Panta Rhei was launched in 2013 with the purpose of reaching “an improved interpretation of the processes governing the water cycle by focusing on their changing dynamics in connection with rapidly changing human systems.” When the idea of Panta Rhei was conceived socio-hydrology was still in its infancy and global warming was about 0.3 degree centigrade lower than today. The subsequent evolution of the research agenda and environmental change proved that Panta Rhei was a brilliant intuition. By building on the IAHS history and legacy, the idea of Panta Rhei catalysed the feeling that change in hydrology and society was an emerging reason of concern and therefore a fascinating field of research. Panta Rhei achieved a major target: by putting together an interdisciplinary community of researchers – mostly early career ones – it set the theoretical basis for an improved understanding of the complex interaction between water and humans. On the other hand, challenging research questions are still unresolved. I had the fortune of chairing the scientific consultation that led to shaping Panta Rhei. I also had the privilege of attending several phases of the Panta Rhei adventure. With this presentation I would like to offer my perspective on the fascinating interplay between water and humans and the achievements and future evolution of Panta Rhei.

How to cite: Montanari, A.: Everything still flows: achievements and future evolution of Panta Rhei, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8104, https://doi.org/10.5194/egusphere-egu23-8104, 2023.

Accelerated climate, environmental and societal change and its dynamics challenge the resilience of complex socio-ecological systems and require constant adaptation. It also requires to better integrate uncertainties into the decision-making process. By comparing two case studies in Tanzania and Germany with different foci in human-water interaction and socio-political backgrounds, patterns of decision-making under uncertainty are identified. Using a (semi)participatory qualitative system analysis approach helps identifying the heterogeneity of actors and their specific ways of reasoning. For example, in the case studies the perception of change and uncertainty differed between the stakeholders and were identified as important drivers for different decision rationales and hence different preferred adaptation strategies. While research in reducing environmental uncertainty through e.g. improved physical understanding and models is important, it is only on side of the equation in complex socio-ecological systems. Especially, the interplay of environmental and socio-economic uncertainty and how this uncertainty loop creates different rooms of action and agency is worth considering. The comparison shows that acknowledging heterogeneity is important across regions and water management issues and supports in developing tailor-made adaptation strategies targeting the environmental issue. Additionally, the approach empowers and enables actors to increase their room of action and adaptation capacity by acknowledging their uncertainty perception.

How to cite: Höllermann, B.: Impact of interplay of perceived environmental and socio-political uncertainties on adaptation decisions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-206, https://doi.org/10.5194/egusphere-egu23-206, 2023.

The coastal zone of northern Java experiences rapid land subsidence. Satellite-derived InSAR data and GPS had provided evidence  displaying the spatio-temporal rates of the subsidence. Interestingly, inhabitants do not always recognize this phenomenon. However, they do recognize that flooding from the sea (called ‘rob’) has changed from gift to disaster, viz. from shallow infrequent flooding that carry inshore fishes, to regular deep and widespread disastrous floods. In the Demak regency, more than 300 families have moved to locations further inland. In some locations rob flooding has caused a coastline retreat of up to 5kms.

Our initial Sentinel-2 analysis comparing 2016 and 2022 images have showed the change of ecosystem in the area. In addition to that, social surveys revealed timely change of the ecosystem and point places where coastlines have moved.

For this study, we use Sentinel-1 imagery for SAR coupled with tide data to determine the behavior of coastline change from 2018-2022. Sentinel-1 is selected due to the temporal resolution and performance in  all-weather. Ground Range Detected (GRD) of Sentinel-1, is single look complex data projected using an earth ellipsoid, will be used as main input in spatial analysis to observe shoreline condition. There are 4 types of polarization of GRD data: HH,VV, HH+HV and VV+HV. Polarization type will be tested and determined to get less noise images result. Image masking and pixel analysis will sequentially be conducted to segregate the land and the sea. The analysis will be managed in Sentinel Application Platform (SNAP).

Tide data plot from nearby station is used to assign at what phase Sentinel-1 imagery is acquired. Additional analysis from tide data plot is applied to predict land/inundation at important sites and when imagery is not available. 

