7 June 2008

Updated: Tangjiashan – flow rate information

Posted by Dave Petley

Xinhua is now reporting that the discharge in the sluice has now reached 40 cubic metres per second. This means that it is less than half that required to balance inflow at the current rate (c. 100 cubic metres per second). So far at least the channel is apparently stable. The same report indicates that the lake volume is now 229.5 million cubic metres.

This is good news. The lake should continue to fill slowly until the water depth is greater enough to drive enough water through the channel to balance the inflow. The potential for erosion will increase, but so far so good. No heavy rainfall is expected for at least a week, which provides time enlarge the channel further to deal with the summer floods.

Updated: an anonymous poster (thanks!) has drawn my attention to this AP image, which is captioned: Water from the Tangjiashan “quake lake” flows down a landside site in the quake-devastated Mianyang City, southwest China’s Sichuan Province.

I suspect that this was taken soon after flow started as this is clearly not 40 cubic metres per second. I guess that the channel on the right us the one that is referred to in the Xinhua posts as having ongoing works to widen it. Note that the main flow, before it starts to split, does appear to be eroding the channel bed at least to a certain degree.