title: Chance-constrained overland flow modeling for improving conceptual distributed hydrologic simulations based on scaling representation of sub-daily rainfall variability.
abstract: Lack of hydrologic process representation at the short time-scale would lead to inadequate simulations in distributed hydrological modeling. Especially for complex mountainous watersheds, surface runoff simulations are significantly affected by the overland flow generation, which is closely related to the rainfall characteristics at a sub-time step. In this paper, the sub-daily variability of rainfall intensity was considered using a probability distribution, and a chance-constrained overland flow modeling approach was proposed to capture the generation of overland flow within conceptual distributed hydrologic simulations. The integrated modeling procedures were further demonstrated through a watershed of China Three Gorges Reservoir area, leading to an improved SLURP-TGR hydrologic model based on SLURP. Combined with rainfall thresholds determined to distinguish various magnitudes of daily rainfall totals, three levels of significance were simultaneously employed to examine the hydrologic-response simulation. Results showed that SLURP-TGR could enhance the model performance, and the deviation of runoff simulations was effectively controlled. However, rainfall thresholds were so crucial for reflecting the scaling effect of rainfall intensity that optimal levels of significance and rainfall threshold were 0.05 and 10 mm, respectively. As for the Xiangxi River watershed, the main runoff contribution came from interflow of the fast store. Although slight differences of overland flow simulations between SLURP and SLURP-TGR were derived, SLURP-TGR was found to help improve the simulation of peak flows, and would improve the overall modeling efficiency through adjusting runoff component simulations. Consequently, the developed modeling approach favors efficient representation of hydrological processes and would be expected to have a potential for wide applications.
authors.affiliation: State Key Laboratory of Hydroscience & Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Jing-Cheng
authors.initials: JC
authors.lastname: Han
authors.affiliation: Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2, Canada. Electronic address: huang@iseis.org.
authors.forename: Guohe
authors.initials: G
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Hydroscience & Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Yuefei
authors.initials: Y
authors.lastname: Huang
authors.affiliation: College of Science and Engineering, Texas A&M University - Corpus Christi, Corpus Christi, TX 78412-5797, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Li
authors.affiliation: Center for Eco-Environmental Research, Nanjing Hydraulics Research Institute, Nanjing 210029, China.
authors.forename: Qiuwen
authors.initials: Q
authors.lastname: Chen
keywords: Modeling efficiency; Rainfall intensity; Scale; Surface runoff; Three Gorges Reservoir; Uncertainty