▲ Causes
1.Due to the 921 Chi-Chi Earthquake in 1999, there was a serious landslide at Shetzukeng, Kuo-Shing town, Nan-Tau. The total damaged area was almost near 195 hectare. The broken rocks blocked the fluid in the branch of Nankong River, Jiotsaihu River and Shetzukeng River. For this reason, there are two barrier lakes at Jiotsaihu River and Shetzukeng River.
2.The inside height of Jiotsaihu River barrier lake is 585 meter. When the water overflow the lake, it flow to Shetzukeng barrier lake, which the inside height is 578 meter. As the reason of wild damaged area, the rocks were more than we can image. So that it is necessary to deal with the problem to forbid the mudflows and landslides.
▲ The general situation of the barrier lake
The landslip of Jio-feng-re-shan is located at the Shetzukeng, Kuoshin, Nan-Tau. The flow of Jiotsaihu River flows together with Shetzukeng River. Now, this place stocked by broken rocks.
The landslide area starts from north of Taipingjao to south of Jiotsaihu River; from east of Kendoushan to west of Chungshing Bridge. The volume of the slide rocks is over 3600 thousand cubic meter.
▲ Handling condition
1.Handling of the overflowing river bed:
Complete 1450 meter of overflowing river bed. Now we decline about 8 meter of the height at 0+650 place. It can reduce efficiently the storage capacity of barrier lake and extend its burst time.
The two other original aqueducts that connect the two barrier lakes will be broadened to draw out efficiently the water from two lakes.
For enforcing the constant edge slope, it is necessary to build a drainage system( but not an underground drainage system). The drainage project includes 1300 Km cutting-water channel, 100 m culvert, and 1000 pieces of drainpipe under the slope.
2.Cutting-water channel set-up:
The accumulation rocks are too near the landslide place. For keeping the stable condition, it's not suitable for excavating. So we set up the cutting-water channel to lead out the water from the barrier lake.
▲ Expecting achievement
‧Expecting the storage capacity of Jiotsaihu River will reduce 296,000 cubic meter
‧Expecting the storage capacity of Shetzukeng River will reduce 354,000 cubic meter
‧The storage capacity of two barrier lakes reduce 650,000 cubic meter. It solves the burst opportunity of the lake.
‧The reconstructive land can strengthen the slope and promote the value of this territory.
‧In length and breadth drainage can reduce the washout of the ground.
‧The excavation can fill the soil in the barrier. There's no problem with the environmental protection.