3.2 Relative contributions of driving forces to urban flooding
Based on the two fitted BRT models (one for considering the driving
forces without buildings, and another for considering all driving
forces), the relative contributions of the explanatory factors to the
urban flooding across the study area are presented in Fig. 4. The
results indicate that landscape shape index, slope, green space ratio,
and waterbody ratio play dominant roles in influencing the density of
flooding hotspots, with total relative contributions reach at 82.36% in
model without considering the buildings. Specifically, the
relative contributions of
landscape shape index, slope, green space ratio, and waterbody ratio are
38.19%, 25.5%, 11.13%, and 7.54%, respectively. The results are
robust in model with considering all driving forces. However, we found
that building metrics play a certain role, with total contributions is
21.03%. Among these building metrics, the relative contributions of the
building congestion degree, building density, 3D shape index, and
building coverage ratio exceed 3.76%.
For the category levels, land
cover configuration has the largest relative contribution (33.69%),
whereas the drainage capacity has the least importance (3.87%). The
importance of the topography, land cover composition, and 3D building
morphology are nearly equal.