment are needed. While many methods to quantify sediment source contributions are available, their applicability is restricted by financial limitations, data availability, and suitability. So, more suitable methods are required. In this work, a rapid integration method is presented. This approach aims to separate and quantify sediments originating from the hydrographic network by water erosion and sediments supplied from the catchment, in-channel storage, and accidental processes. The required data is limited to continuous or semi-continuous sediment concentration-discharge measurements (including turbidity-based sediment concentration). The method is validated and tested for several basins, including watersheds from humid regions, to verify whether it can be generalized.
Assessment of current and future (under climate change) crop water requirement and irrigation strategies under bubbler irrigation system for date palm in Jemna oasis, Southern Tunisia
Authors: Zemni Nessrine , Slama Fairouz , Bouksila Fethi , Dakhlaoui Hammouda , Dhaouadi Latifa , Sidhom Ons , Bouhlila Rachida
Published: September 2022

Oases of southern Tunisia are located in a hostile arid environment. Despite the environmental situation, oases are the place of specific knowledge developed by indigenous populations. Theses agroecosystems, where date palm tree is the dominant crop, are a characteristic example of Saharan arid climate region. Nowadays, oasis land is threatened by soil and water degradation under salinity risk as well as water scarcity, identified as the most important problem for regional and national socio-economic security. The advancement of technologies that ensure efficient use of irrigation water may be needed. This work is evaluating the bubbler irrigation system in Jemna Oasis (southern Tunisia) for date palm for current and future climate. The objective was to quantify root water uptake, yield production and root zone salinity under current and future climate change. Mid and long term precipitations, temperature and date palm water needs were determined from 2 regional climate models forced by general circulation model (GCM-RCMs) issued from EURO-CORDEX project. Field experiments and modelling approach were developed within this work. Different scenarios regarding irrigation frequencies and quantities were tested using Hydrus-1D model. In context of water scarcity, implementing an irrigation schedule in which crop growth stages and soil salinity are considered is strongly recommended for date palm tree. The bubbler irrigation system using 100 % ETc and T3 as irrigation schedule could be considered as a save irrigation method under current and future climate change, if water allocated for irrigation do not exceed 3.2 dSm-1 with crop yield reaching equal to 80% as a mean value and soil salinity about 12dSm-1. Results indicated that  climate change from 2020 to 2090 would increase temperatures and decrease annual rainfall. An increase in events with rainfall amounts exceeding 100 mm/day is noted. During this future period, using both saline irrigation water (5 and 5.5 dSm-1) and irrigation lower than 100% ETc, the date palm crop yield is expected to vary from an average value of 81% in 2020 to about 70 % in 2050 and 55% in 2090 and an increase of soil salinity to 20 dSm-1 will occur.
SAR Altimetry Processing Over the Coastal Zone and Inland Water  - the ESA HYDROCOASTAL Project
Authors: Benveniste Jérôme , Cotton David , Team Hydrocoastal
Published: September 2022

HYDROCOASTAL is a two-year project funded by ESA, with the objective to maximise exploitation of SAR and SARin altimeter measurements in the coastal zone and inland water, by evaluating and implementing new approaches to process SAR and SARin data from CryoSat-2, and SAR altimeter data from Sentinel-3A and Sentinel-3B. Optical data from Sentinel-2 MSI and Sentinel-3 OLCI instruments will also be used in generating River Discharge products. New SAR and SARin processing algorithms for the coastal zone and inland waters will be developed and implemented and evaluated through an initial Test Data Set for selected regions. From the results of this evaluation a processing scheme will be implemented to generate global coastal zone and river discharge data sets. A series of case studies will assess these products in terms of their scientific impacts. All the produced data sets will be available on request to external researchers, and full descriptions of the processing algorithms will be provided.

The scientific objectives of HYDROCOASTAL are to enhance our understanding of interactions between the inland water and coastal zone, between the coastal zone and the open ocean, and the small-scale processes that govern these interactions. Also, the project aims to improve our capability to characterize the variation at different time scales of inland water storage, exchanges with the ocean and the impact on regional sea-level changes.

