bluuebunny/crossref_metadata_2025 huggingface dataset:
Discrete Fracture Network geophysical imaging  from Electrical Resistivity Methods
Authors: Champollion Cédric , Roubinet Delphine
Published: September 2022

Fractures are fundamental discontinuities to understand the exchange and the dynamic of water, matter and energy between the different parts of the critical zone. But except from boreholes and direct observation at rocks outcrops, imaging fracture network from the surface remain a challenging task in geosciences. Classical geophysical methods and their associated imaging methods are in a large extend adapted to retrieve the properties and (part of) the heterogeneities of the rock matrix and not of the discontinuities.

The aim of the study is to present a stochastic imaging method based on the direct simulation of Electrical Resistivity Tomography (ERT) dataset from Discrete Fracture Network (DFN). ERT is one of most used geophysical method in critical zone studies. And one can find numerous examples in literature of interpretation of ERT images as fracture zone, even if the inversion do not have the resolution to retrieve the fracture geometry or properties.

First the direct approach is described (from Roubinet et al., 2014) to simulate ERT dataset. Then from simple cases such one vertical or horizontal fracture, the inversion is detailed with emphasis on the convergence rate, resolution and depth of investigation. Further step towards the inversion of realistic DFN are discussed: how prior information can be used to enhance the convergence rate and how the non-unicity of the solutions can be retrieved from the stochastic inversion scheme. The inversion of DFN from ERT dataset is a first step towards coupled inversion such as pumping tests or tracers tests and ERT.
Soil and water salinization in mediterranean costal area : toward an integrated approach for salinity management - Case study of the Aude lowland
Authors: Marien Laurène , Crabit Armand , Bergé Florian , Alexandre Evaëlle , Colin François
Published: September 2022

Soil and water salinization is a major threat to agricultural land and biodiversity in natural areas. Coastal areas are highly sensitive to salinization leading to a deterioration of resources (water, soil and biodiversity) and ecosystem services. The Aude lowland is longstanding facing this issue. The main solution is to bring massive amounts of fresh water to the surface of the fields, in the form of anthropic flooding, associated with drainage for the leaching of salts. Understanding system equilibrium is crucial in the context of global change, less fresh water available, sea level rise, strong and fast landuse evolution.

To achieve this objective, we propose an integrated approach providing links between high resolution water and soil salinity at lowland scale, lato sensu water management practices and winegrowers perception of the actual state and evolution salinity.

Salinity measurement survey consist in three dimensional sampling with more than 1500 samples on the whole study area. Results exhibit high level of salinity, increasing with depth and heterogeneity at short distance and spatially structured at long distance. Closed questions carried out on 27 winegrowers bring an in-depth knowledge on all winegrowing practices related to water management (tillage, weed control practices, irrigation, drainage). Statistical analysis (MCA, HAC) show five groups of practices associated to different salt control strategies. Perception was investigated using open questions and answers were structured in a matrix including six themes (in column) and 27 winegrowers (in row). Main results show three different types for salinity perception.

The cross analysis between perception, practices and measured salinity brings an integrated vision of the salinization and its management in the study area. This allows to better understand how viticulture can still partially persist despite high soil and water salinity levels. The reason is inside the strategies promoting the adaptation of the practices to salty pressure and soil functioning and not only based on unique practice.
Routing of stemflow water through the soil: A dual labelling approach with artificial tracers
Authors: Pinos Juan , Latron Jérôme , Gallart Francesc , Flury Markus , Llorens Pilar
Published: September 2022

The portion of intercepted precipitation by forest canopies that drains from leaves and branches and is channeled to the stem and reaches the forest floor is defined as stemflow. Some studies have shown that when stemflow infiltrates into the soil, it is funneled preferentially along tree roots and macropores, bypassing the soil matrix and delivering large volumes of water to the deeper soil layers and to the aquifers. This bypass flow promoted by stemflow is of great hydrological and biogeochemical importance. In this context, the main aim of this study was to investigate the stemflow infiltration dynamics and patterns. With this objective we simulated stemflow at a flow rate of 7 L/h around a Scots pine tree with water labelled with deuterium and brilliant blue dye. The stemflow volume simulated (45L) corresponds to a rainfall event of about 50 mm rainfall. During the experiment, soil moisture and shallow piezometric levels, around the tree, were continuously monitored. In addition, 30cm depth small piezometers, located around the bole, were sampled to detect the labeled water arrival. To visualize the dye-stained areas and sample the soil for subsequent isotopic analysis and dye concentration determination, a pit was dig in each cardinal direction of the tree as near as possible of the tree bole. Almost no labeled water was found in the soil matrix, instead blue-dye was visualized near coarse roots and stones. In addition, the labeled water reached the small piezometers, indicating the presence of macropore flow. These results confirm the stemflow funneling effect, which infiltrates as preferential flow, and give some light on the complexity of the hydrological processes in the vadose zone.
Global river water pollution: exploring current challenges and future prospects
Authors: Hannah David , Abbot Benjamin , Khamis Kieran , Kelleher Christa , Lynch Iseult , Krause Stefan , Ward Adam
Published: September 2022

