Rivers provide essential ecosystem services, supporting biodiversity, regulating water flow, and supplying resources important for human societies. However, anthropogenic pressures and climate change are increasingly impacting riverine ecosystems, leading to widespread decline in water quality. While substantial progress has been made in understanding long-term water quality trends, our understanding of water quality variations within different catchments is still limited. Moreover, there is a lack of insight into how these variations relate to each other across catchments, making it difficult to predict and manage water quality dynamics at larger spatial scales. Most studies to date have focused on individual sites or small catchment networks, providing valuable insights into site-specific functioning. However, these site-specific studies only offer limited support for understanding and predicting water quality dynamics across larger spatial scales and complex river networks. Understanding the drivers of these complex water quality dynamics is crucial for effective river management and the protection of aquatic ecosystems.
This study addresses this gap by analysing high-frequency water quality data from over 50 sites across England. We focus on key parameters, such as dissolved oxygen, turbidity, pH, and chlorophyll-a, and investigate how water quality fluctuates on diurnal, seasonal, and event-based timescales. We explore the role of event and catchment conditions—such as precipitation, temperature, antecedent conditions, and seasonal variation—in driving water quality variability, and how their importance shifts across time and space.
This research advances our mechanistic understanding of the complex and dynamic processes that govern water quality in rivers across England, with implications for water resource management, environmental monitoring, and the development of more effective strategies for mitigating pollution and protecting aquatic ecosystems.
How to cite: Knapp, J. and Worrall, F.: Mechanistic controls on river water quality dynamics across catchments, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16699, https://doi.org/10.5194/egusphere-egu25-16699, 2025.
Rewetting of previously drained peatlands in boreal regions has become a highly promoted solution to combat rising carbon dioxide emissions. By plugging drainage ditches and by raising the water table of peatlands, carbon storage is enhanced, and biological breakdown of stored organic carbon is halted. However, how the rise in water tables affects downstream water quality is not yet fully clarified. Possible effects on downstream water quality include increased mercury leaching, increased phosphorous leaching, increased dissolved organic matter and dissolved organic carbon concentrations in runoff, especially during rain events, as well as browning of downstream water bodies. These adverse effects on water quality may have implications for recipient ecosystems and drinking water production. Here we are presenting a field investigation in southern Sweden, that aims at clarifying the effects of peatland rewetting on downstream water quality. In addition to water quality parameters, we propose to measure peatland hydrology and water table depth, both before and after rewetting. The goal of the project is to inform policy makers of best monitoring practices for peatland rewetting efforts. Care must be taken to conduct thorough baseline studies at least during one - preferably two -years before rewetting. To understand the long-term effects of rewetting on downstream water quality, long time series are imperative. Monitoring should thus be continued for multiple years to decades after rewetting.
How to cite: Liess, A., Borgert, J., Rankinen, J., Klante, C., and Alsterberg, C.: Rewetting of a drained peatland – implications for water quality, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5709, https://doi.org/10.5194/egusphere-egu25-5709, 2025.
Tidal wetlands serve as critical interfaces between terrestrial and aquatic ecosystems, playing a significant role in nutrient cycling and pollutant attenuation. This study investigates the dynamics of reactive solute dispersion in tidal wetlands, specifically examining the influence of reversible and irreversible reactions under pulsatile wind conditions. By employing Mei's multi-scale homogenization technique [1], we aim to elucidate how unsteady wind patterns affect the transport and reaction mechanisms of solutes in these unique environments. The impacts of reaction parameters, such as the Damköhler number (Da) and irreversible reaction rate, along with wind parameters and vegetation factors, on solute mixing have been analyzed. It has been found that an increase in the wind oscillation period (τw) corresponds to a decrease in the frequency of wind oscillations, which no longer effectively resist flow pulsation but instead enhance it when the wind aligns with the flow direction, regardless of its strength. When the wind opposes the primary flow, an interesting trend in the dispersion coefficient has been observed for varying wind oscillation periods and amplitudes. The dispersion coefficient first decreases with increasing wind strength, reaches a minimum, and then begins to increase. Vegetation-induced drag is more pronounced when the wind opposes the flow. This significantly reduces dispersion compared to wind flowing in the same direction as the primary flow. Results also indicate that slow phase exchange kinetics (Da<<1) lead to higher dispersion coefficients compared to fast kinetics (Da>>1) in both wind directions. Introducing an irreversible reaction rate causes absorption at the wetland bed, lowering the solute concentration near the channel bed. This creates a depletion effect, where solutes are continuously removed from the fluid phase, leading to an overall reduction in fluid-phase concentration throughout the wetland system.
How to cite: Hossain, S. and W. Tsai, C.: Dispersion dynamics of reactive solutes in tidal wetlands under pulsatile wind conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17391, https://doi.org/10.5194/egusphere-egu25-17391, 2025.
Headwater streams account for 70% or more of total stream length in most catchments, making it crucial to better understand the processes and controlling factors governing streamflow generation as well as water quality. In this context, stream water chemistry longitudinal profiles can provide valuable insights. This study examines longitudinal stream chemistry profiles across six headwater catchments in three mid-mountain ranges in Germany: The Ore Mountains (catchments OM 1 and OM 2), Black Forest (BF 1 and BF 2), and Sauerland (SL 1 and SL 2).
Three to four snapshot sampling campaigns were conducted per catchment across different seasons and catchment wetness conditions. During the campaigns, water samples were collected from 22 stream monitoring points in the Ore Mountains catchments, 14 in the Black Forest, and 14 in Sauerland, and the samples were analyzed for major cations, anions, and dissolved organic carbon. Subsequently, the longitudinal profiles observed were grouped into spatial and temporal patterns.
In the Ore Mountains, solute concentrations were generally stable over time. However, the spatial patterns varied between the two neighbouring catchments (OM 1 and OM 2). OM 2 exhibited chemostatic longitudinal profiles for most solutes, while OM 1 showed pronounced spatial variability in solutes such as nitrate, dissolved organic carbon (DOC), chloride, and sodium. This variability is usually linked to monitoring points located near springs, tributaries, and drainage systems. However, some spikes in ion concentrations along the stream were not linked to these obvious inflows, thus potentially indicating hotspots for groundwater inflow. The Sauerland catchments showed elevated concentrations of DOC, magnesium, calcium, and sodium in July 2023, a period associated with lower streamflow. An increase in concentration from upstream to downstream was here seen in both streams for solutes like calcium and sodium, during all snapshot campaigns. However, other solutes, like nitrate and sulfate, showed different longitudinal patterns and notable shifts in solute concentration during the snapshot campaigns in SL 2. The shifts in patterns indicate a dependency on time-variant factors like seasonal changes in water input, and land use practices. BF 1 catchment in the Black Forest showed a decreasing pattern in DOC, from upstream to downstream, while the neighbouring catchment BF 2 showed a chemostatic trend. These trends could be influenced by the land use changes within the catchments. Notable increased nitrate concentrations were seen along reaches adjacent to grassland areas and at sampling points near tile drains in OM 1, BF 1, SL 1, and SL 2.
Overall, solute spatial and temporal patterns were stream-specific, with no universal behaviour observed across all catchments. This variability likely results from the interplay of factors such as geology, soils, land use, stream morphology, and climate. High-resolution spatial sampling enabled the identification of point sources and hotspots of groundwater inflow which could be missed by sparse sampling. These findings enhance our understanding of the processes regulating water quality and flow in headwater systems, providing a basis for better management of these systems.
How to cite: Gariremo, N., Kuleshov, A., Vis, G., Hartmann, A., Blume, T., and Hopp, L.: Longitudinal Profiles of Stream Chemistry in Headwater Catchments in Germany, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12321, https://doi.org/10.5194/egusphere-egu25-12321, 2025.
