Recent Changes of Water Regime and Resource of the Ganga Lake and Related Some Socio-Economic Aspects

Dambaravjaa Oyunbaatar1, B. Erdenebayar1, G. Davaa1, and D. Saikhanjargal2

1. Research and Information Institute of Hydrology, Meteorology and Environment, Mongolia

2. Ministry of Environment and Tourism, Mongolia

Abstract: The Lake Ganga is located in the Sukhbaatar provincein Eastern Mongola and in terms of wetland service and local natural beauty the lake is very important water bodies. In this paper, lake morphometry, water level fluctuation and water balance of the Ganga Lake have been analyzed to reveal the coupling effects of climate change and human impacts.

It’s water regime and morphometric changes serve as indicator of climate change in the steppe and Gobi region. The lake is very vulnerable for the climate warming and human impacts. In recent years, water level of the lake much dropped and continued its shrinkage of water surface area, especially dramatic lake depletion was observed in summer of 2016. The cause of such changes is mainly climate warming. Summer of 2016 was hottest summer since mid-1940th when started permanent and systematic observation for regional climate, around Ganga lake. Rainless days continued from end of July till early September, covering nearly whole August month of this year and at same time, during this period also observed longest consecutive extreme hot days which exceeds 30°C in the region. As consequences of such extreme weather condition, water surface area reduced till 0.29 km2 which several times smaller than normal lake condition. Water level of the Ganga lake has dropped by 1.5 m since late 1990th where the lake was full and in last 3-4 year lake water level dropped by 50-60 cm.

Recent years, due to drying out of several open water sources, which serve for livestock watering, serious pasture degradation took place around lake area. For instance, additionally 16 herders family moved to Ganga lake site from surrounding area and in summer of 2016 about 31000 of livestock concentrated in the lake area. Such huge concentration of animals in the small lake water also seriously affected to lake water quality and lakebed sediment situation.

Key words: Ganga lake, climate change, water level decline, lake morphometry changes