Modelling urban floods in semiarid environment: a case study in Paradera, Aruba

During the storm of November 20th, 2016 significant parts of the Paradera catchment in Aruba were flooded. The damage to the roads and houses resulted in high costs for the Aruban government and the Aruban people. Many studies have shown a large influence of urbanisation on the occurring of floods, but also climate change can be linked to an increase of floods in Aruba. 

This research answers the questions what the current hazard areas are and how these can be reduced now and in the future. In this research the model AGWA – Kineros2 is used to simulated current and future situations and solutions to floodings. AGWA – Kineros2 uses input files like elevation map, soil map and land use map and table with soil and land use parameters. The input files of the current situation are determined during fieldwork in the winter of 2016 – 2017 and future situations are based on increase in rainfall amount and increase in urbanisation. The solutions modelled in AGWA – Kineros2 are increasing the interception cover in urban area and decreasing the imperviousness of urban area by using the land use parameters of rural areas. 

The hazard areas are mainly found in the urban downstream areas and the more rural upstream areas. Implementing an increase to 55% in interception cover in the urban area leads to a decrease of 80% of runoff in the urban areas. Changing the land use parameters of all the urban areas to rural settings shows a decrease of 30% in the urban planes. 

Based on the results of this research the Aruban government would need to actively increase the vegetation cover in the urban areas and motivate the Aruban people to do the same to decrease the floods and the corresponding damages.