Excess nutrients in aquatic ecosystems cause toxic algal blooms, deoxygenation, fish kills and health risks for humans, resulting in high costs for the environment and society. Next to absolute nitrogen (N) and phosphorus (P) concentrations, the stoichiometric ratio of N to P affects biological activity and thus on potential nutrient retention and the occurrence of adverse eutrophication effects. P inputs to streams have been largely reduced by improved wastewater treatment since the 1980s/1990s. In contrast, N inputs, mainly stemming from diffuse sources, have been reduced more recently and with slower rates. Moreover, diffuse inputs travel from the catchments’ surface along different pathways until reaching the streams with time lags up to decades from application to export, while wastewater is usually disposed directly into streams. These asynchronous changes in N and P inputs and distinct pathways suggest widespread increases in instream N:P ratios. However, little is known about the spatial and temporal variability of these shifts across catchments, their ecological implications, and whether recent improvements in N control and fading P reductions have reversed this trend.
To fill this knowledge gap, we analyze instream N:P trajectories in 767 catchments in France, Germany and Denmark in the period from 1990 to 2019. We classify the catchments based on ecologically relevant classes of molar N:P ratios and their decadal changes. For classification, we consider N-depletion for N:P < 20, P-depletion for N:P > 50 and N&P co-depletion in between, following Guildford and Hecky (2000), both for annual and summer periods.
We found
(1) a widespread increase of N:P in 1990-2010 that is levelling off in the last decade and partly even reversing, primarily controlled by trends in P.
(2) that 40% of catchments experienced at least one shift in depletion class over the decades.
(3) summer N:P ratios to be lower with 50% of the catchments remaining N- or N&P co-depleted in the last decade, despite overall positive N:P trends.
This indicates that, although shifts in nutrient management have intensified P depletion, notable spatial and temporal variations remain, which we intend to investigate in more detail. This study provides the first comprehensive analysis of N:P trajectories in Western European streams, offering new insights into stream water quality and its ecological implications for aquatic ecosystems.
Guildford, S. J., & Hecky, R. E. (2000). Total nitrogen, total phosphorus, and nutrient limitation in lakes and oceans: Is there a common relationship? Limnology and Oceanography, 45(6), 1213-1223. https://doi.org/10.4319/lo.2000.45.6.1213
How to cite: Ebeling, P., Turner, N., Graeber, D., Musolff, A., Dupas, R., Fleckenstein, J. H., Kumar, R., and Winter, C.: Trends in Instream Nitrogen-to-Phosphorus Ratios: A 30-Year Study of Ecological Relevance Across 750 Catchments, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6390, https://doi.org/10.5194/egusphere-egu25-6390, 2025.
High-frequency sampling enables the observation of rapid and subtle variations that can be missed with less frequent observations, which is crucial for understanding the complex interplay of factors influencing water quality. This research analyzes high-frequency data to understand water quality dynamics in the Bode river basin in central Germany, a region characterized by diverse climatic, geological, and land-use conditions.
Using data collected from five monitoring stations over seven years (2013–2020), six variables (electrical conductivity, nitrate, turbidity, water discharge, water temperature, and pH) were analyzed with Principal Component Analysis (PCA). The first principal component (PC1) explained 46% of the variance, and described the typical effect of stream discharge fluctuations throughout the seasons. PC2 highlighted the influence of saline groundwater upwelling during low-flow conditions, while PC3 revealed the role of photosynthetic activity in driving diurnal and seasonal pH fluctuations. Other components unraveled localized processes, including turbidity variability during discharge peaks (PC4, PC5 and PC6), anthropogenic effects, such as the discharge of treated acid mine drainage into the river system (PC7), and agricultural runoff influencing nitrate dynamics (PC8). Together, these components demonstrated how PCA can disentangle diverse influences on water quality, from climatic patterns to human interventions.
Collectively, the PCA results elucidated a wide range of factors influencing water quality, encompassing climatic variations and anthropogenic impacts. High-resolution temporal data revealed intricate dynamics that would otherwise remain undetected with less frequent sampling intervals. PCA proved to be an effective quantitative tool for synthesizing complex, multivariate datasets across multiple monitoring sites, enabling the identification of dominant hydrological controls and interactions between natural and human-driven processes. This methodological framework is adaptable to larger datasets, offering the potential for pattern recognition at regional or global scales and advancing hydrological synthesis. Its application can support adaptive water resource management in regions subject to diverse environmental and anthropogenic pressures.
How to cite: Gutiérrez, K., Lischeid, G., and Rode, M.: Disentangling Spatiotemporal Water Quality Dynamics in a Heterogeneous Catchment Using High-Frequency Data and Principal Component Analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3542, https://doi.org/10.5194/egusphere-egu25-3542, 2025.
Nitrogen cycling has been dramatically altered by anthropogenic activities, impacting water quality and ecosystem functioning of river systems worldwide. Understanding the (a)synchrony between discharge (Q) and nitrate concentration (N) is crucial to revealing the temporal-spatial processes that govern nitrogen dynamics and identify the controlling factors to improve monitoring and management strategies. Here data collected from 66 river catchments across England, spanning 20 years, were analysed to characterise Q-N synchrony patterns and assess spatiotemporal variability. QMax-synced catchments (i.e. max N occurred with max Q, accounting for 28.8% of catchments) are mainly smaller, agricultural catchments, where high-flow conditions can mobilise accumulated nitrate from agricultural soils. By contrast, QMin-synced catchments (i.e. max N occurred with min Q, 25.8% of catchments) have higher proportions of urban area and displayed stronger point-source influences. These catchments are generally larger and have a higher proportion of surface runoff during high-flow periods, diluting nitrate-rich point sources and shifting peak nitrate concentrations to the period of lowest flow. Asynced catchments (46.8%) are also generally larger but with a larger mixture of land use and therefore point and diffuse nitrate sources. Furthermore, the synchrony variability is primarily influenced by sharp topography in QMax-synced catchments, while anthropogenic activities like sewage treatment plant density mainly impact that in QMin-synced and Asynced catchments. Our results demonstrate that the seasonal timing of peak nitrate has a strong and highly contrasting dependence on hydrological conditions that shift with catchment size and availability of diffuse and point sources, with important implications for monitoring and management.
How to cite: Yang, L., Larsen, J., Khamis, K., and Knapp, J. L. A.: Spatial-temporal synchrony between Nitrate and Discharge Varies with environmental and anthropogenic controls, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17984, https://doi.org/10.5194/egusphere-egu25-17984, 2025.
Freshwater salinization impacts the availability of water for human use and ecosystem needs across the globe. In the southwestern United States, it has been estimated that total dissolved solids (TDS; a proxy for salinity) from the Upper Colorado River Basin cause upwards of $300 million per year in economic damages. Substantial resources are devoted to reducing TDS loading to streams and rivers in the basin, with targeted mitigation efforts that have been informed by long-term average models that have identified ubiquitous dissolution of minerals in soils and rocks and relatively small areas of irrigated lands as dominant sources of TDS. Recent work has demonstrated that between 65% and 80% of TDS loading to streams in the basin originates from baseflow, a proxy for groundwater discharge to streams, highlighting the importance of subsurface processes in TDS delivery to streams. This study describes the development and application of two coupled, temporally dynamic Spatially Referenced Regressions on Watershed attributes (SPARROW) models that estimate sources and processes influencing the transport of dissolved solids to streams in the basin at a seasonal time-step over a 35-year period. The key advance is using seasonal estimates of baseflow TDS loads from a baseflow-specific model as explicit time-varying inputs to a total in-stream TDS model, which allows for source tracking through the subsurface and across the landscape over a range of timescales. Results suggest that baseflow is a dominant source of TDS loading throughout the basin, and its relative source proportion varies spatially and across timescales as a function of climate, geology, and land use. Given the lagged delivery associated with baseflow contributions of constituents to streams, this approach of first quantifying baseflow and its drivers relative to all sources has implications for how, when, and where mitigation efforts aimed at reducing TDS loading to streams may be effective.
