High-resolution mapping of China's flooded croplands

Area of Science:

• Environmental Science
• Remote Sensing
• Agricultural Science

Background:

• Climate change and increased flood frequency threaten China's food security.
• Accurate mapping of flooded croplands is vital for effective flood management and adaptation strategies.
• Previous flood mapping faced limitations due to data scarcity and optical satellite image cloud cover.

Purpose of the Study:

• To generate high-resolution flooded cropland maps for China from 2017 to 2021.
• To assess the extent of flooded croplands, including specific impacts on rice and maize crops.
• To provide data supporting flood prevention, adaptation, and rural poverty alleviation efforts.

Main Methods:

• Utilized 4968 near-real-time Sentinel-1 Synthetic Aperture Radar (SAR) images with 10m spatial resolution.
• Developed high-resolution maps to identify flooded areas across China's croplands.
• Quantified inundated areas for total croplands, rice, and maize crops.

Main Results:

• Croplands constituted 43.8%–49.8% of total flooded areas (82,175–122,037 km²).
• Inundated rice areas ranged from 8,428–22,123 km², and maize from 2,619–5,397 km².
• Extensive flooding was observed in rural areas, underscoring the need for targeted flood mitigation.

Conclusions:

• High-resolution flood mapping using Sentinel-1 SAR data is feasible and accurate for croplands.
• Findings highlight the vulnerability of agricultural lands to floods and their impact on food security.
• The generated maps can inform infrastructure investment and policy for flood control and rural development.