bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental flows and integrated water resources management in Colombia
Authors: Cortés-Torres Nicolás , Fernandez Berbeo Maria Camila , Vega Idarraga Juan Diego , Ramos Romero Valentina , Pulgarin Camilo Andrés , Perez Pedraza Martin , Rodríguez Vega Nelson David , Yanala Bravo Jennifer Camila , Alarcón Alejandro , Lopez Bayona Alejandro , Ortega Tenjo Karen Jhoana , Molano Juan Manuel , Cubillos Peña Carlos , Salazar-Galán Sergio
Published: September 2022

In Colombia, around 70% of the energy is from hydropower source and most of its associated hydraulic infrastructure is located in the macro-basin of the Magdalena and Cauca rivers. These projects are generating a drainage network fragmentation and a substantial alteration in natural regimes of both flow and sediment, which is having negative impacts on freshwater ecosystems and their ecosystem services. Nowadays, there is a methodology related to environmental flows, proposed in 2018 by the Colombian Ministry of Environmental and Sustainable Development (not adopted as a regulation), which integrates two sets of stakeholders: environmental authorities for integrated water resources management at regional scale and holders of new projects with high impact on the natural flow regime of rivers. Since it is only a non-binding methodological proposal, there are no known practical applications to evaluate its effectiveness in terms of reduction of environmental impacts, social conflicts, and water governance. In this sense, we propose a step forward in the analysis of the effects of its application in rivers with available hydrological data and under natural regime conditions through a taylor-made computer model (HeCCA 1.0) which is composed of the most important methods contemplated in the above-mentioned methodology.

HeCCA 1.0 allows determining the percentage of monthly use of a river without compromising its ecosystem function, based on it, river discharge data of 15 different watersheds located throughout the entire country were used. In this test, a range of drainage areas (180 to 73000 km2) was covered located between 25 and 2993 meters above sea level. The systems belong to different seasonal behaviors depending on the geographical location (monomodal or bimodal). For the monomodal regime, utilization percentages were obtained between the 61%8 and 77%29; and for bimodal regimen between 14% and 49%32.

These results depend on the geographical location of the basin, the watershed size, if it is related to the runoff seasonality along the year in the different catchment areas of the country. The taylor-made computer model provides stakeholders a holistic overview of the water availability and management, giving quantitative tools for an optimal development of water governance in the region.
Effects of climate change on hydrological safety of dams with gated spillways.
Authors: Soriano Martín Enrique , Mediero Orduña Luis , Petroselli Andrea , Grimaldi Salvatore , De Luca Davide Luciano
Published: September 2022

Dam breaks can origin important economic and human losses. Failure of such infrastructure may be due to flooding that exceeds the design capacity of spillways. Design floods are estimated through a statistical analysis of observed data, but observations are usually short. Furthermore, high return periods are used for estimating design floods and climate change is expected to increase the frequency and magnitude of floods in the future. Therefore, new methodologies to assess hydrological dam safety considering short observed data and climate change are required. 
A stochastic methodology to assess hydrological dam safety considering climate change is presented. The methodology is applied to the Eugui Dam on the River Arga in the north of Spain that has a gated spillway. 
The stochastic model STORAGE (De Luca and Petroselli, 2021) based on the Neymann-Scott Rectangular Pulse Model has been used to simulate long time series of precipitation with a time step of 15 minutes. Delta changes extracted from precipitation projections of 12 climate models, three periods and two emission scenarios (Garijo and Mediero, 2019) are used to consider climate change.
The precipitation time series generated stochastically are transformed into runoff time series by using the COSMO4SUB model (Grimaldi et al., 2021). It is a continuous model that uses a high-resolution digital terrain model, land cover and the precipitation supplied by the STORAGE model as input data, providing 15-min continuous runoff time series as output. The curve number and time of concentration variables have been calibrated by minimizing a set of objective functions.
Inflow hydrographs are extracted from runoff time series simulated by COSMO4SUB. The Volume Evaluation Method (MEV) (Girón, 1988) is applied to simulate the operation of spillway gates, obtaining maximum water levels in the reservoir and outflow hydrographs. The MEV method specifies when the gates should be opened and closed to reach the target water level. Hydrological dam safety is assessed with the frequency curve of maximum water levels in the reservoir for the climate models. Therefore, the methodology proposed allows practitioners and dam owners to assess the hydrological dam safety requirements detailed in the regulations, accounting for climate change.
Exploring institutions, land use and water quality interactions with a socio-hydrological modelling approach in Burkina Faso
Authors: Carr Gemma , Barendrecht Marlies , Balana Bedru , Debevec Liza
Published: September 2022

