Geomorphological Characterization of River Indus and Assessment of Physical Habitat

Abstract

The proposed study aims to achieve a geomorphological characterization of River Indus and attempts to study the geomorphological changes in relation to physical habitat. The remotely sensed data from Landsat (TM, ETM+, OLI), SPOT (Vegetation), HydroSHEDS (HydroBASINS), TRMM (Precipitation) and DFO (Discharge) were acquired to derive information comprising the composition and structure of fluvial landforms and processes. The data was processed by employing various GIS techniques and the information about river’s geometry, planform and discharge was extracted for sixteen (16) years, i.e. yr 2000 - 2015. The temporal analyses at an annual scale enabled a retrospective assessment of the dynamic changes experienced by the river over sixteen (16) years span, i.e. yr 2000 - 2015. The information so derived, was further employed to characterize the geomorphology of river at the spatial scale of sub-basin level (i.e. Pfafstetter level 08) catchments called the geomorphic units. River Indices were calculated based on channel width, degree of braiding, channel sinuosity and meander-ability to quantify the changes in river’s morphology and behavior in each geomorphic unit. The higher channel width and braiding intensity was observed in the central region of the study area. The southern region of the river, though relatively narrow, has higher sinuosity and meander-ability. The maps of vegetation intensity and cumulative annual precipitation were also generated for sixteen (16) years, i.e. yr 2000 – 2015. The parameters were subsequently employed for the assessment of physical habitat changes in each geomorphic unit. The parameters were also evaluated to determine their linkage / relation with the changes in channel planform. The Pearson’s correlation coefficient (r) was calculated to quantify the impacts of physical factors, i.e. vegetation, precipitation and discharge on the channel planform. The effects of high annual precipitation were seen in the form of increased braiding and anastomosing behavior of the river. The areas with high vegetation intensity witnessed higher braiding and decreased sinuosity. The vegetation intensity is observed higher in areas with high precipitation. The study proposed a mechanism to assess the morphology of the river in relation to climate induced factors using satellite remote sensing data.