How to cite: Miller, M., Miller, O., Wise, D., Longley, P., McDonnell, M., and Schmadel, N.: The Role of Groundwater in Contributing to Surface Water Salinization in the Upper Colorado River Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1652, https://doi.org/10.5194/egusphere-egu25-1652, 2025.
Improving water quality at the catchment scale proves difficult as indicated by shifting deadlines of the Water Framework Directive for achieving good chemical and ecological status in European freshwaters. Low-hanging fruits of reducing point sources of pollution have already been targeted in most catchments, with more challenging and persistent diffuse pollution jeopardising widespread water quality improvements. Diffuse pollution originates from a range of anthropogenic activities such as agriculture, forestry and mining and leads to gradual accumulation of pollutants in impacted catchments. These abundant pools of pollution, also known as legacies, can control water quality and limit the effectiveness of mitigation measures in the long term. Yet, our understanding of hydrological and biogeochemical processes controlling mobilisation, transformation, transport and impact of pollution legacies in catchments is still limited. Here, we present results from multiple projects focusing on identifying processes controlling eutrophication and erosion in headwater agricultural catchments to support management and mitigation. We use a suite of experimental and modelling tools from high-frequency stream chemistry data, in situ measurements of dominant processes, laboratory assays, and process-based models to quantify hydrological and biogeochemical processes. Our results show that despite common pollution pressures, agricultural catchments differ in how they modulate pollution legacies. Their resilience/sensitivity to pollution depends on the interplay between hydrological and biogeochemical processes. Biogeochemical processes such as sorption, sedimentation and denitrification show potential for pollution retention and removal; however, their capacity is rapidly exhausted during hydrologic events mobilising large fluxes of legacy pollutants. As the importance of hydrological accumulation increases with catchment size, the cumulative impact of mitigation measures on water quality declines along the stream network. Finally, our modelling approach shows that only large-scale mitigation interventions are likely to bring the required water quality improvements, particularly under future climatic conditions with accelerated biogeochemical and hydrological processes. Understanding these processes is key to effective mitigation and reducing potential pollution swapping in heavily impacted catchments.
How to cite: Bieroza, M., Livsey, J., Hallberg, L., Wynants, M., and Prischl, L.-A.: Improving water quality at the catchment scale through process-informed management and mitigation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4228, https://doi.org/10.5194/egusphere-egu25-4228, 2025.
We review anthropogenic water pollution, and find that it is spreading in rivers and aquifers at an alarming rate. Actions advocated by the United Nations have thus far resulted in more improvements in water quality of surface water than that of groundwater. Here, we argue that the nature of anthropogenic pollution has evolved over time, so that traditional indicators such as biological oxygen demand are no longer adequate. We further argue that overexploitation of groundwater and climate change (extremes and, possibly, reduction of rainfall and/or increase in evapotranspiration) are causing a reduction of the environmental services of groundwater dependent aquatic ecosystems and, specifically, the pollutant removal capacity. Therefore, concerted efforts are needed to restore natural surface water-groundwater interactions. To this end, we need to either reduce pumping (e.g., through conjunctive use) or expand managed aquifer recharge. While these measures would help in improving water quantity and quality simultaneously, current regulations favor neither because of concerns about their possible negative impacts. Determining how to implement these solutions is itself a challenge. Considering that the scientific literature is still centered upon water scarcity and declining water levels, we call for a common front of researchers in hydrology and sister sciences to address this fast-evolving pollution crisis in our water systems. As Bill Clinton famously said,”it’s the pollution, stupid!”.
How to cite: Carrera, J., Bronstert, A., Sawyer, A., Krause, S., deGraaf, I., Zheng, Y., Zheng, C., Morales-Casique, E., and Yadav, B. K.: The blind spot in water sustainability: why do we have such low desire for good water quality?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20325, https://doi.org/10.5194/egusphere-egu25-20325, 2025.
In many European regions, the ecological cycles are changing significantly because of advancing climate change, the ongoing landscape transformation, and intensive agricultural use. Runoff components redistribute towards more surface runoff (more heavy rainfall, less snow cover, compaction, crusting) and thus significantly reduced groundwater recharge, faster runoff concentration (accelerated concentration, secondary water network through drainage ditches and drains, shorter and steeper flow paths), and thus a lower landscape retention capacity. As a result, more soil, nutrients and pollutants are eroded, especially from arable land, threatening the ecosystems and the associated ecosystem services along the watercourses.
The increasingly strict environmental legislation in the EU has recently led to farmers’ protests across Europe, and subsequently to a hasty softening at all governmental levels. The protest is also directed against environmental regulations, as their predicted effect in many cases cannot be substantiated with quantitative figures and there is a lack of coherent concepts for combining measures in small catchments, quantified combined effectiveness analyses, and an understandable roadmap towards the ecosystems’ sustainable use.
The existing data sets are often fragmented, short, focus on individual measures under strictly limited conditions. In particular, the results of studies evaluating agricultural management methods can only rarely be applied to entire catchment areas or landscapes, as neither the cross-scale processes are understood nor do corresponding data sets exist at the landscape scale. Hence, there is no basis for making informed decisions.
Two new open-air laboratories are currently being built in southeast Germany: the almost completed Erosion and Runoff Laboratory (EARL) uses long-term measurements of water and nutrient fluxes of 36 sloping (approx. 10%) agricultural plots (each 660 m²) to monitor the effect of different agricultural systems on the runoff components, soil erosion, as well as the discharge of nutrients and pollutants. The Water and Environmental Landscape Laboratory (WELL) focuses on the effects of management methods combined with measures, monitoring 22 similarly sloped sub-catchment areas (each 0.3 to 0.5 km²) predominantly used for arable farming. In combination with the nearby Hydrological Open Air Laboratory (HOAL), this results in a unique combination of three long-term experimental laboratories in the same natural entity: EARL on the plot scale, HOAL on the slope scale, and WELL on the landscape scale. We would like to present the status of the projects in order to facilitate cooperation for research applications at the European level.
How to cite: Mitterer, J. and Ebertseder, F.: Capturing Hydrological and Sedimentological Connectivity from Cropland Plots to Catchments - Integrating Experimental Sites into a Multi-Scale Approach, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17723, https://doi.org/10.5194/egusphere-egu25-17723, 2025.
