• Energy Research

La gestion des risques a réduit la vulnérabilité aux inondations et aux sécheresses dans le monde1,2, mais leurs impacts continuent d'augmenter3. Une meilleure compréhension des causes de l'évolution des impacts est donc nécessaire, mais a été entravée par un manque de données empiriques4,5. Sur la base d'un ensemble de données mondiales de 45 paires d'événements qui se sont produits dans la même zone, nous montrons que la gestion des risques réduit généralement les impacts des inondations et des sécheresses, mais fait face à des difficultés pour réduire les impacts d'événements sans précédent d'une ampleur jamais connue auparavant. Si le deuxième événement était beaucoup plus dangereux que le premier, son impact était presque toujours plus élevé. En effet, la gestion n'a pas été conçue pour faire face à de tels événements extrêmes : par exemple, ils ont dépassé les niveaux de conception des digues et des réservoirs. Dans deux cas de réussite, l'impact du deuxième événement, plus dangereux, a été plus faible, en raison de l'amélioration de la gouvernance de la gestion des risques et des investissements élevés dans la gestion intégrée. La difficulté observée à gérer des événements sans précédent est alarmante, étant donné que des événements hydrologiques plus extrêmes sont projetés en raison du changement climatique3. La gestión de riesgos ha reducido la vulnerabilidad a las inundaciones y sequías a nivel mundial1,2, pero sus impactos siguen aumentando3. Por lo tanto, se necesita una mejor comprensión de las causas de los impactos cambiantes, pero se ha visto obstaculizada por la falta de datos empíricos4,5. Sobre la base de un conjunto de datos global de 45 pares de eventos que ocurrieron dentro de la misma área, mostramos que la gestión de riesgos generalmente reduce los impactos de inundaciones y sequías, pero enfrenta dificultades para reducir los impactos de eventos sin precedentes de una magnitud no experimentada anteriormente. Si el segundo evento era mucho más peligroso que el primero, su impacto era casi siempre mayor. Esto se debe a que la gestión no fue diseñada para hacer frente a tales eventos extremos: por ejemplo, superaron los niveles de diseño de diques y embalses. En dos casos de éxito, el impacto del segundo evento, más peligroso, fue menor, como resultado de una mejor gobernanza de la gestión de riesgos y una alta inversión en la gestión integrada. La dificultad observada para gestionar eventos sin precedentes es alarmante, dado que se proyectan eventos hidrológicos más extremos debido al cambio climático3. Risk management has reduced vulnerability to floods and droughts globally1,2, yet their impacts are still increasing3. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change3. أدت إدارة المخاطر إلى تقليل التعرض للفيضانات والجفاف على مستوى العالم1,2، ومع ذلك لا تزال آثارها تتزايد3. لذلك هناك حاجة إلى فهم أفضل لأسباب تغير التأثيرات، ولكن أعيق ذلك بسبب نقص البيانات التجريبية4، 5. على أساس مجموعة بيانات عالمية مكونة من 45 زوجًا من الأحداث التي وقعت داخل نفس المنطقة، نظهر أن إدارة المخاطر تقلل عمومًا من آثار الفيضانات والجفاف ولكنها تواجه صعوبات في الحد من آثار الأحداث غير المسبوقة ذات الحجم الذي لم تشهده من قبل. إذا كان الحدث الثاني أكثر خطورة من الأول، فإن تأثيره كان دائمًا أعلى. وذلك لأن الإدارة لم تكن مصممة للتعامل مع مثل هذه الأحداث المتطرفة: على سبيل المثال، تجاوزت مستويات تصميم السدود والخزانات. في قصتي نجاح، كان تأثير الحدث الثاني، الأكثر خطورة، أقل، نتيجة لتحسين حوكمة إدارة المخاطر والاستثمار العالي في الإدارة المتكاملة. إن الصعوبة الملحوظة في إدارة الأحداث غير المسبوقة تنذر بالخطر، بالنظر إلى أنه من المتوقع حدوث المزيد من الأحداث الهيدرولوجية المتطرفة بسبب تغير المناخ3.

This study presents hydrological impacts of future climate change (CC) and land use/cover change (LUCC) for the Srepok River Basin (SRB) in the Vietnam's Central Highlands. The hydrology cycle of this basin was reproduced using Soil and Water Assessment Tool (SWAT) allowing an evaluation of hydrological responses to CC and LUCC. Future climate scenarios of the 2015-2100 period under Representative Concentration Pathways (RCP) 4.5 simulated by five General Circulation Models (GCMs) and LUCC scenario in 2050 were developed. Compared to the reference scenario (1980-2005), future LUCC increases the streamflow (0.25%) and surface runoff (1.2%) and reduces the groundwater discharge (2.1%). Climate change may cause upward trends in streamflow (0.1 to 2.7%), surface runoff (0.4 to 4.3%), and evapotranspiration (0.8 to 3%), and a change in the groundwater discharge (- 1.7 to 0.1%). The combination of CC and LUCC increases the streamflow (0.2 to 2.8%), surface runoff (1.6 to 5.6%), and evapotranspiration (1.0 to 3.1%), and reduces the groundwater discharge (1.5 to 2.7%) with respect to the reference scenario. Moreover, the results noted that the water scarcity may happen in the dry-seasonal months.