Human activities are threatening resilience of vital, interconnected components of our Earth system. Consequences for freshwaters are missing often from this debate. Yet, a functioning terrestrial water cycle is essential with healthy rivers essential for the sustainable provision of freshwater for humans and ecosystems alike. Major international reports released very recently have evidenced concerning trends in river water pollution, with poor water quality shown to be a global and persistent problem – still responsible for 2M deaths each year. Across Europe, 34% of the 130,000 waterway surveyed fail to meet “good” chemical status. In the most current national assessment for the USA, less than a third of rivers received a “good” grade. Deteriorating water quality is apparent for rivers across much of Asia, Africa and South America. Therefore, global river water pollution is a very timely and high profile topic for science and society.

Our contribution aims: (1) to explore current water quality challenges, which vary across regions and with economic development; and (2) to consider future prospects for moving from this crisis towards more sustainable solutions.

We propose a framework (based on distinct contaminant types and mitigation methods) that conceptualises the differences in experiences of upper-income countries versus lower- and middle-income countries. We consider the factors that have made the global water quality increasingly visible and impossible to ignore. Leveraging our framework and understanding of driving factors, we propose solutions to global water pollution challenges based on: latest scientific thinking and data sources; empowering decision makers across different levels of governance; regulating more smartly; and encouraging international cooperation and data/ knowledge sharing between places with varied status of economic development.

 
Post-flood evaluation of the 2010 and 2020 niger river floods in the districts of karimama and malanville in north - benin using remote sensing
Authors: Tabou Talahatou , Mazo Ismaël , Zakari Soufouyane , Yabi Ibouraïma , Amoussou Ernest
Published: September 2022

Abstract

Due to the recurrence of floods in recent years through the Niger River watershed in Benin, it’s necessary to assess the damage caused in order to consider preventive measures. The main goal of this paper is to evaluate and compare floods impact from 2010 and 2020, which are years of major floods in the Niger basin in Benin, particularly in the districts of Karimama and Malanville. The data used in this study are daily flows and were collected through Malanville hygrometric station (from 1981 to 2020), Gaya synoptic station (from 1981 to 2020) and the sentinel images (September 2010 and September 2020) which are used to calculate satellite indices and produce land use maps. Rainfall and streamflow data, that are factors in the occurrence of floods were analyzed using the reduced centered anomaly method.The satellite data were used to calculate the NDPI (Normalised Difference Pond Index), NDWI (Normalised Difference Water Index) and land cover maps for the same dates. The NDPI is used to delineate dry and water surfaces with greater discrimination, and the NDWI is intended to extract water masses, as it maximizes the reﬂectance of water in the green wavelengths. The results show that precipitation increased significantly in both years, especially during the months of July, August and September, but the increase in flow was more significant, with more pronounced values in 2020. The floods of 2020 affected 20276.53 ha of fields and 2987 ha of settlements against 17812.28 ha and 2012.17 ha in 2010. Monitoring the level of flood variation by remote sensing would increase the capacity of action of the early warning and risk management system and disasters associated with floods increasingly recurrent in the context of climate change.

Keywords: North-Benin; Niger Basin; floods; remote sensing.
Inclusive and resilient groundwater assessment towards sustainable development in the Mediterranean region
Authors: Jomaa Seifeddine , Ben-Salem Nahed , Chávez Rafael , Reinecke Robert , Varouchakis Emmanouil , Vasco Silva João , Ceseracciu Chiara , Phuoc Lai Nguyen Thi , Daloglu Cetinkaya Irem , K. Saysel Ali , K. Copty Nadim , Rouhani Amir , Oueslati Maroua , Mino Eric , P. Karatzas George , Roggero Pier Paolo , Rode Michael , Gómez-Hernández J. Jaime
Published: September 2022

The Mediterranean region is experiencing rapid population growth, increasing water demand, and faster climate warming. Groundwater plays a central role in the development of the Mediterranean by ensuring food security, buffering climate changes impacts and maintaining socio-economic stability and ecosystems integrity. However, despite groundwater being recognised as a powerful catalyser against climate- and human-induced effects, its status remains unknown, and its budget is uncertain. Moreover, the lack of appropriate groundwater monitoring programs at a regional scale, data sharing policy, and fragmented water policy and governance have complicated this vital resource's sustainable utilisation and protection.

