bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating the drainage of irrigated areas: a combined crop water balance modeling and remote sensing approach
Authors: Laluet Pierre , Olivera Guerra Luis Enrique , Altés Gaspar Victor , Rivalland Vincent , Simonneaux Vincent , Bustillo Vincent , Bellvert Joaquim , Villar Josep Maria , Merlin Olivier
Published: September 2022

Drainage is the water flowing under the roots when the soil's capacity to hold water is exceeded. It is an important term of the crop water budget, controlling soil salinization, potentially impacting downstream ecosystems, and being a strong indicator of water productivity. Estimating this flux at spatial scales relevant to farmers (plot-scale) and to watershed or irrigation district managers (sub-basin-scale) is thus fundamental for a sustainable management of water, soils, and downstream rivers. However, even though it can be measured or estimated locally with lysimeters or physically-based models, respectively, drainage is generally neglected or considered as a residual variable in crop water balance models. Furthermore, many studies have shown the relevance of using remote sensing data to spatialize crop water fluxes. The aim of this work is thus to estimate drainage from the plot-scale to the sub-basin-scale by using a crop water balance model coupled with remote sensing observations. For this, SAMIR, a crop water balance model based on the FAO-56 method using remote sensing data to constrain the modeled vegetation and the soil water status, is used. The approach is tested over the Algerri-Balaguer irrigation district in northeastern Spain where in-situ drainage measurements are available at an integrated (sub-basin) scale. Those data were obtained from a network of drains feeding four outlets where the drainage is continuously measured. Additionally, four lysimeters were installed on two experimental fields of the area. Firstly, the drainage simulated by SAMIR and by a physically-based model (HYDRUS-1D) are compared with the lysimeters measurements. Preliminary results indicate that both models are able to reproduce the drainage amount cumulated over the season given a site-specific calibration. Secondly, the field-scale SAMIR drainage estimates are aggregated over several sub-basins and compared against the drainage measurements at the outlet of the associated sub-basins. A strategy for calibrating SAMIR at the sub-basin-scale is proposed. The obtained results provide a first assessment of the potential of using a satellite-driven crop water balance to retrieve agricultural drainage at multiple spatial scales.
Experiences from co-developing hydrological forecasting systems across West Africa and eastern Siberia
Authors: Andersson Jafet , Gustafsson David , Lienert Judit , Kuller Martijn , Ali Abdou , Ibrahim Aishatu , Lebedeva Lyudmila , Boyakova Sardana , Arheimer Berit
Published: September 2022

Changes in hydrology and society are growing concerns in West Africa and eastern Siberia. Floods cause loss of lives, damaged infrastructure, and reduced food security. A warming climate impacts river ice conditions, affecting ice roads and summertime river transportation. Operational hydrological forecasting systems are needed to boost climate adaptation and resilience in these regions.

Within the projects FANFAR (www.fanfar.eu) and HYPE-ERAS (www.hype-eras.org), we work with key stakeholders (e.g. hydrological services and disaster managers) to jointly design, develop, operate and evaluate hydrological forecasting systems in each domain.

In West Africa, we used Multi-Criteria Decision Analysis (MCDA) to engage users in the definition and development of the forecasting system. MCDA was employed to clarify and prioritize objectives and system configurations. We found that the most highly prioritized objectives were: high accuracy, clear flood risk information, reliable access, and timely production and distribution of the information. The stakeholders also contributed to forecast evaluation, e.g. by comparing forecasts with field experiences and local observations. Skills vary, with higher probability of detection (POD) in unregulated areas, and lower POD downstream of wetlands and reservoirs. Overall, 75% of the West African agencies considered the forecast accuracy to be “good” or “very good”. This also translated into changed operational warning practices, e.g. in Nigeria where FANFAR information was used to save thousands of lives and property on at least two occasions in 2020.

In eastern Siberia, a key target variable to forecast is river ice breakup date. To this end we combined meteorological data (HydroGFD and ECMWF 1-10day forecasts), hydrological modelling (Artic-HYPE), and local observations of river discharge, water level, ice thickness and river ice breakup dates. In both 2020 and 2021, the model successfully predicted the river ice breakup in the Lena River near Yakutsk up to 10 days in advance. We also found a systematic trend of too early breakup in upstream locations, and too late breakup in downstream locations, indicating problems in ice melt and/or growth calibration.

Here we summarize the research design, results and experiences gained in FANFAR and HYPE-ERAS; indicating that operational forecasting can be useful to boost climate adaptation and resilience.
Exploring the link between drought indices and socio-economic impacts in East Africa
Authors: A. Odongo Rhoda , de Moel Hans , Wens Marthe , Coumou Dim , F.  Van Loon Anne
Published: September 2022

In recent years, East Africa (EA) has been affected by numerous drought events. To better understand the drought hazard and its implications, it is important to analyze the propagation of dry conditions through the hydrological system and identify at what point it leads to negative impacts on society. This way, we define drought events as dry conditions during which actual impacts are felt by communities (i.e. ‘impactful droughts’) rather than using a predefined relative threshold. This study explores the link between standardized and threshold-based drought indices and drought impacts in EA. Drought propagation from meteorological to soil moisture to hydrological drought to finally socio-economic impacts has been investigated in the data-rich regions around the world (i.e. Europe). However, not much has been done in data-poor regions (i.e. Africa), with very different climatic and socio-economic characteristics.