The social research component of the study through preliminary survey data , our initial survey showed residents relocation had been started before the period covered by the SAR data sets. Hence, random purposive sampling will be used for a follow-up mixed-methods survey to gather more data on social and economic dynamics arising from the geomorphological shifts in coastline. 

Ultimately, we hope  our study will help unravel land subsidence and the resulting coastline retreat to provide a strong basis for mitigation and adaptation options by the people and the government.

How to cite: Budiyono, Y., Zahro, Q., Oktaviani, A., Riyalda, B. F., and Siriwardane-de Zoysa, R.: Land subsidence and coastal retreat as observed using Sentinel-1, tide dynamics, and socio-cultural survey of Sayung, Demak, Indonesia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16655, https://doi.org/10.5194/egusphere-egu23-16655, 2023.

Science - policy - society Nexus is important in achieving Sustainable Development Goals (SDG). The current scientific knowledge is sufficient to allow us to implement the best of knowledge to cover the basic needs such as access to safe water and sanitation; however, the implementation rate is slow. Thus, this work looks at state-society relations in reaching SDGs 6.1. and 6.2. in Kazakhstan.

The survey asssessed available 176 water-related functions in the Government of Kazakhstan using the Integrated water resources  management tool-box. Additionaly, the questionnaire of about 1300 villagers was conducted in all the villages (which are 153 in total) of Atyrau region, Kazakhstan during September-November 2022, to assess the access to drinking water and sanitation services and the needs for improvement.

The findings show that in the “Policy” area the functions for adaptation to climate change are poorly expressed, especially climate resilient WASH systems; the role of customary law in the field of both the use of water resources and access to drinking water and sanitation is barely reflected in the legislation. In the "Organization" area there is a lack of functions in operation and monitoring of decentralized water supply and sanitation services; the organization of civil society is not formally expressed; training of water management specialists is not reflected as a responsibility.  In the field of using various tools of Integrated Water Resources Management, the weakest function of the government is communication with society and their reflection in public policy, in particular, the introduction of the concept of virtual water, water footprint, public awareness and education; economic instruments and effective demand management are little reflected in the functions of the state.

More than half of rural citizens use water from decentralized sources and mainly use pit latrines. The field survey has showed the high level of responsibility of the local villagers for decentralized sanitation and drinking water supply services, with high request to be educated on how to maintain those systems in a more sustainable way. It might be concluded that people do have relatively high rate of responsibility to maintain the water supply and sanitation systems. However, the policy and the govenmental functions do lack meeting these societal needs for education and, in a broder context, integrating people into water projects. "The science" or Reserchers could play an important role bridging State and Society to increase the feasibility of water and sanitation state-run programs. 

How to cite: Tussupova, K. and Zhupankhan, A.: Reaching SDGs 6.1 and 6.2 in Kazakhstan: State - society relations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12572, https://doi.org/10.5194/egusphere-egu23-12572, 2023.

The Benford’s Law, outlined in 1938, estimates the expected frequency of the significant first or first two digits of a time series of a generic variable based on a logarithmic pattern. Lower digits (i.e., 1, 2…) are expected to occur with frequencies higher than those associated to numbers with higher first digits (i.e., 8, 9). According to this law digit 1 typically occurs about 30% of the time, while 9 appears as significant first digit in less than 5% of the cases. The validity of Benford’s Law has been proven for a wide variety of data sets and in different contexts (e.g., public elections, false accounting detection, street addresses, stock and house prices, population numbers), among which few of hydrological relevance: lengths of rivers, river flow series, lake and wetlands extents. Nonconformity of hydrologic data sets to Benford’s Law could be a consequence of time series alteration and thus a signal of the presence of biases or errors, data modification, as well as of the fact that the sample is not fully representative of the variable or the series is affected by external drivers (e.g. anthropic alteration of the natural dynamics).

In this work we referred to more than 1200 GRDC sites to test the Benford’s Law validity over stream flow series longer than 40 years, as well as on the longest stream flow series (more than 12 million of data). Streamflow records have been investigated in parallel to other hydrological relevant datasets that serve as proxy for quantifying the potential human impact (e.g., GRanD-Global Reservoir and Dam Database, FFRs-Free Flowing Rivers). Results of this study, together with those of previous investigations (Nigrini and Miller, 2007) advocate that large hydrological data set should conform the Benford’s Law. On the contrary, the nonconformity to it might highlight data integrity and authenticity issue, or reveal alterations of the natural variability due to human activities or other driving factors (perhaps climate change).

