Modeling is an efficient approach for predicting microbial water quality and suggesting related management practices. Escherichia coli or enterococci concentrations are commonly used to indicate microbial contamination and characterize microbial water quality. Small watersheds provide drainage into first- or second-order creeks, exhibit significant variation in land use, management, and conservation practices. Modeling microbial water quality in the small watersheds can help account for and mitigate the heterogeneity within larger hydrologic response units. A model for microbial water quality should incorporate key hydrologic components such as runoff, in-stream water fluxes, and meteorological inputs such as precipitation, air temperature, and solar radiation. Additionally, animal waste management, including the quantity and application schedule, are also important for microbial water quality simulations. The Agricultural Policy Environmental eXtender is a useful tool for hydrological, meteorological, and management drivers of microbial water quality, as it has been developed for small watersheds. Major microbial fate and transport processes include animal waste deposition, degradation, erosion, survival on soil, release from waste and transport by rainfall or irrigation, and microbial survival and resuspension in water or sediment. These processes can be simplified, for instance, by modeling proportional release of the indicators and animal waste during erosion. We can also use a two-phase survival model for manure and temperature-dependent rate of microbial survival in surface waters. Animal waste aging should also be considered in the microbial model, as daily bacterial survival and erodibility are influenced by it. The microbial module in APEX was used to the headwater watershed of Conococheague Creek in Pennsylvania, USA. The total watershed area is 34321.6 ha, with 15 subareas and the dominant land use is deciduous forest. Three years of hourly stage observations with rating curves and weekly E. coli concentrations at the outlet were available. The primary source of E. coli was animal waste from white-tailed deer, with an average density of 19 deer per square kilometers. Deer population dynamics reflect seasonal changes including fawn births, predation, pre-hunting, and post-hunting population phases. E. coli concentrations at the watershed outlet varied seasonally, ranging from 5 to 500 CFU (100 mL)^-1. The model reasonably captured the temporal fluctuations in E. coli concentrations at the outlet. Ongoing improvements to the model include incorporating deer behavior patterns, animal waste preservation in snow, and runoff during snowmelt.

How to cite: Lee, J., Harriger, D., Hong, S., Jeong, J., Guber, A., Hill, R., and Pachepsky, Y.: Modeling fate and transport of indicator microorganisms in small rural watersheds, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7321, https://doi.org/10.5194/egusphere-egu25-7321, 2025.

North China Plain is one of the agricultural region in the world with severe water shortage. Flood irrigation is still the most popular irrigation method in NCP, and have caused very low water use efficiency. Groundwater depletion becomes the most concerned issue for sustainable development. To determine the water & nitrate fluxes is important for better water resouces management. We built up a 48-m in depth of cassion and a 36 lysimeter group for this purpose to study the water budget and water/nitrate movement in the deep vadose zone. In this study, we will present the observation facts using these two facilities to reveal the differences between water transport velocity and celerity in the deep vadose zone of nearly 50 meters. This is the first time to observe the variations or responses of soil potential, moisture, temperature, and electricity conductivity to water inputs from land surface, such as extreme rainfall, directly in the deep vadose zone of 48 meters. We  will also present the fresh observation results from the 36 lysimeters about ET and drainage fluxes of different cropping patterns, with different watering and fertilizing treatments. The latter experiment could provide useful information for improving the water/nutrients management for different cropping systems in NCP, and will be beneficial to sustainable groundwater management at the aspects of quantity and quality. The results of the observatoins using these new facilities is presented at international conference at the first time. We hope it could be interested by the colleagues worldwide. 

How to cite: Shen, Y., Zhang, Y., Min, L., Wu, L., Li, H., and Li, H.: Water/nitrate fluxes and tranport in deep vadose zone of typical irrigated cropland in North China Plain, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6894, https://doi.org/10.5194/egusphere-egu25-6894, 2025.

