NH9.10

Droughts are among the most damaging natural hazards leading to a wide range of impacts also in the water-rich mountain regions. In recent years, drought conditions and impacts have been reported frequently in the European Alpine region, possibly because climate change affects mountain environments more rapidly than others. However, in mountain regions the propagation of drought signals through the hydrological cycle and into different environmental and societal impact occurrence are poorly understood, especially regarding the impacts’ seasonal patterns and delayed effects. This study aims to improve the understanding of the droughts’ characteristics and their impacts from the high elevation headwater regions down to plateau and foothill areas. Specific climate conditions in high elevation regions determine an alpine environment, economy and society that differs from the pre-Alpine regions. Subsequently, impacts are expected to vary as well and indices for drought monitoring may have to be selected specifically for such a region. The European Drought Impact Report Inventory (EDII) compiles text-reports on negative drought impacts across Europe and classifies them into 15 categories with 108 subtypes. An updated version focusing on the ‘Alpine Space’ released as EDII_ALPS V1.0 contains more than 3,200 reports about drought impacts. The most relevant categories are Agriculture and livestock farming and Public water supply. This data allowed an analysis of the seasonal patterns of drought impacts in several categories for four sub-regions in the Alpine Space: pre-Alpine vs. high-elevated region, Northern vs. Southern region. Assigning the impacts subtypes to drought type, soil-moisture drought (SMD impacts) and hydrological drought (HD impacts) allowed the derivation of smoothed seasonal “impact regimes”. The peak of HD impacts occurred later in the year than the SMD impact peak, most clearly in the high-elevation region, with the latest increase of HD impacts in May and strongest decrease between November-December. This pattern is less clear for the Southern region. SMD indices and HD indices that may be used for monitoring and early warning need to be targeted to and tested for capturing these delays.

How to cite: Stephan, R., Erfurt, M., and Stahl, K.: Delayed soil-moisture and hydrological drought impacts in mountain regions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-355, https://doi.org/10.5194/egusphere-egu21-355, 2021.

Drought Early Warning Systems (DEWS) and Drought Monitoring Systems (DMS) are the principal tools used to tackle drought at an early stage and reduce the possibility of harm or loss. They are based on the use of drought indicators attributed to either : meteorological, agricultural and hydrological drought. This means that it is mostly hydro-climatic variables that are used to determine the onset, end and severity of a drought.  Drought impacts are rarely continuously monitored or even not included in DEWS and DMS. In this configuration, the likelihood of experiencing impacts is linearly linked to the severity of climatic features only. The aim of our study is to question the direct linkage between the delivery of hydro-climatic information and the detection of drought impacts and their severity. We reviewed scientific literature on drought drivers and impacts and analyzed how these two compare. We conducted a bibliometric analysis based on 4000+ scientific studies sorted by geographic area in which selected (i) drought indicators and (ii) impacts of drought were mentioned. Our review points toward an attachment to a conceptual view of drought by the main and broader use of meteorological (computed and remotely sensed) drought indicators. Studies reporting impacts related to food and water securities are more localized, respectively in Sub-Saharan Africa and Australasia. This mismatch suggests a tendency to translate hydroclimatic indicators of drought directly into impacts while neglecting relevant local contextual information. With the aim of sharpening the information provided by DEWS and DMS, we argue in favor of an additional consideration of drought indicators oriented towards the SDGs.

How to cite: Kchouk, S., van Oel, P., and Melsen, L.: Selecting indicators of drought impacts: the importance of context, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1134, https://doi.org/10.5194/egusphere-egu21-1134, 2021.

Droughts are slow and silent natural hazards that can lead to long-lasting environmental, societal and economic impacts. Mountain regions are also experiencing drought conditions with climate change affecting their environments more rapidly than other places and reducing water availability well beyond their geographical locations. These conditions call for better understanding of drought events in mountains with innovative methodologies able to capture their complex interplays.

Within this context, the Alpine Drought Observatory (ADO) Interreg Project aims to further improve the understanding of drought conditions in the Alpine Space, with activities spanning from the characterization of drought types’ components in five heterogeneous case studies in Austria, France, Italy, Slovenia and Switzerland. For each case study, different sectors exposed to drought, ranging from hydropower, agriculture to tourism are considered. Moreover, specific socio-economic characteristics were collected for each sector in order to better understand the main drivers leading to drought impacts.