How to cite: Domeneghetti, A., Caroscio, L., and Ceola, S.: Potential applications of the Benford’s Law for the investigation of hydrological time series alteration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11797, https://doi.org/10.5194/egusphere-egu23-11797, 2023.

The water cycle is highly interconnected; water fluxes in one part depend on physical and human processes throughout. For example, rivers are a water supply, a receiver of wastewater, and an aggregate of many hydrological, biological, and chemical processes. Thus, simulations of the water cycle that have highly constrained boundaries may miss key interactions that create unanticipated impacts or unexpected opportunities. Integrated environmental models aim to resolve the issue of boundary conditions, however they have some key limitations, and we find a significant need for a parsimonious, self-contained suite that is accessible and easy to setup. With this in mind, we have developed the WSIMOD – a Python package that allows for the representation of the water system’s demands and impacts of multiple sectors and actors’ decisions within a single tool, which is considered beneficial to increasing a shared understanding of system performance and for more collaborative and coherent decisions on integrated water resources, water quality and flood management. The WSIMOD is a self-contained software package that includes modelled representations of key physical and infrastructure elements of the water cycle (urban and rural), with each type of modelled element generically described as a component. Components are written in such a way that any component can interact with any other component. This enables a flexible representation of a water system that is needed to accommodate the wide variety of different built/natural infrastructure configurations and scales. We will showcase how the WSIMOD tool has been developed and successfully tested through a range of applications in the UK, including integrated analysis of urban water systems, catchment water management and urban water neutrality.  

How to cite: Mijic, A., Liu, L., and Dobson, B.: Water Systems Integrated Modelling framework (WSIMOD): A Python package for simulating human-impacted water quality and quantity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6399, https://doi.org/10.5194/egusphere-egu23-6399, 2023.

The World’s water resources are under severe pressure as a result of unsustainable exploitation and rapidly changing hydroclimatic conditions. In the National Geographic World Water Map project, we combine state of the art hydrological modelling expertise, with storytelling expertise from National Geographic. The World Water Map aims to shed new light on water problems in the world.

In this project we identify 17 hotspots of water scarcity based on state-of-the-art large-scale hydrological modelling results. For the so called “hotspots” we analyze which policies, regulations and climatic changes have resulted in the development of these areas under pressure. We do this by using a literature study of over 175 scientific publications, which helps to identify the drivers and pressure as well as their impact and response for each hotspot. This information is then all included in the online Water Map that provides the general public, policy makers and peers in science with this information. The map consists of an interactive web portal where we tell the untold stories of water scarcity, support water scarcity literacy so that people understand the problems surrounding water scarcity, and provide an interactive platform where people can identify the vulnerability of their local neighbourhoods.

By combining science and storytelling we can shed light on “hotspots” as well as provide the untold stories in these regions. Together with the local and national policymakers we aim to provide much needed open information on pathways forward and future outlooks for “hotspots” around the world.

How to cite: Wanders, N., Leijnse, M., Droppers, B., van Jaarsveld, B., Hoch, J., Götte, J., and Bierkens, M.: The World Water Map of water scarcity hotspots, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9040, https://doi.org/10.5194/egusphere-egu23-9040, 2023.

Water scarcity is a growing concern in many regions worldwide, as demand for clean water increases and supply becomes increasingly uncertain under climate change. Already today, more than 4 billion people experience water scarcity at least one month per year (Mekonnen and Hoekstra, 2016). Developing socio-economic conditions and growing population increase water demands, while climate change leads to changes in freshwater availability. Most studies quantify water scarcity in discrete time windows, with fixed population and climate change signals (e.g., 30 years or long-term averages). Recently, however, Thiery et al. (2021) proposed a novel approach, in which climate change impacts are integrated over a person's lifetime. In this cohort perspective, lifetime impact values are comparable across generations and regions. Evaluating this perspective for natural hazards, they showed, for example, that a newborn will experience a sixfold increase in drought exposure compared to a 60-year-old (Thiery et al., 2021). 

