A critical review on scale concept in GIS-based watershed management studies

Watershed management is critical in achieving sustainable development for water resources. Geographic information system (GIS) provides efficient functions to store, retrieve, analyze, and display spatial data. Therefore, GIS is used to develop watersheds' decision support systems (DSS) to find useful ways of solving waterbodies' problems. Studies on watershed problems need considering both biophysical conditions and information on human-environment relationships, which points to the need to deal with different geographical fields. Definitions of scale in each field and making clear connections among them is essential for having comprehensive and practical water management plans. These scales are spatial, social, and political scale. However, in studies on developing a DSS for watershed management, there is a gap in defining social and political scales and aligning them with spatial scale, which can be a barrier to have concrete and integrated watershed GIS-based DSS's. This study reviews papers in dominating fields of GIS-based DSS's for watershed management and provides proof that studies have focused only on spatial scales, while social and political scales are considerably neglected. This paper aims to point to this problem by reviewing relevant papers, elaborating some critical issues arisen from this neglect, and suggesting some future directions.