Abstract
Water losses from channel have been observed in the middle and lower reaches of the Kherlen River flowing through eastern Mongolia. The objective of this study is to investigate the cause of these water losses. The Kherlen basin is divided into three subbasins: the upper, the middle, and the lower. The analysis of channel water balance is carried out each subbasin using meteorological and hydrological data and a simple water balance model. The analysis produces two main results. (1) The estimated net amount of surface-or ground-water inflow from surrounding areas into channel is plus. (2) The estimated amount of seepage through river bed to aquifer is in proportion to square root of observed river flow; this means that the actual is not zero. These two results support a hypothesis on surface-or ground-water interaction between channel and its surrounding areas. To be more precise, the runoff generated in surrounding areas is consumed by evaporation and seepage and does not contribute to changing river flow in the middle and lower of the Kherlen basin.
