Introduction Water is fundamental to sustaining life. Despite the abundance of water globally, access to clean drinking water is becoming scarce at a rapid rate for multiple reasons, with urbanization being foremost. This causes water resource scarcity and increases water stress, both in large cities as well as in many regions of the world with less infrastructure and support. Population growth and its associated demand on water supply poses a significant challenge in maintain- ing adequate water quality in various sectors. Most water- stressed and lower per capita income regions also suffer additional socio-political issues. Unsustainable increases in water demand have caused growing competition for water resources, tensions among different users, water quality deterioration, and degradation of aquatic ecosystems. Addressing all these issues requires a multi-disciplinary, inter-sectorial, and participatory approach to efficiently manage water resources. The Republic of Armenia is a mountainous country with total area 29,800 km 2 with semiarid climate. About 75% of total 2D land area is located 1,500 m above sea Pol. J. Environ. Stud. Vol. 24, No. 2 (2015), 871-877 Short Communication Modeling River Ecosystem Vulnerability Assessments Due to Climate Change: Case Study of Armenia Alla S. Aleksanyan 1 , Surik Kh. Khudaverdyan 2 , Ashok Vaseashta 3, 4 * 1 Department of Geo-Botany and Ecological Physiology, Institute of Botany of NAS Armenia, Acharyan 1, Yerevan, 0063 Armenia 2 Design and Production of Radio Devices, Armenian National Polytechnical University, Teryan 105, Yerevan, 0009 Armenia 3 Institute for Advanced Sciences Convergence & International Clean Water Institute, NUARI, Northfield, VT 05663 4 Molecular Science Research Center, Claflin University, Orangeburg, SC 29115 USA Received: 7 August 2014 Accepted: 2 November 2014 Abstract Water resources are an integral part of the global hydrologic cycle and are considered among the natur- al systems most vulnerable to climate change. Research indicates that severe problems related to water will affect the globe around 2030, which will further intensify to attain its peak by 2100 unless a different water management trajectory is strategically implemented. To conduct an accurate climate change impact assess- ment it is necessary to conduct parametric analysis for vulnerability to assess for each system by constructing a conceptual hydrogeological model that is then transferred to a mathematical model of overall water resources. We present here a case study outlining plausible impacts of climate change on water resources of Armenia, particularly on river ecosystems. Based on this initial study, we propose certain recommendations for the future to reduce, if not reverse in its entirety, the vulnerability trajectory. We further conclude that vul- nerability assessment of water resources resulting from climate change, as proposed here, can be applied for different countries and will be of considerable interest worldwide. Keywords: climate change, vulnerability, water resources, assessment, Armenia *e-mail: prof.vaseashta@ieee.org DOI: 10.15244/pjoes/31225