The growing need for environmentally friendly wastewater treatment technology has prompted researchers to look into natural alternatives. Among these, algal-bacterial systems have received attention for their capacity to combine biological treatment and biomass production. This study focuses on the use of algal-bacterial flocculent biomass for wastewater treatment in a 400 L pilot-scale raceway pond, with a focus on its potential as a sustainable option for lowering environmental impacts. The synergistic interactions between algae and bacteria in the consortia improve nutrient removal from wastewater, while also providing biomass for future use. The aim was to develop a high-concentration flocculent algal-bacteria biomass. The raceway system was placed in a greenhouse with water temperature 32±8^oC for about 230 days. The pilot-scale experiment evaluates treatment efficiency of domestic wastewater in a batch mode procedure.  The removal of chemical oxygen demand, ammonia, nitrate, and total phosphorus was over 95%.  The biomass concentration stabilized at about 4 g/L after 70 days of operation. The implementation of algal-bacteria flocculent processes for the treatment of domestic or source-separated domestic wastewater shows great promise as a low-cost, sustainable, and efficient solution.

How to cite: Kakavas, D., Biliani, S., and Manariotis, I.: Long-term behavior of syntrophic algal-bacterial biomass in a pilot-scale raceway pond treating domestic wastewater , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6521, https://doi.org/10.5194/egusphere-egu25-6521, 2025.

Climate change significantly impacts water quality and quantity, intensifying extreme weather events, such as floods, droughts, and heat waves. Rising temperatures can increase humidity and dryness, disrupt the water cycle, cause saltwater intrusion into upstream lakes due to sea-level rise, and reduce dissolved oxygen in rivers, thereby deteriorating freshwater quality. Thus, accurate prediction of key climate variables, such as precipitation and temperature, is essential for mitigating detrimental impacts. This study evaluates three modeling approaches, including Process-Based (PB) models, Deep Learning (DL) models, and Process-Based Deep Learning (PBDL) models, to highlight their strengths and limitations.

Our assessment shows that PB models, which are based on physical laws and account for complex interactions between the atmosphere, land, and water bodies, require high parameterization and computational simplifications, which can lead to inaccurate results. DL models can uncover complex relationships from large datasets. They are effective in co-predicting variables, simulating General Circulation Model (GCM) outputs, optimizing PB models, and filling spatiotemporal data gaps. However, their performance depends on the availability of extensive temporal-spatial data, particularly for extreme events. The other group, PBDL models, known as physics-informed or hybrid models, can integrate the strengths of PB and DL approaches. Indeed, these models consider physical laws, such as mass balance and energy conservation, while leveraging DL's pattern recognition capabilities. Even with limited data, these models achieve superior predictions by combining pre-trained PB model outputs, which reduces computational demands.

Although these methods are used to evaluate (actual) evapotranspiration, snowmelt rate, soil permeability, hydraulic conductivity, and the effect of a warming climate on water temperature and streamflow, the interconnected influences on water systems, especially water quality indicators such as dissolved oxygen, heavy metals, nutrients, and water clarity, remain underexplored, presenting a critical research gap. Findings confirm that incorporating simultaneous predictions from DL models with proper variable selection and hyperparameter tuning can further enhance model robustness. Advancing PBDL models through integrating well-calibrated hydrological models, expanding spatiotemporal data coverage, and improving measurement accuracy yields more reliable climate change predictions and bolsters sustainable water resource management strategies.

To identify promising solutions, researchers are encouraged to address the non-stationary behavior of natural systems, considering not only meteorological factors (e.g., wind speed and solar radiation) but also the compound impacts of anthropogenic climate change on water resources. Additionally, selecting appropriate models and coupling them can improve an overall understanding of climate and water system interactions.

How to cite: Karimnejad, A., khorashadi zadeh, F., and Moghim, S.: Assessment of climate change-water resources interaction by different models , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7025, https://doi.org/10.5194/egusphere-egu25-7025, 2025.

Taiwan plays a crucial role in the global supply chain as a major semiconductor manufacturer. Semiconductor production depends heavily on water resources, making the stable supply of industrial water from upstream reservoirs essential to maintaining the global supply chain. However, international water risk assessments often fail to capture Taiwan’s regional hydrological variations due to their large spatial scale, obscuring the real physical and financial risks related to water resources under climate change. Given Taiwan's distinct climate with pronounced wet and dry seasons, short and fast-flowing rivers, and limited surface water retention, reservoirs are critical for regulating water supply. This study employs hydrological models and reservoir operational models to develop a reservoir risk assessment framework, which is the foundation of water resource management. The assessment procedure aids in understanding regional climate-related water risks. Utilizing this assessment tool to adjust reservoir operations will offer strategies for rational water resource management and enhanced climate resilience.