To this end, an international and multidisciplinary team of scientists with complementary skills have joined efforts through two PRIMA-funded projects (Sustain-COAST and InTheMED) towards better groundwater management and governance in the Mediterranean. In this respect, the Sustain-COAST Living Labs provide the setting to explore innovative governance approaches that could be scaled to increase resilience and adaptation capacity across the Mediterranean. At a regional scale, efforts target detailed water policy examination, pathways exploration towards the reinforcement of in-situ data collection, and groundwater modelling. Examination of water policy of the Mediterranean revealed an unbalanced situation between South Europe, characterised by complete, harmonised and straightforward water policy. Conversely, in North Africa and Middle East, water policy was found complex, not regionalised and fragmented in various initiatives. Results also showed the Mediterranean has become increasingly dependent on cereal importation over local food production, which poses a severe threat to its best diet overall and food security. Results suggested that combining in-situ data and regional groundwater modelling can offer further insights into this data-scarce region. Believing “that no one size fits all”, lessons learned from success stories, and tailored solutions to typical demonstration sites from both shores of the Mediterranean region are of extreme importance.

Acknowledgement: This work was supported by Sustain-COAST and InTheMED projects. Sustain-COAST was funded by the German Federal Ministry of Education and Research (BMBF, Germany, Grant 01DH19015) under the EU PRIMA 2018 programme. InTheMED is part of the PRIMA 2019 programme supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 1923.
Climate change and water quality responses in agricultural catchments with high legacy storages of nutrients 
Authors: Fovet Ophelie , Strohmenger Laurent , Dupas Remi , Durand Patrick , Faucheux Mikael , Hamon Yannick , Jeanneau Laurent , Petitjean Patrice , Ruiz Laurent , Gascuel-Odoux Chantal
Published: September 2022

The effects of climate change on the quality of freshwaters remains poorly investigated while these effects are likely to be ambiguous. Indeed, such effects are partly direct such as temperature control on reaction rates, and partly indirect such as decrease of dilution processes with drier low flows. How the fate of a given pollutant responds to climate change can differ depending on its sources, reactivity and mobilization processes. Therefore, investigating the hydrochemical response of streams to climate change requires considering several elements that differ in their sources and pathways, and in their sensitivity to local and global forcings.

A cross-analysis of hydro-climatic variables and the dynamics of three solutes - carbon (C), nitrogen (N) and phosphorus (P) - was conducted at multiple temporal scales using the long-term data sets from a Critical Zone Observatory in Western France (AgrHyS). We identified trends on climatic variables (air temperature increased, winters became wetter and summers drier) and stream concentrations (NO3 concentrations decreased, DOC concentrations increased). However, no effect of air temperature and radiation was observed on stream-water concentrations for the three solutes and there was no clear response of seasonal water-quality signals to increased contrast among hydrological seasons. Therefore, despite observed inter and intra-annual effects of climate on water quality, long-term changes of stream-water concentrations seemed to be more related to agricultural changes than to climate variations.  

In such a temperate and humid region, the seasonal amplitude of climatic variables is higher than the magnitude of their long-term changes. In addition, agricultural catchments of Western Europe have received high inputs of nutrients since the 1960s that led to create legacy storages in particular N and P in the soil, the vadose zone and/or the groundwater. The damped response of water quality may then be related to legacy storage, leading to lower sensitivity to climatic than to agricultural drivers. Disentangling the respective effects of climate and human activities on stream water quality is particularly challenging, even more in such contexts dealing with legacy storages. As a perspective, we show how using ratios of elements with contrasted properties or origin can help addressing this challenge.  
Combining multiple hydrological model structures in a semi-distributed modelling environment.
Authors: Thébault Cyril , Perrin Charles , Andréassian Vazken , Thirel Guillaume , Legrand Sébastien
Published: September 2022

Accounting for the variability of processes and climate conditions between catchments and within catchments remains a challenge in hydrological modelling. To address this issue, various approaches were developed over the past decades. Among them, multi-model approaches provide a way to quantify and reduce the uncertainty linked to the choice of model structure, and semi-distributed approaches propose a good compromise to account for spatial variability of the processes by dividing the catchment in sub-catchments while maintaining a limited level of complexity. However, these two approaches were barely applied together. The aim of this work is to answer the following question: can we improve the efficiency of hydrological models by implementing a multi-model approach within a semi-distributed framework? In this work, the benchmark considered is a lumped model with a fixed structure.