In North America, the Great Lakes contain approximately 20% of the available surface fresh water in the world. As a result, the Great Lakes Basin (GLB) is a well-known region for its extensive agricultural and food production activities. Such agricultural activities are considered one of the most significant non-point sources of nutrient transport, particularly nitrogen and phosphorus, to surface water and groundwater. This is mainly because of the application of synthetic fertilizers and manure for enhanced crop productivity and soil fertility. Such elevated nutrient concentrations can disrupt aquatic ecosystems, degrade surface and groundwater quality, and harm both human and aquatic life. However, quantification of nutrient concentrations in agricultural watersheds is challenging because it is influenced by different process parameters including soil type, climate, and land use conditions. These parameters are highly non-linear and uncertain which hinders the applicability of typical mathematical models in nutrient transport applications in surface water and groundwater quality. Therefore, data-driven models using machine learning (ML) algorithms have been extensively applied to unravel the complexities of nutrient transport in surface water and groundwater, tackling the main challenges associated with the mathematical models. This is mainly because ML algorithms can deal with complex datasets with high uncertainty and non-linearity while considering the interdependence between the process parameters. By leveraging historical datasets, ML algorithms can model the explain the cause-result and intricate interdependencies between process parameters, making them well-suited for simulating nutrient transport processes in surface and sub-surface water applications. In the current study, different ML algorithms were adopted to predict nutrient concentrations in surface water and groundwater in a sand plain agricultural watershed within the GLB in Ontario, Canada. These ML algorithms included regression (e.g., artificial neural network) and classification (e.g., decision trees) techniques to better simulate nutrient concentrations in surface water and groundwater. The ML input variables involved meteorological (e.g., precipitation), hydrogeological (e.g., groundwater levels), and water physico-chemical (e.g., pH) conditions. The performance of these ML algorithms was evaluated using different evaluation metrics such as root-mean squared error and F1-score for regression and classification models, respectively. The optimal ML models were selected according to the outcomes of these evaluation metrics. In addition, the interdependence between the involved process parameters (e.g., land use and precipitation) and nutrient concentrations was interpreted to determine the governing parameters on the nutrient transport process in surface and sub-surface water. The main outcomes of this study can help decision-makers in assessing the most effective management efforts to protect and improve surface water and groundwater quality in agricultural watersheds. In addition, these insights enable the interpolation of nutrient concentrations from discrete sampling points, facilitating predictions at unmonitored locations across the watersheds.
How to cite: Elsayed, A., Levison, J., Binns, A., Larocque, M., and Goel, P.: Harnessing Machine Learning for Water Quality Prediction in Agricultural Watersheds, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14665, https://doi.org/10.5194/egusphere-egu25-14665, 2025.
Watershed health assessment is essential for getting a clear understanding of the present condition of watershed systems, which enables the effective allocation of resources and prioritization of management actions in a river basin. This study used an innovative framework for evaluating watershed health in data-scarce regions by considering the complex interrelations among geophysical, environmental, climatic, and anthropogenic factors. The framework brings together the Analytical Network Process (ANP) and Fuzzy Logic, addressing the challenges of managing interdependent variables.
The methodology is applied to 30 sub-watersheds of the Budhabalanga River Basin, located along the east coast of India. The ANP is used to analyse the intricate interplay among climate variables, topographic factors, non-point pollution sources, and human activities. Further, the Fuzzy Logic is employed to classify sub-watersheds based on their health status. Results show variations in watershed health, with upstream sub-watersheds being healthier compared to those in the middle and downstream regions of the river basin.
The proposed Fuzzy-ANP framework proved to be an effective tool for assessing watershed health in data-scarce regions. It provides a practical approach to sustainable resource management and can be easily adapted to other river basins. Thus providing valuable insights for enhancing watershed resilience and supporting better decision-making.
How to cite: Dhal, L. and Kansal, M. L.: Health Assessment of Agriculture-Dominated Watersheds in a Data-Scarce Region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15610, https://doi.org/10.5194/egusphere-egu25-15610, 2025.
Declines in riverine biodiversity are impacted by catchment connectivity to potential nutrient sources. Many studies have focused on biodiversity as a direct expression of instream attributes, thus neglecting the critical role of catchment connectivity to the river network as key determinants of biodiversity. To protect and restore the ecological integrity and wider ecosystem function of riverine systems, the spatial connectivity of the stream networks to their catchments must be considered in mitigation measures. Given their extent and high connectivity with the surrounding landscape, low-order streams are particularly vulnerable to land-use pressures and demonstrate high sensitivity to nutrients (N and P), impacting the composition and seasonally persistence of benthic algal communities.
Here, we utilise the Sensitive Catchment Integrated Mapping Analysis Platform (SCIMAP) to explore the spatial risk to land-use-driven nutrient pollutant pressures across the River Eden (NW England) catchment.Our results show that the potential source areas for the examined pollutants are in specific locations in the catchment. Therefore, the most effective locations for management measures will differ for different pollutant or ecological endpoints. This means that the Programme of Measures under the Water Framework Directive requires the integration of multiple lines of ecological evidence at the appropriate spatiotemporal scales. We demonstrate that this approach can guide prediction on instream ecological status and identify spatial sources, thus providing a more quantitatively transparent and accurate risk assessment for catchment management and mitigation
How to cite: Reaney, S., Snell, M., and Barker, P.: Identifying the source of anthropic pressures on in-stream benthic algae communities within the River Eden catchment, UK, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11654, https://doi.org/10.5194/egusphere-egu25-11654, 2025.
This study examines the effects of groundwater depletion on salinity and nitrate contamination in a detritic unconfined alluvial aquifer. Over the past five decades, the aquifer has transitioned from shallow groundwater (<20 m) in the 1970s to predominantly deep groundwater (>40 m) due to significant water table declines. Groundwater analysis reveals moderate contamination, with nitrate levels highest in shallow zones but detectable at all depths. Dominant hydrochemical processes influencing salinity include rock weathering, halite dissolution, and reverse ion exchange.
The Haouz Plain, located in central Morocco, covers a significant area within the Tensift Basin. Characterized by an arid to semi-arid climate, it is a center of intensive agricultural and industrial activities, making its water resources highly susceptible to contamination risks.
The thick unsaturated zone formed by water table decline has mitigated surface-borne contamination and reduced evapotranspiration impacts. However, vertical flow dynamics induced by pumping have allowed younger, nitrate-rich groundwater to mix with older, deeper groundwater. Tritium dating indicates that nitrate in deep groundwater likely originates from historical fertilizer use, highlighting the long-term legacy of agricultural practices on water quality.
Continued aquifer depletion poses serious risks. Pumping deep groundwater could mobilize salts, increasing salinity. Moreover, contaminants accumulated in the thick unsaturated zone could migrate downward over time or with increased recharge, further degrading groundwater quality. These findings emphasize the vulnerability of depleted aquifers to salinization and nitrate contamination, underscoring the need for sustainable groundwater management strategies.
Keywords: Pollution, irrigation, hydrochemistry, salinity, quality.
How to cite: Sahraoui, H., Fakir, Y., Bouimouass, H., Tweed, S., and Leblanc, M.: Groundwater Contamination Processes in Depleting Alluvial Aquifers, Haouz Plain Morocco, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20250, https://doi.org/10.5194/egusphere-egu25-20250, 2025.
This study derives an analytical solution of the two-dimensional concentration distribution of a pollutant in a prismatic channel flow with asymmetric velocity pattern over its cross-section. This study also examines pollutant transport phenomena influenced by both irreversible and reversible reactions, along with the bulk chemical reaction of the pollutant with the channel boundaries and the fluid flows, respectively. The effects of mean and transverse concentration distributions are analyzed under the influence of various parameters, including adsorption, desorption, absorption, the asymmetric velocity distribution parameters (α and β), and the bulk chemical reaction parameter. The transverse concentration distribution up to the second-order approximation is derived using Mei's homogenization technique. Over the past two decades, researchers have emphasized that the Taylor dispersion model primarily predicts the longitudinal dispersion of the mean concentration. However, the study of transverse concentration distribution has gained significant importance due to its relevance in environmental engineering and industrial applications. According to the investigation’s findings, an increase in α and β enhances the overall velocity, resulting in a sharper velocity profile when α = β or a more asymmetric profile when α ≠ β . The dispersion coefficient shows non-monotonic behavior influenced by the velocity parameters α and β . Smaller α and β yield moderate velocity gradients and weaker shear, reducing dispersion. As α and β increase, sharper or asymmetric velocity profiles enhance shear effects, increasing dispersion. The mean concentration of the pollutant decreases with increasing α and β in both cases, but the decrease is more gradual in the asymmetric case. Increasing bed absorption and bulk chemical reaction parameters significantly reduces the transverse concentration, while increasing adsorption or desorption parameters raises the transverse concentration. Adsorption and desorption reactions at the boundaries reduce transverse concentration variation in both symmetric and asymmetric cases. The variation decreases with increased reaction rates, with slight non-uniformity observed when α ≠ β. The findings are crucial for enhancing natural stream quality, reducing pollution, and mitigating the effects of reactions.