The variety of demands that people place on water resources, coupled with the dynamics of the natural system, make water resource management highly complex. Case studies provide research opportunities to advance our understanding of complex systems and examine different approaches to resource management. The "Participative Planning for a More Inclusive and Sustainable Water Management in Rural Areas of Burkina Faso" (www.pwgbf.iwmi.org) project ran from 2015-2019, and as part of this, we explored how a socio-hydrological model might support stakeholders to compare different levels of institutional support and different land management strategies for improving water quality. To create the conceptual model of how institutions, agencies, individuals, land and water management interact in the case-study region, literature review was coupled with interviews and field observations of agricultural practices and land and water management. The relationships in the model were described mathematically, and parameters were estimated based on the information collected. The resulting model could explore how the impacts of an increase in institutional capacity (e.g. greater enforcement of land-use regulations), local and regional resources (e.g. investment in irrigation infrastructure at locations far from the river), and individual (e.g. farmer willingness and capacity to reduce use of agro-chemicals, willingness and capacity to relocate or replace vegetable crops with tree crops) could lead to improvements in water quality (reduced concentrations of pollutants and sediments in rivers and reservoirs). Pathways to water quality improvements were modelled, and demonstrate relationships in a semi-quantitative way. For example, water quality can be substantially improved by doubling institutional support to the local water user groups and tripling their internal capacity (e.g. through capacity strengthening, more financial support, and raising gender balance/empowerment). Comparison of different management methods using the model also highlight how economic trade-offs are necessary to achieve improvements in water quality. The systems-dynamics modelling approach taken in this study offers considerable potential for exploring interactions and translating these into management recommendations. However, extensive engagement with stakeholders throughout the entire process is essential.
Change of Rainfall Characteristics in Bangladesh and Sri Lanka using more than 100-years Record
Authors: Kiguchi Masashi
Published: September 2022

South Asian countries are recognized as a vulnerable area of water-related disasters. Due to the recent climate change, the precipitation trends have been changed in some regions. Of course, it is important to examine changes in heavy precipitation because it will cause a flood, but it is also important to describe variation in weak precipitation because weak rainfall is one of the important water resources in agriculture sectors during non-monsoon seasons. Recently Endo et al. (2015) analyzed the precipitation trends in Bangladesh from 1950 to 2008. They showed that as for the total amount of precipitation and the number of the wet day appeared to be increasing over the country. Heavy rain was also increasing in some stations. During the pre-monsoon, seasonal total rainfall, the number of the wet days and weak precipitation were increasing. Heavy rainfall indices showed that inter-annual and decadal variations dominated. The objective is to analyze the long-term rainfall data (1891-2016), and detect the time series variation in Bangladesh and compare with the previous studies.
The results were generally matched with the previous one. By analyzing the short-term trend, it was showed that significant change detected in the research is due to the recent rainfall characteristics change. It implies recent climate change is significant. Trends showed spatial characteristics. Both rainfall amount and intensity are increasing mainly in southern Bangladesh. It will suggest that more active ITCZ could move southward, and this trend will continue. There were different changing trends among seasons. Also, we expand to analyze in Sri Lanka.
Combination of Global and Regional Hydrological Forecasts
Authors: Fontaine Nicolas , Boucher Marie-Amélie , Odry Jean , Lachance-Cloutier Simon , Fortin Vincent , Anctil François , Turcotte Richard
Published: September 2022

In recent years, the number of large-scale hydrological forecasting systems has been steadily growing. This may lead to regions having numerous models spatially overlapping each other. Some of these regions have what we will refer to as a regional, more specialized, model for the area that performs generally better than their large-scale counterpart, considering the coarser spatial resolution and sometimes lack of calibration of the latter. Our work explored the possibility of using simple methods to retrieve hydrological information from a large-scale model, namely the National Surface and River Prediction System (NSRPS) that will eventually cover the Canadian territory, in order to improve the forecasts from a local system, namely the Système de Prévision Hydrologique (SPH) that covers most of the province of Quebec. Outputs from the two forecasting systems were thus combined using methods including the simple mean, a weighted average in which the weights are optimized either using the Kling-Gupta Efficiency (KGE) or the Continuous Ranked Probability Score (CRPS) as cost functions, or weights calculated from the residual errors of the forecasts. Bayesian Model Averaging (BMA) was also explored to combine the ensemble forecasts from both systems. The results show that it is possible to improve the local hydrological forecasts by using simple weighted combinations with forecasts from the large-scale system. Performance was assessed using many well-known criteria such as the Nash-Sutcliffe Efficiency (NSE), KGE and CRPS. Results were averaged over the 61 available gauging stations and analyzed at lead times ranging from 3 to 120 hours. We observed improvements in all criteria for lead times over 60 hours as well as no loss in performance at any lead times. Finally, the methods were also used in a leave-one-out setup to simulate performance on ungauged basins. The performance gain for ungauged basins is similar to that of the gauged basins, hinting at the fact that these simple methods could also improve forecasts in more remote territories where no measurements are available.
Impact of climate change on the contribution of glaciers to the Upper Yukon River 
Authors: Doumbia Cheick , N. Rousseau Alain
Published: September 2022

In the Upper Yukon Watershed (UYW, 20,000 km2), seasonal melt from glaciers contribute significantly to annual runoff and operation of the Whitehorse power plant. This study aims to analyze the impact of climate change on the contribution of glaciers, which covers 5% of the UYW, to the annual runoff using hydrological modelling, GRACE data and machine learning algorithms.

