Responses of flood peaks to land use and landscape patterns under extreme rainstorms in small catchments - A case study of the rainstorm of Typhoon Lekima in Shandong, China

Abstract

Investigations of the formation mechanisms of flood peaks in small catchments facilitate flood prediction and disaster prevention under extreme rainstorms. However, there have been few studies on the responses of flood peaks to land use landscape patterns using field surveys during extreme rainstorm events. Based on field data from 17 small catchments near the rainstorm center of Typhoon Lekima, 7 landscape indices were chosen. The flood peak and its sensitivity to the land use landscape were investigated by combining remote sensing interpretation and related analysis. The conclusions are as follows: (1) The peak discharge of the small catchment was 2.36–56.50 m3/s, the peak modulus was 8.00–48.89 m3/(s·km2), and the flood index K ranged from 3.61 to 4.55. (2) Under similar rainfall conditions, the flood peak modulus, K and the proportion of sloping cropland had significantly positive correlations (p < 0.05). The flood peak modulus was significantly negatively correlated with the proportion of forest-grassland and terrace (p < 0.05), and K and the proportion of forest-grassland and terraced land exhibited a negative correlation. (3) The flood peak modulus and K were positively correlated with the landscape fragmentation. (4) The sensitivities of small catchments to floods were evaluated to be moderate compared to K values from other studies. The ability of small catchments to cope with extreme rainstorms can be improved by increasing the areas of forest-grassland, and terraces and reducing landscape fragmentation. Our results could be applied to provide a basis for land use planning and support for the response against disasters caused by extreme floods.