How to cite: Barik, S. and Srinivasa Raghavan, R.: Pollutant transport in asymmetric velocity distributions influenced by phase exchange kinetics between two parallel plates, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20033, https://doi.org/10.5194/egusphere-egu25-20033, 2025.
Boreal freshwaters are becoming darker. This brownification cooccurs with increasing dissolved organic carbon (DOC) concentrations and affects crucial ecosystem services. Our study investigated constructed wetland optimisation in terms of depth and water residence time (WRT) during different seasons to remedy dark water colour and high DOC concentrations, while retaining nitrogen removal. We conducted eleven-day experiments with deep-brown, shallow-brown and shallow-control treatments, in summer (June) and autumn (November) 2023, using 18 small-scale constructed wetlands at an experimental wetland area in southern Sweden. At the beginning of both experiments, the flow through the wetlands was halted and extracted peat was added to the brown treatment wetlands, thus simulating brownification by increasing absorbance and DOC concentrations. Thereafter, changes in absorbance, DOC concentration and total nitrogen (TN) concentration were measured. Our results showed that optimal WRT for increasing water clarity and reducing DOC concentrations varied between one and two days. A WRT of more than two days during summer, resulted in internal carbon production and darker water colour. The optimal WRT for TN removal was not affected by DOC addition. We conclude that constructed wetlands increase water clarity and boost carbon degradation if their WRT, especially during summer, is sufficiently short. If WRT exceeds two -three days in summer, internal carbon production together with low oxygen levels and increased iron (Fe) mobilization, may instead increase downstream brownification. Overall, our study shows that properly designed wetlands are suitable measures to mitigate the effects of brownification.
How to cite: Borgert, J., Jones, K., Nilsson, J., Sjöstedt, J., and Liess, A.: Seasonal dynamics of brownification mitigation in constructed wetlands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5767, https://doi.org/10.5194/egusphere-egu25-5767, 2025.
Excessive phosphorus (P) drives eutrophication in surface waters, contaminates groundwater, threatening aquatic ecosystems and drinking water quality. Legacy P from past agricultural and urban inputs has shown to create nutrient reservoirs that continue to fuel contemporary P pollution. Different forms of P, such as total phosphorus (TP) and soluble reactive phosphorus (SRP), may show distinct behavior. While SRP is critical because of its bioavailability, TP determines the overall P load in the system including P already incorporated into biomass. Understanding the long-term dynamics of TP and SRP, along with legacy sources and landscape filtering, is essential for managing water quality and reducing environmental impacts.
Using a long-term database of point and diffuse P sources (Batool et al., 2024; Sarrazin et al., 2024) and observational riverine TP and SRP concentrations (Ebeling et al., 2022), we analyzed the retention and export dynamics of P across more than 100 river catchments in Germany over the period 1950–2019. Our analysis focuses on the lag-time behavior between P inputs to the catchments and outputs by river water, incorporating effective transport time distributions (TTDs) to characterize landscape filtering processes. We employed various TTD models, ranging from log-normal to more flexible gamma distributions, and compared key characteristics such as mean, median, and mode of transport times across catchments. Our findings reveal a substantial decline in P point and diffuse sources across German landscapes over the past 70 years, which has not been matched by equivalent reductions in riverine P concentrations. In this presentation, we will discuss the spatial variability of TTs between P input and output, highlighting differences in legacy effects and contrasting contributions from point and diffuse sources in shaping the P dynamics of German river systems.
References:
Batool, M., Sarrazin, F. J., and Kumar, R.: Century Long Reconstruction of Gridded Phosphorus Surplus Across Europe (1850–2019), Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2024-294, in review (accepted), 2024.
Ebeling, P., Kumar, R., Lutz, S. R., Nguyen, T., Sarrazin, F., Weber, M., Büttner, O., Attinger, S., & Musolff, A. (2022). QUADICA: water QUAlity, DIscharge and Catchment Attributes for large-sample studies in Germany. Earth System Science Data, 14(8), 3715–3741. https://doi.org/10.5194/essd-14-3715-2022.
Sarrazin, F. J., Attinger, S., & Kumar, R. (2024). Gridded dataset of nitrogen and phosphorus point sources from wastewater in Germany (1950--2019). Earth System Science Data, 16(10), 4673–4708. https://doi.org/10.5194/essd-16-4673-2024.
How to cite: Wu, S., Musolff, A., Ebeling, P., Batool, M., Nguyen, T. V., and Kumar, R.: Towards understanding the dynamics of phosphorus legacy across German river basins, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11370, https://doi.org/10.5194/egusphere-egu25-11370, 2025.
Floodplain ecosystems worldwide have largely been reclaimed for urbanization and agriculture. In these reclaimed areas, water is managed through artificial canals that serve various purposes, including irrigation, soil drainage, flood safety, and biodiversity support. This study aimed to assess how the use of artificial canals (irrigation and receiving canals) within the floodplain area of the Life Green4Blue project (LIFE18 NAT/IT/000946) affects water quality. The study was conducted in the Po Plain (Italy), an area that has undergone extensive agricultural reclamation in the past century. The irrigation canals are supplied with water from the Canale Emiliano Romagnolo, which diverts water from the Po River during the summer months (April to September). The larger receiving canals primarily act as discharge routes for both irrigation and drainage canals, and to a lesser extent, for irrigation. During autumn and winter (October to March), both types of canals are used to maintain hydraulic safety by lowering the water levels.
Water quality was monitored monthly from January 2020 to December 2023. Cluster analysis (CA) showed a clear distinction between the water in receiving canals and irrigation canals. Principal component analysis (PCA) identified that the differences were mainly due to nutrient and salt concentrations. Water in receiving canals exhibited higher levels of nutrients (such as N-NH4, Ca, K, Mg, P, and S) and higher electrical conductivity (EC) values. The poorer quality of water in the receiving canals is attributed to its origin—soil leachates and water from irrigation canals that have already traveled across agricultural lands—and the lack of freshwater input. Consequently, the water quality index (WQI) was higher for irrigation canals (67) compared to receiving canals (61).
Both canal types showed a decline in water quality during the autumn and winter (AW) seasons, as indicated by the PCA. This decline was linked to higher nutrient and EC concentrations compared to the spring and summer (SS) seasons. The increased nutrient load in the AW seasons is likely due to greater soil leaching caused by higher rainfall. Additionally, the reduced water flow during AW seasons hindered dilution, allowing for more significant exchange of cations and anions from the bed sediments. Interestingly, the decline in water quality was more pronounced in irrigation canals than in receiving ones, suggesting that freshwater input plays a crucial role in maintaining water quality in irrigation canals.
This study underscores the influence of canal usage on water quality and highlights the need for continuous freshwater input throughout the year to sustain the ecosystem services provided by floodplain areas.
How to cite: De Feudis, M., Falsone, G., Trenti, W., Morsolin, A., and Vittori Antisari, L.: Influence of canal use purpose on water quality: A case study in the floodplain area of the Life Green4Blue project, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4498, https://doi.org/10.5194/egusphere-egu25-4498, 2025.