Starting from the risk concept in the IPCC AR5, the Impact Chains (IC) methodology has been applied to characterize the hazard, exposure and vulnerability components in the ADO case studies. IC allowed to pinpoint the main factors affecting drought risk and the relevant socio-economic sectors integrating a mixed-method approach. Quantitative data collection on the hazard and exposure components were coupled with local experts’ knowledge on the main vulnerability factors (e.g., through a questionnaire). Although validation represents a critical part of drought modelling, IC analysis and results were therefor compared with information from the European Drought Impact Inventory (EDII) on local drought impacts collected from scientific publications, unions press releases and newspaper articles over a long time period.

While drought risk assessment through IC can improve the understanding of the main drought events and their underlying factors, they also provide insights to improve planning and management of future drought events in the Alpine Space.

How to cite: Terzi, S., Erfurt, M., Stephan, R., Stahl, K., and Zebisch, M.: Alpine drought impact chains for sector-based climate-risk assessments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-205, https://doi.org/10.5194/egusphere-egu21-205, 2021.

As earth’s climate is changing, there is evidence for abrupt shifts to hotter and drier climate conditions in some locations. These changes may be particularly harmful to coupled human and natural systems in semiarid regions because they exist on marginal water availability and can exhibit strong coupling between land surface and atmospheric conditions which can make droughts more persistent. In the south-central semiarid prairie ecoregion of the US, there has been a significant warming trend over the past 120 years. This ecoregion has also experienced some of the most severe drought conditions in the US during recent decades, particularly in southwest Oklahoma and adjacent portions of Texas. These drought conditions have complex, multi-dimensional impacts on coupled human and natural systems, which are often not adequately quantified or understood. Furthermore, even the severity of drought is often poorly or inconsistently measured, in part due to an overreliance on meteorological or remotely-sensed data as opposed to measurements of stored soil water, surface water, and groundwater. The objectives of this research are to 1) accurately measure the severity and multi-dimensional impacts of recent droughts in the south-central semi-arid prairies of the US and 2) clarify the relationships between drought severity and impacts. We utilize a case-study approach focused on southwest Oklahoma where in situ observational datasets allows for quantification of stored soil water, surface water, and groundwater. Drought impact types were recorded by the US Drought Impact Reporter and quantified using appropriate supplemental datasets and models.

How to cite: Ochsner, T., Hagerman, A., Krueger, E., Lambert, D., Lambert, L., and Weckler, P.: Drought severity and impact relationships: a multidimensional case study of recent droughts in the south-central semiarid prairies of the United States, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6530, https://doi.org/10.5194/egusphere-egu21-6530, 2021.

Drought is the most complex natural hazard that can cause a wide range of impacts affecting the environment, the society, and the economy. Drought is often quantified with one or a set of drought indices, yet these drought indices are limited in capturing such various impacts. This study aimed to understand quantitative relationship between drought impact and drought occurrence in South Korea. We there constructed drought impact inventory by collecting data not only from the existing datasets but also by using a web-crawling method. The collected drought impact data were classified into categories such as agriculture and livestock farming, public water supply, wildfire, and water quality. Also, to quantify the drought occurrence, the standardized precipitation and evapotranspiration index (SPEI) was used as a drought index. We derive the likelihood of drought impact occurrence as a function of the drought index with using the log-logistic regression as well as the random forest algorithmas well as the random forest algorithm. Note that the logistic regression is appropriate with binary data such as drought impact occurrence and Note that the logistic regression is appropriate with binary data such as drought impact occurrence and the random forest algorithm is powerful algorithm to develop a predictive model based on classification and regression trees. As a result, the sector-specific likelihood of drought impact occurrence over the regions are identified. We show the highest likelihood of drought impact occurrence in public water supply for Jeonnam area, wildfire for Gangwon area and water quality for Gyeongnam. This study suggests that such drought impact information can support the decision-making for drought risk reduction.

Acknowledgement

This work was supported by a grant from the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (2020R1A2C2007670).

How to cite: Seo, J., Lee, J., and Kim, Y.: Assessing likelihood of sectoral drought impact occurrence in South Korea, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3718, https://doi.org/10.5194/egusphere-egu21-3718, 2021.

