July 11, 2018

Mozigou Glacier Meltwater Pays High Hydropower Dividend

Posted by Mauri Pelto

Mozigou Glacier is a valley glacier in the Gongga Mountains, Sichuan Province, China that drains into the Dadu River.  In the first 250 km after leaving the glacier this meltwater travels through seven hydropower projects that have a collective capacity of  over 9000 MW. Pan et al (2012) noted that the glaciers of the Gongga Shan have lost 11% of their area since 1966.  They further reported a 300 m retreat of Mozigou Glacier from 1994-2009. The glacier unlike its neighbor Hailuoguo Glacier does not have a debris covered terminus.  Liu et al (2010) report that the main change in the region affecting the glaciers is rising temperature.  The Gongga Shan glaciers are summer accumulation type with the majority of the accumulating snow occurring at the same time that ablation is at a peak lower on the glacier. They also report a steep precipitation gradient, which is key to glacier formation here. Here we examine Landsat imagery from 1994-2017 to indicate retreat of the glacier and Google Earth images of the hydropower projects to underscore the economic output of the runoff.

In 1994 the Mozigou Glacier had a thin terminus tongue extending downslope from the wide terminus area, red arrow.  The snowline is not far above the terminus. In 1995 the thin terminus tongue extending downvalley to the red arrow is still evident.  The snowline remains not far above the terminus.  By 2016 the thin 900 m long terminus tongue has melted away.  In 2017 the two lowest tributaries have been reduced in width. The  terminus is now on a lower sloped region and has extensive crevassing right to the terminus, see Google Earth image below. Both the reduced slope at the terminus and the rapid flow as indicated by the terminus suggest a glacier fed by high accumulation and one where retreat should diminish.

After a drop of water leaves the glacier it flows tinto the Dadu River where it pays dividends at the following: 35 km downstream is the Dagangshan Hydropower Station 2600 MW, 50 km downstream is the Longtoushi Hydorpower station is 700 MW, 115 km downstream is Pubugou Hydropower Station 3300 MW, 190 km downstream is  the Gongzui Hydropower Station 600 MW, 215 km downstream is the Tongjiezi Hydropower Station 700 MW,  225 km downstream is the  Shawan Hydropower station 480 MW and,  250 km downstream is the Angu Hydropower station 770 MW.