In this study, we use this cohort perspective to study how much water scarcity a person experiences during their lifetime. Based on monthly fluctuations in water demand and availability, we estimate the total amount of water demand not met and refer to it as 'lifetime water deficit'. To this end, we use an ensemble of four global hydrological models (MATSIRO, CWatM, LPJmL and H08), each forced by four GCMs and two RCP scenarios from the InterSectoral Impact Model Intercomparison Project (ISIMIP2b). The simulations account for varying population and socio-economic conditions in the historical and future period, following the SSP2 scenario. Combined with country-based population, cohort distribution and life expectancies, lifetime water deficits are quantified for different generations on a country level. 

Our findings reveal high water lifetime deficit values for regions that are already water scarce today, such as the Mediterranean, North Africa and the Middle East. In these regions, more than 70% of the lifetime water demand is not met when needed. Further comparison reveals differences in spatial, intergenerational and climate change scenarios, and provides information on different scenarios. Overall, this study provides a new perspective on quantifying water scarcity and the climate and population impacts. 

References:

Mekonnen, M. M., & Hoekstra, A. Y. (2016). Four billion people facing severe water scarcity. Science Advances, 2(2). https://doi.org/10.1126/sciadv.1500323

Thiery, W., Lange, S., Rogelj, J., Schleussner, C. F., Gudmundsson, L., Seneviratne, S. I., Andrijevic, M., Frieler, K., Emanuel, K., Geiger, T., Bresch, D. N., Zhao, F., Willner, S. N., Büchner, M., Volkholz, J., Bauer, N., Chang, J., Ciais, P., Dury, M., … Wada, Y. (2021). Intergenerational inequities in exposure to climate extremes. Science, 374(6564), 158–160. https://doi.org/10.1126/science.abi7339

How to cite: Vanderkelen, I., Davin, É., Keune, J., Miralles, D. G., Wada, Y., Müller-Schmied, H., Gosling, S., Pokhrel, Y., Satoh, Y., Hanasaki, N., Burek, P., Ostberg, S., Grant, L., Taranu, S., Mengel, M., Volkholz, J., and Thiery, W.: Quantifying lifetime water scarcity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7949, https://doi.org/10.5194/egusphere-egu23-7949, 2023.

During the past years, the county of Kitui in Kenya, has experienced severe droughts. Both the short rain season, in March, April and May and the long rain season, in October, November and December have failed for several years in a row. This has had devastating impacts, leading to widespread water and food insecurity. According to local people, the rain seasons have changed over the past years, thereby increasing drought risk. At the same time, flash floods, destroying farmland and water infrastructure are reported to have increased as well. We investigate whether drought and flood risk in Kitui, Kenya, have increased over the past years and what the role of climate, hydrology and humans is in this increase. In addition, we investigate whether droughts are influencing flood risk and vice versa.

How to cite: Barendrecht, M. H., Weesie, R. V., Busker, T. S., Matanó, A., Mazzoleni, M., and van Loon, A. F.: Drought and flood risk in Kitui, Kenya: are they increasing and why?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8612, https://doi.org/10.5194/egusphere-egu23-8612, 2023.

Climate change and human activities may cause change points in hydrological processes, which have serious impacts on the stability of watershed hydrological ecosystems. The Pettitt test method was used to identify the change point of discharge in the Yangtze River basin, and ecological water demand was estimated based on generalized extreme value distribution. The results show that: (1) the ecological water demand guarantee rate of the Yangtze River basin increased from a viewpoint of the whole basin during the past decades, especially in dry seasons. Due to the regulation of reservoirs and dams in the Yangtze River Basin, the ecological surplus (ecological deficit) tends to increase (decrease) in the dry season of the Yangtze River Basin, while it tends to reverse in the wet season. (2) The degree of hydrological alterations in the trunk stream of the Yangtze River Basin is the highest (D0 reaches 50% or more), and the river hydrological situation and ecosystem are under high risks (the total DHRAM score is more than 10 points), and the biodiversity shows a significant downward trend. (3) Climate change and human activities have the opposite impact on ecological streamflow of the Yangtze River Basin, that is, climate change increases ecological surplus and decreases ecological surplus. Overall, climate change is the leading factor affecting ecological surplus (the contribution is more than 50%).