As the negative impacts of hydrological extremes increase in large parts of the world, a better understanding of the drivers of change in risk and impacts is essential for effective flood and drought risk management and climate adaptation. However, there is a lack of comprehensive, empirical data about the processes, interactions and feedbacks in complex human-water systems leading to flood and drought impacts. To fill this gap, we present an IAHS Panta Rhei benchmark dataset containing socio-hydrological data of paired events, i.e. two floods or two droughts that occurred in the same area (Kreibich et al. 2017, 2019). The contained 45 paired events occurred in 42 different study areas (in three study areas we have data on two paired events), which cover different socioeconomic and hydroclimatic contexts across all continents. The dataset is unique in covering floods and droughts, in the number of cases assessed and in the amount of qualitative and quantitative socio-hydrological data contained. References to the data sources are provided in 2023-001_Kreibich-et-al_Key_data_table.xlsx where possible. Based on templates, we collected detailed, review-style reports describing the event characteristics and processes in the case study areas, as well as various semi-quantitative data, categorised into management, hazard, exposure, vulnerability and impacts. Sources of the data were classified as follows: scientific study (peer-reviewed paper and PhD thesis), report (by governments, administrations, NGOs, research organisations, projects), own analysis by authors, based on a database (e.g. official statistics, monitoring data such as weather, discharge data, etc.), newspaper article, and expert judgement. The campaign to collect the information and data on paired events started at the EGU General Assembly in April 2019 in Vienna and was continued with talks promoting the paired event data collection at various conferences. Communication with the Panta Rhei community and other flood and drought experts identified through snowballing techniques was important. Thus, data on paired events were provided by professionals with excellent local knowledge of the events and risk management practices.

AbstractRisk management has reduced vulnerability to floods and droughts globally1,2, yet their impacts are still increasing3. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change3.

This paper aimed at examining the climate variability and land-use change effects on streamflow and pollutant loadings, namely total suspended sediment (TSS), total nitrogen (T-N), and total phosphorus (T-P), in the Sesan, Sekong, and Srepok (3S) River Basin in the period 1981-2010. The well-calibrated and validated Soil and Water Assessment Tool (SWAT) was used for this purpose. Compared to the reference period, climate variability was found to be responsible to a 1.00% increase in streamflow, 2.91% increase in TSS loading, 11.35% increase in T-N loading, and 19.12% reduction in T-P loading for the whole basin. With regard to the effect of land-use change (LUC), streamflow, TSS, T-N, and T-P loadings increased by 0.01%, 3.70%, 10.12%, and 10.94%, respectively. Therefore, the combination of climate variability and LUC showed amplified increases in streamflow (1.03%), TSS loading (7.09%), and T-N loading (25.05%), and a net effect of decreased T-P loading (10.35%). Regarding the Sekong and Srepok River Basins, the streamflow, TSS, T-N and T-P showed stronger responses to climate variability compared to LUC. In case of the Sesan River Basin, LUC had an effect on water quantity and quality more strongly than the climate variability. In general, the findings of this work play an essential role in providing scientific information to effectively support decision makers in developing sustainable water resources management strategies in the study area.

As more studies were conducted and global events unfold, a greater emphasis is being placed on the importance of preserving the Earth's natural resources and cycles before we face a catastrophic climate crisis. Thus, developed countries are constantly adapting their policies and legislation to promote green development for the sake of sustainable development, which benefits both the environment and the socioeconomic segment. As populations grow and living standards improve, more waste is generated. Appropriate municipal waste management is necessary to avoid harm to the environment, wildlife, and human health. Sustainable municipal solid waste management is even included in the United Nations' (UN) Sustainable Development Goals, which aim to improve the world's environment and economy. The European Union (EU) member states' waste management systems can be considered exemplary. In some countries, landfills have been prohibited, promoting the use of more sustainable technologies such as organic waste incineration, recycling, and composting. However, a divide exists between member countries, with some lagging behind in terms of waste management strategies. Thus, this paper examined the current state of municipal waste in EU member states, followed by a review of the various disposal technologies implemented. The difficulties and environmental concerns that must be overcome are discussed, as are the recommendations and possible future directions.