The technical objectives are to develop and evaluate new SAR and SARin altimetry processing techniques in support of the scientific objectives, including stack processing, and filtering, and retracking. Also, an improved Wet Troposphere Correction will be developed and evaluated.

The presentation will describe the different SAR altimeter processing algorithms that are being evaluated in the first phase of the project, and present results from the evaluation of the initial test data set. It will focus particularly on the performance of the new algorithms over inland water.
Performance assessment of a daily time-step HYMOD conceptual rainfall-runoff model for the Upper Benue River, Cameroon
Authors: Nonki Rodric Merimé , Amoussou Ernest , Tshimanga Raphael Muamba , Koubodana Houteta Djan'na , Kemgang Ghomsi Franck Eitel , Lenouo André
Published: September 2022

Conceptual rainfall-runoff models are commonly used in many hydrological applications in support of water resources management practices. They provide an advantage in data scarce areas due to their ability to use limited data and generate sufficiently reliable information. The main challenge with this type of hydrological models remains the ability to establish an optimal model parameter space due to a number of sources of uncertainties. This study is conducted in the Upper Benue River Basin (UBRB) in Cameroon with the aim to establish a rainfall-runoff model that is fit in the context of hydro-climate characteristics of the basin. The UBRB is the second-largest river in Cameroon and one of the most important water resources in northern Cameroon from both a water supply and hydropower generation perspective. A Monte Carlo procedure was implemented to calibrate the HYMOD conceptual rainfall-runoff model using five statistical performance measures: the Absolute percent bias (PBIAS), the ratio between root mean square error (RMSE) and standard deviation of observed data (STDEVobs) (RSR), the Pearson correlation coefficient (r), the Nash–Sutcliffe efficiency (NSE) and the Kling–Gupta efficiency (KGE). The results reveal that the model performance varies from good to very good with NSE greater than 0.78 and RSR less than 0.46 during the calibration and validation periods. Therefore, this model can be used to support various water resources management initiatives in the basin.
The hydrological system as a living organism
Authors: Savenije Hubert H.G.
Published: September 2022

Hydrology is the bloodstream of the terrestrial system. The terrestrial system is alive, with the ecosystem as its active agent. The ecosystem optimises its survival within the constraints of energy, water, climate and nutrients. The key variables that the ecosystem can modify are the controls on fluxes and storages in the hydrological system, such as: the capacities of preferential flow paths (preferential infiltration, recharge and subsurface drainage); and the storage capacities in the root zone, wetlands, canopy and ground surface. It can also adjust through evolution, the efficiency of carbon sequestration and moisture uptake. Some of these adjustments can be made fast, particularly rootzone storage capacity, infiltration capacity, vegetation density and species composition. These system components are important controls on hydrological processes that in hydrological models are generally considered static and are determined by calibration on climatic drivers of the past. This leads to hydrological models that are dead and incapable to react to change, whereas the hydrological system is alive and will adjust.

The physical law driving this evolutionary process is the second law of thermodynamics with the Carnot limit as its constraint. This physical limit allows optimisation techniques to explore the reaction of the hydrological system and its components to change in climatic drivers. This implies a new direction in the theory of hydrology, required to deal with change and Unsolved Problems in Hydrology.
Conceptual principles of water resources management in irrigated agriculture
Authors: Romashchenko Mykhailo , Bohaienko Vsevolod , Matiash Tetiana , Shatkovskyi Andrii , Kolomiets Serhii , Danylenko Iuliia
Published: September 2022

Climate change manifested in Ukraine by rapid (over 0.6oC in 10 years) increase in average annual air temperature causes a progressive deterioration of natural water supply significantly increasing the need for irrigation to ensure sustainable agriculture.