This research attempts to monetize drought risk in 97 cities around the globe, using multiple climate and socioeconomic scenarios. Subsequently, it identifies possible adaptation actions to mitigate drought risk in these cities. This study is essential because whilst much effort has been put into modelling drought on all spatial scales in recent decades, urban areas are often not explicitly included in these analyses, even though we live in a rapidly urbanizing world. Two types of drought risks for cities are identified and investigated: (1) drought induced food shortages and increased food prices (agricultural drought), and (2) municipal surface water supply shortages (hydrological drought). To assess agricultural drought risk, we represent the hazard using the Standardized Soil Moisture Index, and exposure using physical agricultural areas. For hydrological drought risk, we represent the hazard by linking discharge data from climate models to water withdrawals per city, with exposure data on the total population of a city. The risks are monetized by estimating the replacement costs of freshwater by means of alternative water sources like desalination. Vulnerability is qualitatively included by spatially overlapping the monetized values with vulnerability indicators and primarily gives context to the risk estimates. Finally, an inventory of reactive, preventive and transformative adaptation actions is developed to provide cities with a perspective for action. Cities may use this inventory to identify a mix of adaptation measures, where a combination of the three approaches would be an adequate way to address both short- and long-term risks and opportunities. The overall goal of this research is to provide an order of magnitude of potential drought risk, as well as to identify possible next steps in drought risk research in urban areas.

How to cite: Stolte, T., Ward, P., de Moel, H., van Veldhoven, F., Garg, S., and Farhad, N.: Drought risk in urban areas: a monetization of drought risk in 97 cities around the globe, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10965, https://doi.org/10.5194/egusphere-egu21-10965, 2021.

Droughts have always been part of Earth climate, yet today these phenomena are becoming more alarming due to their increasing severity and their disastrous socio-ecological impacts. Different scientific definitions or diverse understanding of drought risk have been proposed also because of the simultaneously social and ecological complexity which characterizes droughts relative to other hazards and/or vulnerabilities. This work sets out to confront the distinctive complexity of drought risk throughout a novel approach which combines political ecology perspectives with hydro-climatological insights. Our engagement with political ecologies of land, water, and vulnerability helps to explain the socio-political processes that intersect with the production of droughts and their consequences. Concurrently, hydro-climatology unravels the physical or material processes that both constitute and transform drought phenomena into socio-ecological disasters. The drought-stricken Ladismith in Western Cape, South Africa, is the point of departure of our empirical analysis which portrays the socio-ecological disruption reached by this rural community after five years of below-average rainfall (meteorological drought). We show that Ladismith socio-ecological crisis was mostly engendered by a distinct mechanism of capital accumulation through land and water dispossession, which emerged locally in the form of white commercial agriculture. Our interdisciplinary approach examines these socio-political processes in relation to the drought physical transformations over time and across space. By relating societal and physical processes we advance a novel understanding of drought that sheds light on the crucial interactions between social power, climate, land use, and hydrology, which all too often transform a meteorological event into a soil moisture drought, a hydrological drought, and eventually into a major socio-ecological crisis. Secondly, combining hydro-climatology with political ecology reveals that social power not only influences the vulnerability of the systems affected by droughts, but also shapes the occurrence and manifestation of the hazard itself. This novel conceptualization of drought risk as socially produced is key to intercept the material spaces and physical dynamics through which social power plays out in more extreme and disruptive drought events. A similar approach, by identifying unjust and unsustainable socio-ecological changes, can make drought management policies and strategies more proactive rather than constrain them to relief or adaptation measures.

How to cite: Savelli, E., Rusca, M., Cloke, H., and Di Baldassarre, G.: All dried up: An interdisciplinary analysis of drought risk in Ladismith, South Africa , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1991, https://doi.org/10.5194/egusphere-egu21-1991, 2021.

An increasing number of mega-cities, such as Cape Town, Lima, and São Paulo, are confronted with increasing droughts as well as an increase in water demand. Inevitably, this leads to increasing pressure on the available water resources and associated risks and economic impact for the water-dependent sectors (eg. drinking water supply, industry, energy production, agriculture, nature) and different user groups within the sectors (eg. low, middle- and high-income households, self-subsistence farmers, large farms). To address these problems and to develop targeted mitigation strategies, risk analyses are required that quantify the impact of water scarcity on the various sectors and users-groups in different parts of the catchment.

Here, we present the Water Gap Risk Index (WGRI) that quantifies water scarcity and its impacts on a variety of economic sectors and user groups. The WGRI provides a normalized score to reflect high spatial and temporal variability typical for urban catchments that apply to different settings and problems. Index calculation involves the combination of unmet water demand and its characteristics with socioeconomic aspects related to vulnerability and exposure. The Water Gap term quantifies water system performance over a defined time period taking into account the frequency, persistence, and severity of unmet water demand.  Vulnerability metrics provide a score for each sector and user-group separately using context-specific vulnerability indicators of each sector and user-group.

