Evaluation of morphodynamics of Miani Hor, a coastal lagoon of Lasbela, Balochistan, Pakistan

Abstract

Summary: In compliance to the estuarine areas having access to the sea and riverine water, Miani Hor, a coastal water body in Lasbela, Pakistan could be categorized as a lagoon due to its shallowness, elongation to the coast, connectivity with the adjacent Sonmiani Bay and occasional receiving of rainwater. In the present paper, Miani Hor was studied to understand its dynamics, and to compare it with the categories of lagoons as proposed by Kjerfve (1986). The result of the field data of water quality and water movement as well as satellite imagery of different years show that this is a tide-dominated lagoon with a single inlet, and it was formed in the last glaciation period. Its only inlet is stable and remains open even during the period of high energy waves offshore Sonmiani Bay that generate strong littoral drift. The data suggest that unlike choked lagoons, as proposed by Kjerfve (1986) for classification of the single-inlet lagoons with limited tidal influence, Miani Hor has a small (0.08) ratio of the channel cross-sectional area to the lagoon surface area. The lagoon channel filters out high energy waves but allows strong tidal signals to penetrate the lagoon. The paper suggests that Kjerfve (1986) classification requires modification by incorporating another class “relaxed lagoons” for the single inlet tide-dominated lagoons. Keywords: Coastal water body, Lagoon, Tidal constituents, Inlet dynamics