PRELIMINARY STUDY ON ENVIRONMENT GEOLOGICAL HAZARDS DUE TO WATER CONSERVANCY PROJECT OF MINJIANG RIVER

The construction and operation of many water conservancy and hydroelectric projects in the Minjiang River region have brought some significant changes to the hydrodynamic field.Such changes include stream velocity,river discharge,sediment discharge and silt carrying capacity.They have also changed the distribution and intensity of stress field in those coastal belts.Therefore the types,the intensity and the evolution of geological processes have been greatly changed,and many environment geological hazards have also been caused.They hazards are considerably growing in terms of wider distribution and longer duration.This paper makes some preliminary studies on three relations.One relation is between the construction and operation of Minjiang River water conservancy project and the instability hazards of littoral slopes.The second is the earthquakes induced by Shuikou Reservoir.The third is the downstream channel stability behind the dam and its harmfulness.The results show that the instability of the reservoir banks is obvious correlation with the water conservancy project operation and the hazards frequency significantly increases as the operation continued.By enhancing the fluvial erosion behind the dam,the reservoir impounding becomes the important factor which affects the lower river channel and the littoral environment geological hazards.In addition,the impounding and hydration of Shuikou Reservoir are also the important factors inducing an earthquake.Its aftershocks will last for a long period.The point of view that the more intensive and destructive reservoir earthquake may occur in the next few years is put forward.Almost simultaneously the research on the special monitoring and forecasting for geological disasters should be carried out and the regional information monitoring and forecasting system about geological disasters of the water conservancy project should also be established.