China flood havoc highlights poor urban planning

Abstract

Recent relentless flooding and mudslides in China have wiped away large blocks of homesand claimed thousands of lives. For example, a massive mudslide in August in Zhouqucounty, Gansu Province, has claimed nearly 2000 lives (Xinhuanet, http://news.xinhuanet.com/english2010/china/2010-10/14/c_13557206.htm). Deteriorated soil erosion and cli-mate change–derived torrential rains are usually blamed for such disasters (Qian and Zhu2001; Liu and Diamond 2005). However, one more crucial factor is the lack of consid-eration of physical environment during urban expansion. It is apparent that the wisdom of‘‘Design with Nature’’ which seeks the long-term balance between human and nature hasnot been seriously respected (McHarg 1971).Currently, a massive urbanization movement is being implemented across China, and alarge number of rural people are migrating to cities at an unprecedented pace (Qiu 2010;Liu et al. 2010). However, the urban planners emphasized only social and economicbenefits and treated nature as if it does not exist. This is more prominent in western Chinawhere cloud-kissing mountainous areas are not suitable for living, and urbanization iscarried out on narrow floodplains located on the foot of lofty mountains or the alluvial fansof ephemeral rivers. As a result, rapid urban expansion has occupied almost all thefloodplains and alluvial fans, and the water pathways are strictly confined to an extraor-dinarily narrow channel (Fig. 1), which severely undermines the natural regime of fluvialsystems. Water flow can easily exceed transport capacity of the narrowly containedchannels, and the people living on the floodplains and alluvial fans are extremely vul-nerable to floods and mudflows.Increasing frequencies of abnormal rainfalls due to climate change (IPCC 2007), coupledwith environmental degradation caused by anthropogenic activities, are likely to triggermore floods and mudslides in future in the mountain areas, which represent 70% of the entirecountry. Although Environmental Impact Assessment (EIA) has been mandatory for largeinfrastructure projects, natural hazard assessments are largely ignored. Therefore, naturalhazard assessments of mountain cities are desperately needed, and more importantly, serious