Research on the distributed Clark confluence model based on basic watershed units

Abstract

Based on the confluence principle, the confluence should represent the aggregate of net rainfall confluences within each distinct basic watershed unit (BWU) of a basin. The BWUs are categorized as V-type and Horseshoe-type based on their shape characteristics and two types of time–area curves of slope convergence have been derived separately. The cascade river convergence is modeled using a lagged linear reservoir, resulting in the development of a distributed CLARK convergence model based on the BWUs of a basin (BWU-DCLARK). The key findings are as follows: (1) The BWU-DCLARK model effectively captures the runoff convergence process and has been successfully applied in the Yanduhe River basin. Modeling results demonstrate high simulation accuracy. (2) The time of slope convergence indicates that the regulatory and storage effects on runoff of BWUs cannot be overlooked. (3) The BWU-DCLARK confluence model not only enables the calculation of flow at the basin outlet but also facilitates the computation of flow at any node along the river chain which is of great significance for hydrological forecasting in un-gauged basins but the application effect will need further verification. HIGHLIGHTS A distributed confluence model is built.; The BWU-DCLARK model can clearly reflect the process of runoff converging.; The results show that the regulation and storage effect of basic watershed units cannot be ignored.; The confluence model can not only calculate the flow at the outlet of the basin, but also calculate the flow at any river chain node.; The research showed a new method for runoff calculating.;

Keywords

• basic watershed units
• clark model
• distributed confluence model
• unit hydrograph