This study analyzed satellite images and long term climate variables from a high-elevation meteorological station (4730 m) and streamflow records to examine hydrological response of Nam Co Lake (4718 m), the largest lake on the Tibetan Plateau, over the last 50 years. The results show the lake area extended by 51.8 km² (2.7% of the total area) when compared with the area in 1976. This change is associated with an annual precipitation increase of 65 mm (18.6%), annual and winter mean temperature increases of 0.9 °C and 2.1 °C respectively, an annual runoff increase of 20% and an annual pan evaporation decrease of about 2%, during the past 20 years. The year of the change point in annual precipitation, air temperature, annual pan evaporation and runoff occurred in 1971, 1983, 1997 and 1997, respectively. The timing of the lake growth corresponds with the abrupt increase in annual precipitation and runoff since the mid-1990s.

The discharge of one of the world’s largest river - Indus River was reported to be increasing that was not supported by the Karakoram (KK) glacier expansion. A major hydrometric bias was ignored, which seemed similar to the montage that the Himalayan glaciers would disappear. This study proposed a framework for quantifying the bias resulting from inaccurate data affecting hydrologic studies on the Indus. We constructed a statistical model by converting the rating curves of rivers into air temperature (T) – discharge (Q) curves from an adjacent catchment in China where flow measurement was carried out using a standard method. We found that most flow data for the Indus were much greater than the error limits of T-Q curves estimated by daily data, a greater bias occurred in recent decades when discharge increased, the higher the flow was, the larger the bias was. The estimated mean annual and maximum monthly bias was 22.5% and 210%, respectively. These biases indicated that discharge increase in the Indus probably resulted from the large errors of hydrometrics without a scientific basis. We suggested a montage bias was needed in the hydrologic science of KK’s rivers that may strongly affect water resource management.

Flood records of the Kunmalik River in Chinese Tien Shan mountains have showed that glacier- dammed lake outburst floods (GLOF) had occurred almost every year since 1956 from the glaci-er-dammed Lake Merzbacher. However, GLOF in cold season is seldomly studied. The defense and management of the flood need further observation and study. The maximum peak discharge of 825 m3/s occurred on 5th December 1996 with the maximum flood volume of 2.875×108 m3, which was 18 times larger than that of the mean daily discharge in winter over the past six decades. The drainage of the Merzbacher lake is not a mechanical breaking up of the glacier dam, but the release of pressurized water along a subglacial tunnel triggered by quickly surge of the Northern Glacier, the subglacial tunnels are enlarged by both ice melting and frictional heat in the flooding water and heat under the glaciated dam and the lake in winter. There is no correlation between the GLOF size and air temperature of cold season. The floods in cold season have become bigger since 1996 than that before, and the flood duration has been extended from winter to spring. Once the cold GLOF starts, its discharge can be forecasted day by day to extrapolate the monitoring hydrograph as a linear curve.