HS1.1.3 | Approaches, technical perspectives, and nature-based solutions for resilience to floods and droughts
Approaches, technical perspectives, and nature-based solutions for resilience to floods and droughts
Convener: Lea Augustin | Co-conveners: Diego Panici, Lara Speijer, Rudy Rossetto, Alan Puttock, Scott Ketcheson, Roger Auster
| Wed, 17 Apr, 08:30–12:25 (CEST)
Room 2.44
Posters on site
| Attendance Wed, 17 Apr, 16:15–18:00 (CEST) | Display Wed, 17 Apr, 14:00–18:00
Hall A
Posters virtual
| Attendance Wed, 17 Apr, 14:00–15:45 (CEST) | Display Wed, 17 Apr, 08:30–18:00
vHall A
Orals |
Wed, 08:30
Wed, 16:15
Wed, 14:00
Global climate change causes an increasing frequency and intensity of floods and droughts. Both are strongly linked and have the potential to reinforce each other. Floods and droughts cover the entire hydrological spectrum and share many similarities and links between the two types of extremes. Nevertheless, management strategies and technical compensation and mitigation measures are often thought only from one side of the extreme, like flood retention basins releasing the stored flood water within days instead of keeping it in the region. With the significant environmental, social and economic cost associated with such extremes, there is an increasing need for sustainable catchment management strategies that attenuate flow regimes, minimising the risk of flooding and ensuring a sustainable water supply and ecosystem resilience during drought periods.

This session addresses nature-based and technical strategies to mitigate the effects of hydrological extremes on the local water balance.

Nature-based solutions at the catchment scale work with or are inspired by nature to restore the natural functioning of our anthropogenically modified landscapes, providing both greater hydrological resilience to extreme events but critically also a host of additional benefits, particularly for biodiversity, climate, and society. As the popularity of nature-based solutions increases, trans-disciplinary research is required to: (1) determine what constitutes a nature-based solution; (2) maximise the effectiveness of such solutions and how they can be implemented alongside existing water management strategies; and (3) consider the social factors that are inherent in the successful implementation of nature-based solutions, overcoming the conflicts or barriers that may otherwise be associated with their implementation.

Technical solutions like managed aquifer recharge, mainly when applied in drinking water catchments, are often turned off during flooding events due to suspected contamination risks to the aquifer. In contrast, successful management of regional water resources seems to require approaches, tools, and management strategies that combine flood protection and drought prevention techniques, i.e., water retention, treatment, and infiltration in subsurface storage systems (ideally aquifers) for long-term, high-quality uses.

Orals: Wed, 17 Apr | Room 2.44

Chairpersons: Lea Augustin, Rudy Rossetto, Scott Ketcheson
Technical perspectives
On-site presentation
Thomas Baumann and Lea Augustin

Stormwater in small catchments is a threat to agricultural land use and civilization. Increasing ambient temperatures increase the risks for severe rainfall and surface runoff and reduce the amount of groundwater recharge. At the same time, the demand for irrigation water is rising. This development calls for integrated strategies for stormwater protection and aquifer recharge.

In this contribution, we present a case study for a technical solution to infiltrate stormwater into the local aquifer. The site is located in an area well known for hop cultivation. The aquifers are located in tertiary sediments, which are covered with loess and are sometimes semi-confined. Hydraulic conductivities are in the 10-4 m/s range, and specific storage coefficients are between 10-6 (confined) and 0.2 (unconfined). Current stormwater protection plans include retention basins with a capacity of 5500 m³, not all of them fully functional, and flooding events were recorded two times per year. Demand for irrigation was 64 mm for the past five years, with peaks of 118 mm in 2022. Even if only the extreme rainfall events would be recharged into the aquifer, an area of 5-10 ha could be irrigated from the infiltrated water, assuming one extreme event. This is a significant amount of the area (15%) used for hop cultivation around the storage site.

Specific challenges at this site are the flood dynamics, the uncontrolled surface runoff, which brings a lot of fines, and the water quality with regard to fertilizers and pesticides. This requires small settling ponds or intermediate storage facilities and adsorbers. Most of the used products, however, have a medium to strong tendency to adsorb on organic carbon and even inorganic materials. The hydrogeological model indicates that the flood water can be infiltrated at high volumetric flow rates without risking upwelling groundwater tables. A detailed site investigation will be completed by mid-2024.

How to cite: Baumann, T. and Augustin, L.: Coupling stormwater protection and aquifer recharge, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5054, https://doi.org/10.5194/egusphere-egu24-5054, 2024.

On-site presentation
Francesco Maria De Filippi and Giuseppe Sappa

Groundwater is considered worldwide an important and resilient reserve of freshwater for human needs. The increasing demand, combined with climate change impacts, is leading to a remarkable quali-quantitative decay of water resource, especially in many megacities of the Global South, where the rapid urban growing pushed to environmental critical issues as the case of seawater intrusion for coastal aquifers. At the same time, the uncontrolled urbanization without a territorial planning favors the runoff and places ever greater areas in hydraulic danger, increasing the risk of flooding in currently inhabited areas. Dar es Salaam, in Sub-Saharan Africa, is one of these cases: a city of more than 4 million of inhabitants, with a population growth rate of about 5 per cent per year. A high dependence on natural resources ecosystems is mainly due to hybrid rural-urban livelihoods. The urban pressure on the aquifer caused a serious threat on water quality and quantity due to saline intrusion along the coastline, with depletion of groundwater levels and contamination of pumping wells. Moreover, the increasing risk of water scarcity and flooding due to climate change is threatening the local community, with an increasing need for adaptation measures. Catchment imperviousness of Mbezi River basin increased by 41% (2003-16), causing floods, erosion, land and marine pollution.

A new vision needs to integrate the groundwater management strategies, already proposed in the context of the “Adapting to Climate Change in Coastal Dar es Salaam” (ACC-DAR) project, with surface water management too. Aim of this feasibility study is to outline a strategy for a sustainable water management in the Dar Es Salaam territory, through the planning of MAR (Managed Aquifer Recharge) solutions in specific areas. This approach could be helpful to solve or, at least, mitigate the impact of both flooding and groundwater overexploitation in the area, allowing to support stakeholders and public government in implementing local policies and proposing a more sustainable use of the resource.


How to cite: De Filippi, F. M. and Sappa, G.: A new planning strategy for integrating surface water and groundwater management to face climate change impacts in the Dar Es Salaam Plain, Tanzania (Africa)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11760, https://doi.org/10.5194/egusphere-egu24-11760, 2024.

On-site presentation
Xuan Wu, Sotirios Moustakas, Nejc Bezak, Matej Radinja, Mark Bryan Alivio, Matjaž Mikoš, Michal Dohnal, Vojtech Bares, and Patrick Willems

Due to climate change and urbanization, increased extreme weather events and impervious urban surfaces have increased flood and drought risks. Blue and Green Infrastructures (BGIs) that can enhance stormwater management can help mitigate these negative effects. Nevertheless, the long-term performance of BGIs in an urban environment still requires further investigation. For this purpose, a fine-scale hydrological model and long-term water balance analysis are necessary. Accordingly, the first objective of this study is to develop a fine-scale water balance model that simulates runoff formation and propagation and incorporates BGIs. The second objective is to perform a long-term water balance analysis to determine the effectiveness of BGIs in mitigating urban floods and droughts.

The proposed water balance model is developed in Python. Model inputs include meteorological data such as rainfall and evapotranspiration, and catchment characteristics such as land use and pipe networks. This model divides the catchment into underground pipe reservoirs and surface reservoirs based on land use. All reservoirs are then connected by upstream and downstream relationships according to topological information. BGIs can be implemented by altering the properties of the reservoirs where they are proposed. To calculate the generated runoff, the continuous Soil Conservation Service Curve Number (SCS-CN) method is used in permeable reservoirs with infiltration capability, whereas the single-bucket approach is employed in impermeable reservoirs. The continuous CN method utilizes a dynamic CN and accounts for the recovery of initial abstraction between storms. In the single-bucket approach, all impermeable reservoirs are assumed to have inputs, outputs, and a certain amount of storage capacity. Rainfall and inflow from upstream reservoirs can be considered inputs, while discharge to downstream reservoirs and reuse for rain tanks can be considered outputs. These two rainfall-runoff calculation methods are validated by using monitoring data provided by the Czech Technical University in Prague and the University of Ljubljana, respectively, on green roofs and an urban park. After calculating runoff, the linear reservoir function is used as the runoff routing approach to simulate stormwater propagation according to reservoir connection relationships. Following the above processes, the water balance for the catchment can be analyzed, accounting for evapotranspiration, infiltration, reuse, overflow, and discharge at the catchment outlet.