We identify meaningful indicators for region- and sector-specific impact occurrences, focusing on three impact types: crop yield and livestock losses, changes in pasture represented by Normalized Drought Vegetative Index (NDVI), and people affected. In this study, we link these impact types to various drought hazard indices calculated from time series of precipitation, evaporation, soil moisture and discharge for every administrative unit in Kenya, Ethiopia and Somalia. The standardized indices are used with varying accumulation periods (1,3,6,12,24,48 months) to find the best predictors. We use independent but complementary machine learning techniques (correlation, logistic regression and random forest modelling) to identify which indices link best to which drought impacts.

Using the variable threshold based analysis to analyse drought propagation in Isiolo county in Kenya, we find an increase in frequency and duration of hydrological droughts. This has been confirmed in other studies. The correlations and relationships between crop yield anomalies and indices are different in each of the administrative units. The findings in this research will lead to a greater understanding of the effects of drought hazards to communities, and contribute to improved drought monitoring and forecasting. This research can also form the basis for follow up work to explore the effects of adaptation options (i.e. irrigation) on drought hazard and impacts in East Africa.

 
Flood risk in China: observed changes and variability, management, and projections
Authors: Kundzewicz Zbigniew , Jiang Tong , Su Buda , Huang Jinlong , Wang Yanjun
Published: September 2022

Despite massive flood protection efforts, undertaken in China for millennia, disastrous floods continue to plague the country. We discuss flood hazard and flood risk in China, starting from observed changes and variability and then dealing with flood risk management and projections. We also refer to recognized unsolved problems in hydrology.

Observed changes and variability

First, we review results of change detection in observed records of variables related to water abundance, such as intense precipitation, high river flow, and flood damage in China. There is a strong inter-annual and inter-decadal variability, part of which may be due to climate variability, i.e. oscillation in the ocean-atmosphere system (ENSO - El Niño-Southern Oscillation and PDO – Pacific Decadal Oscillation). Particular large flood events (e.g. in 1998 and 2016) coincide with high values of ENSO indices.

Flood risk management

In its efforts to reduce flood risk, China has undertaken both structural and non-structural measures. An emergency manager's nightmare is when several serious emergencies (e.g., covid pandemic and flooding) happen at once, as in the unprecedented covid year 2020, when also record-breaking precipitation occurred in China. Yet, emergency management made it possible to constrain the flood loss.

Flood risk projections

In the warming climate, flood risk is likely to increase over much of China. Projections of flood loss changes for global warming scenarios from 1.5° to 4.0°C above the preindustrial temperature are presented. Projections are based on runoff simulations by a hydrological model driven by multiple downscaled general circulation models, the national GDP projected at shared socio­economic pathways, and the “intensity–loss rate” function. Flood losses in China are projected to soar in the future, particularly in lowland regions subject to rapid economic growth. There is a considerable difference between flood losses corresponding to two global climate policy target thresholds, 1.5° and 2.0°C, amounting to over US$60 billion.

Available flood projections for China are not consistent. Since the spread is large, projections have to be interpreted with caution, because of the impact on decisions related to climate change adaptation and flood risk reduction.
Water based epidemiology: a new wave?
Authors: Licznar-Fajardo Patricia , Bernaud Nicolas , Almakki Ayad , Diaby Aboubakar , Bouazizi Iman , Aujoulat Fabien , Toubiana Mylene , Masnou Agnes , Perrin Jean-Louis , Seguis Luc , Coulibaly Kalpy Julien , Jumas-Bilak Estelle
Published: September 2022

The screening wastewater for SARS-CoV-2 RNA has emerged in over 50 countries as a tool for tracking COVID-19 in population alongside traditional clinical monitoring, highlighting the usefulness of (waste)water-based epidemiology (WBE). Facing the significant problem of antimicrobial resistance (AMR), the monitoring of environmental AMR in epidemiologic aim is still poorly documented. As for COVID-19, WBE could be a proxy of AMR epidemiology in the context of lack of biological data i) at the community level in high income-country and ii) in lower middle-income country when resistance is often non-documented in human infections.

The aim of the study is to explore AMR from surface water running in or in the vicinity of two contrasted densely urbanized areas: Lez watershed, Montpellier, France and Djibi watershed, Abidjan, Cote d’Ivoire.

