Dynamic Insights: Advanced Techniques for Assessing Coastal Sediment Budgets Using DSAS and ArcGIS Spatial Analysis in the Kozhikode Sector along the SW Coast of India
Authors: Mk Rafeeque , Nair L. Sheela 
Published: March 2024

The dynamic equilibrium of a coast is intricately linked to the sediment budget of the region which can be considered as comprising of primary sediment cells&#160; which can be further divided into subcells . Identification of sources and sinks as well as quantifying the sediment inputs/outputs into/from a sediment cell is a challenging task for coastal scientists, and&#160; engineers and&#160;&#160; because of the inherent complexities. Despite advancements in coastal hydrodynamics, topics like&#160; comprehending sediment movements and correlating landform responses with the&#160; innershelf/nearshore dynamics still continues to be a gray area mainly because of the complex nature which display both spatial and temporal changes depending on the time scale.&#160; In this context, a novel technique that can be adopted for sediment budget studies of coastal areas utilizing the Digital Shoreline Analysis System (DSAS) and the spatial analysis tools available in ArcGIS is introduced. The proposed method can be used for computation and comparison of volumetric changes in the coastal region over a defined period.&#160; The capability of this&#160; technique is illustrated through a case study wherein an attempt has been made to study the spatial as well as temporal changes in nearshore sediment dynamics/budget along a micro-tidal, wave dominated Kozhikode coast in Kerala which forms part of the southwest coast of India. The coastal sector considered for the study is quite complex in nature with the presence of three estuaries/river inlets, namely the Kadalundi(major), Chaliyam (major) and Kallayi(minor); several rocky outcrops in the nearshore region; promontories/headlands and also prone to anthropogenic influences due to the construction of hard structures in the form of piers, groins, breakwaters, seawalls etc. as part of coastal protection and fishing harbour/port development activities. For the present study,&#160; the&#160; hydrographic datasets which consist of the bathymetry data spanning the 91-year period from 1920 to 2011 are employed to evaluate the sedimentation rates. The Chaliyar River, a major river which debouches into the Arabian Sea through the Kadalundi estuary located along the Kozhikode coast, contributes substantially to sedimentation from the Western Ghat ranges to the coast.. Thus by integrating geospatial modelling technique along with application of various spatial analysis tools available with ArcGIS software volumetric analyses have been carried out to understand , the temporal variation in the&#160; conspicuous topographical features along the Kozhikode coastal sector. This method can be easily employed to provide valuable insights into the coastal sediment dynamics and variations in volumetric changes in nearshore surface features over a pre-defined period of time which will be very useful information&#160; for the coastal scientists, engineers and managers involved in various coastal related activities such as coastal protection, development and management in addition to the&#160; research endeavours.
Key Words: Coastal Sedimentation, DSAS Application, Nearshore Dynamics, Seafloor Mapping, Coastal Geomorphology