Effects of watershed landscape pattern on runoff and its components in the loess region of western Shanxi Province, northern China

Objective Under the combined effects of climate change and human activities, the surface vegetation coverage of the Loess Plateau has undergone significant changes. In order to provide a theoretical basis for optimizing spatial allocation of watershed vegetation and strengthening water resource management, we explored the impact of different watershed landscape patterns on the hydrological process and the distribution of water cycleelements.

Method This study took the main channel of the Caijiachuan Small Watershed and its four sub-watersheds as the research object, the land use status was interpreted through remote sensing images, and based on the rainstorm runoff data of five small watersheds from 2016 to 2019, using partial least squares regression and Pearson correlation analysis methods to explore the effects of watershed landscape composition and pattern changes on runoff components.

Result (1) Different land-use patterns had different effects on runoff formation. Compared with farmland (dry land), the increase of arbor forest land, shrubland, grassland and orchard reduced watershed runoff. (2) The total watershed runoff was significantly positively correlated with patch density, edge density and Shannon diversity index (P < 0.05), and was significantly negatively correlated with aggregation index, sprawl index and the patch cohesion index (P < 0.05). The reduction of landscape fragmentation or the improvement of connectivity and aggregation had a significant reduction effect on the total runoff of the watershed. (3) There was no significant correlation between the area proportion of different land use patterns, the landscape pattern index of patch and landscape level and the basin base flow index. The impact of landscape pattern on the watershed base flow was small.

Conclusion The change of landscape pattern has a strong regulating effect on the total runoff of the watershed, but the influence on the base flow is weak. The research result can provide useful references for the optimization of watershed landscape pattern and integrated management of water resources.