From June to November 2015, we collected 24 water samples, on 2 urban rivers in the Heart of Montpellier city: 2 sampling sites around the university hospital of Montpellier, 1 site downstream a public park and 1 site in a residential area. From July 2018 to November 2019, we collected 11 water samples in Djibi watershed (n = 11): 2 peri-urban sampling sites just outside of the Abidjan-urban area, 1 site downstream a wetland area and 1 site upstream the Aghien Lagoon.

In both cities, 100% of samples were positive for blaTEM, an endemic beta-lactamase-encoding gene. In Montpellier, blaSHV and blaCTX-M were positive in 21% of samples. In Djibi watershed, 54% and 27% of samples were positive to both blaSHV and blaCTX-M, respectively. For carbapenemase-encoding genes which confer emerging resistance to last resort antibiotics, data were more contrasted between Montpellier and Abidjan. These genes were sparingly detected in Montpellier when the carbapenemase-encoding genes blaKPC, blaNDM, blaOXA-48 were each detected in 27% of samples in Djibi watershed samples.

The worrisome epidemiology of AMR requires to identify AMR environmental reservoirs. AMR in urban settings could represent a hot spot in the dynamics of the epidemiological cycle of AMR. The development of WBE could help to cartography AMR at a small-territory scale to help for medical decisions, alerts and implementation of preventive measures.
Clustering for hydroclimatic extremes: a retrospective synthesis of the literature
Authors: Dogulu Nilay , Brunner Manuela Irene , Fischer Svenja , Knoben Wouter
Published: September 2022

Earth system processes have complex physics and are dynamically interlinked, making modelling and predictions difficult. In particular, current challenges for hydroclimatic systems are in understanding nonstationarity and heterogeneity driven by climatic and human influences. Hence, studying the spatial and temporal occurrences and dependencies of hydroclimatic extremes is becoming increasingly important for water resources management and hydrological services. 

Research efforts that address these issues for extreme hydrological events are large and diverse in their approaches and methodologies. In this respect, multivariate statistical methods such as clustering are approaches commonly used to reveal mechanisms affecting floods and droughts in relation to their trends and magnitude as well as their variability in time and space. Clustering is a convenient tool to analyze large hydrometeorological datasets because of its unsupervised nature. However, there are no structured insights for hydrologists to reflect on the principles and findings of data clustering for hydroclimatic extremes. 

This contribution sheds light on the why’s and how’s of clustering methods for floods and droughts based on a systematic review of the literature. Our aim is to provide a synthesis of hydrological themes and methodological concepts found in papers that investigate floods and droughts through data clustering. These insights are valuable for guiding future applications of clustering methods while enabling wider discussions on the knowledge gaps for modelling extremes in hydroclimatic systems.
Application of Geochemical and Isotopic Tools to Investigate Water Recharge and Salinization in a Coastal Phreatic Aquifer Suffering Severe Natural and Anthropogenic Constraints: Case of the Mornag Aquifer, NE Tunisia
Authors: Ben Alaya Mohsen , Taupin Jean Denis , Masadek Haythem , Ayari Inès , Patris Nicolas , Chabenne Najet , Toumi Beya , Melki Fathedinne
Published: September 2022

The determination of the origin of salinity in the superficial aquifer of Mornag (NE Tunisia), and the understanding of its hydrological and geochemical behaviours related to severe natural and anthropogenic constraints, were approached by the combined study of chemical elements and stable isotopes (2H and 18O). This study indicates that: (1) the high salinities of the superficial aquifer of Mornag are mainly explained by the dissolution/precipitation processes of evaporite minerals in the aquifer formation, (2) the present-day recharge during rainwater infiltration brings downward a high content of nitrates and other dissolved salts, (3) infiltration of untreated sewage from the main urban areas contaminates the aquifer, (4) two other sources of dissolved salts in groundwater exist, favoured by the intensive exploitation of the phreatic aquifer. The first one is due to mineralised water infiltration from Meliane Wadi where activities, mainly a cement factory, discharge their wastewater. Intrusion of marine saltwater is the second source of salinity caused by aquifer over-exploitation. This hypothesis is supported by the high chloride concentration (>240 meq/l), Br/Cl ratios (>1.8 ‰) and the piezometric level lower than sea level. On the other hand, the artificial recharge with low mineralization waters by the Mejerda-Cap Bon Canal and the natural recharge in the valley of wadi El Hma, contribute to a dilution of groundwater. The freshwater/saltwater mixing causes geochemical interactions modifying the water chemistry: cationic exchange, precipitation phenomena. Isotopic tools (2H and 18O) show that the water of this aquifer system is recharging by direct infiltration from the boundary and in the valley of wadis.
Using high-resolution stochastic climate ensembles to model the impacts and uncertainty of hydrology in mountainous catchments
Authors: Moraga Jorge Sebastian , Peleg Nadav , Molnar Peter , Fatichi Simone , Burlando Paolo
Published: September 2022