How to cite: Lai, Y.-P. and Lee, T.-Y.: A Framework for Assessing Water Availability and Risk of Reservoirs in Taiwan under Climate Change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12004, https://doi.org/10.5194/egusphere-egu25-12004, 2025.

The Peruvian coast is undergoing significant landscape transformations driven by environmental and climatic factors, with extreme precipitation events exerting a pivotal influence on the morphology of river channels and floodplains. This study leverages advanced technologies, including unmanned aerial vehicles (UAVs) and post-processing kinematic (PPK) techniques, to address these dynamic changes. The methodology involves co-registering point clouds using ground control points (GCPs) to produce high-resolution and temporally stable digital elevation models (DEMs).The research focuses on a 0.5 km² area within a coastal basin in Peru, with data collection scheduled across two distinct timeframes. The primary objective is to identify areas exhibiting minimal elevation changes and quantify rates of erosion and sediment deposition over a defined period. Specifically, the study measures erosion in gullies and riverbanks, as well as sediment deposition, enabling the estimation of volumetric changes in cubic meters (m³). These findings are critical for advancing the understanding of regional geomorphological processes and informing the development of effective management and mitigation strategies. By employing UAVs and PPK techniques, this research delivers actionable insights into sediment dynamics, supporting sustainable water resource management and land use planning in Peru’s coastal basins. Ultimately, the study contributes to mitigating the adverse impacts of extreme precipitation on the region’s landscapes.

How to cite: Cubas-Arteaga, E. and Cárdenas-Gaudry, M.: Monitoring Geomorphological Changes in the Peruvian Coast Using UAVs and PPK Techniques, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15513, https://doi.org/10.5194/egusphere-egu25-15513, 2025.

Analyzing deep soil water use (DSWU) response to precipitation change and its impact on tree physiology is necessary to disentangle tree mortality mechanisms, especially in drylands. In this study, a process-based model parameterized with in-situ measured fine root distribution data for 0-2000 cm and a root-cutting (below 200 cm) numerical experiment were used to explore DSWU strategies across different precipitation years and its contribution to total water consumption, as well as its relationship to tree gas exchange traits in mature apple (Malus pumila Mill) and black locust (Robinia pseudoacacia L.) plantations in both a wetter (Changwu, 583 mm) and a drier (Yan’an, 534 mm) sites on China’s Loess Plateau. Results showed that DSWU at 200-2000 cm depth in different precipitation years of both species mainly occurred during the early growing seasons. On average, DSWU contributed 22.9% and 25.1% to the total water consumption of apple trees and black locust, respectively, and its contribution increased to 26.0% and 36.7% in extremely dry years. Moreover, the lack of DSWU significantly decreased (p<0.05) stomatal conductance (by 16.9%, 16.9%, 47.4% and 11.4%, respectively) and photosynthetic rates (by 37.1%, 20.1%, 28.5% and 16.4%, respectively) of Changwu apple trees, Yan’an apple trees, Changwu black locust and Yan’an black locust in extremely dry years. Similar reductions occurred only in Yan’an for both tree species in normal years. In contrast, no significant differences were found in gas exchange traits in extremely wet years. Our results highlight that DSWU is an important strategy for plantations in deep vadose zone region to resist extreme drought.

How to cite: Zhao, X., Shao, X., and Gao, X.: Deep soil water use can compensate drought effect on gas exchange in dry years than in wet years for dryland tree plantations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1681, https://doi.org/10.5194/egusphere-egu25-1681, 2025.

Concerning water supply in mountainous regions where surface water plays an important role, the understanding of lake stratification or even hypolimnia can be important for water treatment actions.

The historical dam reservoirs were used for the continuous water supply to the ore mines in the Upper Harz Mountains. The first reservoirs were built in the 16th century. The dam heights reach up to 15 m and the stored water volumes are between 10,000 and 600,000 m³. There are about 70 of such lakes around Clausthal-Zellerfeld. Today only few of them are directly used for drinking water supply in the surrounding communities.

Hydrogeochemical data of the lakes have been investigated for about ten years. The specific electrical conductivity (SEC) of the lakes’ surface water ranges between 30 and 280 µS/cm (Bozau et al., 2015, Schäfer et al. 2024). Three lakes (Kiefhölzer, Langer and Oberer Grumbacher Teich) differing in chemical composition and morphometry (area, mean depth and maximum depth) were selected for the investigation of seasonal changes in the water columns. Samples were taken by boat with a Ruttner sampler. SEC and pH were measured on the boat. The titration for HCO₃ was done directly after sampling. The main ions were analyzed by ion chromatography and the trace elements by ICP-MS.

