China has 177 scenery spots of the national class, and 478 of the provincial, among which 30 sites have been on the World Heritage List. Besides, there are many national forest parks and national geology parks. Diversities in biology, environment, landscape, and evolution are becoming resources of academic studies apart from their entertainment and healthy benefit to tourists.

Almost all parks are made of mountains, waters, and forests or grassed, often accompanied by hazardous processes due to complexity of geology and climate. For instrance, Jiuzhaigou, the famous World Heritage Property, has been long suffering from such menaces, in particular, disaster of debris flow. Debris flow dominated in 33 tributaries, which cut off roads, brought sediment into lakes, and destroyed landscapes. And debris flow caused much more calarnity as well in other national parks like Hailuogou, Huanglong, Huashan, and Lushan. Reports of disasters in parks are recently increasing in number.

The book presented forcuses on studies and controls of bebris flow in Jiuzhaigou, on basis of field surveys, tremedous firsthand data, and series of maps of background. In summarization, the following topics are involved:

(1) From simulation experiment of bebris flow we introduce the concept of quasi-bebris -flow to describe the state of inition, and conditions and mechanism are therefore put forward.

(2) Based on the mechanism formulation, a forecast method and control method have been established, which make it possible to prevent large-scale disaster by using small-sized engineering contructions.

(3) Principles are established for debris flow prevention in national parks, conceming conservation of landscape resources, ecoenvironment, and scenic beauty, harmony between constructions and landscapes,  as well as safety of tourist.

(4) Feasiblr meansure are put into practices, such as making use of landforms in shielding constructions, giving attention to recovery of plant covers. (5) Various pattems and structures of dams are used to block floating wood and sieve fine grains in sediment.

(6) Plant are proposed for managements both of techniques and administrations. These form the system of bebris flow control in national parks, which has led to a successive practice in preventing debris flow in 14 tributares in Jiuzhaigou and is as well to be extrended to other national parks in China.