Hydrological projections in the context of a changing climate may display high levels of uncertainty, particularly when examining small temporal and spatial scales. To project the response of hydrological processes to the increasing global temperatures, scientists and practitioners rely on chains of numerical models, each contributing some degree of uncertainty to the overall outputs. Furthermore, the randomness intrinsic to climate phenomena, known as internal climate variability, contributes to the uncertainty of the hydrological projections in the form of an irreducible stochasticity. In this work, we quantify the impacts and partition the uncertainty of hydrological processes emerging from climate models and internal variability  for two mountainous catchments in the Swiss Alps and across a broad range of scales. To that end, we used high-resolution ensembles of climate and hydrological data produced using a two-dimensional stochastic weather generator (AWE-GEN-2d) and a distributed hydrological model (Topkapi-ETH). We quantified the uncertainty in hydrological projections towards the end of the century through the estimation of the values of signal-to-noise ratios (STNR). We found small STNR values (<-1) in the projection of annual streamflow for most sub-catchments in both study sites that are dominated by the large natural variability of precipitation (explains ~70% of total uncertainty). Furthermore, we investigated specific hydrological components that are critical in the model chain with detail. For example, snowmelt or liquid precipitation exhibits robust change signals, which translates into high STNR values for streamflow during warm seasons and at higher elevations, together with a larger contribution of climate model uncertainty, suggesting that an improvement of the involved models has the potential of significantly narrowing the uncertainty. In contrast, extreme flows show low STNR values due to large internal climate variability across all elevations, which limits the possibility of narrowing their estimation uncertainty due to a warming climate. This study demonstrates that high-resolution hydro-climatic ensembles enable the quantification of hydrological projections across spatial and temporal scales, which can be used to assess the potential for narrowing hydrological uncertainties.
Using of hydrological model and geospatial tool to assess climate change impact on the hydropower potential of the White Bandama watershed in Côte d’Ivoire (West Africa)
Authors: Kouadio Koffi Claude Alain , Amoussou Ernest , Diedhiou Arona , Coulibaly Talnan Jean Honoré , Coulibaly Houebagnon , Didi Regis , Savané Issiaka
Published: September 2022

This study was conducted in the White Bandama watershed (WBW) in Côte d’Ivoire (West Africa). The objective is to assess the impacts of future climate change (CC) on the hydropower potential (HPP) of the WBW. The methodology is based on coupling the SWAT (Soil and Water Assessment Tool) hydrological model with the Geographic Information System (GIS) QGIS to assess HPP on streams and evaluate the impacts of future CC on HPP of the watershed. Historical and climate projection data (precipitation, minimum and maximum temperature) for a set of three Regional Climate Models (RCM) from CORDEX-AFRICA (CCCma-CanRCM4, CCLM4-8-17 and REMO 2009) under RCP 4.5 were used. The biases of the ensemble mean were corrected by the Delta-change method. The relative change of streamflow discharge and HPP was assessed as the relative difference between the projection periods (2041-2070 and 2071-2100) and the reference period (1976-2005). The results showed a total of 22 future hydropower potential sites in the watershed. These sites were identified, geolocated and classified according to their potential capacity of generation in 82% as small (1 MW-25 MW potential capacity), 9% as medium (25 MW-100 MW potential capacity) and 9% as large (more than 100 MW potential capacity) hydropower. The climate models’ ensemble projected an upward trend for both the annual mean discharge of rivers and HPP of the WBW according to RCP 4.5 for the periods 2041-2070 and 2071-2100. The variation in flow rates is projected to have a positive impact on the HPP of the WBW. On the annual cycle, the months of August and September will record the highest monthly mean flows between 150 and 200 m3/s while the months from November to April will record low monthly mean flows on the WBW.
Characterizing major droughts in the context of dry period in Seyhan River basin, Turkey
Authors: Cavus Yonca , Aksoy Hafzullah , Stahl Kerstin
Published: September 2022

Seyhan River Basin has great importance for agricultural production, industry, energy and tourism sectors in Turkey. This study investigates temporal characteristics of meteorological droughts in the river basin at station-scale. Six major droughts were identified lasting 2 years at minimum from the average precipitation time series of 19 meteorological stations over the basin. We have adopted a methodology specifically for the river basin where local meteorological data are limited. The river basin was divided into four sub-basins. Each sub-basin was represented by one meteorological station which has a high correlation with the basin-average precipitation and also covers as many of the major droughts as possible. The Standardized Precipitation Index (SPI) was calculated for the meteorological stations at different time scales. The site-specific drought analysis elucidated the probability of mild, moderate, severe, and extreme droughts. The temporal occurrence illustrates that the river basin has experienced severe prolonged droughts every ten years on average. Mild drought dominates at each time scale and their frequencies increase with increasing time scale although severe and extreme events are observed with a higher probability in some major droughts. A significant change of the probabilities of the drought classes was not found in the representative stations, instead, we observed no consistent change. This analysis presented valuable information for the river basin on the temporal variability of the drought, and also shed light on the need for such analyses for regional drought adaptation and mitigation. Given the limitations that emerged on the determination of the representative stations, it would be advisable to consider additional data (such as remote sensing or satellite) in future studies to gain further insights into the temporal characteristics of drought.
Groundwater floods: linking the hydrodynamic characterisation of the karst aquifer at the Cadarache CEA centre (South of France) to the karst structure using statistical analysis of temperature.
Authors: Erguy Manon , Morilhat Sébastien , Artigue Guillaume , Trincal Julien , Johannet Anne , Pistre Séverin
Published: September 2022