Stratification during summer could be clearly observed in all of the three lakes. The degradation of organic material and accompanying redox reactions are seen in the measured pH, SEC, HCO₃^-, Fe(II), NO₃^-, NH₄⁺ and SO₄^2- concentrations. Each lake showed a characteristic temporal and chemical behaviour. The development of an anoxic hypolimnion above the lake sediments was obvious in the two shallower lakes Langer Teich (max. depth ~ 5 m) and Kiefhölzer Teich (max. depth ~ 7 m) as being accompanied by H₂S-odor in the water column starting ~ 1 m above sediment.  This feature was absent in the deepest lake Oberer Grumbacher Teich (max. depth ~ 9 m), which also showed weaker increase of SEC and HCO₃^- in the profile. The aeration of the hypolimnion started in autumn leading to a well mixed, chemically uniform water column. 

Bozau, E., Licha, T., Stärk, H.-J., Strauch, G., Voss, I., Wiegand, B. (2015): Hydrogeochemische Studien im Harzer Einzugsgebiet der Innerste. Clausthaler Geowissenschaften, 10, 35-46.

Schäfer, T., Bozau, E., and Hutwalker, A.: Reservoir lakes in the Upper Harz Mountains (Germany): GIS Implementation and hydrochemical development, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5085, https://doi.org/10.5194/egusphere-egu24-5085, 2024.

How to cite: Schäfer, T., Bozau, E., and Hutwalker, A.: Seasonal Changes in Water Columns of Historical Reservoir Lakes in the Upper Harz Mountains (Germany), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2730, https://doi.org/10.5194/egusphere-egu25-2730, 2025.

Coffee-banana intercropping, widely practiced by smallholder farmers in South America and East Africa, is recognized for its potential to combine sustainability with resilience to climate change. This practice promotes crop diversification, but may also enhance water-use efficiency. However, its effectiveness may vary depending on the local conditions and agricultural practices. The lack of quantitative data on drought stress and the complexity of interactions within coffee-banana intercropping systems pose significant challenges in modelling and optimizing water use efficiency. This study aims to develop and refine innovative methods to assess drought stress in coffee-banana intercropping systems, with a focus on stable carbon isotope values (δ¹³C), leaf temperature, and mid-infrared spectroscopy (MIRS). While stable carbon isotope analysis is a promising tool, its application may face challenges due to factors such as crop size, canopy heterogeneity, banana-coffee canopy overlapping, leaf age, orientation, or position (leaf morphological aspects), leading to variable competition for water and light. These factors affect the way sampling for stable carbon isotope and leaf temperature analysis should be conducted, in addition to physiological differences between coffee genotypes, agronomic practices, and complexities in data interpretation. Sampling and analytical protocols must be adapted to address these factors and their effects, while accounting for leaf morphology and microenvironmental parameters. Initially, we evaluated the influence of these factors on δ¹³C variability in coffee leaf samples, in addition to their correlation with leaf temperature. Samples were collected from a 0.15 hectares experimental farm managed by the Agricultural Research Company of Minas Gerais (EPAMIG) in Brazil, an intercrop of Arabica coffee and Cavendish banana plants at 3.6 a distance apart. Coffee leaves were sampled using a metal puncher and leaf temperature was measured using an infrared thermometer, considering varying levels of sunlight exposure. Ten plants of the Catuaí Vermelho IAC 44 coffee cultivar were randomly selected: five under conventional management (chemical fertilizers) and five under organic management (cattle manure). For each plant, samples were taken at three different heights (Top, Middle and Bottom), three orientations (South, East and West), and two branch sides, including young and mature leaves, resulting in 36 leaves per plant. The poster presents key findings on the variability of δ¹³C isotopes in coffee leaves within a banana-coffee intercropping system and their relationship with leaf temperature under different management practices (organic and conventional). This presentation highlights the observed effects of leaf sampling parameters, such as age, position, and sunlight exposure, on δ¹³C values, as well as the implications for improving drought stress screening methodologies.

