Relationship between urbanization and river network change in Taihu Lake basin, China

Evaluating the impact of urbanization on changes in river systems is crucial for urban planning and protecting river systems. We selected the Wuchengxiyu and Yangchengdianmao hydrological zones in the lower Taihu Lake basin as regions of study. We compared river system data and land use types from the 1980s and 2010s to identify changes in river system patterns and measure how these changes were related to land urbanization. To measure this relationship, we used global and local autocorrelation analyses and a Geographically Weighted Regression model. The results indicate that drainage density decreased at a rate of 11.3% over the last 30 years in area of study. The 1st-and 2nd-order tributary density decreased at the rate of 18.1% and 11.3%, respectively. The most drastic decreases were observed mainly around large cities. The intensive degradation of the river system, caused by deposition, landfill and annexed by the lakes were the main reasons for the decrease in drainage density. The degradation of tributaries had an exponential relationship with the velocity of land urbanization:the rate of decrease in tributary length accelerated when the land urbanization reached 40%. In addition, the intensity of river system variation and recession increased in regions with greater river density. Thus, more attention should payed to the protection of river systems during rapid urbanization.