Conceptual assessment of (dis)connectivity and its application to the Ganga River dispersal system

Connectivity in river dispersal systems is an important evolving concept and helps in understanding their dynamics. In this study, the types of connectivity have been defined on the basis of two components, namely physical contact and transfer of material. Based on this, four types of connectivity are recognized. These are (a) active connected system, (b) inactive connected system, (c) partially active connected system, and (d) disconnected system. Connectivity indices have been proposed based on the process understanding of different types of connectivity. This conceptual understanding of connectivity has been applied to the Ganga dispersal system, a large river system. Results of the connectivity analysis on the Ganga dispersal system reveal that different sets of data such as sediment budgets, geochemical isotopic data and radiogenic (U-238-U-234-Th-230) data are noncoherent. Therefore, developing rigorous and well constrained quantitative multidisciplinary data sets is needed to have a better understanding of connectivity at multiple spatiotemporal scales in large river dispersal systems; this would ultimately help model the dynamics of such systems. (C) 2010 Elsevier B.V. All rights reserved.