How to cite: Bernardo, T., Vezzone, M., Felizardo, J. P., Rodrigues, C., Moura, W., Gomes Soares, L., Sebastião Sant' Anna Andrade, H., Victor Vieira Queiroz, C., Nakamya, J., Vantyghem, M., Dercon, G., and Meigikos dos Anjos, R.: Unravelling Sampling Bias in δ¹³C Isotope Variability in Coffee-Banana Intercropping for Drought Stress Assessment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9556, https://doi.org/10.5194/egusphere-egu25-9556, 2025.

Transpiration significantly depletes terrestrial subsurface water stores and plays a crucial role in 
the hydrological cycle. While extensive research has been conducted in the Maimai M8 catchment 
(New Zealand) and across many catchments on streamflow generation processes and streamflow 
sources, we still know little about the sources of transpiration and when transpiration and 
streamflow sources are hydrologically connected. Here we leverage M8, a long-term studied 
catchment with well-described streamflow generation mechanisms, to investigate the transpiration 
source water of Pinus radiata and its connectivity to streamflow sources. We combined monthly 
observations of isotopic signatures (δ¹⁸O and δ²H) of xylem, bulk soil water, mobile water, 
subsurface flow, and stream water with continuous monitoring of tree water stress across a 
hillslope to answer: (1) What is the seasonal source of transpiration at Maimai? And (2) how does 
transpiration source water interact with streamflow sources? Our data showed that transpiration 
sources across the hillslope were not distinct but changed seasonally. During summer, when trees 
showed greater periods of water stress, trees relied on shallow soil water. In contrast, during the 
winter, trees’ isotopic signatures plotted along the local meteoric water line (LMWL), overlapping 
with mobile soil and stream water. Xylem isotopic signatures were not statistically distinct from 
stream signatures in the winter, contrasting with distinct isotopic signatures during the summer. 
Our results showed that transpiration source water in the Maimai M8 catchment changes 
seasonally, influenced by tree water stress and wetness conditions. Overall, our findings suggest 
an ecohydrological connectivity between transpiration and streamflow sources during winter 
months in this wet temperate climate.

How to cite: Simmons, C., Dudley, B., McDonnell, J., and Nehemy, M.: Seasonal transpiration source water and ecohydrological connectivity with streamflow sources in the Maimai M8 Catchment , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14282, https://doi.org/10.5194/egusphere-egu25-14282, 2025.

This work introduces a new webGIS tool to estimate the Crop Water Requirement (CWR), using time series of satellite images and meteorological data, at high spatial resolution and a global scale. This CWRweb tool provides users with information on the temporal evolution of the CWR, as a first approach of the crop evapotranspiration, as well as other parameters of interest. This process is implemented via web and requires no proficiency in remote sensing.

The implemented calculation of the evapotranspiration under standard conditions (ETc) stands on the robust FAO-56 methodology, based on the relationship between the Crop Coefficient and the Reference Evapotranspiration (Kc-ETo). The CWRweb tool adopts the single crop coefficient approach, combining the effects of both, crop transpiration and soil evaporation into a single coefficient (Kc). These Kc values derive from the NDVI time series of Sentinel-2 multispectral satellite images, for a broad range of crops (horticulture, woody crops, and other crops) and natural vegetation, assuming a general component for the soil evaporation.

The CWRweb tool benefits from the potential of the Sentinel-2A & B satellite constellation to provide users with free time series of images with a spatial resolution of 10m × 10m and a revisit frequency of 2-3 days. The high frequency of Sentinel-2 imagery allows to obtain daily Kc values through interpolation of NDVI data from cloud-free images at high spatial resolution. Online access to massive databases of satellite images, such as those of the Copernicus Data Space Ecosystem program (https://dataspace.copernicus.eu/), together with recent advances on meteorological numerical models to provide global ETo layers at different gridding size, are boosting the operational use of the CWRweb tool.

The CWRweb tool runs and graphically displays daily ETc, as well as NDVI, Kc, and ETo values used in its calculation, for a selected time interval. Results can be provided at both, field and pixel scales. An assessment of the CWRtool was conducted by comparison against the OpenET tool on a selection of crops-sites in California, USA. An average uncertainty of RMSE=0.9 mm·d^-1, with a negligible bias, was obtained in a performance analysis using the OpenET ensemble outputs as a reference, using 15 different locations, and data for the period 2016-2024. These results are promising and reinforce the potential of the CWRweb tool for the operational estimation of global evapotranspiration at a high spatial resolution.