How to cite: he, Y. and gu, X.: Ecological Instream Flow in the Yangtze River Basin under the Hydrological Change: Changes, Impacts, and Attributions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2070, https://doi.org/10.5194/egusphere-egu23-2070, 2023.

In many mountain regions, the cryosphere is a crucial component of water provision to downstream societies, as it contributes to dry-season flows and sustains diverse ecosystems. However, many of the world’s glacierized watersheds experience far-reaching changes at accelerated pace due to declining glaciers and snowpack, climate change impacts and socioeconomic development in the non-cryospheric parts of the catchment. The implications for downstream water supply are therefore manifold and complex. Coupled effects of reduced and less reliable water availability, changes in water quality, and growing water demand exert increasing pressure on water resources and threaten future water security and management.

We argue that the limited understanding of interactions between the cryosphere, glacial and non-glacial water stores, river runoff and people hamper climate change adaptation and long-term water security. Meaningful assessments of mountain water security require therefore a holistic social-ecological perspective that interlinks the wider catchment hydrology considering both, surface and subsurface stores, and people including human water demand with improved data and process understanding. Water security assessments can then be guided by a fully coupled hydrological risk framework. This approach needs to integrate multiple social-ecological vulnerabilities as well as the degree of exposure to water shortage under a variety of possible future scenarios of glacier shrinkage, catchment alteration and socioeconomic development. Essentially, this requires a thorough understanding of interrelated upstream-downstream systems and the spatiotemporal propagation of meltwater through the terrestrial water cycle.

Improved data and more diverse knowledge collection that point to the missing links in the terrestrial water cycle are a priority. Multiple sources of knowledge should be co-produced and integrated into a collaborative science-policy-community framework, ideally from the early stages of research planning with attention to local practices and governance. This approach can support a wide set of incremental and transformational strategies that guide robust, locally tailored and effective adaptation pathways. These may include, among other, exploring catchment-specific benefits of nature-based solutions to increase the buffer function of wider catchment hydrology against water loss from glacier shrinkage to enhance long-term water security.

How to cite: Drenkhan, F., Buytaert, W., Mackay, J. D., Barrand, N. E., Hannah, D. M., and Huggel, C.: Managing complex social-hydrological systems for water security: the case of the mountain cryosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7977, https://doi.org/10.5194/egusphere-egu23-7977, 2023.

Anthropogenic actions are progressively affecting most river basins worldwide, resulting in changes in hydrological processes and thus influencing water availability. Despite previous studies aimed at quantifying the relationship between urbanization and extreme flooding events at local to regional scales, it is still unclear how human presence has influenced the occurrence of seasonal surface water. As a result, global patterns remain largely unknown.

In this study, we perform a global analysis of large river basins and uncover global trends of annual maximum flood extent and impervious area, as well as their relationships with rainfall and snowmelt, over the past three decades. Hydrological and urban dynamics are computed by using multiple earth observation datasets.

We find that hydroclimatic variability alone cannot explain changes in annual maximum flood extent for 75% of the analyzed river basins worldwide. We also observe increasing trends in both annual maximum flood extent and the urbanized area within floodplains, especially in Asian and African river basins. Our findings reveal an emerging global reciprocal relationship between urbanization processes and maximum flood extent changes. Both rainfall and urbanized area can explain changes in the annual maximum flood extent in 57% of the analyzed basins.

Our findings highlight the need for a better understanding of the influence of human presence on changes in seasonal water dynamics at the global scale. In view of the worldwide rapid development of urban areas, these findings can inform the process of flood risk management and help improve targeted policy and land use interventions

How to cite: Mazzoleni, M., Dottori, F., Cloke, H. L., and Di Baldassarre, G.: Influence of urbanization on flood extent changes at the global level, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2256, https://doi.org/10.5194/egusphere-egu23-2256, 2023.

