Project

GlobeDrought: characterizing drought risks and impacts

Goal: GlobeDrought aims to develop a web-based information system for comprehensively characterising drought events. The project will produce a spatially explicit description of drought risks by considering three components: drought hazard, exposure and vulnerability. It will investigate how droughts impact water resources, crop productivity, trade in food products and the need for international food aid. In terms of methodology, the project aims to link satellite-based remote sensing and analyses of precipitation data with hydrological modelling and yield modelling. This will produce indicators for characterising meteorological, hydrological and agricultural droughts, which in turn will make it possible to quantify drought risks. Analyses of socioeconomic data will provide the basis for quantifying exposure and vulnerability. Within the framework of a co-design process, users and stakeholders will help to shape the content and technical design of the drought information system. The global-scale analyses planned for the project will be supplemented by detailed analyses for regions heavily affected by droughts, in particular Southern Africa, Northeastern Brazil, Western India and the Missouri Basin in the United States.

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Michael Hagenlocher
added 2 research items
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.
The regular drought episodes in South Africa highlight the need to reduce drought risk by both policy and local community actions. Environmental and socioeconomic factors in South Africa's agricultural system have been affected by drought in the past, creating cascading pressures on the nation's agro-economic and water supply systems. Therefore, understanding the key drivers of all risk components through a comprehensive risk assessment must be undertaken in order to inform proactive drought risk management. This paper presents, for the first time, a national drought risk assessment for irrigated and rainfed systems, that takes into account the complex interaction between different risk components. We use modeling and remote sensing approaches and involve national experts in selecting vulnerability indicators and providing information on human and natural drivers. Our results show that all municipalities have been affected by drought in the last 30 years. The years 1981–1982, 1992, 2016 and 2018 were marked as the driest years during the study period (1981–2018) compared to the reference period (1986–2015). In general, the irrigated systems are remarkably less often affected by drought than rainfed systems; however, most farmers on irrigated land are smallholders for whom drought impacts can be significant. The drought risk of rainfed agricultural systems is exceptionally high in the north, central and west of the country, while for irrigated systems, there are more separate high-risk hotspots across the country. The vulnerability assessment identified potential entry points for disaster risk reduction at the local municipality level, such as increasing environmental awareness, reducing land degradation and increasing total dam and irrigation capacity.
Ehsan Eyshi Rezaei
added a research item
Increasing population and a severe water crisis impose growing pressure on cropping systems of Iran to increase crop production meeting the rising demand for food. Little is known on the separate contribution of trends and variability of the harvested area and yield on crop production in severely drought-prone areas such as Iran. In this study, we (a) quantify the importance of harvested area and yield on trends and variability of crop production for the 12 most important annual crops under rainfed and irrigated conditions and (b) test how well the variability in annual crop areas can be explained by drought dynamics. We use remote sensing based land cover and evapotranspiration products derived from Moderate Resolution Imaging Spectroradiometer (MODIS) to quantify cropland extent and drought severity as well as survey-based, crop-specific reports for the period 2001-2016 in Iran. The intensity of drought stress was estimated using the annual ratio between actual and potential evapotranspiration (AET/PET). We found that trends in the production of specific crops are predominantly explained by trends in harvested crop area. Besides, the variability in the harvested area contributed significantly more to the variability in crop production than the variability in crop yields, particularly under rainfed conditions (7 out of 9 crops). In contrast, variability in the production of heavily subsidized crops such as wheat was predominantly explained by yield variability. Variability in the annual cropland area was largely explained by drought, in particular for the more arid regions in the south of the country. This highlights the importance of better and proactive drought management to stabilize crop areas and yields for sufficient food production in Iran.