How to cite: Campoy, J., Sánchez, J. M., Beltrán, A., Pérez, Y., Molina, A., and Calera, A.: Remote-Sensing based Global Evapotranspiration estimates at high spatial resolution through Sentinel-2 satellite imagery and meteorological data. The CWRweb tool., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12878, https://doi.org/10.5194/egusphere-egu25-12878, 2025.

Reducing the carbon footprint of residential buildings has become increasingly crucial for decarbonizing the construction sector globally. Implementing various sustainable practices is essential for attaining carbon neutrality and addressing climate change. Therefore, integrating Green Concrete Materials (GCMs) and Nature-Based Carbon Dioxide Removal (Nb-CDR) strategies represents sustainable solutions for reducing CO₂ emissions and achieving a circular economy (CE) in residential buildings. In this regard, the study aims to investigate the potential synergies of sustainable building materials and eco-friendly building systems by utilizing Recycled Aggregate Concrete (RAC), Fly Ash (FA), Green Roof system (GR), and a Green Façade system (GF) as an attempt for reducing CO₂ emissions for residential building sector significantly. The Design for Integration (DFI) approach is used to develop novel sustainable solutions for future residential buildings and investigate how integrating different strategies can substantially enhance the overall benefits of reducing the sector’s carbon footprint. The system dynamics are used to create a simulation model that can estimate the synergies between GCMs and Nb-CDR to reduce CO₂ emissions and clarify the inner variables’ relations using Vensim software. Thereby, a comparative analysis between the traditional and optimized building designs is applied to the new Egyptian residential buildings. The results indicated potential integration could significantly lower a building’s CO₂ emissions during the building life cycle compared to conventional solutions. Additionally, it promotes circularity performance and decarbonization for the construction sector. The study demonstrated that incorporating eco-friendly materials and green building systems requires more attention in the early design stage of residential buildings. Public awareness should be considered, and new policies should be implemented to promote incentives and influence the effectiveness of Nb-CDR with GCMs in the future.

 Keywords:  Residential Buildings; Green concrete; Nb-CDR; System Dynamics; Design and simulation; CO₂ emissions.

How to cite: Marey, H., Kozma, G., and Szabó, G.: The Potential Synergies Between the Integration of Green Concrete Materials and Natural-Based Carbon Dioxide Removal Strategies in Residential Buildings Sector, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9762, https://doi.org/10.5194/egusphere-egu25-9762, 2025.

Probable Maximum Precipitation (PMP) is a key input in the design and risk assessment of critical infrastructures such as large dams and nuclear power plants. Traditionally, PMP is computed as a fixed upper bound of the precipitation assuming a stationary climate. However, due to climate change, the stationarity assumption may not remain valid in the future. Limited attempts have been made in the past to develop methods for estimating PMP by accounting for non-stationarity in the related hydroclimatic variables. In view of shortcomings associated with those methods, three new nonstationary models are proposed and their potential in determining PMP in a changing climate is illustrated through application to three major flood-prone river basins in India. In this analysis, historical records of precipitation, surface temperature and relative humidity, and their future projections corresponding to eleven CMIP-6 SSPs (Coupled Model Intercomparison Project-6 Shared Socio-economic Pathways) were utilized. The results indicate that PMP estimates obtained using the proposed nonstationary models are significantly higher than those obtained from their underlying conventional stationary model, especially for high-emission scenarios in the near future. The results obtained from this study could be utilized to update historical PMP values and to determine the increase in risk associated with the corresponding probable maximum flood.

How to cite: Bhatt, J. and Srinivas, V. V.: Revising probable maximum precipitation (PMP) estimates under changing climate , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4786, https://doi.org/10.5194/egusphere-egu25-4786, 2025.

Per- and polyfluoroalkyl substances (PFAS) represent a significant and persistent threat to water quality worldwide, posing major challenges due to their chemical stability, resistance to conventional treatment methods, and documented health risks. These contaminants, once released, persist in the environment for extended periods and have been detected in drinking water, surface water, groundwater, and even human blood. Conventional remediation techniques, such as granular activated carbon (GAC) adsorption, ion-exchange resins, and reverse osmosis, often struggle with shorter-chain PFAS compounds and merely shift contamination from one medium to another. As climate change intensifies rainfall and extreme weather, PFAS transport through runoff becomes increasingly likely, heightening the need for advanced treatment solutions.

