An SCS-CN-based time distributed runoff model - Texas A&M University (TAMU) Scholar

The SCS-CN method is extended to develop a four-parameter surface runoff hydrograph model that converts the computed runoff volume into a hydrograph. The model is tested using 9 rainfall-runoff events of a micro urban watershed (area = 300 m2) in Cincinnati (USA), 16 events of a mine-affected Himalayan Jhandoo Nala watershed (area = 17.7 ha) (India), and 7 events of 3F sub-zone watershed (area = 823.62 km2) of Godavary (India). The model performance in hydrograph simulation is evaluated using error criteria of standard error, coefficient of determination, and relative error. Peak discharges and their time of occurrence are simulated well and mass is conserved satisfactorily. An expression for time lag that relates to the SCS-CN parameter potential maximum retention, S, is derived analytically, and it is tested on Cincinnati data. In calibration and validation, the model is found to perform well on Cincinnati data and reasonably well on the data of other watersheds. For Cincinnati watershed, the model parameters infiltration decay coefficient k, storage coefficient K, and final infiltration rate fc exhibit a strong link with the peak rainfall intensity. A sensitivity analysis shows that k and fc insignificantly affect the runoff hydrograph of Cincinnati urban watershed, whereas the hydrograph of mine-affected, porous Jhandoo Nala watershed is greatly affected by all parameters.

An SCS-CN-based time distributed runoff model Academic Article