Objective● Explore the nature of the subsurface flow

generation process and its controlling factors

● Develop an empirical relationship that could be used in subsurface flow estimation without calibration

Approach● Calculated the coefficients related to

subsurface flow generation process from flow data; extracted the climate, soil and topographic characteristics from several online databases for 50 selected catchments in the U.S.

● Using a variable selection scheme to identify the most important controlling factors that determine the observed flow decay behaviors and validating the empirical relationship using data

Regionalization of Subsurface Stormflow Parameters of Hydrologic Models: Derivation from Regional Analysis of Streamflow Recession Curves

Ye S, H-Y Li, M Huang, M Ali, G Leng, LR Leung, S Wang, M Sivapalan. 2014. “Regionalization of Subsurface Stormflow Parameters of Hydrologic Models: Derivation from Regional Analysis of Streamflow Recession Curves.” Journal of Hydrology, early online. DOI: 10.1016/j.jhydrol.2014.07.017

Impact● Found that one of the coefficients in the empirical

relationship is closely related to the catchment hydrologic properties, while the other one is more strongly affected by climate (aridity) at the catchment scale.

● The climate dependence may be attributed to the adaption of landscape properties (e.g., soil, vegetation and topography) to climate at the catchment scale

Comparison of observed and fitted streamflow time series in a well-measured catchment in the U.S.