The export of nutrients from terrestrial ecosystems is characterized by complex interactions between hydrological transport and biogeochemical transformations, posing considerable challenges to the effective management of water quality and the prediction of climate change. Excess nutrient inputs from agricultural activities into freshwater systems have the potential to impact the safe functioning of ecosystem services, while contributing to greenhouse gas emissions. However, quantification of these coupled processes remains challenging due to the variability in residence time of multiple flow paths and the limited ability to observe hydrological and biogeochemical processes in situ because of the involved long timescales and the inaccessibility of the subsurface. In this study, the catchment-scale hydro-biogeochemical reactive transport model (BioRT-HBV), which is based on a parsimonious structure and has minimal data requirements, is employed to explore the role of different processes in nitrogen reaction rates and concentrations in subsurface waters and rivers. The model uses hydrometeorology, discharge, and stream chemistry data from 2008 to 2023, as well as geological conditions from the Nägelstedt catchment, which is located in central Germany and is recognized as one of its most intensively used agricultural regions. The hydrological model demonstrates a good correlation between simulated and observed stream discharge, with high model efficiency. Snowmelt appears to be an important hydrological factor in regulating the discharge flows at the Nägelstedt catchment, leading to additional surface flow and shallow subsurface flow occur during brief periods corresponding with snowmelt events, while the deep subsurface flow contributes almost 80 percent of the annual discharge. Preliminary results show that high stream nitrate concentrations occur when shallow flowpaths connect the shallower soils to the stream, while low nitrate stream concentrations occur during baseflow and lower-flow conditions, when the stream is predominantly fed by deeper flowpaths, resulting in a flushing concentration-discharge pattern. This suggests that nitrate loss processes are driven by the long-term retention or depletion of nitrogen in soils and groundwater within this catchment. The model provides a foundation for comprehending the interdependence of complex nonlinear biogeochemical and hydrological processes and serves as a step toward the prediction of the impact of climatic perturbation and land use changes on chemical exports to river.
How to cite: Duong, T. Q., Knapp, A. S., Sadayappan, K., Smykalov, V. D., Hildebrandt, A., Li, L., and Thullner, M.: A Reactive Transport Modelling Approach for Biogeochemical Transformation in an Agricultural Catchment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15121, https://doi.org/10.5194/egusphere-egu25-15121, 2025.
On cultivated land, ephemeral gullies contribute significantly to soil erosion. Despite their importance, existing models for predicting the location of ephemeral gully initiation and development are very sparse and have limitations. The USDA-ARS National Sedimentation Laboratory and the University of Nottingham developed GIS-based topographic analyses to map potential ephemeral gully locations. In the 1980s they proposed an indicator called Compound Topographic Index (CTI), which was proposed as a predictor of gully location, and which is defined, for a certain pixel located in a watershed, as the product of the watershed area at that point, the local slope and the local curvature. It can be seen that this product is a proxy for the power of the stream at that point. From a digital elevation model it is possible to calculate for each pixel the value of its CTI. Researchers at the aforementioned centers found that pixels exceeding a CTI value, called critical CTI, very often corresponded to the location of areas eroded by ephemeral gullies.
This work aims to test the suitability of the CTI-based method to locate the gullies observed in typical conditions of an agricultural plot as a starting point to evaluate the performance of the QAnnAGNPS model, which develops a whole technology based on this methodology. Although such methodology is old, evaluations of it in real agricultural situations are extraordinarily scarce. In addition, it is still necessary to verify in field conditions that the modeling approach based on headcut occurence and migration, localized by means of CTI, is correct. Thus, an experiment has been initiated in November 2023 in which, first of all, an agricultural plot has been selected in an area of highly erodible silty loam soils located in Pitillas (Navarra). The plot has been tilled with conventional tillage to replicate the initial conditions of an average agricultural plot, which has been kept free of vegetation by using herbicide. After each precipitation event, drone flights have been carried out to obtain digital elevation models (DEM) with a resolution of less than one centimeter and orthomosaics. The DEMs and orthomosaics generated in each flight make it possible to locate the origin of the gullies formed and to determine their dimensions and their temporal evolution, in this case until November 2024, when the plot was tilled again to restart the observations.
These observed data were compared with the data simulated by QAnnAGNPS. For each gully, we first obtained the critical CTI by selecting the one that best explains the origin of the gully. On the other hand, for each gully and time, we have the CTI threshold value that best follows the gully's path. It has been confirmed that CTI gives good results for locating ephemeral gullies in real agricultural conditions and is a good way to predict the path of a gully. Our observations confirm that ephemeral gullies were always formed from generation and migration upstream of headcut, so the theoretical basis of models such as AnnAGNPS is valid.
How to cite: Casalí, J., Barberena, I., van Wiltenburg, K., Chocarro, A., and Campo-Bescós, M. A.: Tracking ephemeral gullies formation and development in agricultural conditions using the mathematical model AnnAGNPS, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19840, https://doi.org/10.5194/egusphere-egu25-19840, 2025.
The frequent occurrence of water anomalies has posed a serious threat to human habitats. Due to the complexity of aquatic environments and the diversity of anomaly types, satellite remote sensing methods still face challenges in accurately detecting and diagnosing water anomalies. In this study, two intermediate parameters, the anomaly water index (AWI) and the advanced water turbidity index (AWTI), were developed using the red edge band of Sentinel-2 imagery. Based on these parameters, we constructed a two-step decision-tree-based diagnostic framework (ADF) to determine types of water anomalies. The proposed indices and framework were comprehensively compared with existing spectral indices and classical supervised learning algorithms in eight globally distributed study areas. The results show that the AWI is effective for identifying multiple water anomalies across diverse aquatic environments, including lakes and oceans, and outperforms existing indices in four mixed cases. Compared to existing indices, the AWTI excels in distinguishing turbid water from algal water. The ADF achieved comparable performance to supervised learning algorithms, with satisfactory time-dynamic monitoring results across four case-study areas and F1 scores exceeding 0.76. In conclusion, this study provides a valuable theoretical basis in the field of water anomaly detection and classification.
How to cite: Ma, G., Zhao, C., and Pan, Y.: A novel red-edge based water anomaly detection index and diagnostic framework., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9013, https://doi.org/10.5194/egusphere-egu25-9013, 2025.
In the South-eastern part of the Netherlands, nitrate concentrations often exceed the limit values in surface water due to agricultural activities. Water bodies should be in good chemical status by 2027 according to the Water Framework Directive, so measures should be taken to reduce nitrate loads to the streams. In this area, many agricultural fields are equipped with tile drainage systems. A way to reduce the nitrate emissions is the installation of woodchip bioreactors which are connected to these tile drainage systems. Residence times of the drainage water should be taken into account, for negative side effects may prevail when these are too high. This includes the production of nitrous oxides, sulfide and ammonia, and leaching of heavy metals.
A woodchip bioreactor was installed and connected to 4ha arable land on sandy soil in the southern part of the Netherlands in 2023. During drainage season, the influent of the bioreactor is connected to the tile drainage system, whereas it is disconnected during low or no flow periods (mainly in summer). The effluent is connected to a small stream. Continuous nitrate sensors were installed at both the in- and effluent, as well as discharge measurements to determine the removal efficiency of the bioreactor. Several piezometers were installed inside the reactor to monitor the biogeochemical processes taking place.
An extensive sampling campaign was carried out in autumn 2023, during the drainage season 2024, autumn 2024 and during the drainage season 2025. It showed considerable removal of nitrate (between 40% and 90%), especially in the first half of the reactor. At specific moments, some leaching of sulfide, ammonia, phosphorus and iron was observed. These leaching events appear to be related to start-up of the reactor in autumn 2023 and 2024 and not specifically to flow rate. The formation of nitrous oxide was determined during operation in 2024/2025 and was negligible.
The woodchip bioreactor proved to be a good area-specific measure to reduce nitrate loads in small streams, but care has to be taken on possible side-effects of the bioreactor on the stream.