The spatial resolution of GRACE data remains too low to discriminate changes in glacier mass signal at the scale of the UYW. Thus, here we applied a spatial concentration function approach to build high resolution monthly time-series of glaciers mass changes over the UYW. To estimate glaciers mass changes, we decomposed four GRACE TWS solutions with different processing assumptions using monthly data from LSM GLDAS v2.1 (Rodell et al., 2004) and WGHM v2.2d (Müller Schmied et al., 2020). Spatial concentration functions were derived from two heterogeneous a priori of different resolutions and sources (Hugonnet et al., 2021; Larsen et al., 2015) and the leakage was subtracted by using glaciers over the Gulf Of Alaska (GOA). To analyze the accuracy of our assessments, we compared the trends resulting from the spatial concentration functions and the constrained forward approach (Doumbia et al., 2020) over the GOA and the Saint-Elias Mountains. To extend/reconstruct glacier mass change up to GRACE-FO (i.e. 2003-2020), we used the Automated Machine Learning (AML) H2O-AutoML (LeDell and Poirier, 2020). Then, glacier mass anomalies were used to calibrate the hybrid (i.e., degree-day/thermal energy balance) glacier melt model of HYDROTEL over UYW.

For the period of 2003 to 2016, the trends in glaciers mass losses over the GOA and Saint-Elias Mountains varied from 41.61 to 53.43Gt/yr and 19.31 to 28.88Gt/yr, respectively. Our results compared well with the glaciers mass losses reported in other studies. The AML algorithms performed well with NSE values varying from 0.75 to 0.99; correlation coefficients from 0.93 to 0.99; P-bias from -2.4 to 4.8 and NMRSE from 0.8 to 49.6. The use of the glacier mass changes, in addition to stream flows, improved the calibration of HYDROTEL. 
Problem 20.  Reducing uncertainty in model prediction: The role of model invalidation
Authors: Beven Keith , Kretzschmar Ann , Smith Paul , Chappell Nick
Published: September 2022

We would like to use models that are fit for a particular purpose in making predictions.   Traditionally, models have been calibrated against historical data and then some sample of those calibrated models used in prediction.   There has been very little consideration of the aleatory and epistemic uncertainties of the pertinent hydrological process and just how that might affect the way we assess models as hypotheses about how catchment systems work.   We suggest that a more Popperian approach is required to assess when models should be considered as NOT fit for purpose.   Model invalidation is, after all, a good thing in that it means we need to do better; that some improvements are required, either to the data, to the auxiliary relations or to the model structures being used.   The question is what is an appropriate methodology for such hypothesis testing when we KNOW there are epistemic uncertainties associated with the observations?   We consider this issue for the case of flood hydrograph simulation using Dynamic Topmodel, making use of a strategy of limits of acceptability for model simulations set prior to making model runs.
Ensemble of geological models of a complex coastal aquifer for uncertainty estimation and groundwater modelling in the framework of the DEM'EAUX ROUSSILLON project.
Authors: Dall'Alba Valentin , Schorpp Ludovic , Lanini Sandra , Issautier Benoît , Lasseur Eric , Renard Philippe , Caballero Yvan
Published: September 2022

The creation of geological and sedimentological models is a non-unique process due to the many choices that must be made during their conception. The choice of the geological and sedimentological depositional concepts, the decision regarding the modeling strategy (stochastic or deterministic), the type of algorithm used for the simulations (MPS, SGS, Kriging, TGS…) are all factors that influence the final models and the corresponding uncertainty quantification.

Regarding the coastal sedimentary Roussillon aquifer (south of France), different sets of geological models have been created and are used for the hydrogeological simulations; homogeneous permeability model, depth relative permeability model, and stochastic models. 

The homogeneous and depth relative models are created based on the large structural envelopes delimiting the main aquifers. The stochastic models are also based on these envelopes but simulate inside complex sedimentary facies and permeability fields using the multiple-point statistics algorithm DeeSse. Different geological concepts were tested depending on the different representations and interpretations of the possible spatial distribution of the sediments. Each model has its own strengths and weaknesses. It is by combining these different approaches that we created an ensemble of geological models deemed to cover some conceptual uncertainty range.

These models are then used to feed hydrogeological simulations to create an ensemble of hydrogeological models and outputs that are used to characterize the hydrogeological uncertainty and help increase the robustness of the prevision. To do so, we developed an integrated process to convert the geological model to physical model and directly used them in hydrogeological simulations. The models run on MODFLOW, using the floPy python interface which helps the automation of the process. These models can then be calibrated in a semi-automatic manner using various inversion methods such as PEST, POPEX, or using ensemble Kalman filters.
Rainfall monitoring using microwave links from cellular communication networks: potential for sub-Saharan Africa
Authors: Uijlenhoet Remko , Overeem Aart , Leijnse Hidde , Droste Arjan , Bogerd Linda
Published: September 2022

Microwave backhaul links from cellular communication networks provide a valuable “opportunistic” source of high-resolution space–time rainfall information, complementing traditional in situ measurement devices (rain gauges, disdrometers) and remote sensors (weather radars, satellites). Over the past decade, a growing community of researchers has developed, in close collaboration with mobile network operators, retrieval algorithms to convert the raw microwave link signals, stored operationally by their network management systems, to quantitative precipitation estimates.