Flood risk is changing over time. Climate change, land-use change, human interventions and socio-economic developments have an influence on the evolution of flood risk. Thus, the future dynamics of drivers influencing hazard, exposure and vulnerability and consequently flood risk evolution is uncertain. Therefore, flood risk management is confronted with deep uncertainties and need to continuously adapt to future circumstances. New management strategies are required to ensure the safety level of humans and their assets and reduce losses from floods. Adaptive flood risk management is a way to cope with such uncertainties. However, the implementation of adaptive flood risk management requires a flood risk monitoring system that screens critical developments of hazard, exposure, or vulnerability and warns the user when a critical point in flood risk evolution is approached. In order to develop a conceptual framework for a flood risk monitoring system, we conducted a systematic review of flood risk evolution assessments. We analysed how flood risk is conceptualised, which factors are assessed to analyse evolutions in one or more risk component, which methods are used to assess flood risk evolution and which risk outcomes are identified. We discuss the main concepts of monitoring the spatiotemporal changes of the components of risks and how the changes of these components contribute to the evolution of risk. We furthermore discuss the data sources, issues of spatial and temporal scales, and how the components of risk coevolve.

How to cite: Rindsfüser, N., Zischg, A. P., and Keiler, M.: Monitoring flood risk evolution: A systematic review of flood risk evolution assessments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13384, https://doi.org/10.5194/egusphere-egu23-13384, 2023.

The understanding of floods has become more complex as the changing climate has made the floods more unpredictable, recurrent, and intensified. The present study focuses on the analysis of behavior of the sub-basins under the extreme rainfall events. For this purpose, an extreme flood event of 2019 in Koyna River Basin located in the Upper Krishna River Basin, Maharashtra was considered. The hydrological responses of the sub-basins of Koyna River basin during this flood event were obtained using a Process-based Soil and Water Assessment (SWAT) hydrological model. The model was configured using the topographical, land use, soil and metrological parameters, respectively. Fathom FABDEM hydrologically corrected DEM were used to delineate the watershed with an outlet near Karad City, just downstream of the Warunji gauging station. The Indian Metrological Department (IMD) 0.25⁰ * 0.25⁰ daily gridded rainfall data and minimum and maximum temperature were used to set up the model. The simulation runs were taken to obtain the responses of the sub-basins for the period of 2016 to 2020.  The study reveals high value of Coefficient of Correlation (R²) being equal to 0.72 indicating that the simulated runoff is closely related with the observed runoff at Warunji Gauging station. The configured hydrological model would be useful in predicting the sub-basin responses under climate change so that the proper planning and preparedness can be made to evolve the robust policies for handling severe floods in the future.

Keywords: Climate Change, Extreme events, SWAT, FABDEM, Koyna River.

How to cite: Ranjan, R. and Keshari, A. K.: Process-based Hydrological Modeling to Analyse Sub-basin Response Under Extreme Rainfall Events in Koyna River Basin, Maharashtra, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1663, https://doi.org/10.5194/egusphere-egu23-1663, 2023.

Floodplain urbanization is accelerating at an alarming rate in recent decades, which has posed grand challenges to flood risk management. Hydraulic engineering infrastructure is often co-developed alongside this acceleration to mitigate flood risks, but to what extent this co-development matches up with the floodplain urbanization rate needs to be better quantified. In this study, we leverage a range of multi-source geospatial datasets including high-resolution floodplain maps, urban impervious area maps, global dam/reservoir datasets, and flood fatality data from the Emergency Events Database (EM-DAT) to assess the dynamics of floodplain urbanization (1985–2015) and its interplay with hydraulic engineering development at the global scale. We will report our assessments at both the basin level and the country level to promote the understanding of the hydroclimatic and socioeconomic contexts of floodplain urbanization. Ultimately, results from this study are expected to inform the prioritized regions for flood risk mitigation.

How to cite: Lin, P., Gao, S., Zeng, Z., Wang, J., Zheng, K., Yin, Z., Yuan, Z., Huang, Z., Zhou, X., and Lei, X.: The dynamics of floodplain urbanization and hydraulic engineering development, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11579, https://doi.org/10.5194/egusphere-egu23-11579, 2023.

The analysis of the factors driving the exploitation of drinking-water sources is fundamental in the modelling and planning of water supply systems. To this end, it is important to assess the impacts of water scarcity, related to periods of hydrological drought, on the use of the available sources. This is of particular interest in touristic regions, where resource management must necessarily take into account also the significant seasonal fluctuation of urban demand.