How to cite: van Driezum, I., van Loon, A., Jansen, S., Rozemeijer, J., Nijboer, M., van Herpen, F., and Verstegen, H.: Woodchip bioreactor as a site specific approach to reduce nitrate loads from agriculture: demonstration in practice, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6420, https://doi.org/10.5194/egusphere-egu25-6420, 2025.
Excessive nutrient and sediment loads are threatening water quality of inland and coastal waters since decades in Norway. The Norwegian Agricultural Environmental Monitoring Programme (JOVA), established in 1992, aims to measure nutrient and sediment losses from agricultural production systems and evaluate the effectiveness of environmental policies. With only 3% of Norway’s land area suitable for agricultural production, preserving agricultural land from degradation, especially erosion, is crucial. Norwegian agricultural land has been shown to experience high suspended sediment losses (on average 100- 2970 kg/ha/yr), underscoring the need for agricultural catchments monitoring to unravel temporal trends in soil losses, disentangle effects of environmental and management factors, and identify best management practices to maintain good water quality and prevent further soil degradation. The monitoring programme is funded by the Norwegian Ministry of Agriculture and Food and conveys a solid base of knowledge for water management and policy makers. Monitoring data are also widely used for research purposes and to develop, calibrate and validate national nutrient export and erosion models.
Catchments (currently eleven) were selected to represent key agricultural regions in terms of climate and production systems. JOVA includes catchments dominated by cereal production in eastern and mid-Norway, vegetable production in southern Norway, intensive and extensive dairy farming including grass production in western and northern Norway. Water monitoring stations were constructed at the outlet of each catchment. At these stations, runoff rate is measured, and flow-proportional composite samples are taken and analysed fortnightly (suspended solids, ashes, total P, PO4-P, total N, NO3-N, pH, electrical conductivity). The above-mentioned data is publicly available at https://jovadata.nibio.no/ free of charge. Agricultural management data, including details on dates of tillage, sowing, fertilization, harvest, and pesticide applications, are available upon written request. Water samples from catchments (currently five) are also analysed for a broad spectrum of pesticides.
Over 30 years of water quality monitoring provided important insights and temporal trends into hydrological regimes, changing agricultural management practices and nutrient and sediment losses from typical agricultural areas in Norway. An increased frequency of large runoff events (>95th percentile) has been observed in some of the catchments, which corresponded with high losses of soil particles and tend to decrease with the prevalence of plant coverage or stubbles. Monitoring data also revealed a response in the frequency of management practices following shifts in subsidy schemes for environmental measures (e.g. incentives for less autumn ploughing in cereal production).
Long-term water quality monitoring remains essential due to disproportionally large effects of climate change on ecosystems in the Nordic region. Future applications of JOVA monitoring could address the impacts of land use, socio-economic factors and innovative management practices on sediment and nutrient losses, and could further support modelling efforts. Furthermore, the technical setup of the monitoring enables the comparison between traditional methods and emerging technology, such as sensors. Transnational scientific collaborations among monitoring programmes can pave the way for a more sustainable agriculture at broader regional scales.
How to cite: Ugstad, H., Gruselle, M.-C., Bechmann, M., and Fischer, F. K.: Thirty years of Agricultural Environmental Monitoring: Insights into Water Quality and Erosion in Norway, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19001, https://doi.org/10.5194/egusphere-egu25-19001, 2025.
Path4Med is a collaborative, multidisciplinary project tackling water and soil pollution in the Mediterranean agro-hydro-system. Bringing together 26 partners from 10 EU and 5 non-EU countries, the project aims to achieve zero through an innovative triple bottom line approach, ensuring economic, social, and environmental sustainability. Path4Med focuses on identifying pollution pathways from farm to sea and implementing both established and novel agricultural management technologies.
To this end, Path4Med recognised the key challenges, namely: i) Agriculture is site-specific while water flows across landscapes, making it difficult for actors to grasp the full impact of agricultural activities on the landscape-river-sea systems; ii) A lack of harmonized data from soil monitoring hinders the ability to assess soil health and inform effective interventions; iii) Overuse and mismanagement of agricultural water as well as nutrients from chemical fertilizers and livestock manures pose a great threat to soil health and water quality both in local farming communities and downstream water bodies; iv) Farmers do not have the luxury of waiting until sustainable soil management and healthy soils deliver their benefits. Factual information is required to support private-sector funding by financial institutions; v) Adoption and application of effective solutions is lagging far behind innovation and emerging technological solutions; vi) Localized or narrow-scope actions are insufficient to tackle large-scale environmental challenges, while large-scale actions often neglect the specific needs of individual farms; vii) Policymakers often start with a broad array of innovative solutions but end up compromising, which limits the effectiveness of policies in addressing agricultural challenges. vii) Many stakeholders, including water authorities/managers, farmers, end users, policy and/or decision-makers, environmentalists and others are curious and concerned about the quality and quantity of irrigation return flows, i.e., IRFs, known as one of the major pollutants that significantly pollute the aquatic environment.
The main ambition of Path4Med is to enable informed decision making and policy design in all scales from farm level to country level and to EU level through the following key elements:
- Map the current status of agro-hydro-system in designated catchments.
- Develop and mainstream novel monitoring technologies (Earth Observation, eDNA, IoT, AI).
- Implement integrated agricultural solutions (smart irrigation, nutrient management, biochar, nature-based solutions etc.).
- Assess the technical and socioeconomic viability of solutions through integrated modelling at different spatial and temporal scales.
- Empower stakeholders to take action against pollution.
The approach includes an open participatory environment which will be implemented in a wide set of large-scale Demonstration Sites across the Mediterranean and other European sea basins, including an open call to replicate solutions. A digital platform will facilitate information sharing, data exchange, and knowledge dissemination.
Ultimately, Path4Med enables informed decision-making and policy design from the farm to the EU level, promoting sustainable practices and a healthy agro-hydro-system.
How to cite: Soulis, K. and the Path4Med team: Path4Med - Demonstrating Innovative Pathways Addressing Water and Soil Pollution in the Mediterranean Agro-Hydro-System, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11873, https://doi.org/10.5194/egusphere-egu25-11873, 2025.
