Rainwater harvesting in Kherlen River Basin, East Mongolia

Water resources of Mongolia are highly vulnerable to climatic conditions due to harsh climate with four distinct seasons, high annual temperature fluctuations, and low rainfall. Average annual temperature ranges between 8.5oC in the Gobi and -7.8oC in the high mountain region. Average annual precipitation is around 200-500 mm and total water resource is estimated at 599 km3. About 64% is surface water and 36% is actually groundwater. Mining is rapidly changing the water consumption and landscape in Mongolia. In 2010, mining only consumed 13%, but the demand for water is projected to increase fivefold from 2012-2030. The future water resources are lacking, and will not be possible to satisfy by water from underground. One of the possible solutions is rainwater harvesting, to collect rainfall or snowfall. Objective of this study is to determine the feasibility of rainwater harvesting system in Kherlen River Basin, East Mongolia. Climate data, between 2000 and 2015, are obtained at three hydrological stations in the Kherlen River Basin. Results show that annual total precipitation ranges from 150-400 mm. About 90% of annual precipitation falls only in the warmer season. The lowest precipitation falls in winter months and the highest occurs in July. This study calculates possible water volume for collecting rainwater. Mungunmorit station is chosen as it is located at the upstream of the river. It will be possible to harvest on an average of 51 million m3 of water in spring and summer seasons according to the last 10 years rainfall records. The collected water can be used for domestic and water consumption of Ulaanbaatar City. In the future, water level may decrease with increasing air temperature due to climate change. Avocation of rainwater harvesting system is urgently needed in the near future.