Operational meteorological and hydrological services as well as private consulting firms are showing an increased interest in using this complementary source of rainfall information to improve the products and services they provide to end users from different sectors, from water management and weather prediction to agriculture and traffic control. The greatest potential of these opportunistic environmental sensors lies in those geographical areas over the land surface of the Earth where the densities of traditional rainfall measurement devices are low: mountainous and to a lesser extent urban areas, but most importantly low- and middle-income countries.

In this presentation we will review the state of the art of opportunistic rainfall monitoring using commercial microwave links, with special reference to its potential and challenges for applications in sub-Saharan Africa.
Caractérisation des occurrences de précipitations dans le sous bassin hydrologique de l’ouémé à Savè : Approche Markovienne et les Réseaux de Neurones Artificiels (RNA)
Authors: Zohou Pierre Jérôme , Alamou Adéchina Eric , Aoga John , Ezin Eugène C.
Published: September 2022

          Dans cet article, nous présentons deux techniques d'analyse des précipitations dans le sous-bassin de l'Ouémé à Savè au Bénin : l'approche markovienne et les Réseaux de Neurones Artificiels (RNA). Pour ce faire, nous avons utilisé une série de données enregistrées durant la période de 1921 à 2020 par la Météo-Bénin.
Ces dernières ont été utilisées pour caractériser les occurrences des précipitations dans la zone de Savè. En utilisant les approches markovienne et les RNA, nous avons pu montrer dans un premier temps, que les occurrences de précipitations sont bien décrites par une chaîne de Markov d'ordre un à trois, à savoir les tendances des événements entre les états pluvieux ou non pluvieux après plusieurs années et la répartition des précipitations entre les états à long terme. Et en suite les RNA ont permis de mieux apprécier l'influence du passé sur le comportement des précipitations. Ainsi, en modélisant une chaîne de Markov d'ordre trois et les RNA, nous avons obtenu une meilleure description des précipitations.
En effet, les probabilités obtenues avec l'approche markovienne et les probabilités à partir des RNA que nous avons calculés sont quasiment identiques.

Mots Clés : Bénin, approche Markovienne, RNA, précipitations.
Numerical exploration of the dynamics of infiltration in hill reservoir 
Authors: Bouteffeha Maroua , Dages Cécile , Molénat Jérôme , Bouhlila Rachida
Published: September 2022

Hill reservoirs are small dams intercepting stream runoff in headwater catchment. These reservoirs have been increasingly used in arid and semi-arid regions, in order to provide water for irrigation and farming. Understanding the hydrological functioning of these reservoirs and especially the losses due to infiltration through the reservoir bed is important in order to improve reservoir management practices notably in mediterranean basin threatened with climatic change and water scarcity.

The present work aims to explore numerically the dynamic of infiltration through the reservoir bed in relation to the water level variation in reservoir. The approach is based on a modeling study of a 2D flow model with the Hydrus model. The simulated domain represents a longitudinal section of the hill reservoir. Different scenarios with three different forms of variations of the daily water level in the reservoir were tested. We also considered different hydraulic properties of porous media underlying the reservoir bed to analyse their effects on the infiltration rate.

The monthly dynamics of simulated infiltration rate in real conditions was consistent with the monthly infiltration estimated in Bouteffeha et al., (2015) based on a hydrological water balance approach. Furthermore, daily infiltration rate seems to vary according to the variation of the reservoir water level. For all scenarios of reservoir water level dynamics and hydraulic properties, the numerical exploration shows that the relationship between infiltration rate and daily water level is hysteretic, involving different infiltration rates for the rising and the recession phases for given water level . As a consequence, linear relationship usually used in hydrologic model to simulate infiltration from reservoir may lead to significant errors, particularly during the rising phase in the wet season when the reservoir is filling up.

References:

Bouteffeha, M., Dages, C., Bouhlila, R., et Molénat, J. (2015). A water balance approach for quantifying subsurface exchange fluxes and associated errors in hill reservoirs in semiarid regions. Hydrological Processes, 29(7), 1861-1872
Service chaining, end-using, and support-to-action of a PUB-hydrograph modelling: the SIMFEN web service API
Authors: Loree Tom , Squividant Hervé , Launay Josette , de Lavenne Alban , Cudennec Christophe
Published: September 2022

