Drought Impacts: Vulnerability thresholds in monitoring and Early-warning Research
Human Geography
Final Report Abstract
Droughts threaten water security in every climate and water use sector. But little research existed which assessed the relations between widely-used physical indicators and drought impacts or adequately incorporates impacts into drought monitoring and early-warning (M&EW). Combining innovative analyses, data visualization and collaborative learning with stakeholders in the UK, the USA, and Australia, the DrIVER project, funded under the Belmont Forum/G8 HORC’s Freshwater Security Call, aimed to improve the understanding of the links between indicators and impacts and the diversity of drought framings in decision making. The three-continent collaboration faced some logistical challenges, but overall was considered successful by the project partners as well as the involved stakeholders. DrIVER’s objective was to compare and evaluate reported drought impacts and physical drought indicators where drought M&EW systems exist and are used. A detailed survey of existing systems and a literature review found that drought index choices used operationally are mostly guided by data availability. Indices on meteorological and agricultural drought are more frequently monitored than hydrological drought and socio-economic or environmental impacts. Impact information is considered by many systems, but not used and employed in a systematic quantitative manner. The DFG funded part of the project, carried out at the Universtiy of Freiburg, targeted these research gaps with quantitative data analysis and statistical modelling of large continental datasets of multiple drought indices and various types of drought impact records (quantitative variables as well as coded text reports). It aimed to identify and compare the general controls of drought and potential thresholds of drought indicators that define the vulnerability of society and economy in order to better understand the coupled socio-hydrological drought system. The results include a quantification of the general controls on drought characteristics, incl. aspects such as river regulation on hydrological drought. Differences in the delay between meteorological drought and the occurrence of impacts various sectors suggest that thresholds and trigger levels for management actions need to be adapted locally to regionally, depending on a particular water supply source, such as surface vs. groundwater, and depending on different drought stages such as onset, peak, termination. Impact data can be linked to the indicators statistically. The project tested the potential of such empirically derived 'impact functions' and found that where sufficient impact reports are available, the impact function approach could be used to add the likelihood of impact occurrence to the commonly used indices provided by M&EW. The transdisciplinary objectives in the project were to explore through a series of workshops the capacity of stakeholders to make drought management decisions based on M&EW information systems. Despite regional differences, stakeholders’ decision-making was found often directed by specific drought plans and organizational requirements setting trigger levels depending on asset states and demand. Although drought impacts (or their probability as described above) were recognized, they were not easily incorporated into decision-making due to a lack of suitable indicators and confidence in reliability. Water management decisions such as drought mitigation measures can also modify the indicator thresholds. A more detailed assessment of feedbacks with impacts and management decisions is still needed as well as tools to analyse these and react. Drought scenarios based on historical analogues of index and impact information were elaborated in the workshops and found to be a promising avenue for resilience building. The project’s research results suggest that additional efforts are needed to better monitor and report drought impacts at the local level to provide higher resolution information and better correlations with hydro-meteorological drought indicators. This would also enhance the tracking of drought impacts over time as a result of changing social/ecological dynamics and management strategies that are implemented to reduce drought impacts.
Publications
- (2015) Exploring the link between drought indicators and impacts. Nat. Hazards Earth Syst. Sci. 15, 1381–1397
Bachmair, S., Kohn, I., Stahl, K.
(See online at https://doi.org/10.5194/nhess-15-1381-2015) - Enhancing drought Monitoring and Early Warning by linking indicators to impacts. In: Drought: Research and Science-Policy Interfacing. Edited by Joaquin Andreu Alvarez et al. CRC Press 2015, Pages 287–292
Hannaford, J., Acreman, M., Stahl, K., Bachmair, S., Svoboda, M.D., Knutson, C., Crossman, N.D., Overton, I.C. & Colloff, M.J.
(See online at https://dx.doi.org/10.1201/b18077-49) - (2016) A quantitative analysis to objectively appraise drought indicators and model drought impacts. Hydrol. Earth Syst. Sci., 20, 2589–2609
Bachmair, S., Svensson, C., Hannaford, J., Barker, L.J., Stahl, K.
(See online at https://doi.org/10.5194/hess-20-2589-2016) - (2016) Controls on hydrologic drought duration in near-natural streamflow in Europe and the USA, Hydrol. Earth Syst. Sci., 20, 4043–4059
Tijdeman, E., Bachmair, S., and Stahl, K.
(See online at https://doi.org/10.5194/hess-20-4043-2016) - (2016) Drought forecasting isn’t just about water–to get smart we need health and financial data too. The Conversation. The Conversation Trust (UK)
Crossman, N., Overton, I., Hannaford, J., Stahl, K.; Collins, K., Svoboda, M., Acreman, Mike, Wall, N.
- (2016) Drought indicators revisited: the need for a wider consideration of environment and society. Wiley Interdisciplinary Reviews: Water
Bachmair, S., Stahl, K., Collins, K., Hannaford, J., Acreman, M., Svoboda, M., Knutson, C., Smith, K., Wall, N., Fuchs, B., Crossman, N., Overton, I.
(See online at https://doi.org/10.1002/wat2.1154) - (2016). Drought indicator time series for European NUTS regions based on remote sensing data (2000-2015). NERC Environmental Information Data Centre
Tanguy, M.; Bachmair, S.; Stahl, K.; Hannaford, J.
(See online at https://doi.org/10.5285/5b3fcf9f-19d4-4ad3-a8bb-0a5ea02c857e) - (2016). Gridded drought indices based on remote sensing data for Europe (2000-2015). NERC Environmental Information Data Centre
Tanguy, M.; Bachmair, S.; Stahl, K.; Hannaford, J.
(See online at https://doi.org/10.5285/4e0d0e50-2f9c-4647-864d-5c3b30bb5f4b) - 2016. Meeting Summary: Stakeholder co-inquiries on drought impacts, monitoring and early warning systems. Bulletin of the American Meteorological Society
Collins, K., Hannaford, J., Svoboda, M., Knutson, C., Wall, N., Bernadt, T., Crossman, N., Overton, I., Acreman, M., Bachmair, S., Stahl, K.
(See online at https://dx.doi.org/10.1175/BAMS-D-16-0185.1) - (2017) Developing drought impact functions for drought risk management, Nat. Hazards Earth Syst. Sci. Discuss.
Bachmair, S., Svensson, C., Prosdocimi, I., Hannaford, J., and Stahl, K.
(See online at https://doi.org/10.5194/nhess-2017-187)