Karst environments can be subject to rising water tables leading to rapid kinetic floods (a few hours) of great amplitude (about tens of meters) due to heavy rainfall. The Cadarache centre of the French Alternative Energies & Atomic Energy Commission (CEA), located in the French Mediterranean region (Bouches-du-Rhône), is subject to this type of underground flooding. For example, in November 2011, a cumulative rainfall of 225 mm in 72 hours was recorded at the centre, leading the Cretaceous limestone water table to a rise of nearly 40m, locally. The Cadarache centre of 1,600 hectares, has an exceptional hydrogeological monitoring network of 8 rain gauges and more than 400 piezometers, including 230 equipped with pressure/temperature sensors (115 measuring the Cretaceous aquifer). This dense monitoring network has enabled the acquisition of a large database (rainfall, water-level and temperature) over more than 15 years.

The goal of this study is to improve the understanding of the Cretaceous karst aquifer hydrodynamic behaviour by analysing temperature data. This would allow an improvement of groundwater floods prediction on the site. This variable is little studied but it can provide interesting information on the aquifer hydrodynamic response and specifically the role of karst structures on pressure and mass transfers at kilometer scale.

For this purpose, statistical analyses were conducted on measured temperature data in various piezometers defined as representative of the aquifer. Sorted temperature data and correlations analyses were made for different types of rainy events. This study aims to: i. Identify potential flow dynamics (deep or superficial flows), ii. Compare the temperature signal with those of rainfall and water levels.
Spatial and temporal variations in baseflow across headwater streams in the Jonkershoek valley, South Africa.
Authors: Mokua Retang Anna , Glenday Julia , Mazvimavi Dominic
Published: September 2022

An understanding of processes and factors accounting for spatiotemporal variations of baseflows is necessary for sustainable water resources management, particularly in semi-arid regions. Most of the southern part of the Western Cape Province of South Africa experiences a Mediterranean climate typified by long dry summers. Thus, baseflows of rivers draining areas with Table Mountain sandstones sustain water for humans and ecosystems. Processes and factors accounting for spatiotemporal variability of baseflows in these rivers are not adequately understood. This study aimed to determine the spatial and temporal variations of baseflows across streams in a mountainous region with Table Mountain Group. The study was done on three sub-catchments (1.0 to 2.5 km2) within the Jonkershoek Valley that drains the Hottentots Holland Mountains. A two-parameter recursive digital filtering method (RDF) was combined with the conductivity mass balance method (CMB) to separate baseflow from daily streamflows during the 1946-2019 period. The results of baseflow separation using the CMB method were used to calibrate the RDF parameter (BFImax).  The results showed that annual baseflow contributions varied spatially and the temporal variations were minor. Baseflows contributed 38 to 86 % of the annual streamflows. This wide range was unexpected considering that the sub-catchments were adjacent to each other and with similar geology. The variations could be explained by rugged topography and spatial irregularity of fracturing.  The results also showed seasonality in baseflow contributions. All three sub-catchments had as expected higher contributions from baseflow in the dry summer compared to wet winter. For  Bosboukloof baseflows contribute 89% of summer flows and 82 % in winter, Tierkloof 73 % and 60 %, while these were 50% and 34 % for the Langrivier.  Differences in topography and vegetation were considered to account for the spatial variations of baseflow contributions. For instance, Bosboukloof has the lowest slopes and most scree material and had the highest proportion of baseflow. The decreasing trend in monthly baseflow was noted during the driest months (Oct-Dec). This indicates the vulnerability of baseflow. Again, this was particularly the case for Bosboukloof, the site most fully afforested with pines that may tap into the deeper water sources.
Elite consumptions trigger water shortages: Modelling heterogeneous interactions between drought and society
Authors: Savelli Elisa , Mazzoleni Maurizio , Cloke Hannah , Di Baldassarre Giuliano , Rusca Maria
Published: September 2022