A consolidated geomorphology-based approach for discharge Prediction in Ungauged Basins (PUB) through deconvolution of discharge signals from gauged donor catchments, their transposition and their convolution towards target outlets, has been made available online to end-users through a Web Processing Service Application Programming Interface (WPS API)  for the synoptic peninsular region of Brittany, France. In the spirit of hydrological services, the SIMFEN WPS API (https://geosas.fr/simfen, Dallery et al., in press) allows anyone to execute the hydrological modelling package transfR (https://CRAN.R-project.org/package=transfR) online through: (1) Open Geospatial Consortium (OGC®) interoperability standards; (2) collection and use of public hydrometric data; (3) connection to the pre-existing MNTSurf WPS API for geomorphometric analysis; (4) visualization using a collaboratively developed Mviewer; and (5) innovative WPS API chaining workflows. The ability to model discharge series at any ungauged outlet of the synoptic region is offered to specialists of other disciplines, non-modeller water practitioners and interested citizens to support interdisciplinarity, water monitoring and management, and related science-society-policy debates and actions. This communication will demonstrate how hydroinformatic developments have been made openly available, ergonomy has been designed, and contextual informations are additionally provided to end-users. It will also show thanks to non-academic metrics how the users’ community is actually active; and how it is considering further chaining developments in the spirit of web service interoperability and reusability, towards hydrochemical, hydroecological, and hydroclimatic aspects.

 

Dallery D. et al., in press. An end-user-friendly hydrological Web Service for hydrograph Prediction in Ungauged Basins. Hydrological Sciences Journal, https://doi.org/10.1080/02626667.2020.1797045

de Lavenne A., Cudennec C., 2019. Assessment of freshwater discharge into a coastal bay through multi-basin ensemble hydrological modelling. Science of the Total Environment, https://doi.org/10.1016/j.scitotenv.2019.02.387  

de Lavenne A. et al., 2016. Transferring measured discharge time-series: large-scale comparison of Top-kriging to geomorphology-based inverse modeling. Water Resources Research, http://dx.doi.org/10.1002/2016WR018716
Spatio-temporal characteristics of heavy precipitation observed over the last 20 years on French Riviera coastal catchments
Authors: Vigoureux Sarah , Brigode Pierre , Poggio Julie , Nomis Stan , Dreyfus Raphaëlle , Delestre Olivier , Ramos Maria-Helena , Moreau Emmanuel , Laroche Christophe , Tric Emmanuel
Published: September 2022

The French Riviera, located in the eastern part of the French Mediterranean coast, has experienced devastating flash floods during the last 10 years. Several of these floods were generated by local and very intense rainfall events, leading to significant material and human losses, especially on small coastal catchments, which often have sparse rain gauge networks and are mostly ungauged in terms of streamflow. For example, the October 2015 event affected the Riou de l’Argentière, Frayère and Brague coastal catchments (respectively 47 km², 21 km² and 72 km² to the sea) with intense rainfall (up to 200 mm in only two hours) characterized by a significant spatial variability (up to two times more precipitation on the downstream part of the catchments). In this context, the estimation of catchment rainfall statistics needs to be performed using datasets with high space and time resolutions. The COMEPHORE dataset is a rainfall observational dataset with hourly and kilometric resolution over the entire French metropolitan territory. It is produced by Météo-France, merging both raingauge and radar observations and currently available from 1997 to 2020.

The objective of this study is to explore the COMEPHORE dataset to estimate and gain knowledge on heavy rainfall characteristics over French Riviera coastal catchments. The work focuses on 45 coastal catchments draining more than 10 km² and less 1000 km². Various spatial and temporal descriptors are calculated to describe the intensity and the temporal and spatial dynamics of the precipitation over this Mediterranean region. The temporal evolution of the descriptors is evaluated over the 23 years of available data. Additionally, a focus is made on significant rainfall events observed during the last decades, in order to discuss their frequency, associated weather patterns and their (dis)similarity at the regional scale. Finally, we discuss how the proposed description of the spatial and temporal characteristics of heavy rainfall events affecting the French Riviera can be useful to improve rainfall forecasting, as well as to forecast the associated hydrological responses of the coastal catchments at very short lead times and, ultimately, how it can contribute to reduce losses generated by flash floods.
Global downscaling and assimilation of soil moisture
Authors: Lakshmi Venkataraman , Fang Bin , Kim Hyunglok
Published: September 2022

There is a requirement of higher spatial resolution of soil moisture as the 9km resolution from SMAP is not adequate. In this work we use MODIS 1km and ECOSTRESS VIIRS 400m vegetation and surface temperature to downscale the SMAP 9km soil moisture to 1km and 400m. We have validated the global 1km soil moisture extensively using global networks. With the CyGNSS and SMAP missions, we have the ability to assimilate sub-daily soil moisture into land surface models. In this talk we will examine the performance of data assimilation of soil moisture using triple colocation.
Evaluating radium as a time tracer for infiltrated surface water in unsteady surface -groundwater interaction areas
Authors: Veuille Sabine , Baudron Paul , Barbecot Florent , Claveau-Mallet Dominique
Published: September 2022