The case study is done for the campus “Arenberg III” at the University of Leuven (KU Leuven) in Belgium. Three BGIs are proposed: permeable pavements, rain tanks and green roofs. Then five BGI scenarios are developed to evaluate the effectiveness of both single BGIs and combined BGIs: (1) campus without new BGIs, (2) every building has a green roof, (3) each building has a rain tank, (4) replacing impermeable parking lots with permeable pavements, and (5) all the BGIs listed above are implemented. The long-term water balance analysis is performed for the period 2010-2019. Initial results show that the combined BGIs scenario (5) yields the best results, as it can significantly reduce runoff and overflow, as well as provide substantial rainwater reuse and infiltration. Therefore, combining BGIs with different functions can be effective in mitigating both urban floods and droughts.

How to cite: Wu, X., Moustakas, S., Bezak, N., Radinja, M., Alivio, M. B., Mikoš, M., Dohnal, M., Bares, V., and Willems, P.: Evaluating the performance of Blue and Green Infrastructures in an urban area through a fine-scale water balance model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1677, https://doi.org/10.5194/egusphere-egu24-1677, 2024.

Virtual presentation
Jan Stautzebach, Jörg Steidl, and Christoph Merz

Water stress is increasing in Northeast Germany due to climate change. New approaches for water management are needed to mitigate the impacts on the water resources. Therefore, our study deals with the development of a web-based toolbox to manage subsurface water storage by artificial groundwater recharge with focus on the lower catchment of the river Spree in the federal state of Brandenburg.

Our approach is based on a systematic combination of site selection criteria and spatial data on land use, soil, groundwater and potential water sources. The aim is to provide relevant information for the preliminary planning of managed groundwater recharge measures by authorities and water suppliers. This includes a wide range of project scales that can be covered by the tool. However, as necessary volumes for large scale recharge projects are unlikely to be found in concentrated form, small scale projects with low demand of infrastructure and energy, are of main concern. Considering surpluses from runoff and surface waters, also caused by extreme weather events, suitable locations for surface-induced recharge will be identified. Thereby, solutions with low environmental impact, like the use of natural depressions for recharge, are highlighted to the user. This will allow for a stabilization of the local water balance, induced by a large number of low impact measures.

Supported by additional modelling-based indications for implementation, efficiency and costs, as well as simplified site selection through a query system, the toolbox will offer an initial knowledge for such planning considerations.

How to cite: Stautzebach, J., Steidl, J., and Merz, C.: Development of a water storage toolbox for surface-induced near-nature managed groundwater recharge, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2114, https://doi.org/10.5194/egusphere-egu24-2114, 2024.

On-site presentation
Sarah Ho, Chantal Kipp, Hans Goeppert, Johannes Hoefer, Frank Seidel, and Uwe Ehret

As climate change drives intensification and increased frequency of hydrological extremes, the need to balance drought resilience and flood protection becomes critical for proper water resources management. Recent extreme droughts in the last decade in Germany have caused significant damages to ecosystems and human society, prompting renewed interest in sustainable water resources management. At the same time, protection from floods such as the catastrophic 2021 event in the Ahr Valley remain heavy in the public conscience. In the state of Baden-Württemberg in Southwestern Germany alone, over 600 small (< 1 million m3) to medium-sized (1-10 million m3) reservoirs are currently operated for flood protection. In this study, we investigate optimal reservoir operating (storage and release) rules in a dual flood-drought protection scheme for selected modeled flood reservoirs in Baden-Württemberg. Daily target releases for drought protection are proposed based on modeled inflows from the calibrated hydrological model LARSIM. In a first step, the reservoir operation is optimized in a scenario of perfect knowledge of the future by using  meteorological observations as artificial weather forecasts in LARSM. The results of different operating rules are then evaluated based on their adherence to the target releases and flood protection performance. Rulesets that result in worsened flood protection relative to the current (flood-only) operation were eliminated as potential operation schemes. Based on provisional results, we will present and discuss the maximum potential benefit of adapting and retrofitting existing flood reservoirs for drought water storage.

How to cite: Ho, S., Kipp, C., Goeppert, H., Hoefer, J., Seidel, F., and Ehret, U.: Is drought protection possible without compromising flood protection? Estimating the maximum dual-use benefit of flood reservoirs in Southwest Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5542, https://doi.org/10.5194/egusphere-egu24-5542, 2024.

On-site presentation
Marta Faneca Sànchez, Corine ten Velden, Felipe García Grez, Bernhard Becker, and Hans van Duijne

Reservoir operation and groundwater management, and specifically Managed Aquifer Recharge (MAR) are often tackled separately despite the common objective to store water when it is available and provide water when needed. Few studies focus on the conjunctive management of reservoirs and aquifers to optimize IWRM in basins. This work takes into consideration the combined management of reservoir operation and MAR for the Elqui Basin in the Coquimbo region, Chile and proposes a conceptual model for integrated modelling. The conceptual model captures the complexity of integrated management in terms of contributing processes, time and spatial scales, risks, data and models and proposes approaches for an integrated tool. The Elqui Basin is located in the northern part of Chile. The last decade it has been exposed to prolonged and severe droughts. This has posed enormous pressure on the already scarce water resources, causing overexploitation of groundwater resulting in drastic lowering of the groundwater table. To analyse optimization of water allocation in the basin (including reservoir management and MAR), in addition to the conceptual model, a real time control model (RTC-tools) is developed by coupling a hydrological model (WFLOW) and a groundwater model (iMODFLOW) to RTC-tools. The RTC-tools exercise shows when and how much water would be available to infiltrate through MAR, whilst also considering the water demand of the many different users in the basin. Preliminary results show that while infrastructure should be adapted to conduct and infiltrate water in the region, reservoir operation and water allocation could be optimized to make MAR possible.

How to cite: Faneca Sànchez, M., ten Velden, C., García Grez, F., Becker, B., and van Duijne, H.: Integrated and conjunctive Reservoir and Aquifer Management to improve water security in the Elqui Basin, Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21269, https://doi.org/10.5194/egusphere-egu24-21269, 2024.

On-site presentation
JongChun Kim and Seokhwan Hwang

A representative example of how extreme rainfall events caused by climate change can be directly recognized is the increase of property damage due to urban flood. This surge in urban flood damage is not merely corresponding to an augmentation in probable rainfall depth but rather a result of urbanization with densely populated and concentrated flooding. Despite this circumstance, we have mostly revolved around increasing the return period, primarily focusing on the augmentation of probable rainfall depth to mitigate the flood damage by climate change. In terms of the temporal distribution of design rainfall, conventional methods such as the Huff method and alternating blocking method are still in use; however, they cannot accurately capture the real rainfall distribution. In this context, we investigate the viability of enhancing design standards by adjusting the temporal distribution of design rainfall without artificially inflating a return period for design. To achieve that, it is necessary to understand the impact of temporal rainfall distribution on the design flood.

We generate 449 dimensionless time-rainfall distributions for short-term(less than 6 hours) and 5,789 for long-term(6 hours or more) durations considering rainfall data from both meteorological observations by the Korea Meteorological Administration and d4PDF(Data for Policy Decision Making for Future) scenarios. Based on these distributions, total 25,860 hyetographs are synthesized for five rainfall durations. We repeatedly estimated the design flood using a rainfall-runoff model, revealing that the peak discharges varied up to 10 times depending on the time-rainfall distribution. Considering that increasing the return period from 50 years to 100 years generally results in only a 10% rise in probable rainfall depths, adjusting the temporal distribution of design rainfall provides a more adaptable approach to increasing design floods. These outcomes have the potential to broaden the perspective for applications of rainfall scenarios in data-based model or establishing the design flood standards.