Cities face increasing droughts and water shortages as a result of extreme meteorological conditions and expanding human pressure. Future projections estimate that over one billion urban residents will experience severe droughts and water shortages in the near future. Most scientific and policy debates emphasize climate change, population growth and urbanization as the major forces at the genesis of this apocalyptic future. In this paper we argue instead that the root causes of urban water crises have to be retraced in the socioenvironmental injustices enmeshed with the development of a city. For it is not society as a whole that reshapes drought events or trigger water shortages. Usually, the most powerful groups with greater privileges and access to resources, are those who play a more prominent role in decisions on water resource use and allocation, thereby shaping the propagation of drought phenomena more significantly.  Accounting for the heterogeneity of human societies is thus key to understand the dynamics of human-water systems and, more specifically, the temporal and spatial propagation of drought phenomena. Sociohydrological models have not yet accounted for the manners in which heterogeneous social groups intersect with drought propagation. This work advances current analyses by modelling heterogenous interactions between human and water systems alongside their unequal influences on the transformation of drought into uneven water crises. The Day Zero crisis in Cape Town constitutes the empirical basis of this work. On the one hand Cape Town’s urban geography epitomizes an unequal landscape of water access and vulnerabilities. On the other hand, Day Zero exemplifies an extreme drought event that will most likely occur across many urban areas. Using a system-dynamic framework we retrace the uneven consumptions of water across Cape Town metropolitan area and estimate the drought resilience trajectories for different social groups. In turn, the socio-hydrological model explores the distinctive implication that each trajectory has for the sustainability of urban water systems. Ultimately, we argue that the unsustainable water uses of the elite can transform a meteorological drought into an urban water crisis.
A modelling approach for the assessment of irrigation water requirements spatial and temporal distribution in Greece
Authors: Soulis Konstantinos , Tsesmelis Demetrios , Psomiadis Emmanouil
Published: September 2022

Agriculture is an essential driving force in the management of water resources in Mediterranean countries as it has a dominant role in sustaining the growth of rural areas and at the same time represents by far the major water consumer. However, detailed assessment of the irrigation water requirements spatial and temporal distribution is challenging in the case of poorly gauged regions and especially in countries characterized by vast spatial and temporal variability like Greece, as water absractions in agriculture are spatially scattered, various water sources are used in each field, and the corresponding monitoring infrastructure is scarce.

This study presents a modelling approach for the assessment of irrigation water requirements spatial and temporal distribution in Greece on the basis of farm structure survey data, annual crop statistics and meteorological data. The proposed methodology is using an entirely spatially distributed, continuous hydrological model, in order to estimate the spatial distribution of the hydrological balance components at every point of the studied region as well as plants water deficit, and irrigation water requirements in a daily time step for the entire country. The developed approach is directly relevant to agricultural water policies design and evaluation. A special algorithm that is able to link each farm parcel polygon (over 6,000,000 polygons) of the spatial database of the Integrated Administration and Control System (IACS) with the nearest corresponding grid cell of the model was also developed. In this way, the developed approach utilizes all the information included in the IACS database (e.g. irrigation system, water source, applied agri-environmental measures) and provides very precise information at farm parcel level facilitating further analysis. Remote sensing data (Sentinel-Copernicus) and methods were also used for the validation of the crop patterns and of the irrigated fields in IACS database. The model was applied for 34 years reference period (1971-2004) at a daily time step. The obtained results were analyzed to identify spatial patterns and relationships, to investigate the temporal variability and the presence of trends and to provide detailed information on the water requirements of various crops and regions providing valuable information concerning agricultural water management.
Review of groundwater age of a transboundary aquifer system using 14C and 36Cl, case of the Continental Intercalaire aquifer in Algerian Sahara and Southern Tunisia
Authors: Hakimi Youcef , Orban Philippe , Deschamps Pierre , Brouyère Serge
Published: September 2022

The Continental Intercalaire aquifer (CI) (North Africa) is one of the largest transboundary aquifer systems in the world. It contains around 20 000 × 109 m3 of groundwater. The recharge comes mainly from the occidental part of the aquifer (southern foothills of the Saharan Atlas, Algeria) going east to the outlet area in South Tunisia. Several studies have showed, using 14C, that the principal recharge has taken place in Late Pleistocene and Holocene. However, doubts exist about the results of some of these studies as it was demonstrated that samples containing less than 10pmc could have been contaminated by modern air during the sampling procedure.

Based on a new field survey and the combination of new 14C and 36Cl data, the data of the previous studies are reviewed and new insights on the groundwater age are given. Close to recharge area, 14C age showed a significant amount of modern recharge (less than 2Ky B.P.). Any sample was found to have an age between 2 to 11Ky P.B. This means that during this period, Northern Sahara was dominated by a hyperarid climate. From 11 to 30Ky, it is observed that there is cyclicity of approximately 4Ky between given ages. This indicates that this period is dominated by an arid climate. Those 14C ages are calculated using F&G model.

