LAUSR

This research aimed to study the applicability and limitations of a distributed hydrological model under discontinuous steep topography and hydrogeological conditions. Based on GIS spatial analysis, typical cases of steep and gentle terrains were selected to construct the distributed hydrological model framework of the research areas (Qinhuangdao and Zhuanghe City, China). The observed runoff was used to test the applicability of the model in different terrain watersheds and to analyze the versatility of the model structure and the relevant parameters of the core modules. The results show that: in the process of using a distributed hydrological model to build models for different regions, problems such as a discontinuous dislocation of the empty area and poor connectivity of the water system will appear in the process of sub-basin division of a steep terrain. By determining the optimal threshold, selecting the best node, discontinuous dislocation, void fusion and other methods, we put forward the corresponding solutions to the problems in the division process and constructed the research area’s distributed hydrological model. The rainfall–runoff process in the study area was simulated accordingly, and the SUFI2 algorithm was used to calibrate the relevant parameters in the model. The relative error (Re), correlation coefficient (R2) and Nash–Sutcliffe efficiency (NSE), which meet the runoff accuracy in the study area, were obtained. The model verification results show that the NSE of steep terrain is 0.90, and R2 is 0.98; the NSE of gentle terrain is 0.91, and R2 is 0.984: the simulation values fit the measured values well, which makes the calibrated model suitable for both steep and gentle terrains. The results can provide a reference for the construction of a distributed hydrological model in watersheds with different terrain.