Acknowledgement: This research was supported by a grant(2022-MOIS61-002(RS-2022-ND 634021)) of ‘Development Risk Prediction Technology of Storm and Flood for Climate Change based on Artificial Intelligence’ funded by Ministry of Interior and Safety(MOIS, Korea).

How to cite: Kim, J. and Hwang, S.: Considering temporal distribution of design rainfall for enhancing urban flood resilience in response to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-45, https://doi.org/10.5194/egusphere-egu24-45, 2024.

On-site presentation
Sustainability Analysis of Climate Change Mitigation Measures to Support Community Adaptation against Compound Flooding
Hassan Davani
On-site presentation
Copper Lewis and Ian Pattison

The implementation of Natural Flood Management (NFM) measures theoretically provides an opportunity to build resilience into flood risk management systems in a way that incorporates sustainable practices and holistic management of the landscape. However, there remains a lack of clear understanding of these solutions, and in practice this can hinder the uptake of NFM;  there is a need to expand the emerging evidence base in order to quantify and demonstrate their effectiveness in a range of catchment and storm event scenarios.

This study focuses on an NFM scheme implemented across a 22km2 rural, lowland catchment in Lincolnshire, UK. An additional 46,000m3 of storage has been created through the construction of five offline attenuation ponds and a number of field-edge swales alongside the channel network. Land management practices in this catchment have resulted in significant modifications to the hydrological processes through historical realignment and modification of the channel network, intensive agricultural practices and the installation of tile drainage beneath arable fields. The Swaton Eau catchment is located in a lowland area with an elevation range of less than 50m across the catchment. It is important to investigate how NFM features are expected to perform in catchments that are characterised by hydro-modifications and low gradients as there currently is a lack of research of this.

An array of monitoring has been installed across the catchment in a nested structure to gather empirical evidence on the performance of the NFM scheme both at a feature scale and at a wider sub-catchment and catchment scale. Water level sensors are located throughout the channel network to track the propagation of the peak flood level. Transects of soil moisture sensors are buried in the shallow sub-surface in chosen swales to monitor short time-scale movement of water through these features.

The first major test of the features occurred in October 2023 during Storm Babet and Storm Ciaran. Field evidence indicates that the flood wave was attenuated through the catchment with a less flashy catchment response observed compared to a pre-NFM event in 2012. Soil moisture data collected within the swales indicates that they are intercepting pathways of water through the catchment and preventing runoff entering the surface water drainage network.

How to cite: Lewis, C. and Pattison, I.: Understanding the role of natural flood management in a ‘not-so-natural’ catchment: field observations of an NFM scheme in rural, lowland Lincolnshire, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11525, https://doi.org/10.5194/egusphere-egu24-11525, 2024.

Coffee break
Chairpersons: Diego Panici, Lara Speijer, Alan Puttock
Nature-based solutions
On-site presentation
Claudia Bertini, Muhammad Haris Ali, Andreja Jonoski, Ioana Popescu, and Schalk Jan van Andel

Climate change has caused an increase in the frequency of hydrometeorological extremes world-wide, opening new challenges for decision makers and stakeholders in managing and regulating water. Among the adaptation strategies available, Nature-based Solutions (NBSs) gained increasing attention in recent years, because of their efficiency in reducing hydrometeorological risks while also providing additional benefits for biodiversity, landscape and society. Despite the ever-increasing interest for NBSs, many stakeholders still doubt their potential, as the quantitative effects of NBSs over long periods of time are still to be assessed.

In this research, we show how several types of NBSs, such as wetlands restoration, infiltration ponds, ditch blocking and others, can be used to adapt to drought conditions under the future climate projections. We use as a pilot case the transboundary Aa of Weerijs catchment, shared between Belgium and the Netherlands, which recently became drought-prone. We develop a fully distributed coupled MIKE SHE-MIKE 11 model to mimic the hydrological behaviour of the catchment in present (2010-2019) and future climate conditions (2050-2059, scenario KNMI ‘23). The same hydrological model is then used to test the effectiveness of different drought adaptation measures, based on single type or combinations of NBSs. To quantify the impacts of the chosen strategies to adapt to drought conditions and in consultation with some local stakeholders, we define a set of Key Performance Indicators (KPIs) that provide tangible results for stakeholders and decision makers. Finally, we show the results of the different adaptation strategies implemented on a web-app, which can be accessed and used by decision makers and stakeholders as an aid tool to select the best adaption strategy.

This research has been developed within the project EIFFEL (Revealing the role of GEOSS as the default digital portal for building climate change adaptation and mitigation applications, https://www.eiffel4climate.eu/), funded by European Union’s Horizon 2020 research and innovation programme under Grant Agreement Νο 101003518.

How to cite: Bertini, C., Ali, M. H., Jonoski, A., Popescu, I., and van Andel, S. J.: Revealing the role of Nature-based Solutions as drought adaptation strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5105, https://doi.org/10.5194/egusphere-egu24-5105, 2024.

On-site presentation
Roland Löwe, Martina Viti, Karsten Arnbjerg-Nielsen, and Jacob Ladenburg

Space is a highly valued asset in cities. This is a key reason why nature-based solutions (NBS) for water management are often perceived to be more expensive than traditional grey
solutions. Promoting NBS implementation requires methods for quantifying their non-market benefits that are widely accepted and easy-to-apply in early planning and brainstorming stages.

In this work, we develop a predictive metamodel for the total economic value of urban and peri-urban nature, based on 114 stated-preference valuation studies of nature in (peri-)urban areas and openly available geographic data from across the world. The dataset covers the entire range of NBS types with sizes from 0.5 to 900.000 ha. We employ a mixed-effects modelling approach and use a cross-validation procedure to determine which factors affect the willingness to pay for (peri-)urban nature. We consider the predictive performance of 8.4 million model permutations that consider different combinations of site properties and topographic and socio-economic characteristics of the surroundings as input.

We find that the total economic value is determined by the size of the nature areas and population densities in their surroundings. There is clear evidence for substitution effects where available nature areas reduce the willingness to pay for new nature. Beyond the dependency on area, there is little evidence for making distinctions between nature types. Economic values do depend on the average income at a site, but these variations are entirely captured by purchase power corrections. Our value estimates are aligned with related literature and range between 150 and 400,000 USD/ha/year. We have implemented our metamodel into a freely available Python program, which generates maps of the predicted values for any location in Europe in a spatial resolution of 100m.

How to cite: Löwe, R., Viti, M., Arnbjerg-Nielsen, K., and Ladenburg, J.: Co-benefit valuation of urban and peri-urban nature in high resolution on continental scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11339, https://doi.org/10.5194/egusphere-egu24-11339, 2024.

On-site presentation
Guan-Yu Lin, Kuo-Wei Liao, Pohsaun Lin, Kai-Lun Wei, and Tsungyu Hsieh

In response to the increasingly complex challenges faced by our environment and society, there's a paradigm shift in flood management practices within the field of hydraulic engineering. Traditional approaches using gray infrastructure are giving way to Nature-based Solutions (NbS), which prioritize sustainability and ecosystem-based approaches. Despite widespread discussions about NbS potential, there's a lack of a clear framework for its application and evaluation. This paper aims to apply Nature-based Solutions (NbS) measures for the Huang River Watershed, located in northern Taiwan. A clear process for planning and assessing the benefits of NbS is established while providing relevant case studies as demonstrations. The planning process thoroughly considers the opinions of stakeholders. To evaluate the effectiveness of the implemented measures, several methods such as hydraulic modeling using HEC-RAS 2D, ecosystem service assessment via Integrate Valuation of Ecosystem Services and Tradeoffs (InVEST), and flood risk analysis through reliability analysis are adopted. Results shown that the designed wetland can reduce the flooded area downstream of the Huang River by 9.86% for a 50-year flood and by 3.95% for a 2-year flood; the designed wetland will increase carbon storage by 75.74% and reduce soil erosion by 50.77%, while habitat quality will be maintained at a similar level and the probability of flooding reduces to 3%. By leveraging the above assessment methods, this study can bridge the gap between engineering and ecological conservation fields via demonstrating the benefits of NbS implementation. The outcomes of this research are intended to serve as a valuable reference for future studies and inform decision-making processes related to similar projects.

