In recent years the incidence of floods has increased in North India because:

Forests and dense vegetation cover in a river's catchment and embankment areas act as a natural sponge: tree roots bind the soil, plant canopies intercept rainfall, and leaf litter promotes infiltration, so a large share of rainwater soaks into the ground instead of running off immediately. When this vegetation cover is removed, the soil loses its binding and absorptive capacity, surface runoff speeds up, and a much larger volume of rainwater reaches the river channel in a short time.

In North India, large-scale clearing of forests along river embankments and in the upper catchments over recent decades has reduced this natural absorption. With less vegetation to hold back and soak up rainwater, more runoff drains rapidly into the rivers, river levels rise faster and higher during the rainy season, and the frequency of flooding in the plains has correspondingly increased.

Contrasting the other listed factors against this mechanism:

• the rate of silting in dam areas — sediment build-up inside a reservoir reduces that dam's water-storage capacity over time, but this is a slow, localized effect on individual reservoirs, not a general driver of rising flood frequency across the North Indian plains.

• expansion of agricultural land — cropland use can reduce natural vegetation in places, but tilled, seasonally vegetated fields retain far more soil structure than a completely cleared surface, so their effect on runoff is much smaller than large-scale deforestation.

• an increase in annual rainfall — recorded rainfall totals for North India over recent decades do not show a sustained rise; year-to-year variability is more pronounced than any steady upward trend, so this does not account for the increase in flood incidence.

This is why the destruction of forests in the embankment areas, rather than the other listed factors, is identified as the reason for the rising incidence of floods.