Risk Level Methodology & Notes
LOW
Low mean potential soil loss (11–24 PSL), low annual rainfall (1.6–8.3 mm), and low population (814,497–2,533,388 people).
MEDIUM
One factor at medium level in soil loss 24–35 PSL, rainfall 8.3–25.7 mm, and population 2,533,388–3,895,285 people.
MED-HIGH
At least one factor in high level, either in soil loss 24–35 PSL or rainfall 8.3–25.7 mm: NOT in population 2,533,388–3,895,285 people.
HIGH
At least two factors at high level, either High mean potential soil loss (35–75 PSL), high rainfall (25.7–69.6 mm), or high population (3,895,285–7,676,681 people).
Data was taken from HydroSense Lab, IIT Delhi for soil erosion data — soil erosion lessens soil permeability and increases surface runoff of rivers and creeks, raising flood risk. Annual rainfall amounts were taken from FISC WRD (Flood Management Improvement Support Centre from the Water Resources Department from the Government of Bihar).
District population statistics (2011) are from citypopulation.de.Data used reflects annual or mean amounts, but the Southwest Monsoon is the most significant and deadly monsoon season, which is why this map focuses on high risk for that particular season.
"The 2025 Southwest Monsoon drenched nearly half of India in record-breaking rainfall, leaving behind floods, landslides, and over 1,500 lives lost. The season ended with 108% of the long-period average (LPA) rainfall, marking the second consecutive year of above-normal monsoons."
— Global Climate Risks, "India's Changing Monsoon"