Ecohydrologic Processes Modify Urban Rainfall Intensification in Land-Atmosphere Simulations

Ecohydrologic processes change urban water and energy cycles, influencing convective rainfall. Coupled land-atmosphere models, however, lack the ability to represent urban ecohydrology. This study integrates fine-scale urban ecohydrologic processes into land-atmosphere simulations to assess changes in convective rainfall during ten events in Milwaukee, Wisconsin. We compare simulations that resolve processes like tree canopy overhanging pavement and runoff routing from impervious to pervious surfaces to existing urban land surface representations. We find that detailed representation of urban ecohydrology produces cooler and wetter atmospheric conditions ahead of rainfall due to higher evapotranspiration. Further, more rainfall is infiltrated during storms. Simulated rainfall aligns more closely with observed rainfall when ecohydrologic processes are considered, especially in an area of known urban rainfall intensification. Our findings highlight the importance of proper model representation of urban ecohydrology to better understand rainfall mechanisms and to improve the flexibility of models for exploring city-scale climate adaptation strategies.