How to cite: Lin, G.-Y., Liao, K.-W., Lin, P., Wei, K.-L., and Hsieh, T.: Study of Nature-Based Solutions for the Huang River Watershed, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7837, https://doi.org/10.5194/egusphere-egu24-7837, 2024.

On-site presentation
Vassilios Pisinaras, Konstantinos Babakos, Anna Chatzi, Dimitrios Malamataris, Vassiliki Kinigopoulou, Evangelos Hatzigiannakis, and Andreas Panagopoulos

Nature-based solutions (NBS) offer innovative and sustainable approaches to address irrigation water management challenges, since they can contribute significantly to enhancing water retention, reducing soil erosion, and optimizing water use efficiency. Within this framework, the Soil & Water Assessment Tool (SWAT) model was applied in the Pinios Hydrologic Observatory (PHO) in central Greece to quantify the impact of two NBSs on irrigation water use: a) effective soil water management through irrigation scheduling and b) increased soil water holding capacity through mulching and mowing. Encompassing an area of approximately 55 km2, PHO comprises forested and agricultural lands, predominantly cultivated with apples, followed by cherries and other orchards.

The SWAT model was applied in the PHO watershed for the period 2018-2022 and calibrated against soil water content with daily observed data obtained from soil moisture sensors installed both in forested and agricultural areas. A hybrid land use map, compiled by combining CORINE land cover and field-scale crop distribution, was utilized and the watershed was subdivided into 15 sub-watersheds and 696 Hydrologic Response Units (HRUs). Monitoring of actual irrigation water consumption in 10 orchards revealed an average of 670 mm per cultivation period. Simulation of irrigation scheduling using the SWAT model indicated a potential reduction of more than 20% in irrigation water consumption in the apple orchards.

Continuous cultivation for several decades, irrational irrigation and the excessive use of herbicides practiced in PHO affect soil health, potentially leading to soil organic content (SOC) depletion, microbial activity disruption, and overall soil fertility compromise. Augmenting SOC enhances soil water holding capacity, fostering improved moisture retention and resilience against drought conditions. Analysis of over 500 soil samples collected from orchards implementing mulching/mowing practices compared to those predominantly using herbicides revealed an average SOC 1.2% higher for soil depths of 0-10 cm and 0.6% higher for depths of 10-30 cm. This increase in SOC is estimated to potentially raise soil available water content by 2%, contributing to 3% more irrigation water savings when coupled with effective soil water management through irrigation scheduling. While this water-saving potential may not be high, it can contribute significantly to mitigating water scarcity during drought periods, whilst should SOC increase is achieved by mulching/mowing and no use of herbicides, soil erosion is prevented, soil aeriation is improved, natural pollinator population is increased and agrochemicals’ runoff potential is reduced.



This research was funded by PRIMA program supported by the European Union, grant number 2041 (LENSES—Leaning and Action Alliances for Nexus Environments in an Uncertain Future) (Call 2020 Section 1 Nexus IA).

How to cite: Pisinaras, V., Babakos, K., Chatzi, A., Malamataris, D., Kinigopoulou, V., Hatzigiannakis, E., and Panagopoulos, A.: Preliminary Assessment of Nature-Based Solutions Performance for Improving Irrigation Water Management Using the SWAT Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16242, https://doi.org/10.5194/egusphere-egu24-16242, 2024.

On-site presentation
Benjamin Jackson, Alan Puttock, Diego Panici, and Richard Brazier

The Eurasian beaver (Castor fiber) is being reintroduced to Great Britain after an absence of ~400 years. Beavers are well known for their considerable engineering capabilities. Given the right conditions, beavers construct dams, excavate channels and maintain wetlands. These changes have been demonstrated to have a significant impact upon hydrological extremes in the English environment. There is the potential for beaver re-introduction to have a transformative impact as a widespread nature-based solution (NBS). However, there is a need for policy and management relevant understanding at a national level.

Funded by the Environment Agency in England, the aim of this study was to use a modelling approach to be able to estimate how catchments in England may respond to extreme events following the re-introduction of beavers. To accomplish this, we have applied the 2D version of the hydraulic model HEC-RAS to sites across England. Sites were selected that had the potential for beavers to construct dams.

Beaver dams are represented within HEC-RAS by digitising a series of weirs intersected by culverts, allowing water to leak through the dam as well as overtopping the weir. To account for uncertainty in dam properties, we configured the model to simulate different configurations of dam height, as well as the “leakiness” of each dam.

Using the approach described, HEC-RAS was used to simulate the impact of hypothetical beaver dams on storm events of different magnitudes in addition to low flow scenarios. Results suggest that the impact of beaver dam sequences on hydrology is highly dependent on channel and floodplain topography.

We were then able to apply these results to produce an estimation of the impact of beavers on flow regimes at any river stretch in England. This was estimated for three scenarios with high, moderate and low presence of beavers across England. It is hoped that these modelling tools can be used to strategically determine where and how beavers may be able to provide a hydrological NBS and where supporting their wetland creation could be most valuable.

How to cite: Jackson, B., Puttock, A., Panici, D., and Brazier, R.: Modelling the impact of beaver dams on hydrological extremes following the re-introduction of beavers in England , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4675, https://doi.org/10.5194/egusphere-egu24-4675, 2024.

On-site presentation
Sim Reaney

Nature-based solutions have the capability to slow and store water during storm events, leading to the attenuation of flood peaks and the capturing of sediments and associated nutrients. These features can also provide important habitats for wildlife and pollinators. However, these features do take land that may be agriculturally productive and require maintenance, both factors mean that they have potentially significant ongoing costs. Therefore, it is important to ensure that they are effective and correctly located within the landscape. For all pressures, the location needs to be in a location where the problems are likely to originate. However, for flood waters, it is important to target locations that are likely to contribute to moving water out of the flood peak and into the receding limb of the hydrograph, rather than moving water from the rising limb into the peak. It is also important not to move water from the peak discharge of one community into the peak discharge of another. Therefore, careful analysis and planning are needed to ensure that the benefits from the nature-based solutions are maximised for all in the catchment.


The SCIMAP Toolkit provide an approach to assess the potential source area of flood waters, sediments, nutrients and FIOs and to ensure that the multiple benefits of the nature-based solution are realised. The toolkit uses a reduced complexity approach to map the generational of rapid runoff, the mobilisation of material and connectivity to the receiving waters. The SCIMAP-Flood module then considers the travel times to the impact points within the catchment, such as a community or key infrastructure.  This analysis is undertaken in a time-integrated way such that the potential benefits of a nature-based solution are optimised over a range of storms rather than fitting to the unique dynamics of a past event. The analysis is undertaken at landscape extent with sub-field detail, normally at a ground resolution of 1m with the catchment extent covering 1000s of km2.  This presentation shows the application of the SCIMAP approach to the spatial targeting of flood mitigation features and how these locations can co-deliver water quality benefits.

How to cite: Reaney, S.: Opportunity mapping for nature-based solutions for flood hazard reduction and water quality improvements with the SCIMAP toolkit, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18566, https://doi.org/10.5194/egusphere-egu24-18566, 2024.

On-site presentation
Inci Güneralp, Mahbub Hasan, Rakibul Ahasan, Billy Hales, and Anthony Filippi

Aimed at achieving environmentally and economically smart growth in lowland riverscapes in the face of exacerbating flood threats, the elements of natural riverscapes, such as floodplain landforms, riparian forests, and wetlands can provide solutions to flood risk reduction. Geomorphological knowledge is crucial to working effectively with river processes and landforms in addressing flood hazards. In addition to unique landforms and habitats that can support flood mitigation, landscape-level geomorphological characteristics, such as geomorphological heterogeneity and connectivity, can also impact the attenuation and retention of downstream fluxes of water, sediment, and other materials, and thus resistance and resilience to floods. In this study, we employ a geomorphological approach to delineate the natural elements of lowland riverscapes as geomorphological habitats to assess their susceptibility to floods and erosion/sedimentation as well as their capacity to alleviate the negative impacts of floods. To delineate geomorphological habitats, we utilize a range of classification approaches and geospatial data including LiDAR-derived digital terrain models, airborne and satellite images, raster/vector data on vegetation, soils, and land-cover land-use. We then quantify the diversity, heterogeneity, and connectivity of delineated habitats using landscape ecological approaches and in the context of flood impacts and mitigation. Our geomorphological approach to riverscape characterization provides new insights on fundamental knowledge of natural elements as geomorphological habitats and their interconnections and interdependencies. This new knowledge has a high potential for developing geomorphologically derived nature-based solutions to flood management and enhancing flood resilience of lowland riverscapes.

