Wind-driven estuarine turbidity maxima in Mandovi Estuary, central west coast of India (original) (raw)
Related papers
Estuaries and Coasts, 2010
Systematic seasonal variations of suspended particulate matter (SPM) along a 44 km transect of the Mandovi estuary reveal that the concentrations of SPM are low at river-end stations, increase generally seaward, and are highest at sea-end stations of the estuary. An estuarine turbidity maximum (ETM) occurs at sea-end stations during June-September when river discharge is high and also in February-May when river discharge is low. These are the two windiest times of year, the former associated with the southwest monsoon, and the latter characterized by a persistent sea breeze. The salinity vs. SPM plot shows that high SPM is a seaward deposit and skewed landward. Suspended matter comprised of floccules, faecal pellets and aggregates that consist of clay and biogenic particles occur everywhere in the estuary. Diatoms are the most common and are of marine type at the sea-end and freshwater-dominated at river-end stations of the estuary. SPM is characterized by kaolinite-rich and smectite-rich clay mineral suites at the river-end and sea-end stations, respectively. Smectite concentrations increase seawards with the increase in SPM content and are not influenced by salinity.
Estuarine Coastal and Shelf Science, 2011
Suspended particulate matter (SPM) collected at regular stations from the Mandovi and Zuari estuaries indicates that the peaks of high SPM coincide with peaks of high rainfall and low salinity and also with peaks of moderate/low rainfall coupled with high salinity during the monsoon. The estuarine turbidity maximum (ETM) is a characteristic feature, it occurs in the channel accompanying spring tide during the monsoon and pre-monsoon, and shifts to the bay on neap tide during post-monsoon. ETM remains at the same position in the Mandovi River, both during the monsoon and pre-monsoon, whereas in Zuari it stretched upstream during monsoon and migrates seaward of the channel during pre-monsoon. The ETM coincides with the freshwatereseawater interface during the monsoon and is formed by the interaction between tidal currents and river flows. The ETM during pre-monsoon is associated with high salinities and is generated by tidal and wind-induced currents. The turbidity maximum on neap tide during postmonsoon may be due to the erosion and resuspension of sediments from the emergent tidal flats and transport of these turbid waters into the bay. Funneling effect of the narrowing bay in the Zuari estuary and associated physical processes effectively enhance the magnitude of the currents and transports sediments to the channel. SPM retention percentage indicates that the estuarine channel is prone to siltation.
2000
The influence o f clim ate on the physico-chemical param eters and its resultant effect on the distribution o f suspended m atter within M andovi river estuary is discusseu in the paper. Mandovi is a tropical estuary remarkably influenced by the monsoonal-maritime type o f climate. Most profound changes in physico-chemical param eters like salinity, pH and tem perature are observed during south w est m onsoon. Changes in these param eters show a distinct transform ation o f the estuary ftom being well mixed during prem onsoon, stratified during m onsoon and partially mixed during post monsoon. The impact o f these changes is seen in the distribution and variations in the total suspended matter, however, it is further engineered by the m orphologic setup o f the estuary. Distinct sources o f sediment ftom seaward and hinterland are discernible during fairweather and m onsoon seasons respectively. M onsoon season shows a very high content o f suspended matters.
Marine Environmental Research, 2009
To better understand topography-dependent characteristics of suspended particulate matter (SPM) in a tropical shallow estuary during dry season, the physical factors causing an increase in SPM and the sources of SPM were investigated at the western coast of Thailand. Single and multiple regression analyses using physical parameters as independent variables indicated that periodic tidal current-driven resuspension, episodic wind-driven resuspension, and river-borne inputs were the most important factors controlling SPM increases in areas surrounded by sand bars, areas directly facing the ocean, and areas close to the river mouth, respectively. The assessment of the origin of increased SPM over the background levels estimated from the chemical signatures (d 13 C and C/N ratio) at all investigated locations and for each event responsible for an increase in SPM confirmed the results of the multiple regression analyses. The results suggested that specific characteristics of SPM at each location were highly contributed by sedimentary materials and could be rather consistent through the season under similar weather conditions.
Estuaries, 2000
Data on hydrography, nutrients, suspended particles, and sedimented particles were collected at weekly intervals from November to May during 1995 to 1997 at a station in the coastal waters of Dona Paula Bay, India. Suspended and sedimented particles were analyzed for total suspended matter (SPM), total sedimented particulate matter (TPM), particulate organic carbon (POC), particulate organic nitrogen (PON), chlorophylla (chla), and diatom abundance. Variations in hydrography and nutrients influenced the quantity and composition of sedimented particles. The TPM, POC, PON, and chla fluxes showed small-scale seasonal variations and were higher in the summer (February to May) than in the winter (November to January). Resuspension of carbon accounted for approximately 25% of the gross POC and was highest in April 1997 (45%). The mean net POC flux was 197±90 mg C m−2 d−1 and accounts for 4.6% of the TPM. The average C∶N (w∶w) ratio of the sedimented material was 13.2±6.6. The POC:chla ratio was relatively higher in the sedimented material as compared to the suspended material. The particulate carbon reaching the bottom sediment was 39% of the primary production. The low organic carbon concentration (approximately 0.1% of dry sediment) in the sediments implies that about 98% of the sedimented carbon was either consumed at the sedimentwater interface or resuspended/advected before it was finally buried into the sediments.
