Wenchuan Earthquake has seriously caused many huge landslides in the rivers in Si Chuan Province.As a result

huge water volume was blocked in the rivers and numerous dammed lakes appeared in the following days

which may result in inundation on the lake area and flooding disaster in the lower reaches.Therefore

it is urgent to reconnoitre the exsited dammed lakes and its spatial distribution

to monitor the stability of these dams and to evaluate the potential inundation area when the dam-break events occur.Incorporating the basic information of dammed lakes provided by other ministries

high resolution remote sensing imageries（including Spaceborne

Airborne and Unmanned Aerial Vehicle） from May

12 to June

12 2008

were used to confine the spatial distribution and to reconnoitre these dammed lakes.Based on the ’Atlas of Sichuan Province in 2001’

combining with ’Sichuan Electronic Map in 2008’ and ’1∶50000 topographic map’as well

most of the dammed lakes were named from the nearest village at the same riverside

while other dammed lakes located deeply in the mountains with scarce villages were named from a nearer village

with serial numbers.Up to June 12

2008

we have identified total 52 dammed lakes in the heavily-affected area of’Wenchuan Earthquake’.The spatial distribution with high precision longitude and latitude of the dammed lakes

indicates a significant linear feature

which is consistent with earthquake faults.The risk evaluation of the dammed lakes in the heavily-affected area of ’Wenchuan Earthquake’

was carried out mainly by using the monitoring results of high resolution remote sensing datasets and the authoritatively published results.According to the scale

the composition of the dams

the size and water storage capacity of these lakes

the distribution of the downstream cities and towns

population status and economic development levels

the possible affected area and the potential impact

the risk of the dammed lakes were divided into three levels: Extremely Dangerous

High Dangerous and Dangerous.Of the 52 dammed lakes

Tangjiashan is the only one in the Extremely Dangerous level

while the XiaoJiaqiao

Laoyingyan

Shiban’gou

Tangjiaba（Nanba）

Changtan（Xiaogangjian） are 5 dammed lakes in the High Dangerous level

and the rest 46 dammed lakes are in Dangerous level. Principles for determining the potential flooded area when dam-break occurs were developed: 1.the safety

is taken as the most important objective;2.the inundation area should be determined in accordance with sufficient and reliable monitoring results and basic datasets;3.the region should not be over-extended.Further

we also developed the methods for confining the potential inundation area

by which the total acerage of the potential inundation area determined amount to 963.27 square kilometers

involving the 134 townships of 18 counties（districts）.At last

preliminary suggestions were proposed to avoid risks of the secondary disasters of dammed lakes in the reconstruction planning for heavily-affected area in ’Wenchuan Earthquake’.