To this end, a large set of 147 catchments in France was assembled, with precipitation, evapotranspiration and flow data at an hourly time step over the 1998-2018 period. The semi-distribution set-up was kept simple by considering a single intermediate catchment between a downstream station and one or more upstream catchments. The multi-model approach was implemented with two versions of the GR model (namely GR4H and GR5H). Within a semi-distributed framework, the two models were either used individually, i.e. applied on all sub-catchments (called GR4H-SD and GR5H-SD respectively), or combined using a simple and a weighted mean.

The first step of this work was to check whether past conclusions published in the scientific literature, obtained with lumped multi-models, were the same in a semi-distributed framework. In other words, does the multi-model approach generate better performance than individual models in a semi-distributed context?

Another possible combination of the semi-distributed and the multi-model approaches would be to make different choices of model structures or combinations on each sub-catchment. Intuitively, it makes sense to propagate the flow simulated by the best model from upstream to downstream. The second analysis therefore focuses on the following question: is the best upstream model always the most useful downstream?

The results and the operational implications of this work will be analyzed in the case of the Rhône basin.
Exploring the interplay between human distance to rivers and drought events across Africa
Authors: Ceola Serena , Mard Johanna , Di Baldassarre Giuliano
Published: September 2022

Hydrological extremes, such as floods and droughts, are significantly affecting the human society and the environment. Whereas it is well-acknowledged that people after flood events tend to protect themselves against future events by either enhancing structural defenses such as river embankments, or moving away from flooded areas, we still do not know if people tend to move closer to rivers during or after drought events. To test this hypothesis, we analyze the mutual relation between human distance to rivers and drought events across Africa. In particular, we inspect how this relation changes in space and time from 1992 to 2013. To this aim, we use remotely sensed nighttime data, as a proxy of human presence and activity, and several distinct classes of distance to the river network to compute the human distance to rivers. Drought events are identified based on two alternative datasets: SPEI values and EM-DAT. Significant patters of decreasing human distance to rivers after drought events are found in several African countries. Our results show that droughts may trigger a higher human proximity to rivers, which then results in a higher exposure to floods, if a flood event is taking place, with remarkable damages and losses afterwards. Thus, the proposed methodology, by shedding light on the coevolution of society and drought, complements previous findings on the dynamics between people and floods.
Impact of water stress on Mediterranean oak savanna grasslands productivity
Authors: Muñoz-Gómez María J. , Andreu Ana , Gómez-Giráldez Pedro J. , Carbonero María D. , Blázquez-Carrasco Ángel , González-Dugo Maria P.
Published: September 2022

Seminatural grasslands located in Mediterranean areas support a remarkable species diversity and provide multiple ecosystem services, including pasture and forage production and high levels of carbon sequestration. The presence of sparse oak trees in these grassland ecosystems creates a variety of microclimates that contributes to increasing the diversity of plant communities. The phenology and production of the grassland are highly controlled by the water availability, hence the large inter-annual variability in production is directly linked to the variability of the Mediterranean climate. In this work, we have analyzed the links between grassland production and water stress using satellite data to assess the evapotranspiration and biomass accumulation from 2001 to 2018 over the oak savanna grasslands of a region of Southern Spain. 

A surface energy balance model, SEBS (Surface Energy Balance System), has been applied to estimate evapotranspiration (ET) at monthly scale and 0.05-degree pixel size for the study period, using MODIS data and a global atmospheric reanalysis dataset. The anomalies of the ratio of ET to reference ET were used as an indicator of agricultural drought at the monthly and annual scales, and to characterize the main drought events that occurred in this period.

The biomass production was estimated using an adaptation of the Monteith crop production model, based on the relationship between plant growth and incident solar radiation. This adaptation pays special attention to the presence of a tree layer with a variable density as part of the ecosystem that influences spectral data, and to the empirical estimation of the light use efficiency for these seminatural grasslands using biomass field measurements. For this model, the scale of application was 250 m and 16 days.

The close links between grassland production and drought events at the regional scale and over ten selected farms has been analyzed, taking into account the need for external livestock feeding at both scales during these dry events.  
Rainfall-runoff processes of Koupendri catchment north-west, Benin: a modeling approach.
Authors: Azuka Chukwuebuka
Published: September 2022