Eklavyya Popat
added 2 research items
Drought is understood as both a lack of water (i.e., a deficit compared to demand) and a temporal anomaly in one or more components of the hydrological cycle. Most drought indices, however, only consider the anomaly aspect, i.e., how unusual the condition is. In this paper, we present two drought hazard indices that reflect both the deficit and anomaly aspects. The soil moisture deficit anomaly index, SMDAI, is based on the drought severity index, DSI (Cammalleri et al., 2016), but is computed in a more straightforward way that does not require the definition of a mapping function. We propose a new indicator of drought hazard for water supply from rivers, the streamflow deficit anomaly index, QDAI, which takes into account the surface water demand of humans and freshwater biota. Both indices are computed and analyzed at the global scale, with a spatial resolution of roughly 50 km, for the period 1981–2010, using monthly time series of variables computed by the global water resources and the model WaterGAP 2.2d. We found that the SMDAI and QDAI values are broadly similar to values of purely anomaly-based indices. However, the deficit anomaly indices provide more differentiated spatial and temporal patterns that help to distinguish the degree and nature of the actual drought hazard to vegetation health or the water supply. QDAI can be made relevant for stakeholders with different perceptions about the importance of ecosystem protection, by adapting the approach for computing the amount of water that is required to remain in the river for the well-being of the river ecosystem. Both deficit anomaly indices are well suited for inclusion in local or global drought risk studies.
Electricity production by hydropower is negatively affected by drought. To understand and quantify risks of less than normal streamflow for hydroelectricity production (HP) at the global scale, we developed an HP model that simulates time series of monthly HP worldwide and thus enables analyzing the impact of drought on HP. The HP model is based on a new global hydropower database (GHD), containing 8,716 geo-localized plant records, and on monthly streamflow values computed by the global hydrological model WaterGAP with a spatial resolution of 0.5°. The GHD includes 44 attributes and covers 91.8% of the globally installed capacity. The HP model can reproduce HP trends, seasonality, and interannual variability that was caused by both (de)commissioning of hydropower plants and hydrological variability. It can also simulate streamflow drought and its impact on HP reasonably well. Global risk maps of HP reduction were generated for both 0.5° grid cells and countries, revealing that 67 out of the 134 countries with hydropower suffer, in 1 out of 10 years, from a reduction of more than 20% of mean annual HP and 18 countries from a reduction of more than 40%. The developed HP model enables advanced assessments of drought impacts on hydroelectricity at national to international levels.
Ehsan Eyshi Rezaei
added a research item
Drought is one of the extreme climatic events that has a severe impact on crop production and food supply. Our main goal is to test the suitability of remote sensing-based indices to detect drought impacts on crop production from a global to regional scale. Moderate resolution imaging spectroradiometer (MODIS) based imagery, spanning from 2001 to 2017 was used for this task. This includes the normalized difference vegetation index (NDVI), land surface temperature (LST), and the evaporative stress index (ESI), which is based on the ratio of actual to potential evapotranspiration. These indices were used as indicators of drought-induced vegetation conditions for three main crops: maize, wheat, and soybean. The start and end of the growing season, as observed at 500 m resolution, were used to exclude the time steps that are outside of the growing season. Based on the three indicators, monthly standardized anomalies were estimated, which were used for both analyses of spatiotemporal patterns of drought and the relationship with yield anomalies. Anomalies in the ESI had higher correlations with maize and wheat yield anomalies than other indices, indicating that prolonged periods of low ESI during the growing season are highly correlated with reduced crop yields. All indices could identify past drought events, such as the drought in the USA in 2012, Eastern Africa in 2016–2017, and South Africa in 2015–2016. The results of this study highlight the potential of the use of moderate resolution remote sensing-based indicators combined with phenometrics for drought-induced crop impact monitoring. For several regions, droughts identified using the ESI and LST were more intense than the NDVI-based results. We showed that these indices are relevant for agricultural drought monitoring at both global and regional scales. They can be integrated into drought early warning systems, process-based crop models, as well as can be used for risk assessment and included in advanced decision-support frameworks.