In the critical zone, infiltrated surface water within porous media drives many biogeochemical processes that lead to a natural attenuation of contaminants. In the case of induced bank filtration (IBF), quantifying residence time is required to anticipate water quality issues. Due to combined hydroclimatic regimes and variable pumping sequences, groundwater flow is unsteady and classical residence time quantification approaches often fail to account for such dynamics. Radium is a geogenic element with four isotopes offering ideal half-life ranges for estimating groundwater residence time. Its potential to characterize water mixing processes or date seawater has been widely proven. These advances were supported by the development of affordable analysis devices such as delayed coincidence counters (RaDeCC). In freshwater, the radium adsorption ability on the porous matrix affects its mobility and reduces its availability in dissolved form. These direct consequences of adsorption i) restrict the representativity of water samples, ii) impact the ability to measure dissolved radium by RaDeCC and iii) drastically reduce the temporal range for using radium as a chronometer of surface water residence time in an aquifer. Without a paradigm change, radium as a temporal tracer in freshwater won’t reveal its full potential. However, the third point may be appropriate for tracing dynamics of unsteady flow such as those prevailing for infiltrated surface water in IBF site. A two-years study led in an IBF site equipped with eight wells and 10 piezometers allowed 200 samples to be analysed with a RaDeCC for 223, 224, 228 and 226 radium isotopes. Preliminary results suggest that dissolved radium is more controlled by flow than by a differential adsorption, as no clear correlation was found between dissolved radium and geochemistry (ORP, pH, EC). The spatial distribution pattern of short-lived isotopes at the site was related to the pumping regimes. Annual amplitudes of dissolved radium isotopes presented a periodicity for all the wells. These first results show a satisfactory tracer response to spatial and temporal hydrodynamic flow changes, either from natural or anthropogenic origin in critical zone.
Is Water the Achilles Heel of Regenerative Agriculture?  A critical examination of the roles and omissions of soil-water and water in ‘Regen Ag’
Authors: Lankford Bruce , Orr Stu
Published: September 2022

The paper seeks to gain greater water literacy and numeracy in the connections between water and Regenerative Agriculture (RA). By identifying the many roles and quantities of water and soil-water, our paper argues that water is the Achilles Heel of RA.  At a basic level, RA is failing to fully appreciate and incorporate the many varied inputs, processes and outcomes of water. In ‘outcome’ terms, RA intends to improve soil-water properties and catchment hydrology so that, for example, rainfall seeps into soils rather than running off land surfaces.  In ‘process’ terms, RA adopts agricultural practices such as maintaining a protective cover that aims to enhance soil physical fertility (such as bulk density) and soil-water properties such as infiltration and available water holding capacity.  While these outcomes and processes are idealized and laudable, they miss the many ways in which water and RA intersect. For example water and hydrology are not only affected by RA, but water is also an input to RA. The latter is necessary when soil moisture is required to bolster soil organic accumulation and biological activity.  Accordingly, we find two interconnected fault lines. First, the descriptive and quantified roles of soil-water and water in RA are often missing or poorly explained, and secondly, narrative tropes and terms (e.g. ‘net zero’ or ‘net positive’ water) for describing the benefits and aims of RA are, at best, lacking context or, at worst, are misleading and incorrect. We conclude that scientists and decisions-makers should more thoroughly interrogate how RA is being applied in the context of basin water availability and attempt to bring more precision in regards to quantities of water required – and recognize the competition for those resources as well as opportunity costs. How those quantities overlap with local policies, allocations and hydrology, including farmers’ individual views and policy choices, are critical to RA success. 
Evaluation of GPM IMERG products and ERA5 reanalysis for flood modeling in a semi-arid watershed
Authors: Rachdane Mariame , El Khalki El Mahdi , Saidi Mohamed El mehdi , Tramblay Yves
Published: September 2022

Satellite-based and Reanalysis rainfall products could be a valuable source of data for precipitation for hydrological modeling over data-scarce regions. The objective of this study is to assess the suitability of ERA5 Reanalysis and GPM IMERG V06 data (GPM-Early, GPM-Late and GPM-Final) for flood modeling over a Moroccan semi-arid watershed (Rheraya) during 2013–2018.  Both statistical scores and an event-based model were used to evaluate the performance of these products to estimate precipitation and simulate flood events. The results showed that the four products often overestimate the observed precipitation. The highest bias (124% and 145%) was obtained with GPM-E and GPM-L while the bias for GPM-F and ERA5 was much lower (31% and 42%). However, the four products showed acceptable correlations with observed data. In terms of precipitation detection capability on the hourly time scale, the GPM-E and GPM-L products presented satisfactory performance. They were the most efficient for different rainfall thresholds. In addition, by comparison with observed rainfall, flood modeling results showed that the GPM-E and GPM-L were the most efficient for flood event simulation (Nash greater than 0.4 for the majority of events and correlation coefficients greater than 0.7). This study showed that the different precipitation products tested herein have satisfactory performance for the hydrological modeling of floods. These sources of precipitation could be an alternative in ungauged or poorly gauged basins for flood simulation.
Defining socio-hydrological indicators of WEFE Nexus: preliminary insights from the PRIMA Nexus-Ness project in four Mediterranean living labs
Authors: Merheb Mohammad , Cudennec Christophe , Nardi Fernando
Published: September 2022

