Search

A barred tidal flat has grown in the north of Subarnarekha river estuarine system along the western coast of Bay of Bengal, Talsari, Odisha, over the last twenty years, from 2002 to 2022. The channels form an integral part of the tidal flat and act as conduits for supplying and draining sediments with flood and ebb flows. Multiple drainage basins with quantifiably different channel patterns are identified within the Talsari tidal flat. Two major types of tidal channels, namely through-flowing and dead-end channels, are recognized in the Talsari Tidal flat. Channel morphometric analysis reveals that the sand:mud ratio in the tidal flat sediments, along with slope, tidal range, current strength, vegetation cover and climate, strongly controls the channel pattern evolution in drainage basins within the tidal flat. Channel migration and filling patterns develop distinctly different sedimentary bodies with respect to laterally adjacent flat areas. High-energy climatic storms played an important role in transporting silty-muddy sediments to the tidal flat and also brought changes in channel morphometry along with the development of regionally developed scours. [ABSTRACT FROM AUTHOR]

During their flow through an area, the streams are used to erode, transport and re-deposit sediments in the number of cycles following the climatic variation in an area. This cycle in turn affect the chemistry of these sediments and hence the geochemical study of these sediments helps to understand the palaeo-climate, source-area weathering and provenance of the study area. In order to understand the geochemical classification of sediments, palaeo-climate, source-area weathering and provenance for stream sediments of the Eastern Ghats Mobile Belt (EGMB), 364 stream sediment samples were collected from the area around Daringbadi, Kandhamal district, Odisha, India and analyzed for major oxides, trace elements and rare earth elements. These sediments are geochemically classified as shaly and wacke type, moderately mature and derived through the high intensity of weathering of source rock under warm and humid climatic condition. The positive correlation between Al2O3 and Fe2O3, MnO, and MgO, indicates multiple sources for sediment and these oxides are associated with clay minerals. The discrimination function diagram suggests a felsic igneous as well as quartzo-sedimentary provenance for these sediments whereas the ratio of Al2O3/TiO2 and concentration of V-Ni-Th suggest a felsic igneous source rock. The high concentration of LREE, slight enrichment of HREE and negative Eu anomaly indicate terrestrial or continental crust source rock. Hence the source rock for these sediments are granite gneiss, charnokite and khondalite present in and around Daringbadi area. [ABSTRACT FROM AUTHOR]

Chilika Lake, Asia's largest brackish water lagoon, is located in the state of Odisha on the east coast of India. It was designated as a Ramsar site in 1981, being the first Indian wetland of international importance under the Ramsar convention. Siltation of the lake is become a major concern, because it is leading to various geomorphic changes that are affecting the shape and size of the lagoon, which receives a major silt load through the Daya and Bhargovi rivers (both being branches of the Mahanadi river) via the Kathajodi and Kuakhai rivers. The Naraj barrage was constructed at the mouth of the Kathajodi river to regulate its inflow, and also its silt load, into the lagoon. Two observatories are established in the Daya and Bhargovi rivers to determine the quantity of silt entering Chilika Lake through the rivers, with the bed load and suspended (total solids) being measured. Various effects of siltation in the lagoon because of the barrage are analysed in this study, to include the pre- and postconstruction situation. By considering different flood situations in the Mahanadi river, various alternate strategies for operation of the Naraj barrage were studied, with the goal of minimizing the siltation in Chilika Lake. These alternate operation strategies, and their potential effects on the inflow into the lagoon, are analysed and discussed in this report. [ABSTRACT FROM AUTHOR]