The utility of Google Trends as a tool for evaluating flooding in data-scarce places

Google Trends (GT) offers a historical database of global internet searches with the potential to complement conventional records of environmental hazards, especially in regions where formal hydrometeorological data are scarce. We evaluate the extent to which GT can discern heavy rainfall and floods in Kenya and Uganda during the period 2014 to 2018. We triangulate counts of flood searches from GT with available rainfall records and media reports to build an inventory of extreme events. The Spearman rank correlation (rho) between monthly mean search interest for flooding and monthly Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) rainfall totals was rho = +0.38 (p < 0.005) for Kenya and rho = +0.64 (p < 0.001) for Uganda. Media reports of flooding were used to specify a threshold of detectability to give the same overall frequency of floods based on GT search interest. When the GT search index threshold was set at >= 15 and >= 29, the correct detection rate was 75% and 64% within a five-day window of known flood events in Kenya and Uganda, respectively. From these preliminary explorations we conclude that GT has potential as a proxy data source, but greater skill may emerge in places with larger search volumes and by linking to historical information about environmental hazards at sub-national scales. Wider applicability of the GT platform might be possible if there is greater transparency about how Google algorithms determine topics.

Automated summary

The study evaluates the potential use of Google Trends as a complementary record of environmental hazards and finds a positive correlation between search interest and actual rainfall in Kenya and Uganda. By setting specific thresholds for GT search index, it is possible to accurately detect flood events within a certain time window. Further research is needed to explore the capabilities of GT in areas with higher search volumes and improve skills in linking to historical information about environmental hazards.