Accounting for socio-hydrological interactions and synergies is needed when investigating barriers and opportunities affecting the mainstreaming of WEFE (Water-Energy-Food-Ecosystem) Nexus approaches. Identifying socio-hydrological indicators is crucial to set the diagnostic of actual situations and identify paths of transition. This work presents preliminary insights from four Mediterranean case studies: the lower River Cornia coastal plain in Italy, Adaja River in Spain, Wadi Jir basin in Tunisia and Wadi Naghamish in Egypt, chosen as Nexus Ecosystems Labs (NELs) in the context of the PRIMA funded Nexus Nature Ecosystem Society Solution (NEXUS-NESS) project. The methodology consists of (i) bibliographic review on socio-hydrological indicators with particular focus on the Mediterranean region, (ii) data analysis for the hydrological and socio-economical characteristics of the four NELs in order to (iii) identify, adapt or define new indicators that best fit them. The definition of these indicators will build on a co-identification process (e.g. with stakeholders based on participatory methods to extrapolate the local knowledge) in each of the NELs. This ongoing work is carried out within a transdisciplinary approach integrating experts and knowledge from various fields including hydrology, water resources management, economy, and social sciences. The resulting indicators will be used to help determine pre-analytical choices used in the biophysical modeling of the studied catchments. Moreover, these indicators will permit the quantification of impacts of various scenarios outcomes in a way that is easy to understand by stakeholders, hence facilitating participation and decision-making procedures. Finally, this work will add to ongoing research in socio-hydrology, in agricultural contexts, within the framework of the IAHS Panta Rhei decade.
Seasonal forecasts offer economic benefit for hydrological decision making in semi‐arid regions
Authors: Portele Tanja C. , Lorenz Christof , Dibrani Berhon , Laux Patrick , Bliefernicht Jan , Kunstmann Harald
Published: September 2022

Increasing frequencies of droughts require proactive preparedness, particularly in semi‐arid regions. As forecasting of such hydrometeorological extremes several months ahead allows for necessary climate proofing, we assess the potential economic value of the seasonal forecasting system SEAS5 for decision making in water management. For seven drought‐prone regions analyzed in America, Africa, and Asia, the relative frequency of drought months significantly increased from 10 to 30% between 1981 and 2018. We demonstrate that seasonal forecast‐based action for droughts achieves potential economic savings up to 70% of those from optimal early action. For very warm months and droughts, savings of at least 20% occur even for forecast horizons of several months. Our in‐depth analysis for the Upper‐Atbara dam in Sudan reveals avoidable losses of 16 Mio US$ in one example year for early‐action based drought reservoir operation. These findings stress the advantage and necessity of considering seasonal forecasts in hydrological decision making.
Analysis of Historical Flood Frequencies and Magnitudes and Future Scenarios Forecasting in the Mono River Basin, West Africa
Authors: Koubodana Houteta Djan'na , Tall Moustapha , Nonki Rodric Mérimé , Djaman Koffi , Patel Nilanchal , Atchonouglo Kossi
Published: September 2022

Global warming impacts are known as increasing in rainfall magnitude and frequency that lead to more intense and frequent river flooding. In recent years, there is an upward trend of floods in West African regions. As result, many countries like Togo and Benin have had catastrophic floods that affected thousands of people with loss of lives, damages, and properties. Mono catchment is indeed subject to flooding due to anthropogenic and natural climate changes impacts. This study aims to predict streamﬂow for the period between 1990 and 2020 using hydrological modeling at gauge stations; to analyze flood frequency and magnitudes over the Mono catchment for the historical period through an investigation of hydroclimate indices. Moreover, projected changes in floods hydroclimate indices in the catchment under representative concentration pathway (RCP) from a multi-model ensemble model are investigated. The results show that hydrological modeling reproduces seasonal streamflow with acceptable performance with Kling-Gupta Efficiency (KGE) and percent over calibration and validation periods. Finally, an upward flood frequency and magnitude are observed both for historical and future periods. The outcomes of this study suggest an urgent need to improve the functionality of early warning systems and increase societal resilience to warming climates over the catchment through sustainable policy strategies and governance measures.

Keywords: Flood Frequency and magnitude, Flood forecasting, Mono catchment, Togo-Benin
Imaging flood depth from space: a method based on the fusion of topography and synthetic aperture radar data
Authors: Ayoub Vita , Delenne Carole , Pelich Ramona-Maria , Chini Marco , Matgen Patrick , Hostache Renaud
Published: September 2022

With growing urbanisation and climate change, flooding is likely to become even more frequent and severe.  Therefore, it is essential to constantly monitor water level changes at a large scale. Synthetic Aperture Radar (SAR) images are often used for flood mapping as they allow a rather straightforward detection of water bodies, at almost all weather and illumination conditions. As the number of satellite observations and global digital elevation models (DEMs) are becoming more available, this mapping approach is gaining in popularity.

In this study, we propose three different approaches to retrieve water level maps based on the combination of satellite and topographic data, hereby referred to as the global Height Above Nearest Drainage (HAND), the local HAND and the local DEM methods.

