Seasonal Occurrence of Unique Sediment Plume in the Bay of Bengal

Abstract

The movement of sediment plumes, detectable from ocean color sensors [Klemas et al., 1975; Khorram, 1981; Nezlin and DiGiacomo, 2005], depends primarily on coastal circulation [Fong and Geyer, 2002]. Hence, sediment plumes become tracers for studying circulation patterns. The Indian remote sensing satellite Oceansat 1 carries an ocean color monitor (OCM) sensor along with a microwave sensor. Using the OCM data, we studied the suspended sediment concentrations (SSC) during 1999–2006 and observed a plume coming off the Krishna‐Godavari River Basin (KGB) that is the only plume within the Bay of Bengal whose movement is controlled by prevailing currents. The KGB is located in the central part of the east coast of India between 16°43′, 17°00′N and 82°15′, 82°22′E (Figure 1a). Though high sediment concentration is present all along India's east coast, the offshoot of the plume is present only at the coast of Kakinada. The presence, extent, orientation, and intensity of this plume have both seasonal and interannual variations.

Response to comments of anonymous reviewer #2

“…Higher δ 13 C OC values in the upper basin reflect a greater preponderance of C 4 vegetation in the upper basin while lower OC loadings are attributed to a wide range of factors, including erosion of heavily weathered soils that are relatively depleted in OC and notably enriched in high-surface area smectiterich secondary minerals due to erosion of basalts of the Deccan Plateau (Table S1). This interpretation is consistent with other independent observations within the Godavari Basin and its adjacent margin (Kessarkar et al, 2003;Philips et al, 2014;Shrivastava and Pattanayak, 2002;Srivastava et al, 1998). Assessment of relationships between OC loading and 14 C OC show that samples with higher OC loadings are generally more enriched in 14 C (Fig.…”

Short communication: Massive erosion in monsoonal central India linked to late Holocene land cover degradation

“…Offshore from the Godavari mouth, a persistent sediment plume extends over 300 km during the monsoon season, when over 90 % of the fluvial sediment is discharged (Sridhar et al, 2008). Because the shelf in front of the delta is unusually narrow (i.e., under 10 km at our core location) copious sediment deposition takes place directly on the continental slope, resulting in sediment accumulation rates as high as 250 cm kyr −1 .…”

Temporal variations in 87Sr/86Sr and ɛNd in sediments of the southeastern Arabian Sea: Impact of monsoon and surface water circulation

“…[28] The observation that the isotopic composition of LGM stratum in SS-3101G is similar to those in western Bay of Bengal , that there is enhanced flow of low salinity water from Bay of Bengal to southeastern Arabian Sea during this period and that the existence of sediment plumes in the coastal and open Bay of Bengal [Sridhar et al, 2008a[Sridhar et al, , 2008bRajawat et al, 2005] is an indication that sediments from the western Bay of Bengal may be transported to this core site. However, clay mineral studies of sediments from southeastern Arabian Sea have yielded divergent conclusions; Kessarkar et al [2003] suggest that the sediments of the southeastern Arabian Sea largely represent hinterland flux and are not influenced by sediments transported from the Bay of Bengal waters during the intensification of NE monsoon.…”