This study calibrated and validated rainfall-runoff model (WaSiM) to aid decisions on sustainable management of scarce water resources in Koupendri catchment. Data on soils and soil hydrological properties in combination with land use and short-time series data of climate and discharge were used for the calibration and validation of WaSiM model. The most sensitive parameters of soil and land use parameters were identified and optimized. The model was successfully calibrated (NSE= 0.61; R2=0.61, RMSE= 0.63) and validated (NSE= 0.68; R2= 0.78; RMSE= 0.57) for the catchment. Though the model underpredicted some of the peak flows, the overall calibration result can be adjudged satisfactory with a p-factor of 0.94 and an r-factor of 0.93 which are all within the acceptable range of uncertainty. Evapotranspiration and discharge constituted 98%–99% of the total water balance of the catchment while the change in soil moisture storage constituted only < 2%. Surface runoff was the predominant streamflow component (86%–90%), suggesting infiltration excess overland flow as the main runoff generation mechanism for the catchment. The water balance reflected the hydro climatic conditions of the catchment with actual evapotranspiration ranging between 68% and 75% of the total annual rainfall.
Estimating the Structural Uncertainty of Lumped Parameter Models in Karst Hydrology: a Bayesian Model Averaging (BMA) Approach  
Authors: Yohann Cousquer , Vianney Sivelle , Hervé Jourde
Published: September 2022

Uncertainty quantification in hydrological modeling, and noticeably in the lumped modelling of karst systems, generally attributes source of uncertainty only to parameters or to input data.  Uncertainty in model conceptualization, which often leads to one unique model structure, is frequently neglected. This issue is particularly important for karst hydrology, where hydrological systems are highly heterogenous and information about the structure is difficult to obtain. In this work, we present a Bayesian Model Averaging (BMA) approach to assess predictive uncertainty with errors due to either model structure and model parameters. A set of plausible model structures is first selected, and a prior parameter space is sampled. For each model structure, the ability of the model to reproduce the observed behavior (discharge and water level) of the karst system is evaluated and a likelihood measures of acceptable structure is assigned to the model.  Then, the likelihood measures of each acceptable structure are integrated over the parameter space to obtain total likelihood of model structures. The latter is used to weight the predictions obtained with each model structure in the ensemble predictions. This method is illustrated with the KarstMod modeling platform that allows to run large range of lumped parameter model structures dedicated to karst hydrology. Then, the importance of structure error to predict spring discharge and water table levels of a well known karst system, the Lez karst system (Montpellier, France), is discussed.
Impact of river basin morphology and climate on geomorphic scaling laws for floodplain mapping
Authors: Annis Antonio , Karpack Marissa , Morrison Ryan R. , Nardi Fernando
Published: September 2022

Hydrogeomorphic scaling laws, providing consistent flood flow depth estimations as a function of contributing drainage areas, are widely used by DTM-based parsimonious floodplain delineation methods. Recent research demonstrated the suitability of hydrogeomorphic floodplain delineation models from basin to global scale across diverse climatic and morphological settings. However, distributed analysis of scaling laws performances in semi-arid to humid and low-gradient to steep basins are missing. In this work, we considered eleven basins in the west-central United States to assess flow depths – contributing areas scaling law parameters with varying basin slope and average annual rainfall. The outcomes of this scaling law parametrizationanalysis were used to test improved performances of the GFPLAIN hydrogeomorphic floodplain delineation model. Outcome of this work show improved performances and effectiveness of the GFPLAIN modelwith varying morphometric and climatic factors using as main input largely and freely available global climate and topographic datasets.
Contribution of an organochlorine transport model in the evaluation of groundwater contamination risks in the Abidjan aquifer.
Authors: Deh Serge Kouakou , Kouame Kan Jean , Aka Konan Alexandre
Published: September 2022

This study is being carried out on the Abidjan groundwater, the exploitation of which has made it possible to equalize the price per cubic meter in Côte d'Ivoire. However, the quality of these waters is increasingly tested by various sources of pollution, particularly the dumping of toxic waste in 2006.

With a view to ensuring an effective water supply for the people of Abidjan, this study aims to develop a decision-making tool to protect the water table against pollution. To achieve this objective, it was necessary to model the transport of dissolved perchloroethylenes through the water table using the Feflow code. Various data were used to develop the conceptual model and the input parameters for the groundwater flow model coupled with the transport.

The calibration of the flow model allowed us to obtain an NRMS = 4.77%, revealing the convergence of the model which was furthermore veriﬁed by the modiﬁcation of the number of meshes. The model was then used for predictive simulations of dissolved perchloroethylene transport at the five selected waste disposal sites. The simulation of the transport of perchloroethylene allowed the horizontal trajectory of the pollutant within the Continental Terminal slick to be understood. The contamination times vary from 9 to 47 years. This study undoubtedly favours the sustainable management of groundwater resources in the District of Abidjan by resolving accidental or point source pollution problems.