Ehsan Eyshi Rezaei
added a research item
One of the major sources of uncertainty in large-scale crop modeling is the lack of information capturing the spatiotemporal variability of crop sowing dates. Remote sensing can contribute to reducing such uncertainties by providing essential spatial and temporal information to crop models and improving the accuracy of yield predictions. However, little is known about the impacts of the differences in crop sowing dates estimated by using remote sensing (RS) and other established methods, the uncertainties introduced by the thresholds used in these methods, and the sensitivity of simulated crop yields to these uncertainties in crop sowing dates. In the present study, we performed a systematic sensitivity analysis using various scenarios. The LINTUL-5 crop model implemented in the SIMPLACE modeling platform was applied during the period 2001–2016 to simulate maize yields across four provinces in South Africa using previously defined scenarios of sowing dates. As expected, the selected methodology and the selected threshold considerably influenced the estimated sowing dates (up to 51 days) and resulted in differences in the long-term mean maize yield reaching up to 1.7 t ha−1 (48% of the mean yield) at the province level. Using RS-derived sowing date estimations resulted in a better representation of the yield variability in space and time since the use of RS information not only relies on precipitation but also captures the impacts of socioeconomic factors on the sowing decision, particularly for smallholder farmers. The model was not able to reproduce the observed yield anomalies in Free State (Pearson correlation coefficient: 0.16 to 0.23) and Mpumalanga (Pearson correlation coefficient: 0.11 to 0.18) in South Africa when using fixed and precipitation rule-based sowing date estimations. Further research with high-resolution climate and soil data and ground-based observations is required to better understand the sources of the uncertainties in RS information and to test whether the results presented herein can be generalized among crop models with different levels of complexity and across distinct field crops.
Olena Dubovyk
added a research item
Agricultural production and food security highly depend on crop growth and condition throughout the growing season. Timely and spatially explicit information on crop phenology can assist in informed decision making and agricultural land management. Remote sensing can be a powerful tool for agricultural assessment. Remotely sensed data is ideally suited for both large-scale and field-level analyses due to the wide variability of datasets with diverse spatiotemporal resolution. To derive crop-specific phenometrics, we fused time series from Landsat 8 and Sentinel 2 with Moderate-resolution Imaging Spectroradiometer (MODIS) data. Using a linear regression approach, synthetic Landsat 8 and Sentinel 2 data were created based on MODIS imagery. This fusion-process resulted in synthetic imagery with radiometric characteristics of original Landsat 8 and Sentinel 2 data. We created four different time series using synthetic data as well as a mix of original and synthetic data. The extracted time series of phenometrics consisting of both synthetic and original data showed high detail in the final phenomaps which allowed intra-field level assessment of crops. In-situ field reports were used for validation. Our phenometrics showed only a few days of deviation for most crops and datasets. The proposed data integration method can be applied in areas where data from a single high-resolution source is scarce.
Eklavyya Popat
added a research item
Drought is understood as both a lack of water (i.e., a deficit as compared to some requirement) and an anomaly in the condition of one or more components of the hydrological cycle. Most drought indices, however, only consider the anomaly aspect, i.e., how unusual the condition is. In this paper, we present two drought hazard indices that reflect both the deficit and anomaly aspects. The soil moisture deficit anomaly index, SMDAI, is based on the drought severity index, DSI, but is computed in a more straightforward way that does not require the definition of a mapping function. We propose a new indicator of drought hazard for water supply from rivers, the streamflow deficit anomaly index, QDAI, which takes into account the surface water demand of humans and freshwater biota. Both indices are computed and analyzed at the global scale, with a spatial resolution of roughly 50 km, for the period 1981–2010, using monthly time series of variables computed by the global water resources and the model WaterGAP2.2d. We found that the SMDAI and QDAI values are broadly similar to values of purely anomaly-based indices. However, the deficit anomaly indices provide more differentiated, spatial and temporal patterns that help to distinguish the degree of the actual drought hazard to vegetation health or the water supply. QDAI can be made relevant for stakeholders with different perceptions about the importance of ecosystem protection, by adopting the approach for computing the amount of water that is required to remain in the river for the well-being of the river ecosystem. Both deficit anomaly indices are well suited for inclusion in local or global drought risk studies.