Beyond 30 Ky P.B., the use 14C is critical because of its limited half-time. 36Cl is more relevant in that case (half-time equal to 301Ky). Samples close to recharge area, where 14C activities are sufficiently high and halite dissolution is not significant, are explored in order to define initial values of 36Cl. There, the initial 36Cl/Cl ratio is around 145 × 10-15 at/at and the initial chlorine concentration is around 175mg/L. Based on these values, the age of CI groundwater in the Great Oriental Erg basin and South Tunisia has to be 300 to 700Ky old instead of 40 to 50Ky calculated by 14C. This is supported by the ages calculated by 81Kr performed in the South Tunisia. However, the applicability limit of each technic has to be investigated.
Using the information on rainfall intensities to represent the variability in time of dominant processes in a hydrological model 
Authors: Astagneau Paul C. , Bourgin François , Andréassian Vazken , Perrin Charles
Published: September 2022

High-intensity precipitation events activate heterogeneous catchment processes and trigger flood events for which hydrological models are known to have limited predictive efficiency. The goal of this study is to find a way to inform the structure of a hydrological model on the time variability of dominant processes by using precipitation intensities as a surrogate for the activation of fast heterogeneous runoff processes. Accurately simulating flood generated by high-intensity rainfall events occurring on dry soil-moisture conditions, during or after the summer period, is a particular challenge (Astagneau et al., 2021), typically in southern France in a Mediterranean context.

Starting from the concept developed by Peredo et al. (2021), we made three modelling hypotheses on the explicit dependence of the storages and fluxes of a conceptual hydrological model on rainfall intensity rates. The modifications introduced increasingly modify model functioning as rainfall intensity increases, and are neutral in case of low rainfall intensity. We evaluated these hypotheses over a large set of 229 catchments in France representing a large variety of conditions, and we used a selection of 10,652 flood events to evaluate model performance. We used the GR5H model at the hourly time step as structural basis for model improvement. The relevance of our approach was assessed against several event and catchment characteristics (precipitation intensity and spatial variability, antecedent wetness conditions…) characterising very different flood generating processes.

Results showed significant improvements in the simulation of summer floods resulting from high-intensity rainfall events in several catchments of the Mediterranean area, while maintaining a limited level of complexity of the model structure.

References

Astagneau, P. C., et al., (2021). When does a parsimonious model fail to simulate floods? Learning from the seasonality of model bias. Hydrological Sciences Journal, 66(8), 1288–1305, https://doi.org/10.1080/02626667.2021.1923720

Peredo, D., et al., (2021). Investigating hydrological model versatility to simulate extreme flood events. Hydrological Sciences Journal, In Review.

 
A comparative assessment of event based and continuous rainfall runoff modeling for small and ungauged watersheds in Upper Blue Nile Basin, Ethiopia
Authors: Ayalew Dessalegn Worku , Petroselli Andrea , De Luca Davide Luciano , Apollonio Ciro , Grimaldi Salvatore
Published: September 2022

Ethiopia is characterized by observed rainfall and runoff data scarcity and consequently, still nowadays the rational formula is commonly applied for estimating the design peak discharge.

In this contribution we would like to verify if more advanced hydrological tools can be applied in such challenging conditions and we provide a comparative assessment of event based and continuous modeling approaches in estimating the design hydrographs for small and ungauged basins.

The event based approach is applied using the freeware software named EBA4SUB. It is a classical approach, specifically tailored for ungauged conditions, that consists in selecting a design rainfall event based on the Depth-Duration-Frequency (DDF) curves’ parameters, estimating the rainfall excess, and transforming it into the direct hydrograph. The continuous approach is applied using the freeware software named STORAGE and COSMO4SUB. STORAGE is designed for generating long and high resolution synthetic rainfall timeseries based on scarce raingauge observations, like daily rainfall amount and DDF parameters, while COSMO4SUB is the continuous rainfall–runoff module.

Results seem promising, in particular we verified that the Ethiopian small and ungauged watersheds can be modeled using advanced approaches that offer more complete design information for the practitioner as respect to the rational formula.
Impact of climate change on the flows of the Mitidja plain basins (Northern Algeria)
Authors: Meddi Mohamed , Abdi Ishak , Mahe Gil
Published: September 2022

The water deficit of recent decades has negatively affected agricultural production as well as surface and underground water resources in Algeria. To assess he impact of the future climate, for (2020-2060) and (2060-2099), on the water resources in several basins, we used analysis of historical average flows and compare them to those that could result from changes in temperature and rainfall. The methodology is based on the GRM2 model with the development of prospective climate change scenarios for both horizons. To study the impact of climate change on water resources, we used the climate projections of the CORDEX Arica model with the two pessimistic (RCP 8.5) and optimistic (RCP 4.5) scenarios. The results of the simulations of the future scenarios showed that the historical seasonality of precipitation fades away for the RCP 4.5 and 8.5 scenarios, and gives way to a more irregular pattern where rainfall is abundant in late autumn and spring.  Furthermore, this interannual evolution of the RCP scenarios indicates an increase in extreme events during these periods, thus increasing the risk of flooding considerably. The results of the simulations of the future scenarios showed a clear decrease of the flows. This decrease varies, for the seven sub-basins composing the plain, between 17 and 50% for the near future and the RC4.5 scenario. For scenario 8.5, the decrease varies between 37 and 55%. For the distant future (2060-2099), the reduction in flows varies between 27 and 45% for the near future and the RC4.5 scenario. For scenario 8.5, the reduction varies between 40 and 62%. We note that the basins which drain part of the Blidean Atlas present lower projected reductions for the future compared to the other basins of the plain. The two stations of the first two are located at the entrance to the plain.