In response to this pressing need, our work investigates an innovative remediation approach employing far-UVC radiation (222 nm) delivered by krypton chloride (KrCl*) excimer lamps. Unlike conventional low-pressure UV (LPUV) systems, which typically emit at 254 nm, or vacuum UV (VUV) systems at 185 nm, far-UVC at 222 nm offers a unique balance of high photon energy and minimal absorption by water. This balance enables deeper penetration into the water matrix and provides the potential for enhanced PFAS photolysis and subsequent defluorination. Preliminary findings indicate that certain PFAS, previously resistant to direct UV photolysis, may be more susceptible under far-UVC irradiation, thereby opening a promising new pathway for their degradation.

While direct photolysis at 222 nm shows considerable promise, integrating far-UVC treatment with electrochemical oxidation (EOP) and UV-advanced reduction processes (UV-ARP) can further enhance PFAS degradation. EOP effectively removes dissolved organic matter (DOM), which often competes with PFAS for reactive species, thus reducing the overall efficiency of PFAS degradation. Meanwhile, UV-ARP generates highly reactive hydrated electrons (e_aq⁻) capable of breaking down PFAS. Although adding sulfide ions is one way to produce e_aq⁻, applying a sufficiently negative potential at a GAC cathode can also generate e_aq⁻ without introducing sulfur species. This approach requires careful consideration of competing hydrogen evolution reactions (HER), which may be thermodynamically unfavorable at a GAC cathode. By combining EOP with in situ e_aq⁻ generation in UV-ARP, PFAS can be more effectively targeted and degraded without adding extra chemicals. This integrated treatment aims to meet or surpass stringent U.S. Environmental Protection Agency (EPA) standards, ultimately facilitating the development of a portable, cost-effective, chemical-free, point-of-use water treatment system. Such a system would be especially valuable for communities experiencing environmental vulnerabilities, such as those in Puerto Rico studied by the PROTECT Center at Northeastern University, where limited infrastructure, contaminated water sources, and heightened susceptibility to adverse health outcomes underscore the urgency for sustainable PFAS remediation solutions.

By advancing the understanding of PFAS photolysis under far-UVC radiation and harnessing the combined power of EOP and UV-ARP, this work endeavors to provide an innovative solution. In doing so, it seeks not only to bridge the gap between laboratory research and practical application but also to enhance the resilience of water treatment systems against emerging contaminants and the challenges posed by a changing climate.

How to cite: Arekhi, M., Ehsan, M. F., and Alshawabkeh, A.: Enhancing PFAS Degradation through Far-UVC Photolysis Coupled with Electrochemical Oxidation and UV-Advanced Reduction Processes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2175, https://doi.org/10.5194/egusphere-egu25-2175, 2025.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a class of anthropogenic organic chemicals that have emerged as persistent environmental contaminants. In 2013, widespread contamination of surface water, groundwater, and drinking water was identified in three provinces of the Veneto Region, northern Italy, significantly impacting nearly 30 municipalities. The contamination was mainly caused by industrial discharges of fluorinated chemicals into local water bodies from a chemical manufacturing facility and other industrial activities. While the production and use of PFAS chemicals have since been regulated in the region, concerns remain regarding the long-term persistence of PFAS in groundwater due to their environmental stability. This study analyzes groundwater monitoring data collected over a 10-year period (2013–2023) to evaluate temporal trends and spatial variability in PFAS concentrations across the region. The dataset contains concentrations of key PFAS compounds, including perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and other prevalent species, collected from multiple groundwater monitoring wells. We used statistical methods to analyze temporal patterns and geostatistical methods for spatial mapping of contamination hotspots. Preliminary findings indicate heterogeneous spatio-temporal trends among various PFAS compounds, with some exhibiting significant variations over time and location, while others remained relatively stable. These findings provide valuable insights into the behavior of PFAS in groundwater, aiding in developing future monitoring strategies and mitigation efforts.

How to cite: Younas, A., Aruffo, E., Lanuti, P., Tariq, M., and Di Carlo, P.: Spatio-Temporal Variability of PFAS Compounds in Groundwater in the Veneto Region, Italy (2013–2023), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12081, https://doi.org/10.5194/egusphere-egu25-12081, 2025.