Progradation of the Godavari Delta -a Fact or Empirical Artifice? Insights from Coastal Landforms

Sedimentary micro-environmental characteristics, landforms and morphostrati graphic details of the Godavari delta reveal that the progradational trends of the delta are favoured by channel bifurcation and lengthening in upper deltaic plain. In the lower deltaic regime, formation of barrier bar followed by lagoon and lagoon infilling lead to deltaic progradation over sea. The progradational process was such that, initially, the delta front deposits developed low gradients in continental shelf over which spit and distributary mouth bars were deposited that paved way for the development of lagoonal conditions. It was followed by creation of swamps and marshes that in turn were overlapped finally by flood plain as a complete sequence of delta progradation. The neotectonic activity has played a pivotal role in this progradational process by tilting fault blocks that provided adequate gradient and alternative activation of various distributaries of the river. On the basis of facies architectural elements, sedimentary processes and the pattern of sedimentation, the Godavari delta can be considered as modern analog of abandoned Lafourche delta of Mississippi delta complex. Analyses of shoreline features, ongoing sedimentary pattern and the role of depositional and erosional agents over different sedimentary environments indicate that the delta currently engages erosional phase in view of rising sea level coupled with subsidence and is not prograding over sea as happened during its evolutionary history.