Michael Hagenlocher
added a research item
Drought is a recurrent global phenomenon considered one of the most complex hazards with manifold impacts on communities, ecosystems, and economies. While many sectors are affected by drought, agriculture's high dependency on water makes it particularly susceptible to droughts, threatening the livelihoods of many, and hampering the achievement of the Sustainable Development Goals. Identifying pathways towards more drought resilient societies by analyzing the drivers and spatial patterns of drought risk is of increasing importance for the identification, prioritization and planning of risk reduction, risk transfer and adaptation options. While major progress has been made regarding the mapping, prediction and monitoring of drought events at different spatial scales (local to global), comprehensive drought risk assessments that consider the complex interaction of drought hazards, exposure and vulnerability factors are still the exception. Here, we present, for the first time, a global-scale drought risk assessment at national level for both irrigated and rain-fed agricultural systems. The analysis integrates (1) composite drought hazard indicators based on historical climate conditions (1980-2016), (2) exposure data represented by the harvest area of irrigated and rainfed systems, and (3) an expert-weighted set of social-ecological vulnerability indicators. The latter were identified through a systematic review of literature (n = 105 peer-reviewed articles) and expert consultations (n = 78 experts). This study attempted to characterize the average drought risk for the whole study period. Results show that drought risk of rain-fed and irrigated agricultural systems display different heterogeneous patterns at the global level with higher risk for southeastern Europe, as well as northern and southern Africa. The vulnerability to drought highlights the relevance to increase the countries’ coping capacity in order to reduce their overall drought risk. For instance, the United States, which despite being highly exposed to drought hazard, has low socio-ecological susceptibility and sufficiently high coping capacities to reduce the overall drought risk considerably. When comparing irrigated and rain-fed drought hazard/exposure, there are significant regional differences. For example, the northern part of Central Africa and South America have low hazard/exposure levels of irrigated crops, resulting in a low total risk, although high vulnerability characterize these regions. South Africa, however, has a high amount of rain-fed crops exposed to drought, but a lower vulnerability compared to other African countries. Further, the drivers of drought risk vary substantially across and within countries, calling for spatially targeted risk reduction and adaptation options. Findings from this study underline the relevance of analyzing drought risk from a holistic and integrated perspective that brings together data from different sources and allows for reproduction in varying regions and for different spatial scales, and can serve as a blueprint for future drought risk assessments for other affected sectors, such as water supply, tourism, or energy. By providing information on the underlying drivers and patterns of drought risk, this approach supports the identification of priority regions and provides entry points for targeted drought risk reduction and adaptation options to move towards resilient agricultural systems.
Michael Hagenlocher
added a research item
Droughts continue to affect ecosystems, communities and entire economies. Agriculture bears much of the impact, and in many countries it is the most heavily affected sector. Over the past decades, efforts have been made to assess drought risk at different spatial scales. Here, we present for the first time an integrated assessment of drought risk for both irrigated and rainfed agricultural systems at the global scale. Composite hazard indicators were calculated for irrigated and rainfed systems separately using different drought indices based on historical climate conditions (1980–2016). Exposure was analyzed for irrigated and non-irrigated crops. Vulnerability was assessed through a socioecological-system (SES) perspective, using socioecological susceptibility and lack of coping-capacity indicators that were weighted by drought experts from around the world. The analysis shows that drought risk of rainfed and irrigated agricultural systems displays a heterogeneous pattern at the global level, with higher risk for southeastern Europe as well as northern and southern Africa. By providing information on the drivers and spatial patterns of drought risk in all dimensions of hazard, exposure and vulnerability, the presented analysis can support the identification of tailored measures to reduce drought risk and increase the resilience of agricultural systems.
Michael Hagenlocher
added a research item
The devastating impacts of drought are fast becoming a global concern. Zimbabwe is among the countries more severely affected, where drought impacts have led to water shortages, declining yields, and periods of food insecurity, accompanied by economic downturns. In particular, the country's agricultural sector, mostly comprised of smallholder rainfed systems, is at great risk of drought. In this study, a multimethod approach is applied, including a remote sensing-based analysis of vegetation health data from 1989-2019 to assess the drought hazard, as well as a spatial analysis combined with expert consultations to determine drought vulnerability and exposure of agricultural systems. The results show that droughts frequently occur with changing patterns across Zimbabwe. Every district has been affected by drought during the past thirty years, with varying levels of severity and frequency. Severe drought episodes have been observed in. Drought vulnerability and exposure vary substantially in the country, with the southwestern provinces of Matabeleland North and South showing particularly high levels. Assessments of high-risk areas, combined with an analysis of the drivers of risk, set the path towards tailor-made adaptation strategies that consider drought frequency and severity, exposure, and vulnerability.