How to cite: Güneralp, I., Hasan, M., Ahasan, R., Hales, B., and Filippi, A.: Enhancing Flood Resilience: Geomorphological Insights into Lowland Riverscapes for Nature-Based Solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6391, https://doi.org/10.5194/egusphere-egu24-6391, 2024.

On-site presentation
Maria Elenius, Charlotta Pers, Sara Schützer, and Berit Arheimer

Historical drainage to improve agricultural and forestry practices has resulted in almost 1 million km of artificial channels in Sweden. This has reduced the storage of water in the landscape, and there are concerns related to the potential impacts on extreme flows, biodiversity, greenhouse gas emissions and nutrient outputs. A large national restoration program aims to rewet 100 000 hectares forested peatland. However, there is limited evidence in what the impacts will be.

Here, we implemented national information on ditches to the hydrological model HYPE and investigated the conditions at which removal of ditches in forested peatland could mitigate extreme flows under various conditions of the climate and local hydrology. We found that the impact on discharge at the level of 10 km2 sub-catchments or larger was small, mostly because only small fractions of the catchments consist of drained forested peatlands, meaning there is considerable mixing with other runoff. However, smaller streams with runoff primarily from the restored peatlands could have substantial impacts of restoration, which may be important for local biodiversity.

For instance, a modelling sensitivity study showed the minimum runoff per year from forested peatlands increased by up to about 15 % after removing ditches and the maximum runoff was reduced by up to about 25 %. Importantly, an increase in the minimum runoff was only obtained if the minimum groundwater level was low enough in relation to the depth of ditches. Similarly, a reduction of the largest yearly runoff required that ditches were not too deep.

If conditions were not favorable to mitigate extreme runoff, the opposite situation often occurred instead, with worse extremes. Therefore, although the impact on extreme flows was negligible at the level of 10 km2 catchments or larger, it is crucial to choose appropriate sites for restoration with respect to runoff extremes if there are sensitive smaller streams with runoff deriving mostly from the peatlands. The work presented here shows how this can be performed with the use of indicators for groundwater levels and ditch drainage prior to rewetting. Specifically, the minimum runoff is expected to increase only if the minimum groundwater level prior to rewetting is below the depth of ditches, or close to that depth. Reductions in the maximum runoff require ditches are not too deep, and large reductions cannot be expected if the groundwater level was already temporarily above the soil surface prior to rewetting, for example due to lateral inflow.

How to cite: Elenius, M., Pers, C., Schützer, S., and Arheimer, B.: When can rewetting of forested peatlands reduce extreme flows?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17611, https://doi.org/10.5194/egusphere-egu24-17611, 2024.

On-site presentation
Lien De Trift and Estifanos Addisu Yimer

Droughts are classified as the most expensive climate disasters as they leave long-term and chronic impacts on the ecosystem, agriculture, and human society. The frequency, intensity, and duration of drought events have shown a historical increase and are projected to escalate globally, continentally, and regionally in the future. Nature-based solutions (NBS) are highlighted as effective solutions to cope with the future impacts of these events. Until now, there has been a lack of a comprehensive suitability mapping framework that considers drought-specific criteria. To address this gap, a novel framework is introduced, targeting the identification of suitable areas for two drought-mitigating NBS types—detention basins and managed aquifer recharge—on a regional scale. 

This new framework incorporates diverse criteria to specifically address drought conditions. For example, by incorporating climate change scenarios for both surface and groundwater, it identifies suitable and sustainable locations capable of managing extreme drought events. Executed through Boolean logic at a regional scale in Flanders (Belgium), the framework's strict approach yields significant potential areas for detention basins (298.7 km²) and managed aquifer recharge (867.5 km²). Incorporating multi-criteria decision-making (MCDM) with the same criteria introduces a higher degree of flexibility for decision-makers. This approach shows a notable expansion across Flanders, varying with the level of suitability. The results underscore the highly suitable potential for detention basins (2840.2 km²) and managed aquifer recharge (2538,7 km²), emphasizing the adaptability and scalability of the framework for addressing drought in the region.

How to cite: De Trift, L. and Yimer, E. A.: Framework for identifying large-scale Nature-Based Solutions for drought mitigation: regional application in Flanders , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10085, https://doi.org/10.5194/egusphere-egu24-10085, 2024.

Virtual presentation
Jorge Martínez León, Miguel Ángel Marazuela Calvo, Carlos Baquedano, Jon Jimenez, Samanta Gasco Cervero, Jesica Rodríguez-Martín, Juan Carlos Santamarta, and Alejandro García-Gil

Advancing Climate Resilience in the Canary Islands: Insights from the NATALIE Project on Nature-Based Solutions


Jorge Martínez León1, Carlos Baquedano1, Miguel Ángel Marazuela1, Jon Jimenez2, Samanta Gasco Cervero3 Jesica Rodríguez-Martín4, Juan Carlos Santamarta5 and Alejandro García-Gil1,


1Geological and Mining Institute of Spain (IGME), Spanish National Research Council (CSIC), Madrid, Spain (a.garcia@igme.es)

2Department of Earth Sciences, University of Zaragoza, Zaragoza, Spain

3Madrid Health Department, Madrid City Council, Spain.

4 Department of Techniques and Projects in Engineering and Architecture, University of La Laguna (ULL), Tenerife, Spain.

5Department of Agricultural and Environmental Engineering. University of La Laguna, Tenerife (Canary Islands), Spain


This communication outlines the research framework of the NATALIE project, emphasizing the application of Nature-Based Solutions (NBS) to address pressing climate change challenges across three distinct case studies in the Canary Islands—Gran Canaria, Tenerife, and Fuerteventura. The primary focus is on utilizing NBS as transformative measures to bolster resilience throughout the archipelago. Identified challenges encompass escalating extreme rainfall intensities leading to floods, uncontrolled runoff, water quality degradation from sewer overflows, desertification, and the management of groundwater bodies under future climate change scenarios.


The showcased activities include a series of NBS and Sustainable Urban Drainage Systems (SUDS) in Gran Canaria, with specific attention given to the Maspalomas lagoon. Tenerife's La Laguna case study highlights innovative NBS aimed at preventing flooding, presenting cost-effective alternatives for the construction of new drainage systems. Fuerteventura's initiative involves implementing natural treatment systems to combat nitrogen and pollutants, coupled with the utilization of regenerated water for restoring degraded wetlands. Furthermore, the research explores the monitoring of retention and infiltration capacities of traditional agricultural and rainwater storage systems.


The overarching goal of this research is to advocate for a comprehensive and diverse implementation of NBS, thereby contributing significantly to the resilience of the Canary Islands against the multifaceted impacts of climate change.


How to cite: Martínez León, J., Marazuela Calvo, M. Á., Baquedano, C., Jimenez, J., Gasco Cervero, S., Rodríguez-Martín, J., Carlos Santamarta, J., and García-Gil, A.: Advancing Climate Resilience in the Canary Islands: Insights from the NATALIE Project on Nature-Based Solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19873, https://doi.org/10.5194/egusphere-egu24-19873, 2024.

Posters on site: Wed, 17 Apr, 16:15–18:00 | Hall A

Display time: Wed, 17 Apr 14:00–Wed, 17 Apr 18:00
Chairperson: Roger Auster
Lara Speijer, Simon Six, Bas van der Grift, Gijsbert Cirkel, Goedele Verreydt, Jef Dams, and Marijke Huysmans

Flanders (Belgium) is expected to experience more severe drought and flooding events in face of climate change. Infiltration to increase groundwater recharge is therefore adopted as policy strategy to deal with both hydrological extremes. Stormwater provides an interesting water source for managed aquifer recharge, given the high urbanization and imperviousness level of the region. Furthermore, the historical ban on infiltration in groundwater protection zones for drinking water production has been removed to encourage infiltration practices. This could potentially enhance groundwater recharge in the groundwater abstraction zones, but concerns remain regarding the impacts on groundwater quality due to the potential contamination of stormwater with a wide range of pollutants originating from traffic, building materials, weed control and other more diffuse sources.

