The influence of landscape pattern on the risk of urban water-logging and flood disaster

Most Chinese cities face a series of 'urban diseases' or problems during rapid urbanization, and of which urban precipitation and subsequent water-logging is a severe hotspot. A better understanding of the influence of urban land-use patterns on water-logging will be helpful for enhancing urban flood resistance. The relationship between the characteristics of land-use patterns and the risk of urban water-logging and flood disaster (UWLFD) was analyzed in this paper, using landscape pattern indicators to describe the land-use structure. These included patch density (PD), edge density (ED), landscape division index (DIVISION), contagion (CONTAG), Shannon's evenness index (SHEI), and Shannon's diversity index (SHDI). The risk of UWLFD was measured using the topographic slope and urban surface cover. Based on GIS and remote sensing data in 2003 and 2013, a case study of the metropolitan region of Kunming City showed that the risk of UWLFD had a positive correlation with landscape fragmentation (e.g., PD and ED), and strong negative correlation with landscape contagion (e.g., CONTAG) during the study period. This implied that landscape fragmentation aggravated the risk of UWLFD while landscape connectivity reduced the risk. Measures such as unified and long-term urban planning and design and the construction of green infrastructure will reduce the risk of UWLFD. The relationship between the landscape pattern and the risk of UWLFD provides a new perspective for systematic urban planning.