Review on regional water resources assessment models under stationary and changing climate

A comprehensive assessment of the water resources available in a region or a river basin is essential for finding sustainable solutions for water-related problems concerning both the quantity and quality of the water resources. Research on the development and application of water balance models at different spatial and temporal scales has been carried out since later part of the 19th century. As a result, a great deal of experience on various models and methods has been gained. This paper reviews both traditional long-term water balance methods and the new generation distributed models for assessing available water resources under stationary and changing climatic conditions at different spatial and temporal scales. The applicability and limitations of the methods are addressed. Finally, current advances and challenges in regional- and large-scale assessment of water resources are presented.