Therefore, tools need to be developed to weigh out benefits of groundwater replenishment relative to potential groundwater quality risks. This research aims to contribute to the knowledge on the hydrological aspects of this quantity-quality balancing exercise by investigating the potential of stormwater managed aquifer recharge to replenish the groundwater system in Flemish groundwater protection zones. For this, potential stormwater volumes that could supply managed aquifer recharge are calculated and compared to the actual groundwater recharge and pumping volumes for drinking water production to assess the significance of this practice in protection zones.

Results indicate a variable, but high stormwater infiltration potential in Flemish protection zones, providing up to 29% extra groundwater recharge in all protection zones combined. Furthermore, this practice could compensate up to 32% of abstracted phreatic drinking water volumes. Locally, the potential can be higher, reaching 100% in protection zones located in highly urbanized areas, including zones around the city of Leuven. Stormwater infiltration can therefore be considered as an important drought adaptation measure in Flemish protection zones, given the same order of magnitude of stormwater and pumping volumes in these areas. However, recent studies raise concern on the occurrence of organic micropollutants in stormwater and data in the Dutch and Flemish setting is insufficient. Therefore, additional research on occurrence and fate of these substances is needed.

How to cite: Speijer, L., Six, S., van der Grift, B., Cirkel, G., Verreydt, G., Dams, J., and Huysmans, M.: Enhancing groundwater recharge in face of hydrological extremes: assessment of stormwater managed aquifer recharge potential in Flemish drinking water protection zones (Belgium), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5423, https://doi.org/10.5194/egusphere-egu24-5423, 2024.

Tahra Al-Rashdi

Sultanate of Oman produces a high volume of wastewater on a daily basis. Since conventional / mechanical wastewater treatment methods are mostly used in the country, a respectively high volume of sludge by-product is also generated daily. Sludge is defined as a mixture of water, organic matter and inorganic matter resulting from the biological treatment of wastewater. Oman manages the generation of sludge by discharging about 84% of it in the landfills, especially the Sewage Treatment Plants (STPs) located outside the capital city of the country (Muscat Governorate), while about 16% of produced sludge is collected by Oman Water and Wastewater Services company and is further processed through composting to produce a fertilizer (‘Kala’ brand name).

For these reasons, revolutionary and cost-effective means and ways are needed to manage the sludge for environmentally friendly sound disposal and reuse. One of the promising and state-of-the-art sustainable technologies is the constructed wetland technology for dewatering and stabilization of sludge. The Sludge Treatment Wetland (STW) system depends on the type of substrate, type of plants and microbial communities that play an important role in the treatment and dewatering of the sludge. In addition, it contributes to the decentralized management of sludge, a parameter that is crucial for small and medium STPs.

This study focuses on the construction of STWs, i.e., vertical flow constructed wetland designed for sludge dewatering, using local common reed plants (Phragmites Australis) to treat activated sludge from Alseeb STP. A pilot scale experiment was conducted in an agricultural experiment station. This study is the first one in Oman and across the Arabic peninsula that tests the STW technology. The study consisted of 18 mesocosms tanks. Each tank has dimensions of 89 cm in height and 0.5 m² surface area. The freeboard in each tank was 54 cm above the top gravel layer. The units are filled with substrate media from top to bottom: 15 cm fine gravel (2-6 mm), 15 cm medium gravel (15-25 mm) 5 cm and drainage layer of cobbles (40-60mm). Two plastic tubes extending vertically with an open top are embedded in the bottom of each unit. The various units have different construction and operation parameters such as planted and unplanted beds (i.e., presence and absence of plants) and three different sludge loading rates (SLR; 75, 100, 125 kg/m²/year).

The results showed the dewatering efficiency reached 97% for the planted STWs compared to 91% for the unplanted beds. The total solids content in the dewatered sludge for the three SLRs (75, 100 and 125 m²/kg/year) were between 23 -56%, 16-57% and 11-42%, respectively. These first results demonstrate that a high total solid content in the dewatered sludge can be achieved even at a relatively high SLR of 100 m²/kg/year after almost 2 years of operation. This means that the dry content can be further increased in the final resting phase that is going to be applied before the emptying of the biosolids from the units.

How to cite: Al-Rashdi, T.: Dewatering and Treatment of Domestic Sewage Sludge Using Constructed Reed Bed , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9875, https://doi.org/10.5194/egusphere-egu24-9875, 2024.

Scott Ketcheson and Jennifer Attema

In Canada’s Western Boreal Plain, catchment runoff is typically low but spatially variable. Localized landscape soil and vegetation cover types, along with the hydrophysical properties of underlying glacial deposits and regional slopes, are important controls for the partitioning of precipitation into runoff, evapotranspiration, and soil water storage. Wetlands are abundant, covering up to 50% of the landscape, despite a regional sub-humid climate. Local topographic highs, including Stony Mountain, have been identified as water generation hotspots, with the goal of this research to evaluate the hydrology and importance of small headwater catchments on a local topographic high for water generation and availability in downgradient systems.

Hydrologic interactions between forestlands and adjacent wetlands were characterized and related to observations of small-scale (headwater) catchment runoff dynamics within the Stony Mountain Headwater Catchment Observatory (SMHCO) in northern Alberta, Canada. Catchment runoff efficiency, or runoff coefficients (i.e., the proportion of rainfall the is produced as runoff), were evaluated for 40 events across six wetland-dominated catchments ranging in size from <0.5 km2 to ~ 200 km2. Water table configurations indicated varying exchanges among forested hillslopes and adjacent wetland systems, with the magnitude of runoff response to rainfall events controlled largely by antecedent water table configurations. Small (<10 km2) headwater catchments demonstrated highly variable runoff efficiencies, ranging from 10 to 90% (average 35%). Larger meso-scale catchments (up to 200 km2) demonstrated lower runoff efficiency (average = 25%; range 10 to 40%). The higher catchment runoff efficiencies observed in smaller headwater catchments identifies these regions as highly productive regions for water generation on a per-unit area basis. Accordingly, the findings of this research demonstrates that smaller sub-catchments within headwater regions of larger catchments represent an important area for water supply and availability for down-gradient ecosystems and water courses.   

How to cite: Ketcheson, S. and Attema, J.: The importance of headwater catchments for water availability in the lower Athabasca River Basin, Canada., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11839, https://doi.org/10.5194/egusphere-egu24-11839, 2024.

Malina Ruck, Lea Augustin, and Thomas Baumann

River quality is expected to change significantly as a consequence of climate change. Extended drought periods and decreasing groundwater levels will lower the contribution of groundwater to receiving streams and heavy rain will cause excessive surface runoff effects. Constant sources, like discharge from wastewater treatment plants or industrial installations, will be diluted in largely different ratios. The overall hydrochemical dynamics will, therefore, likely increase. This affects flood management schemes and other potential uses of river water.


This study links trace substances (hydrochemistry, colloids) to the hydrological dynamics in the catchment. From this data the feasibility of infiltrating excess river water into a nearby aquifer (Flood-MAR) is assessed. The upper part of the study area is characterized by forests and meadows. There is a small village with one sewage treatment plant (1000 inhabitant equivalents) and a few hamlets. Additional emissions can be expected from surface runoff of one national road (deicing, tire abrasion, etc.).


The hydrochemical characteristics show a decrease in the main cations and anions during a flooding event. Nitrate concentrations were low in both cases. Although particle concentrations were increasing during the flooding event, the overall concentrations were still below our expectations. This indicates that the meadows behind the retention dam, which were partly flooded, served as a settling ponds and filters. During low water conditions, organic material and algae were dominant. Few calcite particles and silicates are indicative of the composition of the quaternary gravels that make up the aquifer.


The results confirm the risk assessment of the study area. The water quality during a flooding event met the legal thresholds set in the German Soil Protection Act, so infiltration into the downstream aquifer should be feasible.

How to cite: Ruck, M., Augustin, L., and Baumann, T.: Indicators for anthropogenic and natural water contributions to a small river, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11325, https://doi.org/10.5194/egusphere-egu24-11325, 2024.

