Introduction

Background

Informal and poor neighbourhoods in cities in developing countries, are often located in flood prone areas. This is particularly the case for Dar Es Salaam – Tanzania. The Tanzanian Red Cross Society has a volunteering network for relief actions, but there is no timely information about flood hazards and no means of communication to act upon them. Forecasting systems and monitoring are to expensive to maintain and use locally. FloodTags develops software and methods to use social media as a means to monitor floods as they appear, and to actively and passively involve the local community in the forecasting process. The result is being served to the audience through the web. In past projects (in particular TKI project DEL018), Deltares made a connection between early warning systems using Delft-FEWS, en this social media harvested information, and to convert flood locations into probabilistic flood maps. The result is a method to prepare real-time flood maps from social media. This method is succesfully being applied in the Phillippines (see TKI project DEL018). In this way, provision of information during floods becomes feasible, community-based and cost effective, which may lead to rapid and tailored relief actions after a flood.

These innovations make it feasible to strongly involve local communities in the forecast process, and activate them for response. The question is: can the developed technology also be used to activate them before an event? A prerequisite is that good quality models must be available to predict and event's impact, before the event strikes. Good quality models, predicting flood genesis and impacts are usually not available, because these require long historical records of meteorological conditions (rainfall and other parameters), hydrological data (water levels and rated flows) and impact information (amount of affected houses/households, damage, casualties). Furthermore, a cascade of hydrological, hydraulic, flood iniundation and impact models is likely to result in a cascade of uncertainties as well. Hence, the accurate simulation of impacts is very much dependent on local quality of flood models, quality of hydrometeorological forcing, as well as exposure data on presence of infrastructure, houses, and population in potentially affected areas. 

Doel

In this project, we will establish and apply an impact-based forecast model for Tanzania, and specifically Dar Es Salaam. Other than traditional approaches, we will circumvent the requirement of a hydrology-hydraulic-flood-impact (4 models in total) model cascade, but instead use data-mined relationships between monitored events and impacts in public and social media, and large amounts of globally available hydro-meteorological Earth Observation data, established in the Deltares-led Earth2Observe project. Hence, the innovation in this project is not operational monitoring and flood mapping, but derivation of impact models using historical media records and data on hydro-meteorology, and applying these in an operational setting for predictions and early warning. During the project we will assess at what scale (provincial/country/neighbourhood) we can establish and apply such impact models.

By using social and public media (instead of a physical impact model cascade, requiring enormous amounts of local and accurate data) and globally covering hydro-meteorological data, we can in principle establish a first-order impact-forecasting system anywhere in the world, providing insight in how many people and assets may be affected by floods in the forthcoming time (hours/days). Hence when this project succeeds, the result will be a scalable and innovative method to establish impact models in data poor areas. This is in stark contrast with traditional, more physically based models, requiring very accurate data on the drainage system, terrain and exposed people, houses, roads and other objects. 

We will develop and apply this for Tanzania. The found relationships will form the basis for a first impact-based forecasting system and dashboard, aimed for support of the Disaster Management Department of the Tanzania Red Cross Society (TRCS). The relationships found can also be used to establish and validate more hhysically based models at a later stage. This is part of an ongoing application for Partners voor Water. With this project, we connect to the challenge in the Water and ICT KIC (translating large amounts of data of different quality to useful information aimed for decision-making for complex questions with many stakeholders). Besides this we contribute to the challenge that earth observation data should be used more appropriately. 

Inception

Requirements

The inception phase of the project included a design workshop, to identify the needs and product requirements for two products, the media monitoring dashboard (this part is co-funded by GFDRR-DFID Challenge Fund) and the impact-forecasting product, envisaged in this TKI project. The design workshop was used. The consortium visited the Tanzania Meteorological Agency (contact persoon Hellen Msemo), the Tanzania Red Cross Society (contact persons Nyambiri Kimacha and Renatus Mkaruka) and the local World Bank office (contact person Edward Anderson). The following product requirements were identified.

Concept

Results

Activities

2017:

• Design inception mission Dar Es Salaam with the parties involved, these include the Tanzania Meteorological Agency and Tanzania Red Cross Society.
• Set up of Delft-FEWS environment, standard data feeds and media monitoring dashboard / SMS warnings
• Review of methods and datasets in Earth2Observe and other reanalysis projects - result: list of historical meteorological/hydrological time series potentially useful for impact forecasting
• Review of online media data availability, setup of queries and access to repositories. The result is an online media dataset of public media based flood conditions and impacts in Tanzania / Dar Es Salaam (including geolocations at provincial, city or neighbourhood scale)

2018:

• Development of a correlation method to relate hydrometeorological thresholds in Earth2Observe data to events, found in historical media-based database. 
• Applying method in Dar Es Salaam and 1 other region in Tanzania, selected with visited groups during the inception mission
• Setup of data feeds for impacts models in Delft-FEWS
• Monitoring and testing period (monitoring real events)

Contact

Questions about this project, possible applications elsewhere and related new applications, can be directed to:

• Hessel Winsemius (hessel.winsemius@deltares.nl)
• Jurjen Wagemaker (wagemaker@floodtags.com)