Assessment of Geomorphic Evolutionary Pathways and Hydrological
Connectivity of Kaabar Tal (Wetland) Using Multi-Source Remotely Sensed
Datasets
Abstract
The alluvial wetlands are one of the most important ecosystems of the
world and are in abundance in the vast Indo-Gangetic plains. The
wetlands of this region are of variable sizes and characteristics but
currently face similar problems of drying-out and fragmentation. It is
empirical to understand the evolutionary pathways and hydrological
connectivity of these wetlands for planning and execution of management
and restoration for them. These pathways have been studied for a wetland
namely, the Kaabar Tal, situated in the Kosi-Gandak interfan region of
the eastern Gangetic plains. Its geomorphic evolutionary pathways have
been established using satellite imageries, DEMs, toposheets, and high
resolution aerial imagery obtained using unmanned aerial vehicle (UAV).
Various geomorphic units characterized by an assemblage of geomorphic
features have been mapped for the Kaabar Tal and its surroundings.
Seasonal, annual, and decadal variability in the hydrological status of
this wetland were estimated for a time-period of 1976-2017 using the
historical Landsat datasets. Seasonal variability in hydrological
connectivity structure of the wetland with its catchment for the
time-period of 1989 to 2017 was estimated in a GIS framework. The
structural connectivity was estimated using the technique of diffusion
kernel interpolation. The dynamic connectivity was estimated using the
Getis-Ord Gi* statistic and Mann-Kendall trend test using the concepts
of space-time cubes. The detailed geomorphic mapping revealed that this
wetland primarily originated through fluvial processes. A historical
reconstruction of its hydrological status revealed that in the recent
times the wetland is getting fragmented, and the connectivity potential
of different areas of the catchment is a function of the prevalent
land-use and land-cover (LULC) pattern and seasonality. Therefore, the
heterogeneity and complexity of the geomorphic units of the wetland and
the historical LULC patterns of the catchment should be considered in
designing any management and restoration plan.