Yared Abayneh Abebe, Samikshya Chhetri, Laddaporn Ruangpan, and Zoran Vojinovic

One of the benefits of nature-based solutions (NBS) is providing environmental benefits, which regulate and maintain ecosystem services and foster positive impacts on ecosystems. Environmental benefits of NBS include enhancing water quality, habitat changes, improving biodiversity and carbon sequestration and storage. In this research, we developed a method to assess changes in habitat areas using remote sensing data.

Since mapping habitats is a harder task, our method is based on mapping and detecting changes in land cover over a region and translating that to changes in habitat area. We employed the CORINE Land Cover (CLC) classes and EUNIS habitat classes, two commonly used classification systems for land cover and habitat types, respectively. To assess the change in habitat type and area before and after implementing NBS, the CLC Level III classes were transformed into EUNIS Level I habitat types. The CLC datasets of 2000 and 2018 were used as the land covers before and after implementing an NBS. We applied the method in Aarhus, Denmark, in two study areas called Egå Engsø and Lystrup. An artificial lake and wetland that covers an area of 115 hectares was implemented in 2006 in Egå, surrounded by 35 hectares of grazed meadows. The NBS in Lystrup includes basins, gullies and rainbeds. The purposes of the NBS are to reduce the flood risk from the river Egå and isolated storms, reduce the nitrogen supply to Aarhus Bay and improve the natural conditions in the area.

Results showed the conversion of a cultivated habitat to an inland surface water habitat. A bogs, mires and fens habitat had also emerged west of the wetland. In the southwest of the wetland, an agricultural habitat had changed to a complex habitat, and the south of the region was surrounded by an artificially dominated habitat. Finally, a complex habitat had changed to a constructed habitat in the southeast of the wetland. On the other hand, habitat changes had not altered significantly in Lystrup despite the implementations of NBS projects. It is also possible that NBS-induced modifications could not be recorded by the method as the area was a complex habitat characterized by a heterogeneous blend of different habitats. One limitation of this method could be that it is difficult to delineate changes within complex habitats. Additionally, the limitation arises from the translation of the land cover classes to habitat classification. However, the research offers a method to quantify one of the environmental benefits NBS generate to encourage decision-makers to implement and scale them up further.

How to cite: Abebe, Y. A., Chhetri, S., Ruangpan, L., and Vojinovic, Z.: Assessing habitat area changes from large-scale nature-based solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14321, https://doi.org/10.5194/egusphere-egu24-14321, 2024.

Cai Chun Lai and Yuan Chien Lin

Water is an essential natural resource for human survival and development. In recent years, global climate change has led to noticeable shifts in rainfall patterns. In Taiwan, the gap between wet and dry years has gradually widened, and rainfall has become shorter in duration but more intense. This has increased the frequency of spring droughts in Taiwan. Hence, there is an urgent need to propose a new water utilization model.

The bucket model is employed to estimate parameters that are challenging to measure, while Bayesian networks are utilized to establish causal relationships among environmental factors. In addition, Bayesian Network is a systematic network based on conditional probability for constructing relationships between factors. It has been shown to capture crucial groundwater flow properties and uncertainties in groundwater systems. This study seeks to alter the previous management strategy, which prioritized the use of surface water during the rainy season. Consequently, two distinct theoretical models were established for comparison. Model 1 gives precedence to surface water usage, whereas Model 2 prioritizes groundwater usage. Compare the remaining water in surface and groundwater before the next rainy season. The results indicate that, under 'high' conditions, the capacity of groundwater and surface water in Model 2 will be 18% greater than in Model 1. This is attributed to groundwater resources flowing to the surface or serving as a source of submarine groundwater discharge due to saturated aquifers. Additionally, Bayesian networks were employed to conduct a sensitivity analysis of factors. The two most influential factors on the target node are rainfall and groundwater inflow and outflow from the outside area.

How to cite: Lai, C. C. and Lin, Y. C.: Conjunctive management strategies of groundwater and surface Water: a case study of meinong reservoir in Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7123, https://doi.org/10.5194/egusphere-egu24-7123, 2024.

Ata Joodavi and Rudy Rossetto

Combining flood dams with aquifer recharge may enhance water resource sustainability, flood protection and drought prevention. In an off-stream reservoir with a high seepage rate, some of the stored surface water can infiltrate into the aquifer. The recharged water can later supplement the water released from the reservoir to fulfill the requested water demand. In such cases, optimal reservoir management requires consideration of the leakage losses (aquifer recharge rate). In this study, a methodology, based on the combination of a calibrated numerical groundwater flow model (MODFLOW, Harbaugh et al., 2017) for simulating reservoir-aquifer interaction, and an optimization model, for the reservoir operation management considering surface/groundwater interactions is presented. The groundwater flow model was developed by means of the FREEWAT platform (Rossetto et al., 2018) and used to obtain a leakage function representing the reservoir's leakage loss to the aquifer in response to different water levels in the reservoir. The leakage function is embedded to the reservoir mass balance equation in the optimization model. The optimal policy was derived based on maximizing the reservoir's water yield while considering different constraints such as the water demand and storage constraints. The modeling method proposed in this study was applied to an off-stream artificial lake located atop an alluvial aquifer in the north-east of Iran. The reservoir was built to store the flood flows of the Bar river for water supply for domestic and industrial needs and with the secondary objective to intentionally recharge the aquifer. Based on the results, the distance between the total demand (12 Mm3/year) and optimal release from the reservoir (5.7 Mm3/year) could be largely supplied by groundwater via pumping wells while the aquifer recharge provided by the leakage is 7.26 Mm3/year. This study demonstrates that the possibility to move surface water to aquifers offers an opportunity to better manage water resources, increase water supply reliability and resiliency (Joodavi et al., 2020). Furthermore, the methodology presented can be tailored for application to any reservoir (artificial lake) system, enhancing its operational, planning, and management aspects. This allows for a precise evaluation of the impact of operational policies on lakebed seepage.


  • Rossetto, R., De Filippis, G., Borsi, I., Foglia, L., Cannata, M., Criollo, R., Vázquez-Suñé, E., 2018. Integrating free and open source tools and distributed modelling codes in GIS environment for data-based groundwater management. Environ. Model. Software 107. https://doi.org/10.1016/j.envsoft.2018.06.007
  • Harbaugh AW, Langevin CD, Hughes JD, Niswonger RN, Konikow LF, 2017. MODFLOW-2005 version 1.12.00, the U.S. Geological Survey modular groundwater model: U.S. Geological Survey Software Release, 03 February 2017, http://dx.doi.org/10.5066/F7RF5S7G
  • Joodavi A, Izady A, Karbasi Maroof MT, Majidi M, Rossetto R, 2020. Deriving optimal operational policies for off-stream man-made reservoir considering conjunctive use of surface- and groundwater at the Bar dam reservoir (Iran), Journal of Hydrology: Regional Studies. 31, 100725, https://doi.org/10.1016/j.ejrh.2020.100725

How to cite: Joodavi, A. and Rossetto, R.: Study on operation strategy for a multi-objective off-stream reservoir with large lakebed seepage to enhance climate resilience , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10272, https://doi.org/10.5194/egusphere-egu24-10272, 2024.

Siham El Garroussi, Fredrik Wetterhall, Christopher Barnard, Francesca Di Giuseppe, and Cinzia Mazzetti

Future climate change is expected to exacerbate hydrological drought in many parts of Europe, making effective management of water resources more imperative to ensure groundwater sustainability. The EU biodiversity strategy for 2030 suggests a strategic target to turn at least 10% of the EU’s agricultural areas into high-diversity landscape features like hedges and trees. 
In this study, we investigate how afforestation would affect hydrological conditions in Europe under climate change, focusing on three scenarios: (1) an hypothetical extreme scenario transforming all agricultural land into forests under current climate, (2) a more realistic scenario aligning with the EU biodiversity strategy which envisages converting 10% of the land under current climate, and (3) a scenario involving the conversion of 10% of agricultural land into forests, but under a climate that is 2°C warmer. 
We use the LISFLOOD hydrological model setup across Europe at a spatial resolution of ~2km forced by gridded observed precipitation and temperature over a time period of 1991-2020 under the current climate scenario. The results were evaluated as changes in evapotranspiration, groundwater levels, and river discharge peaks. The findings from the afforestation scenario indicated a rise in evapotranspiration, higher groundwater levels, and diminished river flow peaks, suggesting an improvement in water sustainability as well as an increased resilience to flooding. This study highlights the hydrological benefits of strategic land use changes, offering key insights for European water resource management and policy formulation in the face of climate change.

