Differences in temperature, duration of irradiation, wind speed, watershed shape, slope, and rainfall are the factors that determine the amount of evaporation and discharge flow also characterizing of the watershed. As noted, the difference between the maximum and minimum temperatures is over6 and the dry season happens mostly from May to October in West Sumatra Province each year. It, of course,will affect the magnitude of potential evapotranspiration and the minimum water flow that tend to decrease. Therefore, a particular evaluation of the impact of drought or susceptibility to water potential of the watersheds in the Areas of Akuaman River of West Sumatra should be undertaken. The methods used were the standard of Ministry of Forestry of Indonesiathe Agency for Research and Development of Forestry and the Center for Research and Development of Conservation and Rehabilitation 2012 and Arc-GIS-10.3 software to determine the index of vulnerability to drought and Cropwat-8to calculate evapotranspiration by Penman-Monteith method. The evaluation results show evapotranspiration value was 5.32 mm / day, 161.7 mm / month and the category of susceptibility tended to be medium and somewhat vulnerable. A review of the aspect of service levels of the use of water and minimum specific discharge is seen that in small watersheds is more susceptible to get drought than larger basins. It is therefore suggested to stakeholders to consider the possibilities for watershed integration as a solution to improve water supply for irrigation.