Eklavyya Popat
added a research item
Droughts continue to affect ecosystems, communities, and entire economies. Agriculture bears much of the impact, and in many countries it is the most heavily affected sector. Over the past decades, efforts have been made to assess drought risk at different spatial scales. Here, we present for the first time an integrated assessment of drought risk for both irrigated and rain-fed agricultural systems at the global scale. Composite hazard indicators were calculated for irrigated and rain-fed systems separately using different drought indices based on historical climate conditions (1980–2016). Exposure was analyzed for irrigated and non-irrigated crops. Vulnerability was assessed through a social-ecological systems perspective, using social-ecological susceptibility and lack of coping capacity indicators that were weighted by drought experts from around the world. The analysis shows that drought risk of rain-fed and irrigated agricultural systems displays heterogeneous pattern at the global level with higher risk for southeastern Europe, as well as northern and southern Africa. By providing information on the drivers and spatial patterns of drought risk in all dimensions of hazard, exposure, and vulnerability, the presented analysis can support the identification of tailored measures to reduce drought risk and increase the resilience of agricultural systems.
Michael Hagenlocher
added a research item
environmental and social impacts. The vulnerability to droughts, however, is complex to assess and strongly depends on the sectoral focus as well as on the geographical context of the assessment. This report presents the results of an expert survey that was conducted to weigh drought vulnerability indicators according to their relevance for agricultural systems and domestic water supply. Indicators originate from multiple dimensions (social, economic, infrastructure, crime and conflict, environmental and farming practices) and are grouped into four subcategories: social susceptibility, environmental susceptibility, lack of coping capacity and lack of adaptive capacity. The findings underline that the relevance of indicators strongly varies depending on the sector which is susceptible to the negative impacts of drought. Hence, the most relevant indicators for agricultural systems differentiate significantly from the most important ones for domestic water supply. The results are used in the GlobeDrought project to include expert judgement in the vulnerability assessments. This information will be compiled together with drought hazard and exposure information into a global drought risk assessment.
Olena Dubovyk
added a research item
Droughts have significant negative impacts on livelihoods and economy of Kazakhstan. In this study, we assessed and characterized drought hazard events in Kazakhstan using satellite Remote Sensing time series for the period between 2000 and 2016. First, we calculated Vegetation Condition Index (VCI) and Standardized Enhanced Vegetation Index anomalies (ZEVI) based on 250 m Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time series. Second, we assessed vegetation cover changes for the observation period. Third, we analyzed different characteristics of the drought hazard as well as spatial distribution of the drought-affected areas within the country. The results confirmed that drought was one of the environmental challenges for Kazakhstan in 2000–2016. The obtained maps showed that drought hazard conditions were observed every year, though the areal coverage of the drought conditions largely varied between the analyzed years. The calculated drought indices indicated that in years 2000, 2008, 2010, 2011, 2012, and 2014, more than 50% of the area of the country were affected by drought conditions of different severity with the largest droughts in terms of the areal spread occurring in 2012 and 2014. We concluded that the pre-requisite of successful implementation of drought hazard and risk mitigation strategies is availability of spatially explicit, timely, and reliable information on drought hazard. This suggests the necessity of incorporation of remote sensing–based drought information, as was demonstrated in this paper, in the national drought monitoring system of Kazakhstan.
