Mapping and assessment of flood regulation supply and demand in Vilnius (Lithuania)

Heavy rain events are expected to be more frequent and intense due to climate change, which will likely increase the vulnerability of the urban area to flood episodes. In this context, it is crucial to identify the areas with a high capacity to retain water and the areas where flood protection is more needed. To address this problem, this work aims to map and assess the flood regulation supply and demand ecosystem services in Vilnius, Lithuania. The results showed that Vilnius has a large area with a flood regulation supply, especially in the northeast and southern areas. The areas with high flood regulation demand were located in the old town and several urbanizations scattered inside the city limits. We used the soil-vegetation adjusted index (SAVI) to validate the flood regulation supply index using linear regression. In contrast, the flood regulation demand index was validated by comparing the historical flood points with the model results. SAVI predicted acceptably (r2 = 0.43), and the flooded points identified were located in the areas with high flood regulation demand index. Both models were mismatched (-0.50. P < 0.001), showing that they have different spatial patterns. These results obtained in this work can help planners and decision-makers better plan the areas with a high capacity to retain water and identify the areas where the demand is high.