How to cite: El Garroussi, S., Wetterhall, F., Barnard, C., Di Giuseppe, F., and Mazzetti, C.: Advancing water resource resilience through agroforestry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2557, https://doi.org/10.5194/egusphere-egu24-2557, 2024.

Alejandro Gil, Juan Carlos Santamarta, Carlos Baquedano, Jorge Martínez León, Miguel Ángel Marazuela, Samanta Gasco Cavero, Jon Jimenez, Teresa Alonso Sánchez, Miguel Ángel Rey Ronco, José Ángel Sánchez-Navarro, Alicia Andreu Gallego, and Juan Miguel Tiscar Cervera

The SAGE4CAN project focuses on investigating the shallow geothermal potential of the Canary Islands. During the project execution in 2021, the Tajogaite volcanic eruption took place. This eruption resulted in the deposition of lava flows, totaling approximately 200 million cubic meters, with temperatures ranging between 400 and 900°C. Remarkably, these materials represent a shallow geothermal reservoir of exceptionally high enthalpy, deviating from conventional shallow geothermal reservoirs that typically maintain temperatures close to the annual atmospheric average.

This study presents the calculated results of harnessing geothermal energy from these deposits during the cooling period of the lava flows. The goal is to extract heat from the reservoir to generate both electricity and domestic hot water. The unique nature of this geothermal reservoir, characterized by its elevated temperatures, challenges the conventional understanding of shallow geothermal systems, offering an exceptional opportunity for sustainable energy utilization in the Canary Islands. Moreover, these findings provide a framework for redefining shallow geothermal potential, traditionally associated only with depth. While depth remains a crucial factor, our study highlights the exception that proves the rule, demonstrating that geothermal anomalies, such as the one observed here, contribute valuable insights to the broader understanding of shallow geothermal resources in the Canary Islands.

How to cite: Gil, A., Santamarta, J. C., Baquedano, C., Martínez León, J., Marazuela, M. Á., Gasco Cavero, S., Jimenez, J., Alonso Sánchez, T., Rey Ronco, M. Á., Sánchez-Navarro, J. Á., Andreu Gallego, A., and Tiscar Cervera, J. M.: High Enthalpy Shallow Geothermal Energy: The Anomaly, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17780, https://doi.org/10.5194/egusphere-egu24-17780, 2024.

Posters virtual: Wed, 17 Apr, 14:00–15:45 | vHall A

Display time: Wed, 17 Apr 08:30–Wed, 17 Apr 18:00
Chairperson: Lara Speijer
Md Humayain Kabir, Md Arif Chowdhury, Md Nazmul Hossen, Shahpara Nawaz, Syed Labib Ul Islam, and Md Lokman Hossain

South Asian countries are highly susceptible to different forms of hydro-meteorological extremes (HMEs) like cyclones, storm surges, floods, erosion, sea level rise, etc., while changing patterns of climate variability also make the situations worse. Nature-based Solutions (NbS) in different forms, like mangrove forests, coral reefs, salt marshes, beach nourishment, reforestation and afforestation, wetland restoration, etc., can help to reduce the magnitude of impacts. This study was conducted in South Asia countries to understand the existing practices, challenges, and potentiality of NbS regarding HMEs. The findings of sea level rise-induced extreme events are summarized as follows: (a) Significance of coastal ecosystems in mitigating impacts of HMEs, (b) NbS approaches for coastal protection and restoration, (c) Co-benefits of NbS for coastal protection and restoration, (d) Coastal Protection and NbS: South Asia Perspective- (i) Current practices of NbS to protect the coastal region, (ii) Challenges to ensure NbS regarding coastal protection, and (iii) Potentiality of NbS to protect the coastal region.

Unusual rainfall patterns and their connection to landslides, along with the environmental and socioeconomic consequences and threats to vulnerable groups, are examined. We also delve into NbS interventions that stabilize slopes and prevent erosion-related events, emphasizing the significance of early warning systems, community-based strategies, and disaster preparedness measures to enhance resistance and resilience. Case studies from Chittagong Hill Tracts and Rohingya Camps in Bangladesh demonstrate the customization of NbS approaches to meet particular needs.

An in-depth analysis of diverse NbS approaches, including forest and floodplain restoration, construction of wetlands and green infrastructure, and several other solutions for urban flood prevention, is presented. The extent of their effectiveness and barriers to expanding NbS practices are discussed, encompassing a range of contexts from high-income urban areas to medium and low-income regions. The focus lies on the adaptability and potential impact of NbS in various contexts, providing valuable insights into their applicability. Barriers to large-scale implementation of NbS for urban flood prevention are elucidated, encompassing legislative, financial, and societal challenges that impede the integration of NbS in practice and policies, which hinder employing initiatives for a long-term national plan for NbS. Strategies to surmount these barriers are discussed, offering insights for stakeholders seeking to navigate the complexities of NbS integration. We conclude that although NbS can be considered a cost-effective and sustainable way to protect natural ecosystems and human properties, it needs more concentration to integrate into decision-making aspects from policy to practice perspectives.

How to cite: Kabir, M. H., Chowdhury, M. A., Hossen, M. N., Nawaz, S., Islam, S. L. U., and Hossain, M. L.: Nature-based solutions for hydro-meteorological extremes in South Asian countries: Current practices, gaps, and opportunities , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12100, https://doi.org/10.5194/egusphere-egu24-12100, 2024.

Hayath Zime Yerima, Martin Seidl, Marie-Christine Gromaire, Abdelkader Bensaoud, and Emmanuel Berthier

Faced with high levels of soil sealing combined with the effects of climate change, stormwater trees offer an adaptive solution for stormwater management. A stormwater tree is a street tree that has been designed to manage runoff from the adjacent pavement, while enhancing its development and various ecosystem services. It's a natured based solution for sustainable source control of runoff that's developing more and more, but whose operation is not yet completely mastered. The aim of the present study is to analyze and better understand the hydrologic functioning of such a device for a better application in the city, based on an experimental prototype, implemented in SenseCity, in Paris conurbation. SenseCity is a mini-city made up of a roadway and walls simulating a Canyon Street, with ball maples (Acer platanoide Globosum) planted on either side, one side of which is fed by runoff from 88m2 of pavement - these are the stormwater trees. The three stormwater trees are planted in a 1.6m-diameter reservoir with two main substrate layers, the first consisting of 20cm of Rainclean, a depollution filter providing temporary storage before infiltration into the deeper 60cm layer of topsoil. The runoff infiltrates through these two layers before reaching the clayey natural underground, where it can be exfiltrated to the soil and excess water can be collected in an underdrain. Various sensors were installed to study this system. These include inflow (Krohne Optiflux electromagnetic flowmeter), soil water content (Campbell SoilVue TDR probe), sap flow (Edaphic Implexx sensor) which allows to assess the evapotranspiration flux from the trees, outflow from the underdrain (Précis Mécanique 2x1-liter auger) and meteorological parameters. Most parameters are measured at 15-minute time steps.
The results obtained over one year (April 2022-March 2023) show exfiltration and transpiration rates on the system to represent respectively 53% and 27% of the inflow. Annual drainage accounts for around 19%. Exfiltration and transpiration are the main means of reducing runoff volumes. These different processes are not evenly distributed over the months. Transpiration rates are highest in summer, helping to cool the urban microclimate, while drainage and exfiltration is highest in winter. In summer, for example, transpiration rates were 41% and drainage 11%, while in winter transpiration was reduced to 5% and drainage increased to 32%.

How to cite: Zime Yerima, H., Seidl, M., Gromaire, M.-C., Bensaoud, A., and Berthier, E.: Stormwater trees in urban runoff management: Water balance of the SenseCity Experimental Device , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21660, https://doi.org/10.5194/egusphere-egu24-21660, 2024.