Salinity and suspended sediment transport in a shallow estuary on the east coast of India
Regional Studies in Marine Science, 2016
h i g h l i g h t s • Pronounced seasonal variations in the transport of salt and suspended sediments were observed in the Muthupet estuary. • The salt moved in the upstream and downstream direction from the salt plug. • Salt transport affected the movement and removal of Fe from the water column. • Concentration of Cu and Cd was affected by resuspension of sediments. • The cause of more transport of suspended sediments was due to lower settling velocity of suspended sediments.
Depositional environment and silting in the Sharavati estuary, central west coast of India
Variation in textural characters (silt sand ratio, mean size, sorting and skeweness) of the Sharavati estuarine sediments has been studied to understand their depositional environment. Seventeen locations within the estuary and two locations just at the entrance of the sea were selected for the study. During September 2000, medium grained (1.36-1.86φ), well sorted to moderately well sorted sediments were observed in the estuary, whereas they were fine grained (2.67-3.φ) and poorly sorted in the entrance of the sea (0.84). The estuarine sediments were relatively fine-grained during December 2000 (postmonsoon) (1.3-2.18φ) and February 2001(premonsoon) (1.15-2.3φ) as compared to the monsoon season. The siltation in the estuary is mainly due to offshore source brought by tidal currents followed by mixing of saline and fresh water in the estuary. [Key words: Estuary, silting, depositional environment, texture, Sharavati river] Introduction Tropical estuaries are highly dynamic owing to v...
All the physico-chemical parameters such as temperature, turbidity, pH, salinity, dissolved oxygen, biological oxygen demand and nutrients like ammonia, silicate, nitrate, and nitrite were studied in two selected stations (mouth & mangrove area) Thengaithittu estuary, south-east coast of India for a period of three year (January 2009 -December 2011. Atmospheric temperature varied from 26 to 38.5 o C, water temperature 26 o C to 35.5 o C, turbidity ranges from 4 to 13 NTU, pH varied from 6.8 to 8.4, salinity value ranges from 12 to 32.5 ppt, dissolved oxygen 3.3 to 4.7 mg/l, BOD values of 0.2 to 3.8 mg/l. Concentrations of nutrients viz., ammonia ranges from 0.05 to 0.18µmol/l, reactive silicate varied from 25.5 to 99.0µmol/l, nitrate 0.41 to 6.92µmol/l and nitrite value ranges from 0.090 to 0.78 µmol/l were also shows variations independently throughout the study period.
A present study has been undertaken to report to the water quality parameters of Pennaiyar estuary compared the concentration of water quality parameters like temperature was ranging from 26.0 to 32.4°C, salinity values ranging from 23 to 34ppt, pH was ranging from 7.2 to 8.3, dissolved oxygen content was ranging from 3.36 to 5.36 mg/l, ammonia was ranging from 0.136 to 0.683μmol/l, nitrate was ranged from 7.39 to 8.29μmol/l, nitrite was ranging from 1.83 to 2.15μmol/l, total phosphorus was ranging from 0.046 to 1.553μmol/l, and silicate was ranging from 1.193 to 2.293μmol/.were studied from Pennaiyar estuary, Cuddalore, southeast coast of India from July 2013 to June 2014.Above the water level due to the ceaseless release of domestic manure and trade waste matter in the estuary. The duration of the estuary concentrations of nutrients and other water quality parameters potency have been controlled by the anthropogenic inputs from point and non-point sources
2018
To understand the source of materials and processes operating, the sediment cores collected from mudflats representing middle region of Sharavathi and Gurupur estuaries were analysed for grain size, organic carbon, clay mineralogy, bulk metals and clay chemistry. Relatively higher concentration of sand in the Sharavathi and higher clay and organic carbon content in the Gurupur estuary indicated variations in the depositional environment between the two estuaries. Further, higher sand in middle section and silt in the upper section in Sharavathi and Gurupur estuaries respectively indicated variations in the depositional conditions with time in both the estuaries. The kaolinite was the most abundant clay mineral, and the abundance and distribution of clay minerals in the two estuaries revealed the role of catchment area geology and river-sea water mixing conditions as major factors in sediment deposition. All the metals showed similar distribution pattern to finer sediments and organi...