Michael Hagenlocher
added a research item
Reducing the social, environmental, and economic impacts of droughts and identifying pathways towards drought resilient societies remains a global priority. A common understanding of the drivers of drought risk and ways in which drought impacts materialize is crucial for improved assessments and for the identification and (spatial) planning of targeted drought risk reduction and adaptation options. Over the past two decades, we have witnessed an increase in drought risk assessments across spatial and temporal scales drawing on a multitude of conceptual foundations and methodological approaches. Recognizing the diversity of approaches in science and practice as well as the associated opportunities and challenges, we present the outcomes of a systematic literature review of the state of the art of people-centered drought vulnerability and risk conceptualization and assessments, and identify persisting gaps. Our analysis shows that, of the reviewed assessments, (i) more than 60% do not explicitly specify the type of drought hazard that is addressed, (ii) 42% do not provide a clear definition of drought risk, (iii) 62% apply static, index-based approaches, (iv) 57% of the indicator-based assessments do not specify their weighting methods, (v) only 11% conduct any form of validation, (vi) only ten percent develop future scenarios of drought risk, and (vii) only about 40% of the assessments establish a direct link to drought risk reduction or adaptation strategies, i.e. consider solutions. We discuss the challenges associated with these findings for both assessment and identification of drought risk reduction measures and identify research needs to inform future research and policy agendas in order to advance the understanding of drought risk and support pathways towards more drought resilient societies.
Michael Hagenlocher
added a research item
In times of drought, water resources are insufficient. These water shortages often have negative effects on agricultural productivity and on associated socioeconomic factors, causing reduced income, food shortages and even famines. The overall objective of GlobeDrought is to develop an integrated drought risk information system which will adequately describe causal links in the formation and development of droughts, connections between the various types of drought hazards (meteorological, hydrological and soil moisture), and associated vulnerabilities. With its planned monitoring and experimental early warning system, the project aims to reduce the time between satellite-based data collection, identification of a drought risk and the implementation of potential countermeasures by political decision-makers and those involved in international humanitarian aid. The global-scale analyses focusing on drought impacts on agricultural systems will be supplemented by detailed analyses for regions heavily affected by droughts such as Southern Africa (South Africa and Zimbabwe), Eastern Brazil, Western India, and the Missouri River Basin of the United States. The results of literature reviews and expert consultations show that it is very important how drought risk analyses are conceptualized and that there is no consolidated, commonly shared framework and methodology for drought risk assessments at the moment. GlobeDrought is therefore also going to contribute to methodological improvements and more precise terminology in drought risk and impact assessments. First outcomes of the global and regional studies show that the modeling tools and sensor data used in GlobeDrought provide a consistent picture of drought development across the domains meteorology, hydrology, agronomy and economy.
Michael Hagenlocher
added a research item
Drought impacts are widespread and affect directly or indirectly human and environmental systems globally. In order to understand the determinants of such impacts, drought risk, i.e. the likelihood of drought impact occurrence, is analysed. The development of reliable drought risk assessments (in all its components of drought hazards, exposure and vulnerability) is understood to be one of the essential steps to foster resilience to drought. But the variety of sectors impacted, and the different interests of the specific users the analyses are made for, resulted in a wealth of conceptual definitions and methodological approaches to analyse drought risk. This study discusses the current state of drought risk analysis based on a systematic literature review with the aim to disentangle issues of scale and focus on the different facets of risk, such as application, indicator and data selection, hazard identification, vulnerability assessment, impact information application and the theoretical foundations and methodological approach of risk analysis. Commonalities between studies and approaches are apparently lacking. The review highlights a lack of national and regional investigations in the Americas, as well as Northern and Eastern Asia. The majority of assessments focuses on the agricultural sector, but also studies that reflect overall unspecified risk of a region are common. Drought risk analyses differ by the temporal aspect of analysis, information/predictor selection criteria and the methods applied to combine such information. Hereby, a lack of statistical evidence for predictor selection as well as validation of final results became evident. Further, the majority of studies use static approaches and only few studies developed future scenarios of risk. The analysis of existing studies suggests that there is only little agreement on what a drought risk analysis entails. Nevertheless, common paradigms of data application-and combination practice could be identified and resulted in the overall recommendation that the components of hazard predictors, exposure, vulnerability and impact information should be considered in the frame of statistical and expert models. The common practice to preferably apply existing data which might not optimally suite the purpose of the analysis, rather than the integration of novel information has to change. Predictor selection should become more transparent, and should also be based on both statistical evidence and expert knowledge. In order reduce the gap between natural and social science, and to account for transferability of studies, more efforts to validate approaches against each other in comparative analyses are needed. Therefore, more efforts to collect standardised impact information are necessary. In summary, the collected information on common practice of applied methodological approaches and data with regard to the location, spatial resolution and thematic focus paves the way forward for a drought risk catalogue, giving sectors specific guidance on risk analysis criteria. All those factors together determine drought risk, which can be managed by developing drought risk reduction policies and drought risk management plans that are adapted to the regional, national and local context.
