LarNO is a memory-efficient, discretization-invariant neural operator for large-scale urban flood spatiotemporal forecasting. It learns continuous-space hydrodynamic mappings to predict water depth distributions based on dynamic rainfall and static terrain.
Key capabilities:
Zero-shot super-resolution: trained at 20 m resolution, applied at 5 m with no retraining
~940× faster inference than MIKE+ hydraulic solver (with TensorRT)
Few-shot transfer to unseen catchments via fine-tuning
Large-scale: handles ~100 km² at 5 m / 5 min resolution
Performance
Benchmarked on Futian district, Shenzhen (~100 km²) — 5 m resolution, zero-shot super-resolution (trained at 20 m):
Method
Params
Inference†
Speedup
MAE (m) ↓
CSI ↑
MIKE+ (hydraulic solver)
—
~8.9 h
1×
Reference
Reference
UNO
109.1 M
710 s
~570×
0.024 ± 0.007
0.343 ± 0.026
FNO
29.1 M
760 s
~530×
0.019 ± 0.004
0.620 ± 0.027
LarNO (ours)
29.1 M
34 s ‡
~940×
0.008 ± 0.003
0.722 ± 0.016
† Single 6-hour event on NVIDIA RTX 4090.
‡ LarNO inference uses TensorRT (TRT) acceleration; UNO and FNO do not support TRT.
Note: The released dataset is a 20 m downsampled version for accessibility. Metrics on the released 20 m data will differ from the 5 m paper results above.
1@article{cao2026large,
2 title={Large-scale urban flood modeling and zero-shot high-resolution generalization with LarNO},
3 author={Cao, Xiaoyan and Yao, Yao and Wang, Zhi and Zhao, Zhangxinyue and Borthwick, Alistair GL and Qin, Huapeng},
4 journal={Journal of Hydrology},
5 pages={135686},
6 year={2026},
7 doi={10.1016/j.jhydrol.2026.135686},
8 publisher={Elsevier}
9}