"Irrigation and Drainage Strategy in Ukraine until 2030" provides for an  increase of irrigated lands area up to 1.5-1.7 million hectares and the corresponding significant increase in water consumption from the current 1.5-1.8 billion m3 to 5-6 billion m3. Given that climate change has a negative impact not only on the state of natural water supply, but also on the state of available water resources, their rational use in irrigation is an important component of sustainable water management.

Effective tools for its implementation in irrigation are decision support systems. Their usage provides a capability to achieve maximum irrigation efficiency when complying with the following provisions:

- Irrigation should maintain root layer moisture content in a narrow range of high values (from 0.8-0.85 of field capacity to field capacity);

- Tensiometric pressure should be used as a criterion of moisture content and moisture availability for plants;

- Water retention curves should be used to determine field capacity, pre-irrigation thresholds, and optimal ranges of moisture available to plants;

- Moisture transfer models for saturated-unsaturated soils stated in terms of pressure can accurately predict irrigation schedules and rates;

- The combined use of several methods for evapotranspiration assessment improves the accuracy of calculations;

- Remote sensing data can be used to tranfer irrigation schedules and rates predictions to the areas not covered by instrumental monitoring tools.

The application of these principles provides for

- an increase in crop yields accompanied by irrigation water volumes reduction;

- irrigation with environmentally friendly rates minimizing water losses for infiltration, and the development of flooding and secondary salinization processes.

The introduction of these principles in practice will increase the sustainability of water management in agriculture in the conditions of climate change, and the use of decision support systems at full scale will ensure the maximal materialization of the potential of crops’ varieties and hybrids.
Attribution of streamflow changes to future climate projections across Europe
Authors: Clemenzi Ilaria , Du Yiheng , Ilias Pechlivanidis
Published: September 2022

Ongoing warming strongly influences the water cycle at the regional scale and increases concerns about future streamflow changes with consequences for water availability and potential intensification of hydrological extremes, i.e. floods and droughts. Detecting and identifying controlling factors of future streamflow changes is a key point to understand the hydrological response to changing climate and develop tailored strategies for the water resources management and risk adaption. In this study we investigate the streamflow changes, including extremes, across Europe in the mid (2041-2070) and late (2070-2099) century. We used streamflow simulations from the E-HYPE hydrological model and the EURO-CORDEX climate model projections. The sensitivity of streamflow changes to the climatic factors compared to the reference period (1981-2010) is evaluated with the climatic elasticity method based on the Budyko framework. Moreover, we assess the spatial consistency and uncertainty of the streamflow changes due to the ensemble variability. Results show that the sensitivity of streamflow changes to climatic change varies depending on the climatic gradient and physiographic properties of the domain.
Seamless meteorological forecast production and evaluation towards hydrological decision-making in France : CIPRHES projet
Authors: Gbangou Talardia , Viel Christian , Rousset Fabienne , Willemet Jean-Marie , Etchevers Pierre , Munier Simon , Ramos Maria-Helena , Bourgin François
Published: September 2022

Hydrological drought conditions have negative implications for environmental and socio-economic activities in France. Operational drought forecasts with adequate timing and quality can guide decision-makers to prepare and make informed decisions on water management. Available ensemble meteorological forecasting systems, used to force hydrological models, differ in configuration, resolution, timescale, release frequency, and accuracy. These differences in atmospheric forecasting systems limit their usefulness for operational drought forecasts. To address this challenge, we proposed an approach to produce seamless atmospheric forecasts (SeamF). SeamF were constructed from the extended- and long-range ensemble prediction systems (ECMWF and Météo-France, respectively) using a random concatenation member by member method in a first step.

The new SeamF system provides a 144-day outlook of hourly and daily precipitation and temperature variables, updated once a week, suitable for hydrological modelling over the country. In addition to the practicability of these integrated forecasts, as compared to stand-alone extended- or long-range forecasts, the level of deterministic and probabilistic verifications metrics suggests a promising improvement in hydrological applications. This approach builds a basis for more sophisticated seamless forecast production and application for hydrological decision-making in France.