In the novel WGRI special attention is paid to the vulnerability of different water user-groups, based on their socio-economic status level (expressed in income, consumption, or other indicators) and respective water use. We consider that 1 liter of water does not have the same utility for different user groups, based on the principle of the diminishing marginal utility curve. As a result, the impact of water scarcity and mitigation measures will also play out differently for these different user groups.

The novel WGRI is being applied in the context of the WaterLOUPE approach[1], to the catchment of Sao Paolo, Lima, and Chennai.

[1] https://doi.org/10.5194/egusphere-egu2020-20505

How to cite: Taner, M. U., Hendiriks, D., Huesken, L., Mulder, N., Irato, D. M., Faneca Sànchez, M., Aalst, M. V., and Vermooten, S.: The Water Gap Risk Index – a novel approach for spatially distributed and sector-specific water scarcity risk calculations in urbanized catchments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14587, https://doi.org/10.5194/egusphere-egu21-14587, 2021.

Managing water-human systems in times of water shortage and droughts is key to avoid overexploitation and reduce drought impacts. Drought policies are designed to structure water management response and avoid crisis management, aiming to sustain both environmental and anthropogenic water demand. However, the impact of drought policies on the hydrological cycle is rarely assessed. We developed a socio-hydrological model, simulating feedbacks between water availability and managed water use for 3 decades. Thereby, we aim to assess the impact of drought policies on both surface water and groundwater droughts. We tested this model in an idealised catchment driven by English climate data, representing English water resource management practices and drought policies. The model environment includes a surface water storage (reservoir), a range of hydrogeological conditions for the groundwater module, and an option to import surface water or groundwater that could all be used to satisfy anthropogenic and environmental water demand. Modelled scenarios represent four aspects of drought policies: 1) increased water supply, 2) restricted water use, 3) conjunctive water use, and 4) maintained environmental flow requirements that were evaluated in separate and combined scenarios. Results show that hydrological droughts are mitigated in scenarios applying conjunctive use, particularly in low groundwater storage systems. In high groundwater storage systems, maintaining environmental flows reduces hydrological droughts most, particularly for surface water droughts. Scenarios that gradually increase water supply or restrict water use have opposite impacts on droughts and these scenarios are in balance when combined according to the policies in the resources management plans. Most combined scenarios reduce the severity and occurrence of hydrological droughts, although the dependency on importing water increases, satisfying a third of the total anthropogenic water demand. The increased dependency on imported water shows the considerable pressure on water resources and the delicate balance of water-human systems during droughts that calls for short-term and long-term sustainability targets within drought policies.

How to cite: Wendt, D. E., Bloomfield, J. P., Van Loon, A. F., Larsen, J. R., and Hannah, D. M.: Socio-hydrological modelling to manage and mitigate hydrological droughts, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12548, https://doi.org/10.5194/egusphere-egu21-12548, 2021.

Ongoing research to capture the socio-hydrologic feedbacks between human adaptation decisions and agricultural drought risk has brought agent-based modelling (ABM) tools to the foreground. We explored how such ABM can be used to integrate heterogeneous individual adaptive behaviour in a drought risk framework. Our ABM framework focuses on adaptation decisions (irrigation, land management) by individual farmers and their interaction with drought hazard, exposure and vulnerability. This framework enables us to more correctly reflect the dynamic nature of drought risk in time and space. Moreover, as the effectiveness of disaster risk reduction policies rests on the complexities of drought adaptive behaviour of the targeted group, we completed multiple data collection activities to understand the adaptation decisions of smallholder farmers under drought risk. These activities, inclusing smallholder farmer questionaires, choice experiments and stakeholder interviews, were based on behavioural theories and their links to socio-economic aspects in semi-arid Kenya, so we could assess what drivers and barriers determine the adoption of drought adaption measures in this context.  Moreover, people’s preferences towards ex-ante cash transfers, timely extension services, tailored early-warning systems, and access to credit markets were tested.

The framework and data collection results were used to calibrate the decision rules in a new ABM (ADOPT), to simulate small-scale agricultural adaptation decisions in response to drought risk in the past. The protection motivation theory is compared with scenarios of no adaptation dynamics and of economic rationality, so as to test different behavioral assumptions. Capturing the spatio-temporal feedbacks between bounded-rational adaptation decisions by smallholder farmers and seasonal weather conditions, ADOPT is capable of mimicking the evolution of heterogeneous adaptation decisions and trends in historic yields over time. We show the benefit of assessing drought risk (poverty, food security and aid needs) on an individual household level. Additionally, we adjusted ADOPT to simulate how smallholder farmers in Kenya respond to drought policy interventions by the government and (future) drought events, explicitly modelling adoption incentives and constraints and the social interactions among farmers. As such, the effect of pro- and reactive top-down decisions by governmental institutions on the household and community vulnerability to droughts could be evaluated in order to find maximized effects on drought resilience.