Ehsan Eyshi Rezaei
added 2 research items
The potential impacts of climate warming on grain yield, water, and nitrogen consumptions of maize have been repeatedly assessed across different regions of the world. However, to date, there is no comprehensive, large-scale evaluation on the effects of climate warming on the cropping systems of Iran. The objective of the current study was to quantify the effects of climate warming on the length of the growing period and grain yield of maize. We also tested the potential of changes in irrigation, nitrogen application rate, and using late maturity cultivars of maize to offset the negative impact of climate warming in order to maintain the current levels of grain yield (4 to 10 t ha−1 depending upon the province) in Iran. The crop modeling framework SIMPLACE was used to evaluate the effects of the warming temperatures, nitrogen application rate, and changes in thermal requirements of the cultivar scenario combinations on grain yield of maize in Iran. The climate, soil, and management inputs of the crop model were obtained from global datasets as grid cells at 0.5° × 0.5° resolution, and the outputs of the crop model were aggregated to the province level. Results of the grain yield projections showed a decline (− 0.1 to − 22%) in maize, especially in the Southern provinces (Khuzestan, Fars, and Kerman) under different warming scenarios by + 0.5 to + 2 °C, an increase from the baseline. The grain yield decline appeared to be mainly driven by a shortening of the length of the growing season and extreme heat stress during anthesis, the most sensitive period of crop growth. Increasing temperatures during the growing season lead to a marginal increase of absolute irrigation requirements over the maize growing areas. For all provinces, application of 10–25% more nitrogen than the current rate (170 kg N/ha-1) was able to offset the negative effects of higher temperatures (+ 0.5 and + 1.0 °C) during the growing season. However, the increased nitrogen application rates were not able to maintain the baseline level of grain yield under the + 1.5 and + 2.0 °C warming scenarios. Introducing late maturity cultivars, which required 20% more temperature sum than current cultivars to reach maturity, improved the grain yield in the cooler provinces by up to 10%. In conclusion, the grain yield baseline level may not be maintained under the highest magnitude of warming by increasing nitrogen application rates or using late maturity cultivars. Furthermore, more water is needed to produce a unit of grain under a warming climate. This study also suggests that combined adaptation strategies should be considered by policymakers in order to mitigate the negative impact of climate warming on the cropping systems of Iran.
Eklavyya Popat
added a research item
Development of a global drought information system (DIS) useful for: To comprehensively quantify (potential) droughts impacts Support possibility of better drought management and reduce drought vulnerability, especially for affected area with lower capacity drought capacity. Provide DIS capacity to all drought prone regions Background
Stefan Siebert
added a project goal
GlobeDrought aims to develop a web-based information system for comprehensively characterising drought events. The project will produce a spatially explicit description of drought risks by considering three components: drought hazard, exposure and vulnerability. It will investigate how droughts impact water resources, crop productivity, trade in food products and the need for international food aid. In terms of methodology, the project aims to link satellite-based remote sensing and analyses of precipitation data with hydrological modelling and yield modelling. This will produce indicators for characterising meteorological, hydrological and agricultural droughts, which in turn will make it possible to quantify drought risks. Analyses of socioeconomic data will provide the basis for quantifying exposure and vulnerability. Within the framework of a co-design process, users and stakeholders will help to shape the content and technical design of the drought information system. The global-scale analyses planned for the project will be supplemented by detailed analyses for regions heavily affected by droughts, in particular Southern Africa, Northeastern Brazil, Western India and the Missouri Basin in the United States.