The three approaches are based on the optimization of a threshold applied on the topography (HAND or DEM) data enabling a best fit with the SAR-extracted flood map. The optimized threshold values provide at the same time the normalized water levels (with respect to the drainage network). The water depth map is thus computed from the difference between the water level and the DEM. The global HAND method applies a single optimized threshold to the HAND map, over the entire area of interest. The local HAND method is based on the same concept but optimizes and applies the HAND threshold value locally, using a sliding window. The local DEM thresholding method employs the same principle as the second method but directly on the DEM.

We evaluate these methods using hydraulic model simulation results and ground truth data, and we carry out several experiments using various SAR images (Envisat, TerraSAR-X and Sentinel-1) and topographic datasets (SRTM, CopDEM and LiDAR).

The best results are obtained while combining a high-resolution image (e.g:TerraSAR-X) with: 1) a high-resolution dataset (e.g: LiDAR DEM), using the local DEM approach, or 2) a coarse-resolution dataset (e.g: Srtm DEM), using the global HAND approach. RMSDs on the derived water depth maps reach respectively 0.52m and 0.93m.
Theoretical framework for the stochastic synthesis of the variability of global-scale key hydrological-cycle processes and estimation of their predictability limits under long-range dependence.
Authors: Dimitriadis Panayiotis , Iliopoulou Theano , Koutsoyiannis Demetris
Published: September 2022

Uncertainty and change in geophysical processes can be robustly quantified by analyzing the observed variability. A challenging task in engineering studies is to introduce a framework that can simulate this observed variability while preserving only important stochastic attributes. An innovative methodology for genuine simulation of stochastic processes is presented based on the recent work by Koutsoyiannis and Dimitriadis (2021). The proposed algorithm includes the demanding task of simulating any second-order dependence structure of a process (with a focus on long-range dependence behaviour) and any marginal distribution (with focus on heavy tails) through the explicit preservation of its autocovariance function and its cumulants. The long-range dependence behaviour (i.e., power-law drop of variance vs. scale) and heavy-tails are known to be highly associated with the variability magnitude of a process, through which the range of its predictability-window can be also quantified. To estimate this range, an extensive global-scale network of stations of key hydrological-cycle processes (i.e., near-surface hourly temperature, dew point, relative humidity, sea level pressure, atmospheric wind speed, streamflow, and precipitation; for details see Dimitriadis et al., 2021) is analyzed using ensemble techniques and the proposed stochastic simulation algorithm. The limitations of existing methodologies for the stochastic simulation and estimation of the predictability-window, and how can they be tackled through the proposed approach, are discussed over applications in flood risk management.

Koutsoyiannis, D., and P. Dimitriadis, Towards generic simulation for demanding stochastic processes, Sci, 3, 34, doi:10.3390/sci3030034, 2021.

Dimitriadis, P., D. Koutsoyiannis, T. Iliopoulou, and P. Papanicolaou, A global-scale investigation of stochastic similarities in marginal distribution and dependence structure of key hydrological-cycle processes, Hydrology, 8 (2), 59, doi:10.3390/hydrology8020059, 2021.

Acknowledgment: This research is in the context of the project “Development of Stochastic Methods for Extremes (ASMA): identification and simulation of dependence structures of extreme hydrological events” (MIS 5049175), which is co-financed by Greece and the European Union (European Social Fund; ESF).
History and expectation of investigations on sediment yield with the Upa River basin
Authors: Ivanov Maksim , Golosov Vanentin
Published: September 2022

The Upa River basin is located in the Northern part of the Central Russian Upland. This is the area with a high proportion of cultivated lands and at the same time, the part of the basin was affected by serious radioactive contamination after the Chernobyl accident in 1986. Chernobyl-derived 137Cs turned to be a very suitable tool for assessing mean rates of erosion and accumulation during the post-Chernobyl period. A high concentration of radionuclides in soils and accumulated sediments results in a rapid examination of a large number of gamma-radiation measurements, including in situ measurements, and obtaining a large amount of data, which were published in international and national scientific journals during last years.

Using radiocesium techniques the series of small key catchments, floodplain sites, and artificial reservoirs were explored. The evaluation of sediment budget and resulting sediment yield required adequate extrapolation of achieved results over the territory of the Upa River basin for the desired period. Presented work is argued to generalize results obtained in different locations of the Upa River basin during the last 26 years (from 1995 to 2021). Sediment yield for the two big parts of the basin was assessed: the Plava River basin and the basin of the Sheckino reservoir, located in the Upper Upa basin.

Taking in mind observed experience and resulting estimations, the expectation of the following studies are discussed. Future studies may be split into three directions. The first is linked to the inclusion of new techniques and a combination of new techniques during field studies and lab processing. The second direction of investigation is related to the creation of monitoring systems within basins of typical small rivers. The third is one is an exploration of environmental archives like bottom and floodplain sediments, which may record trends in formation sediment yield for the territories not covered with hydrologic and sedimentary observations for the last decades. 

The work was conducted under financial support of the Russian Scientific Fund, project 21-55-00050