“Lake water seepage exists in Nam Co, south-central Tibetan Plateau,” according to ITP scientist Dr. ZHOU Shiqiao, “and it contributes to an average outflow of 120-190 m3s-1or 5-8 mm lake water depth per day.”
This conclusion is drawn from a five-year hydrological observation in the basin of Nam Co, where precipitation, runoff, evaporation and lake level were observed in detail from 2007-2011. Based on first such detailed long-term water balance observation over the large Tibetan lake as Namco, Dr. Zhou and his colleagues focused on two catchment runoff coefficients at differing catchment scales and two glacial runoff depths. By distinguishing the contributions from glaciated and non-glaciated areas at two additional catchment scales, the surface water inflow to the lake was quantified, revealing the largest portion of the input as contributed by the runoff from the non-glaciated areas, followed by the precipitation contribution and the meltwater inflow from the glaciers. The water input in Nam Co was found to surpass the output of the lake during a 5-month period in 2008, as well as in 2007 and 2009-2011. As there is no surface outflow from the lake, surface water seepage is thus evidenced in the Nam Co region.
This scientific discovery was reported in a paper recently accepted for publication in Journal of Hydrology. The paper can be accessed at http://www.sciencedirect.com/science/article/pii/S0022169413002394. Dr. Zhou also proposed in the paper that the main pathway for lake water seepage is likely through the sub-surface fault system.