The calamity of mud-rock flow is very seveve in the upper reaches of the Changjiang River，and has broad destroy to traffic，channel，communication，irrigation works，ploughed field and dwelling etc，and have brought about are economical loKses very great．

    The main factor to occur calamity of nmd-rock flow is complex geological structure，frequent movement of modern earthquake，broken rock and unsteady moutain．The landform of high mountain and gorge influence an atmospheric circulation，precipitation distribution is not even，concerttraIire precipitation often b11ing about mud-rock flow，the region of the Jinsa River has malty calamity of the nqud-rock flow，unreasonable developing natural resources quicken the calamtical environnlent in the mud-rock flow have been forming．It is improtant measure to strengthen pretection and build ecological environment in the prevent calamity of the mud-rock flow．