Open Mind 2015
Technology for society
Tropical Cities Sensing Rain (TROP-RAIN)
Background
Since 2014, more than half of the world’s population lives in urban areas. In many cities worldwide,
urban flooding is a severe problem. Especially in tropical regions, where monsoon rains with high
spatial variability bring extensive flooding and cause huge damage to urban societies. It is not possible
to fully prevent flooding in cities, as costs are prohibitive. Still, damage and casualties can be
prevented if authorities and citizens have reliable, real-time information on where floods are occurring
or expected to occur. Traditional monitoring programs cannot provide such information at the high
resolution in space and time that is required for urban flood management. Instead, crowdsourcing
offers huge potential to collect rainfall information in cities because the number of potential sensors,
citizens, is large. To use this source of information for rainfall and urban flood management, a
fundamental weakness need to be overcome: crowdsourced data are notoriously unreliable and
methods for quality control have not yet been developed. Data needs to be complemented with other
data sources for validation and to reach sufficient resolution in space and time.
Project
The central goal of TROP-RAIN is to establish a reliable, real-time rainfall information product that can
be used by authorities and citizens in tropical cities to better prevent urban flood damage. A recently
developed “Social Weather app” will be used that makes it possible for everyone with a smartphone to
report and make photos of rain or flooding in their area. This information will be combined with data
from a network of innovative, low-cost disdrometers and an existing traditional weather station.
The key scientific challenges are:
1. Processing data in order to make them suitable to be integrated despite different nature and
quality. The challenge here is to map rainfall impressions of smartphone users, expressed by
selecting rainfall categories, onto a rainfall data format.
2. Assessing quality of rainfall data collected using innovative sensing techniques: low-cost
disdrometers and smartphone app reports. The challenge here is to validate rainfall data of
different nature and quality.
3. Integrating rainfall data from data sources of different nature and quality into one, high space-time
resolution rainfall product. The challenge here is to develop a learning framework for data
assimilation in which we take full advantage of information qualities of the different data sources.
For smartphone app data in particular, explore the flexibility of human sensors: more intensive
monitoring where rain intensity is high and uncertainties are large.
The city of Yangon in Myanmar can serve as testing ground for the project. The city suffers from
frequent flooding during the rainy season and authorities have expressed keen interest in improved
rainfall and flooding information. to be able to better cope. Close collaboration has been established
with Yangon Technical University (YTU) and YTU students can be involved in setting up data
collection and testing of the smartphone app. Yet other tropical cities can also be considered.
Supervision and more information
Dr. ir. Marie-claire ten Veldhuis. E-mail : j.a.e.tenveldhuis@tudelft.nl
Dr. ir. Martine Rutten. E-mail : m.m.rutten@tudelft.nl
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