Land Use Zoning in Three-Gorge Reservoir Region:A Case Study of Fengdu County in Chongqing Municipality

Taking Fengdu County in Three-Gorge Reservoir region as an example,this paper applies the dynamic clustering analysis model, and divides land resource utilization of Fengdu County into three zones: Yangtze River valley economic zone,low mountains and hills agricultural zone,and low and middle agricultural,forestry and animal husbandry zone. It also analyzes current situation and existing problems in the land utilization of every zone,and finally puts forward corresponding recommendations.

Current Situation of Land Use in Three-gorges Reservoir Region in 2010

Land is rare natural resource.Production and construction of all sectors in a region must be based on land.Thus,overall research and analysis on current situation of land use can reveal scope,depth and reasonableness of land use,is helpful for analyzing internal mechanism land use change,and can reflect production scale,level and characteristics,and also can provide basis for optimization and adjustment of land use structure.Based on RS and GIS technologies,with the aid of TM image data of the Three-gorges Reservoir Region in 2010,the data of current situation of land use in Three-gorges Reservoir Region was obtained,and current land use situation was analyzed using geographimetrics and landscape ecology methods.Results show that since natural,social and economic conditions are different,land type diversity,combination type and location index of counties in the Three-gorges Reservoir Region are varied.In the land use diversity index,Xingshan County has the most single land use type(mainly forest land); in land use degree,Yuzhong District has the highest land use degree; in the integrated index of land use,Changshou District has the lowest integrated index of land use.This study is expected to provide reference and basis for formulating policies of protecting ecological environment of the Three-gorges Reservoir Region.

Three-Gorges Reservoir Area on the Yangtze River Faced with Risk of Induced Destructive Earthquakes

The Three-Gorge Water Conservancy Project on the Yangtze River started to impound water by locking gates on June 1, 2003. A swarm of more than 2000 small earthquakes suddenly occurred densely along the river section in Xinling Town north of Badong, Hubei Province, on June 7. This caused grave concern in the following years, but, with the completion of the second- and third-phase engineering construction, the water level in the reservoir will rise up to 156 m and 175 m respectively, no matter whether it can induce larger and stronger earthquakes. After an analysis of the distribution of active faults in the eastern part of the reservoir area, their intersections and capability to generate earthquakes from a seismo-tectonic viewpoint, we consider that after the reservoir impounding, two potential focal zones existing in Badong and Zigui counties may generate M 5.5 earthquake, the seismic intensity of which may reach Ⅷ. It will induce landslide bodies in the reservoir area to be reactivated and slide. The evidence is the large-scale landslide occurring on the Shazhenxi Creek river in Zigui County on June 12, 2003.

Theoretical and experimental study on seismic response control on top of Three-Gorges ship lift towers using magnetorheological intelligent isolation system and its key technique

A vertical ship lift under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the ship lift towers.This paper proposes a roof magnetorheological(MR)intelligent isolation system to prevent the seismic whipping effect on machinery structures.Theoretically,the dynamic models of MR damper and the mechanical model of ship lift was established,the inverse neural network controlling algorithm was proposed and the fundamental semi-active control equation for the Three-Gorges ship lift where the MR intelligent isolation system was installed was deduced.Experimentally,the experimental model of the ship lift was given,the vibrating table experiment of the MR intelligent isolation system controlling the whipping effect was carried out and the results of the inverse neural network control strategy and passive isolation strategy were compared.In practical aspect,the large-scale MR damper(500 kN)and a sliding support with limited stiffness were designed and fabricated.It was proven that the MR intelligent isolation system with proper control strategy can greatly reduce the seismic whipping effect on the top workshop of the ship lift and be simple and effective enough to be applied to real engineering structures.

DEVELOPING TREND ANALYSIS AND FORECAST OF DEBRIS FLOW ACTIVITIES IN THE THREE-GORGE RESERVOIR AREA

The water level of the Three-Gorge Reservoir will reach the height of 135m, and the government pays great attention to security of cities/towns and emigration villages that may be affected by debris flow activities. How will the debris flow activities develop when the water level of the Reservoir reaches 175 m in height in 2009? This paper analyzes the change of environment for debris flow before and after storing water comprehensively, and special attention is given to the effects of the Reservoir bank rebuilding-process on debris flow activities, and the probability of appearance of new manmade debris flow due to irrational human activities during the construction of the Reservoir. 11 items of predicted results on the developing trend of debris flow activities in the Reservoir area and a suggestion are presented for relevant branches as references in the discussion and implementation of prevention and control of geological disasters in the Reservoir area.

Fission Track Method to Date Fault Activity—As Exemplified by the Three Gorges Dam Area of the Yangtze River Valley, China

The Xiannushan and Jiuwanxi are the two major fracture belts adjacent to the Three Gorges Dam Site. Apatites are selected from fracture clay and fracture\|cliff rock in the fracture belts and examined with the fission track dating method. Our study shows that the Xiannushan and Jiuwanxi fracture belts were tectonically active at 0.60±0.04Ma and 0.29±0.04Ma ago, respectively. Their ages are close to those obtained by the U\|series method.