An investigation into the role of crowdsourcing in generating information for flood risk management

Flooding is a major global hazard whose management relies on an accurate understanding of its risks. Crowdsourcing represents a major opportunity for supporting flood risk management as members of the public are highly capable of producing useful flood information. This thesis explores a wide range of issues related to flood crowdsourcing using an interdisciplinary approach. Through an examination of 31 different projects a flood crowdsourcing typology was developed. This identified five key types of flood crowdsourcing: i) Incident Reporting, ii) Media Engagement, iii) Collaborative Mapping, iv) Online Volunteering and v) Passive VGI. These represent a wide range of initiatives with radically different aims, objectives, datasets and relationships with volunteers. Online Volunteering was explored in greater detail using Tomnod as a case study. This is a micro-tasking platform in which volunteers analyse satellite imagery to support disaster response. Volunteer motivations for participating on Tomnod were found to be largely altruistic. Demographics of participants were significant, with retirement, disability or long-term health problems identified as major drivers for participation. Many participants emphasised that effective communication between volunteers and the site owner is strongly linked to their appreciation of the platform. In addition, the feedback on the quality and impact of their contributions was found to be crucial in maintaining interest. Through an examination of their contributions, volunteers were found to be able to ascertain with a higher degree of accuracy, many features in satellite imagery which supervised image classification struggled to identify. This was more pronounced in poorer quality imagery where image classification had a very low accuracy. However, supervised classification was found to be far more systematic and succeeded in identifying impacts in many regions which were missed by volunteers. The efficacy of using crowdsourcing for flood risk management was explored further through the iterative development of a Collaborative Mapping web-platform called Floodcrowd. Through interviews and focus groups, stakeholders from the public and private sector expressed an interest in crowdsourcing as a tool for supporting flood risk management. Types of data which stakeholders are particularly interested in with regards to crowdsourcing differ between organisations. Yet, they typically include flood depths, photos, timeframes of events and historical background information. Through engagement activities, many citizens were found to be able and motivated to share such observations. Yet, motivations were strongly affected by the level of attention their contributions receive from authorities. This presents many opportunities as well as challenges for ensuring that the future of flood crowdsourcing improves flood risk management and does not damage stakeholder relationships with participants

Correlating surface water flood damages in three Indonesia cities [Abstract]

Despite a high growth rate of over 5%, the insurance penetration rate in Indonesia is low, at roughly 2.77 percent and is one of the least developed insurance market among ASEAN economies. A primary explanation for the lack of motivation for taking up insurance is due to the lack of understanding of the multitude of risks from natural hazards the Indonesian market faces, principally of flooding. The purpose of this research is to assess the flood correlation between three of the major cities (Jakarta, Semarang, and Solo) on the island of Java. These highly populated and financial centres of Indonesia are most prone to the rainfall extremes during the Monsoon Season (November – March), many of which causes flooding. All the historical rainfall events were extracted from ECMWF’s ERA-5 hourly rainfall dataset (1979 – 2018). The top 10 events for each city were selected based on peak rainfall intensity. For the selected events in a city, rainfall records of the same period were extracted for the other two cities. This results in 30 simulations per city. Using a 2D hydraulic modelling tool (FloodMap), surface water flood footprints were generated for the events. In the absence of depth-damage curves, the number of buildings flooded under each event were used as an approximation to building damages. Damage to buildings due to surface water flooding in Solo and Semarang were found to be most correlated, with a significant number of buildings flooded in both cities in 15 out of the 20 paired events. Solo and Jakarta show some correlation (7 out of 20) whilst flooding in Semarang and Jakarta are least correlated (4 out of 20). This study is an initial analysis relevant to the modelling of catastrophes in a relatively data sparse environment, providing an approximation of the correlation of flooding between three Indonesian cities. Further studies are required to develop pragmatic approaches to complement catastrophe modelling that integrate the spatial correlation between flood damages in cities.</p

Spearman’s rho between sub-basin averaged phosphate and nitrate concentrations (n = 57) and microscale and macroscale variables.

<p>*AHWS refers to the Adjusted Human Water Security, [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0162684#pone.0162684.ref029" target="_blank">29</a>]. **Significant p-values, considering multiple hypotheses are below 0.002 (Bonferroni correction).</p

a) Global location of study areas, b) Sub-basins and sampling sites examined by citizen scientists in Buenos Aires, c) Curitiba, d) São Paulo, e) Rio de Janeiro, f) Mexico City and g) Vancouver.

<p>Basemap image reprinted from Esri under a CC BY license with permission from Esri and its licensors, original copyright June 2009.</p

Average concentrations of phosphate (a) and nitrate (b) measured in each sampled sub-basins (Level 10 HydroBasins on y axis) in Buenos Aires, Curitiba, Mexico City, Rio de Janeiro, São Paulo and Vancouver.

<p>Bars indicate 2 standard errors (SE).</p

(a) Microscale pollution sources identified by citizen scientists reported as the average sum of each pollution source category per sub-basin averaged by city and (b) percentage of land cover/use recorded by citizen scientists per sub-basin averaged by city.

<p>(a) Microscale pollution sources identified by citizen scientists reported as the average sum of each pollution source category per sub-basin averaged by city and (b) percentage of land cover/use recorded by citizen scientists per sub-basin averaged by city.</p

Receiver Operating Characteristic curve for the phosphate concentration eutrophication threshold of 0.1 mg L^-1 for sub-basins against microscale observations of the sum of pollution sources and macroscale data related to phosphorus loading.

<p>The x-axis is denominated as 1 minus Specificity or the false positive rate. </p

Disruption of emergency response to vulnerable populations during floods

Emergency responders must reach urgent cases within mandatory timeframes, regardless of weather conditions. However, flooding of transport networks can add critical minutes to travel times between dispatch and arrival. Here, we explicitly model the spatial coverage of all Ambulance Service and Fire and Rescue Service stations in England during flooding of varying severity under compliant response times. We show that even low-magnitude floods can lead to a reduction in national-level compliance with mandatory response times and this reduction can be even more dramatic in some urban agglomerations, making the effectiveness of the emergency response particularly sensitive to the expected impacts of future increases in extreme rainfall and flood risk. Underpinning this sensitivity are policies leading to the centralization of the Ambulance Service and the decentralization of the Fire and Rescue Service. The results provide opportunities to identify hotspots of vulnerability (such as care homes, sheltered accommodation, nurseries and schools) for optimizing the distribution of response stations and developing contingency plans for stranded sites.<br