How to cite: Wens, M., van Loon, A., Mwangi, M., Johnson, M., Veldkam, T., and Aerts, J.: Integrating adaptation dynamics in drought risk modelling: The case of smallholder farmers in Kitui, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5631, https://doi.org/10.5194/egusphere-egu21-5631, 2021.

As drought risk is projected to increase in many countries around the world, global drought risk assessments incorporating hazard, exposure, and vulnerability are deemed to be useful to inform decisions on which countries should be targeted for the implementation of risk reduction, risk transfer, risk financing and adaptation strategies. This holds particularly true for existing climate change related financing mechanisms, such as the Adaptation Fund (AF), the Green Climate Fund (GCF) or the InsuResilience Solutions Fund (ISF), which have the mandate to concentrate on the “most vulnerable” or “most at-risk”, and therefore need comparative risk information. However, by virtue of the scale of assessment some countries and regions that experience the negative impacts of drought might not appear in the highest risk categories in global comparisons. This limits, and potentially biases, the ability of decision-makers, regional organisations or funding mechanisms to recognise which countries under their remit should be targeted for assistance.

This research aims to explore and overcome this issue by conducting an indicator-based drought risk assessment for agriculture at the global scale, compare these results to risk assessments for different clusters of countries of particular relevance for international climate and disaster risk policy, and discuss implications for decision making. Clusters of countries considered here include different World Bank income groups, UNFCCC Annex I and Non-Annex I countries, least developed countries (LDCs), the Vulnerable 20 (V20), as well as geographic regions. Additional clusters were created from countries that either rely on the agriculture sector in terms of their GDP, labor force, or are considered breadbaskets. 

Our analysis revealed that when assessed on a global scale, the higher risk is concentrated in Africa, countries with a reliance on agriculture in employment, and low middle income countries. High income countries and Annex I countries display lower risk on average. However, when assessed by cluster, risk patterns change compared to the global assessment. The most change occurs in the High Income, Latin America and the Caribbean, and Breadbasket clusters of countries. The least amount of change is seen in the Non-Annex I and LDC countries. On an individual country level, some countries moved from a lower quintile of risk in the global assessment to the highest quintile in the cluster assessment. For example Romania and Serbia, not classified as high-risk in the global assessment, emerged in the highest quintile in the Europe cluster. 

Findings of this study can be used directly by decision makers targeting regions or specific groups of countries for drought DRR planning or funding. More broadly, this analysis shows the importance of analysing risk at multiple scales, as different patterns emerge that could influence financial flows, decision making, and ultimately disaster risk outcomes.

How to cite: Dudley, A. L., Meza, I., Naumann, G., and Hagenlocher, M.: Leaving no country behind? How scale influences outcomes of drought risk assessments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16436, https://doi.org/10.5194/egusphere-egu21-16436, 2021.

Droughts are recurrent phenomena that are intrinsic to any climate. In Spain, as in many countries in the Mediterranean region, forecasts derived from climate change models predict an increase in the frequency and intensity of this type of phenomena. This makes even more necessary to focus efforts on strengthening social and institutional capacities through prevention, mitigation and adaptation strategies to mitigate the possible impacts of drought on the society and the environment. Despite the progress achieved at the scale of river basin districts and large municipalities, small and medium-sized towns often do not have drought risk management tools adapted to their specific needs. This study developed a participatory methodology for the elaboration of drought risk management plans in small and medium-sized towns. The methodology was tested and validated in three pilot municipalities: Madridejos (Toledo), Puente Genil (Córdoba) and Xàbia (Alicante). As a result, a methodological guide was developed to facilitate the preparation and adaptation of these plans to the different contexts, realities and needs of each municipality. The communication presents the key elements of this participatory methodology and the lessons learnt from the experience in the three pilot sites.

How to cite: De Stefano, L., Vargas, J., Hernández-Mora, N., Ballester, A., Herrera, T., Lacalle, A., and Paneque, P.: A methodology for a participatory approach to the elaboration of drought risk management plans in small and medium towns, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16544, https://doi.org/10.5194/egusphere-egu21-16544, 2021.