Answer:
The increased flooding may occur due to climate change, deforestation, or erosion.
Climate change may have made the climate of the city wetter, leading to higher river flows that naturally cause more flooding.
Deforestation is also a common cause of higher flooding. Trees serve almost as anchors on the land, and keep the land from overflooding.
Land erosion, due to the river itself, or to agriculture, can also made the soil more prone to flooding.