Key words: Pollution, Abidjan groundwater, modelling, transport, perchloroethylene, Feflow, Abidjan District.
Technical, economic and social rehabilitation of old canals to cope with global change: the case of the Neste Canal (France)
Authors: Garin Patrice , Montginoul Marielle , Lepercq Daniel , Chisne Pascal
Published: September 2022

Many canals were built during the 19th century to satisfy multiple uses. The priorities among them reflected the societal needs of the time: navigation, drinking water, irrigation, hydroelectricity, minimum flow in rivers for sanitation goals, etc. Today, multiple changes affect these priorities: the decline of available resources makes it difficult to satisfy all uses. In addition to climate change, these water infrastructures are subject to controversies as a result of changes in agriculture and irrigation, claims for minimum flows for aquatic ecosystems, the urban sprawl, and the need for hydropower. Everything is questioned: the hydraulic management and indicators, the economic model for recovering the sustainable cost, the social contract that defines priority uses, and the fair distribution of powers and duties between the stakeholders. To summarize, the role of these old canals in global change adaptation strategies is being questioned, as dam projects. Our hypothesis is that these old hydraulic works can help the territories to adapt, if reforms of their hydraulic, economic and institutional management are carried out at the same time.

The recent history of the Neste Canal illustrates this complex ongoing transformation. Since 1962, it has diverted yearly 220 Mm3 from the Neste River, a tributary of the Garonne River in the foothills of the French Pyrenees, to supply 17 rivers in Gascony. Artificial lakes have progressively filled out this complex interconnected hydraulic system. This "Neste system" covers a territory of 8,400 km2, irrigates about 60,000 ha, and supplies 350,000 inhabitants with drinking water (see map). In this paper, we describe the evolution of the multiple uses as well as the decrease in the flows derived over the last 70 years, and then the structural imbalance of its economic model. Its future depends on i) the political recognition of its contribution to the minimum water flows of the rivers of Gascony, ii) the introduction of a payment for this ecological function, and iii) changes in hydraulic regulation system to satisfy this last function previously managed as a hydraulic constraint.
Farmers’ risk reduction strategies during drought events in the Po river basin: an assessment from surveys.
Authors: Borzì Iolanda , Monteleone Beatrice , Bonaccorso Brunella , Martina Mario
Published: September 2022

The Po River Basin is the largest Italian watershed, covering a surface of 71.000 km², and is the main agricultural area of the country (Figure 1). It was interested by several drought events in the past years with severe impacts on agriculture; between 2005 and 2007 agricultural losses caused by droughts were estimated to be around 1.850 M€.

Surveys have been proposed to local farmers to identify past droughts and heatwaves that have impacted their crops and to understand their water management strategies during those events. Past droughts have also been identified computing the SPEI. The comparison between the events identified through the SPEI and the ones reported in survey evidenced coherence in timing and lengths of the events. In particular three main events happened in 2003, 2017 and 2019.

Adaptation strategies to cope with droughts and heatwaves have been retrieved from the collected surveys. Farmers were asked to answer the following questions: if they applied irrigation during past droughts, which were the preferred irrigation strategies (i.e., irrigate at night, irrigate a reduced area to their full irrigation, irrigate the full area to a reduced irrigation, crop prioritization, etc) and which were their decisional criteria to establish when to start irrigation during a drought. Information on the availability of insurance coverages were collected, as well as on the grade of satisfaction of farmers about them.

Surveys highlighted how droughts occurring in different plant growing stages caused very different economic damages in terms of yield reduction and economic losses. The main source for water supply in the Po area are private wells, river and lakes. Farmers who did not apply irrigation reported a 55% yield reduction, while farmers who irrigated have lost only 20% of their yield. In addition, the farmers’ grade of satisfaction on insurance coverage was evaluated. Farmers who applied irrigation did not acquire insurance coverages, while farmers who haven’t used irrigation trusted more on insurance.

Future perspectives for the study are to assess the effectiveness of management strategies evaluated from surveys, though the use of simulation models, comparing them with other strategies to cope with water crisis.

 
Spatial non-stationary extreme precipitation modelling in the Mediterranean region.
Authors: Hammami Hela , Carreau Julie , Neppel Luc , Elasmi Sadok
Published: September 2022

Intense precipitation events often occur in Mediterranean regions. These phenomena depend on the presence of mountainous and hilly reliefs combined with masses of humidity caused by the proximity of the sea. Floods are the most significant natural hazards in the region that may cause widespread devastation. Therefore, a proper characterization of these extreme precipitation events is crucial.

Extreme Value Theory (EVT) is a branch of statistics that provides a suitable framework for the statistical modelling of extreme events. Owing to the spatial heterogeneity of the Mediterranean area, the distribution of extreme precipitation events is non-stationary in space. To take non-stationarity into account, the parameters of the distribution can be viewed as functions of covariates that convey information on the spatial heterogeneity. Such functions may be implemented as a generalized linear model (GLM) or with more flexible non-parametric non-linear models such as Artificial Neural Networks (ANN).

