Causes of water shortage for Dak R’Tih hydropower reservoir-Dak Nong province

Abstract

Recently, hydropower reservoirs in Dak Nong province are continually significantly deprived of water in dry season; it is not as the initial designed capacity. Dak R’tih hydropower reservoir has just been completed and worked since December 2011 but this phenomenon also occured. Therefore, it is recommendable to carry out investigation and calculation of water volume flowing in and out of Dak R’tih reservoir by establishing and solving an equilibrium equation of water volume in the reservoir. Field survey, groundwater level monitoring, field test and sampling for labortory tests were carried out simultaneously. Analysing the investigated results together with collected geological, engineering geological, rainfall and forest area data in the researched zone, we can determine that. The permeability is not a cause for water shortage in the Dak R’tih reservoir. The real cause is decrease of rainfall, especially during the dry season. The forest area in the zone has decreased more than 80% from 2005 to 2010. Hence, the water amount flowing in the reservoir and recharge for the aquifer has been decreased.