 
Niger River Basin - Hydrological Modelling: Enhancing Framework Accuracy.
Authors: Koné Salif , Mahé Gil , Bamba Fatogoma , Paturel Jean Emmanuel , Dezetter Alain , Servat Eric
Published: September 2022

In hydrology, enhancing existing models are good ways to establishing efficient and accurate conceptual frameworks for hydrological simulation’s purposes. Methodologically, a framework that has two parameters and three input variables, called SimulHyd, is used in this study to modelling runoff data, on sixteen watersheds of the Niger River and its tributaries, from 1950 to 1999. Purposely, this paper focuses on a model’s inter-comparison method, which summarizes, in tables, then in graphics and in maps, the obtained results. We enhance modelling outputs both in modifying the former french’s GR2M model to obtain a model called SimulHyd model and in developing a semi-distributed modelling from a lumped modelling approach.  SimulHyd stands for Simulation of Hydrological systems.
Rôle hydrogéologique des linéaments dans l’optimisation de la productivité des forages en milieu de socle : cas de la région du Bounkani (Nord-est de la Côte d’Ivoire)
Authors: Bouadou Rock Armand Michel , Kouassi Kouamé Auguste , Gnagne Théophile , Coulibaly Adama
Published: September 2022

Abstract

The National Development Plan (PND) 2021-2025 reveals that access to drinking water remains the first priority of the population in Bounkani, a locality located in the middle of the ploughshare in the North-East of Ivory Coast. However, the mobilisation of this resource in the area is experiencing productivity difficulties. Thus, our study consists in demonstrating the influence of lineaments in the productivity of water wells in Bounkani in order to optimize their implementation. By relating the parameters of the lineaments to those of the boreholes, we obtained significant results between them. Statistical analysis of the lineament and borehole parameter data showed a significant correlation using the SOM (Self Organizing Map) method. Thus, the lineament density in relation to the borehole parameters yielded threshold values of 30 m, 40 m and 1.29.10-4 m2/s for weathering thickness, depth of drilled basement and transmissivity respectively. The inflow depths between 17 and 40 m represent the inflow depth range with good lineament density. The flow rate and specific flow rate gave thresholds of 6.2 m3/h and 0.69 m3/h/m respectively, which resulted in minimum lineament densities of 0.48 km/km2 for a cumulative length of 11.90 km for flow rate and 0.49 km/km2 for a cumulative length of 12.15 km for specific flow rate.

Keywords : Lineament, productivity, drilling, Bounkani region, Ivory Coastent, productivité, fourrage, région du Bounkani, Côte d'Ivoire
Exploring ways to improve agricultural water management on two Mediterranean irrigated systems : promises of wireless low-tech sensor networks 
Authors: Vandôme Paul , Belaud Gilles , Leauthaud Crystele , Moinard Simon , Mekki Insaf , Zairi Abdelaziz , Charron François , Leconte Julien , Ferchichi Intissar , Ajmi Tarek
Published: September 2022

Unsustainable use of water resources and climate change will exacerbate the already existing tensions on resources, especially in the Mediterranean context. Despite investments in modern, economically and energetically costly equipment, the performance of irrigated agriculture remains below expectations, notably because of the lack of water data available and limited use of decision support tools. Access to information at an unprecedented level, via easily accessible low-cost and low-tech sensors, may be a major lever for better identifying achievable performance gains, at different spatial and temporal scales, and for guiding the choice of actors towards more virtuous practices. To explore this hypothesis, two Mediterranean irrigated systems (Provence, France, and Cap Bon, Tunisia) with major water use efficiency issues were selected. The agrarian diagnosis revealed the main local needs and constraints that limit sustainable water management. Innovative technological systems (water sensors, automation, IoT networks) have been developed in response and implemented on field through a participatory approach. The technologies have been designed to be low energy, low-tech and low-cost, based on the hypothesis that the lack of accessibility - investment and O&M costs, system readability - of existing equipment was a brake to the dissemination of innovations in the agricultural sector, especially in the global South. We believe that the adoption of such technologies will contribute to improve irrigated systems sustainability by playing on several dimensions: supporting decision- making and promoting suitable and sparing water use; maintaining agricultural production and economic results of production systems by reasoning the inputs; improving water users labour conditions; generally, accompanying the transition towards more virtuous practices, by making the quantification of the flows, and thus the understanding and experimentation, accessible to the irrigated territory stakeholders. The performance gains achievable with these innovations, heeding their inherent weaknesses (eg. lower robustness and accuracy), and the potential impacts of their adoption at larger scale remain to be assessed in an integrated way.