As part of the European project SIMTWIST (Simulating Tourism Water Consumption with Stakeholders), the study analyses the factors influencing both the demand for drinking-water supply of the city of Rimini and the apportionment of the supply among the different sources available to the water manager (RomagnaAcque-Società delle Fonti SpA). In fact, the city is supplied with both surface water, from the Ridracoli reservoir in the Apennines, and groundwater from well fields on the alluvial fans of the Marecchia and Conca rivers.

The drivers include socio-economic variables (tourist attendance), climatic variables and hydrological availability. In particular, it is analysed how the exploitation of the groundwater source varies as a function of water availability at the Ridracoli reservoir, characterizing such availability through meteorological and hydrological drought indices computed on the upstream catchments.

The analysis, in addition to confirming how the management of the resource cannot, in Mediterranean regions, disregard tourism factors, helps to understand the link between hydrological droughts, governing the availability of river-fed reservoir supply, and the choices made by water managers in the exploitation of the groundwater sources.

How to cite: Toth, E. and Neri, M.: Drinking-water supply sources and hydrological droughts: influence of tourism demand and reservoir availability on groundwater exploitation for the Rimini case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9402, https://doi.org/10.5194/egusphere-egu23-9402, 2023.

Disaster risks are the results of complex spatiotemporal interactions between risk components, impacts and societal response. In the context of the water supply chain, human processes have altered hydrological processes through the construction of reservoirs to dispose of the water resources with higher predictability and productivity. While reservoirs may attenuate flood events and help to bridge through period of water scarcity, they may also aggravate drought events in terms of duration and severity. The long-term effect associated to the presence of reservoirs is an over-reliance on the water supply hypothesized as constant and abundant as provided by the hydraulic structure, which in turn increases the vulnerability and the economic damage in case of a drought event occurrence. In addition, socio-economic and political changes should not be underestimated, as the social, economic, and political context can influence the impact and response to extreme events. Indeed, it has been observed that during long periods of drought, variations in exposure and in vulnerability have occurred, due to social dynamics taking place as a result of the extreme event, e.g. the natural migration of the population to water sources.
Here we aim at understanding the changes in risk components and the resulting impacts of structural measures, such as reservoirs, and also of nature based solutions in relation to consecutive extreme events. Different case studies around the world are considered to untangle the complexity of the dynamic relationship between human and hydrological processes.

How to cite: Ridolfi, E., Soncin, L., Matano, A., Russo, F., Napolitano, F., Di Baldassarre, G., and Van Loon, A.: Assessment of change in drought risk influenced by water management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15219, https://doi.org/10.5194/egusphere-egu23-15219, 2023.

Drought risk is modified through hazard, vulnerability and exposure, and exacerbated by management shortcomings. A quantitative understanding of the combined effects of these drivers is required to effectively lower risk. Yet, knowledge about the dynamics and effects of risk drivers over time and space and the human-natural feedbacks that steer them is largely lacking. In this study, we propose using GEB, the first large-scale coupled-agent based hydrological model that simulates all individual farmers at field scale, to systemically quantify the relations between dynamic hazard, vulnerability, exposure, management and drought risk over a multi-drought period in the Bhima basin, India. First, we parametrized the coupled hydrological model with meteorological and hydrological data to capture hydrological drought  conditions of different paired drought events. Next, we develop the agent based model part to simulate the drought management behavior of two million farmers and how they respond to drought events. To simulate this behavior, we applied the protection motivation theory, supplemented by theory of planned behavior, to describe farmer agent behavior. The parameters of these theories were parametrized with survey data of Indian farmers fitted to the statistical distribution of the two million Bhima basin farmers. To study the dynamic attribution of the three risk drivers, a Global Sensitivity Analysis of all factors was performed at consecutive time intervals, showing the interaction of drivers before and after each drought event, as well as between the two events. The results are expected to further the understanding of drought risk dynamics and what disaster risk reduction measures can optimally reduce impacts in the long term.

How to cite: Kalthof, M., De Bruijn, J., De Moel, H., Kreibich, H., and Aerts, J.: Dynamic risk modelling of a coupled human-drought system under multi-drought conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15238, https://doi.org/10.5194/egusphere-egu23-15238, 2023.