In this, karst systems located in the Akyaka district, Ula county, Muğla city, SW Turkey were investigated because the systems are unique geological formations created by the dissolution of soluble rocks through the action of surface water or groundwater. These formations, typically developed in carbonate rocks and gypsum over extended periods, are shaped by environmental and climatic factors. For this study, 16 measurement points were determined and collected water samples from the points. The collected water samples were chemically analyzed for major ions. Analyzed of the data indicated that the groundwater quality in the studied area demonstrates low to moderate ionic and physicochemical content, making it suitable for diverse uses, including domestic and irrigation purposes. Electrical Conductivity (EC) values, ranging from 248 to 1054 µS/cm, with an average of 508.69 µS/cm, indicate moderate salinity. Classification per the U.S. Salinity Laboratory Staff (1954) places most samples (85.72%) in the medium-salinity category (C2), with limited samples in low (C1) and high salinity (C3) categories. Compared to prior studies, such as those by Altun et al. (2017), the EC values align closely, suggesting consistent regional groundwater quality. Calcium (Ca²⁺) and magnesium (Mg²⁺) concentrations range from 1.58–8.85 mg/L and 0.21–6.2 mg/L, respectively, with averages suggesting soft to moderately hard water. These levels ensure lower scaling potential in plumbing, supporting both residential and industrial applications. While the concentrations exceed the WHO’s recommended limits for drinking water, their moderate variability contributes to a balanced ionic composition. Sodium (Na⁺) and potassium (K⁺) are present at lower concentrations, with averages of 0.87 mg/L and 0.10 mg/L, respectively. Chloride (Cl⁻), sulfate (SO₄²⁻), bicarbonate (HCO₃⁻), and carbonate (CO₃²⁻) show significant variability, with HCO₃⁻ dominating among anions, indicative of carbonate mineral dissolution. Total Dissolved Solids (TDS) range between 172 and 739 mg/L, categorizing all samples as freshwater. The chronological order of major ions follows Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ for cations and HCO₃⁻ > Cl⁻ > SO₄²⁻ for anions. Elevated bicarbonate and calcium levels highlight carbonate rock dissolution, supported by the geological context, which includes extensive carbonate formations like dolomites and limestones. The Piper diagram analysis underscores the dominance of Ca-Mg-HCO₃ groundwater type, revealing the influence of alkaline earth metals and weak acids over alkali metals and strong acids. Water salinity indices further reflect the suitability of groundwater for agricultural use. The majority of samples (85.714%) fall within the medium salinity hazard category (C2), appropriate for irrigation with moderate leaching. However, higher salinity samples, such as GK1 and KZ1, with EC values of 1054 µS/cm and 737 µS/cm, respectively, are limited to salt-tolerant crops and require careful management in soils with restricted drainage. Importantly, none of the samples fall into the high-salinity hazard category (C4), indicating overall positive irrigation potential. Geological formations, including Quaternary alluvium, Jurassic-Triassic dolomitic limestone, and Mesozoic peridotites, shape groundwater chemistry. For example, the low EC value at UB01 (248 µS/cm) reflects limited interaction between surface water and surrounding carbonate-rich formations.
How to cite: Erdem Altın, G.: Mapping Groundwater Concentration in the District of Ula, Muğla, Türkiye Using Spatial Interpolation Methods and Geostatistics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19769, https://doi.org/10.5194/egusphere-egu25-19769, 2025.
Posters virtual: Fri, 2 May, 14:00–15:45 | vPoster spot A
EGU25-10589 | ECS | Posters virtual | VPS11
Integrated catchment and treatment strategies for safeguarding drinking water quality: an adaptive decision-making toolFri, 02 May, 14:00–15:45 (CEST) | vPA.5
Ensuring the safety and sustainability of drinking water sources is a critical component of modern water resource management. The recast Drinking Water Directive (EU 2020/2184) emphasizes the delivery of safe drinking water by strengthening protections along the entire supply chain, from source to tap, and adopting a risk-based approach to water safety as recommended by the World Health Organisation. Assessments of water treatment costs tend to focus on the current level of treatment, and not the potential additional costs associated with treatment of new emerging contaminants, many of which are of low molecular weight requiring specialist treatment technologies with expensive CAPEX and OPEX costs. The impacts of climate change on the raw water quality source water abstractions are also likely to result in increasing costs of water treatment systems. In Ireland, the inclusion of emerging substances on the 2023 Drinking Water Regulations and on the first European Commission’s Watch List reflects the evolving nature of water safety management in response to pollutants of emerging concern and environmental pressures. This study presents a robust methodology with a view to inform future funding and targeting of water quality measures and source protection work. Applied across six case studies, the four-stage process (pre-screening, coarse screening, fine screening, and final comparative analysis) guides decision-making. The framework incorporates open-source data from the Environmental Protection Agency (EPA) of Ireland, including land-use maps, Water Framework Directive (WFD) waterbody status and significant pressures such as agriculture, forestry, industry, and hydro-morphology, alongside local pressures on water sources. Source protection measures and treatment technologies were derived from extensive literature review of national and international projects and were tailored to specific goals for each case study, with independent evaluations for both strategies. The process concludes with a comparative analysis to identify optimal solutions for each scenario. The study provides recommendations, based on economic assessments and the evaluation of environmental and technological gaps to support the stakeholders in decision making and policy development. The selected strategy for each case is dependent on a suite of site-specific features, including the raw water source type, the catchment size, the mapped WFD pressures exerted into the water source and the latest WFD status and the Water Treatment Plant capacity. The findings highlight the importance of adopting integrated approaches to ensure the resilience of drinking water systems in the face of future uncertainties.
How to cite: Sousa, D., Ali Khan, U., Bradshaw, S., and Grace, M.: Integrated catchment and treatment strategies for safeguarding drinking water quality: an adaptive decision-making tool, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10589, https://doi.org/10.5194/egusphere-egu25-10589, 2025.
EGU25-15376 | Posters virtual | VPS11
Enhancing Agricultural Efficiency through an IoT-Based Soil Moisture Monitoring Network Utilizing LoRaWAN and Edge ComputingFri, 02 May, 14:00–15:45 (CEST) | vPA.6
This study explores an IoT soil moisture monitoring network designed to improve agricultural efficiency and sustainability. The system integrates LoRaWAN-enabled soil moisture and temperature sensors, strategically deployed across agricultural fields, with a Raspberry Pi 4 gateway that processes and transmits data to the cloud. The combination of low-power, long-range communication and dual connectivity options—Wi-Fi and LTE 4G—ensures reliable operation even in remote areas, making the system ideal for large-scale agricultural monitoring.
The core of the network is a robust edge processing framework that enhances data accuracy, security, and efficiency. The framework begins with noise filtering, using techniques such as median filtering to remove anomalies from raw data. Once filtered, the data is aggregated over specific time periods to reduce transmission bandwidth and provide actionable summaries of soil conditions. Adaptive data rate adjustments further optimize resource use by increasing data collection frequency during significant environmental changes and reducing it during periods of stability.
Data security is ensured through encryption at the edge, protecting sensitive environmental information from unauthorized access. Local processing also supports predictive analytics, using models like decision trees or linear regression to forecast future soil moisture and temperature conditions based on historical trends. These forecasts enable proactive decision-making, such as adjusting irrigation schedules to maintain optimal soil moisture levels, improving resource efficiency and crop health.
Anomaly detection is another critical component of the system, identifying unusual patterns in sensor readings that could indicate malfunctions or unexpected environmental changes. This ensures data integrity by flagging or excluding erroneous data. In addition, real-time event-driven alerts notify users of critical thresholds, such as dangerously low soil moisture or rapid temperature changes, allowing for immediate interventions. Alerts are delivered through SMS, email, or cloud dashboards for maximum accessibility and responsiveness.
The system's scalability supports the seamless addition of sensors, accommodating expanding agricultural operations without significant modifications. Local data logging provides redundancy, preserving raw and processed data even during network outages. This ensures uninterrupted monitoring and allows for post-event analysis, enhancing reliability and resilience.
The network’s design offers substantial benefits for agriculture. Adaptive resource management conserves bandwidth, power, and computational resources, reducing operational costs while extending system lifespan. By combining edge processing with cloud analytics, the system provides timely and actionable insights, empowering farmers to make data-driven decisions. Enhanced security through encryption protects sensitive data, while predictive analytics and anomaly detection ensure proactive and accurate responses to changing field conditions.
Overall, the IoT soil moisture monitoring network is a robust and efficient solution for modern agriculture. It enhances real-time monitoring, decision-making, and resource management, enabling farmers to optimize irrigation, improve crop health, and boost productivity. The system's scalability and adaptability make it a practical choice for addressing the growing demands of precision agriculture, contributing to sustainable farming practices and improved food security.
Acknowledgement:
This research has been funded by European Union’s Horizon Europe research and innovation programme under ScaleAgData project (Grant Agreement No. 101086355).
How to cite: Vlachos, M., Mitro, N., and Amditis, A.: Enhancing Agricultural Efficiency through an IoT-Based Soil Moisture Monitoring Network Utilizing LoRaWAN and Edge Computing, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15376, https://doi.org/10.5194/egusphere-egu25-15376, 2025.