In this work, we aim at evaluating and comparing several statistical models that allow to interpolate spatially the distribution of intense precipitation events. The statistical models combine the distribution of extremes with a GLM and an ANN for the spatial interpolation of distribution parameters. Key issues are the proper selection of the complexity level of the ANN (i.e. the number of hidden units) and the proper selection of geographical covariates.

Three sites that form a north-south aridity gradient are included in our study : a region in the French Mediterranean, the Cap Bon area in North-East Tunisia and the Merguellil catchment in central Tunisia. The comparative analyses aim at assessing the genericity of state-of-the-art approaches to interpolate the distribution of extreme precipitation events.

KEYWORDS: Intense precipitation events, non-stationarity in space, extreme value theory, spatial interpolation.
Index-based Insurance to Mitigate Drought Financial Losses for Water Supply Sector
Authors: Gesualdo Gabriela , Benso Marcos , Navarro Fabricio , Rápalo Luis , Mendiondo Eduardo
Published: September 2022

Mitigation and management strategies for extreme events become essential for the development and maintenance of society as these events become more frequent and intense. Drought management strategies have focused on structural measures, however, they are not sufficient to prevent water supply disruptions and economic losses. In this concept, adaptation plays the role of anticipating the adverse effects of extreme events and taking appropriate measures to prevent and minimize them. Thus,  insurance is a valuable adaptation tool to reimburse unexpected losses and prevent financial damage from turning into long-term economic damage. We simulated indexed insurance for the Cantareira Water Supply System, responsible for providing water to 5 million people in the São Paulo Metropolitan Region (SPMR). Our methodology comprises (1) characterizing the indexed variable, (2) calculating economic losses by event magnitude and, (3) estimating the premium based on low, medium, and high coverage levels. To find the optimal premium value, we generated 100 synthetic series of 30 years sample (3000 years) and assessed its losses probability. We found two years lag accumulated precipitation as the index variable and a daily direct loss of USD* 480,000.00 due to drought in the distribution reservoir. Our results show that each person should pay an annual amount of USD 0.43, 0.87, and 1.73 to obtain a drought coverage level for 3, 6, and 12 months (Low, medium, and high) respectively. These values correspond to 1.7, 3.4, and 6.7% of the annual fee paid by water users. The premium fee can be implemented in the water bills as a new strategy to pool the risk between users and prevent them from being exposed to surcharge fluctuations. As disruptions are difficult to remedy in a short-run basis, the index insurance has the potential to significantly reduce the costs of managing financial risk and disruptions. Given that extreme weather events will become more frequent and intense in the future, we recognize the critical importance of financial tools to mitigate losses as an additional solution for water resources management.

* Data are in constant 2020 U.S. dollars (USD1.00 =BRL 5.15)
A combined mixing model for high-frequency concentration-discharge relationships
Authors: Tallec Gaëlle , Tunqui Neira José Manuel , Andréassian Vazken , Mouchel Jean-Marie
Published: September 2022

Streamflow is the major factor influencing the evolution of solute concentration in river water and different modelling approaches exist to characterize the dependency of concentration to discharge: the simplest are based on measurable quantities (stream discharge and stream water concentration) but do not allow for an explicit, physical, flow-path interpretation; the more complex are based on mixing assumptions with different end-members sources, but require the knowledge of (unmeasurable) flow components. We present here an approach allowing to combine the simple concentration-discharge (C-Q) models with the Mass Balance (MB) mixing approach. This combined model tested on high-frequency ionic concentration series from the ORACLE-Orgeval observatory (France), where it clearly outperforms the commonly-used models applied separately. Thanks to the temporal density of the dataset, model performances are tested at different hydrological scales.
Analysis of rainfed cereal-legume mixture cropping water productivity in Lebna catchment, Cap-Bon, Tunisia.
Authors: Mekki Insaf , Zitouna-Chebbi Rim , Benyoussef Salah , Abdelghaffar Aya , Jacob Frederic , Albergel Jean
Published: September 2022

