CN-China: Revised runoff curve number by using rainfall-runoff events data in China

Area of Science:

• Hydrology
• Environmental Science
• Water Resource Management

Background:

• The United States Department of Agriculture (USDA) Curve Number (CN) method, established in 1954, is a globally recognized approach for estimating surface runoff.
• Its direct application in diverse international contexts, particularly those with complex natural environments like China, presents significant challenges and necessitates localized adjustments.
• Previous modifications to CN values in China have been fragmented, lacking a comprehensive and representative framework.

Purpose of the Study:

• To address the limitations of the standard USDA CN method in China by developing regionally adjusted CN values.
• To enhance the accuracy of surface runoff estimation across various natural conditions within China.
• To provide a more reliable reference for hydrological modeling and water resource management in the region.

Main Methods:

• Collection and analysis of a substantial dataset of rainfall-runoff monitoring data from 55 study sites across China.
• Adjustment of Curve Number (CN) values based on the collected empirical data to reflect local hydrological conditions.
• Validation of the revised CN values against observed runoff data.

Main Results:

• The study revealed significant discrepancies between the revised CN values (CN-China) and the original USDA CN look-up table.
• Direct application of USDA CN values in China was found to lead to substantial errors in surface runoff estimation.
• The developed CN-China values demonstrated improved accuracy for runoff prediction in Chinese environments.

Conclusions:

• The revised CN-China values offer a more accurate and reliable method for surface runoff estimation in China compared to the standard USDA CN method.
• This research provides essential updated guidelines for scientists and engineers working on water resource management and hydrological studies in China.
• The methodology and findings can serve as a valuable reference for similar adjustments in other countries with unique environmental characteristics, promoting better global hydrological modeling.