Under climate change conditions, optimizing water resources management in rainfed agricultural production systerms requires the reasonable choice of crops. In this context, the adoption of crops diversification is promoted to increase the agricultural production and the added value per cubic meter of rain water (green water) used by crops. Contributing, therefore, to increase agricultural production and to preserve soil and water resources. The objective of this study is : i) to identify mixed crops within agricultural fields and, ii) to evaluate the biomass production and the water productivity in the Lebna watershed (Cap-Bon, Tunisia) using remote sensing and field measurements. The study area, covering 210 km2, is characterized by a semi-arid Mediterranean climate, the predominant of cereals, legumes and fodder cropping systems, and the degradation of soil resources. The field investigation and experiments allowed the quantification of crop evapotranspiration and the observed biomass production at the agricultural field plots. The use of the sentinel images and the observations at different agricultural fields allowed to produce NDVI maps. The results first confirmed a good correlation between biomass production and NDVI vlaues. The linear relationships showed a values of R² greater than 0.9 and  values of RMSE less than 0.35. The use of sentinel images and GIS allowed to compute water productivity from field to watershed scale.  The results revealed a considerable spatial variation in water productivity values  for different crops. Compared to a single crops, the cereal-legume mixture cropping improved the water productivity. Theses results help to recommed adaptation measures in agricultural production systems to climate change. Ongoing work coupling field experiments, remote sensing and agro-hydrological model aim to develop simulation and evaluate the agri-environmental impacts from field to regional scale.
Assessing the significance of Water resource management in improving the socio-economic and environmental status of a fast-growing urban community: A case study from Southern India
Authors: Mariappan Rinisha Kartheeshwari , Lakshmanan Elango
Published: September 2022

Integrated water resource management is paramount in this existing scenario, where population growth along with climate and land-use change become obstreperous. The huge turbulence of rainfall pattern in recent decades, give chances for contrast climate extremities like pluvial floods and droughts along with water scarcity more often. The present study focuses on the southern hydrological basins of Chennai in India, which are Adyar and Kovalam (Ad-Ko) basins. The study area experienced floods in 2015 and 2021 recently, in which almost 75% of 1400 mm (average annual rainfall) poured in a single month. Discrepantly, in 2019, a severe drought, which almost created day zero by completely draining all the water bodies due to inappropriate water management. The Ad-Ko basin comprises 1650 Km2, among which, 11% are water bodies. This 11% is further distributed as abandoned quarries, lined canals, reservoirs, tanks, rivers, streams and wetlands. So, the inference is that the Ad-Ko basin already has sufficient natural and man-made water storage and draining facilities. But, it got affected due to a lack of people’s awareness leads to encroachment and improper water management. Though extremities due to climate change are inevitable, several interventions on water management can improve the subsisting condition. MIKE software was chosen to assess and evaluate the benefits of stream diversions and deepening of water bodies, which were incorporated based on the topography. The resulting water balance is optimistic in handling extreme situations. Moreover, the water samples were collected and assessed for their physicochemical properties from various water bodies that could be intervened, periodically between 2019 and 2021. The analysis was carried out based on the American public health association (APHA) and compared with the Bureau of Indian Standards (BIS), World health organization (WHO) limits and found to be suitable for water managing measures. Thus the peer concentration on water management by a highly aware urban population can reduce the impact of severe climate extremities and improve the socio-economy and environment of the community substantially. 
WMO recent developments to contribute to open science and education in operational hydrology
Authors: Caponi Claudio , Cullmann Johannes
Published: September 2022

One of the main drivers of the recent WMO governing bodies reform is to enhance the contribution of WMO to the international water agenda. In this respect, the Extraordinary World Meteorological Congress held in October 2021 has adopted a new WMO Vision, Strategy and Plan of Action for Hydrology.

In the Vision and Strategy, WMO Member States declare that by 2030 a cooperative global community should be successfully addressing the growing challenges related to hydrological extremes, water availability and quality, and food security, by advancing operational hydrology through enhanced science, infrastructure, capacity-building, and related services, in the context of sustainable development and enhanced resilience.

In the Action Plan, WMO Members, National Hydrological and Meteorological Services, UN organizations, other partner international organizations and relevant public, private and academic institutions are urged to collaborate in implementing a strategic suite of activities to enhance services for operational hydrology to be supported by WMO in the period 2022–2030. Congress also endorsed the WMO Hydrological Research Strategy 2022–2030: “Operational Hydrology Research Priorities”, as an input to the global research community on the areas of priority research needed to support the provision of improved hydrological services. 

In a landmark Water Declaration, Congress set the following aspirations:

That by 2030 early warnings for early action related to floods and droughts will be available for people everywhere on the planet to access

That policies for water and climate action developed within the sustainable development agenda be integrated to yield maximum benefit for our people

That these goals will be pursued through partnerships for capacity development, knowledge exchange and information sharing, formulating policies, institutional and legal/regulatory frameworks.

Finally, Congress adopted a new WMO Unified Data Policy to dramatically strengthen the world’s weather, climate and hydrological services through a systematic increase in much-needed observational data and data products from across the globe. The new policy reaffirms the commitment to the free and unrestricted exchange of data, which has been the bedrock of WMO since it was established more than 70 years ago.

 

 