Dynamics of salinity intrusion in the surface and ground water of Sundarban Biosphere Reserve, India

Sundarban is the world’s largest transboundary contiguous mangrove ecosystem and home of the mangrove dwelling tigers. Sea level rise is destabilizing this ecosystem which is experiencing a rising salinity in surface and ground waters (shallow aquifer). In this study ground water salinity was investigated across Sundarbans and surface water seasonal salinity changes has been investigated along East-west gradient in the region. Statistically significant seasonal as well as spatial variations has been observed in the surface water salinity pattern across this gradient. The post monsoon average surface water salinity was 10.58 ppt while in pre-monsoon it was 27.31 ppt. Ground water salinity was lowest (0.95 ppt) in monsoon while highest in the pre-monsoon season (7.4 ppt). There was a clear east-west gradient in the surface salinity distribution across the delta, indicating a source of fresh water in the eastern corner, bordering Bangladesh. Increasing salinity indicate impact on mangrove diversity with salinity sensitive species (Heritiera fomes, Nypa fruticans) limited to the eastern corner while salinity resilient species (Avicennia marina and Phoenix paludosa) were dominating the western and central part of the Indian Sundarbans. Mangrove associate Acanthus ilicifolius and Heliotropium currasavicum were abundant in the forests under anthropogenic disturbances.

Integrating Various Sources of Indicators and Water Measurements Data of Different Degree of Uncertainty: Understanding Aquifer Encroachment and Resulted Water Breakthrough to Gas Producers

Opishnyanske Field is a mature Ukrainian gas field that began producing in 1972 from three formations: Visean, Serpukhovian, and Bashkirian. A reservoir simulation study was implemented to understand the movement of the water in the reservoir and to maximize the field recovery. Some wells showed high water production at their late life and this was the key question that we wanted to understand. If this was a water breakthrough, which means that the aquifer water swept the gas in the reservoir and reached these wells, then there is little potential left in this field. If this was not a water breakthrough, there could still exist some unswept areas to be produced. The second key question was to understand the aquifer strength and direction to be integrated into the simulation model. The field has different sources of data that could be used to understand the water movement in the reservoir, which are: Observed production data Water analysis reports (surface water salinity and density measurements) Production logging data Pressure data and geological maps to understand the communication between the wells Although different sources of data are available, each one has a level of inaccuracy, which was the key challenge. The field also has some other challenges, such as: Commingled production Contradiction between the observed water/gas ratio (WGR) and water analysis data Limited water analysis data points in some wells Issues with backallocation of the observed data. Integrating all the available data had a significant effect on understating the water behavior. Data analysis and integration resulted in excluding all the data anomalies and reaching a good understating regarding: The wells that are showing a water breakthrough Aquifer strength and direction

Wetland Availability and Salinity Concentrations for Breeding Waterfowl in Suisun Marsh, California

Availability of wetlands with low salinities during the breeding season can influence waterfowl reproductive success and population recruitment. Salinities as low as 2 ppt (3.6 mScm–1) can impair duckling growth and influence behavior, with mortality occurring above 9 ppt (14.8 mScm–1). We used satellite imagery to quantify the amount of available water, and sampled surface water salinity at Grizzly Island, in the brackish Suisun Marsh, at three time-periods during waterfowl breeding (April, May, July) over 4 years (2016–2019). More water was available and salinity was lower during wetter years (2017, 2019) than during drier years (2016, 2018), and the amount of water in wetlands decreased 73%–86% from April to July. Across all time-periods and years, the majority (64%–100%) of wetland habitat area had salinities above what has been shown to negatively affect ducklings (> 2 ppt), and up to 42% of wetland area had salinities associated with duckling mortality (> 9 ppt). During peak duckling production in May, 81%–95% of available water had salinity above 2 ppt, and 5%–21% was above 9 ppt. In May of the driest year (2016), only 0.5 km2 of low-salinity water (< 2 ppt) was available to ducklings in the study area, compared to 2.6 km2 in May of the wettest year (2017). Private duck clubs own the majority of wetland habitat at Grizzly Island and consistently had a greater percentage of land flooded during summer than did publicly owned wetlands, but private wetlands generally had higher salinities than public wetlands, likely because they draw from higher-salinity water sources. By July, few wetlands remained flooded, and most had salinities high enough to impair duckling growth and survival. Local waterfowl populations would benefit from management practices that provide fresher water during peak duckling production in May and retain more water through July.

Breeding Waterbird Populations Have Declined in South San Francisco Bay: An Assessment Over Two Decades

Availability of wetlands with low salinities during the breeding season can influence waterfowl reproductive success and population recruitment. Salinities as low as 2 ppt (3.6 mScm–1) can impair duckling growth and influence behavior, with mortality occurring above 9 ppt (14.8 mScm–1). We used satellite imagery to quantify the amount of available water, and sampled surface water salinity at Grizzly Island, in the brackish Suisun Marsh, at three time-periods during waterfowl breeding (April, May, July) over 4 years (2016–2019). More water was available and salinity was lower during wetter years (2017, 2019) than during drier years (2016, 2018), and the amount of water in wetlands decreased 73%–86% from April to July. Across all time-periods and years, the majority (64%–100%) of wetland habitat area had salinities above what has been shown to negatively affect ducklings (> 2 ppt), and up to 42% of wetland area had salinities associated with duckling mortality (> 9 ppt). During peak duckling production in May, 81%–95% of available water had salinity above 2 ppt, and 5%–21% was above 9 ppt. In May of the driest year (2016), only 0.5 km2 of low-salinity water (< 2 ppt) was available to ducklings in the study area, compared to 2.6 km2 in May of the wettest year (2017). Private duck clubs own the majority of wetland habitat at Grizzly Island and consistently had a greater percentage of land flooded during summer than did publicly owned wetlands, but private wetlands generally had higher salinities than public wetlands, likely because they draw from higher-salinity water sources. By July, few wetlands remained flooded, and most had salinities high enough to impair duckling growth and survival. Local waterfowl populations would benefit from management practices that provide fresher water during peak duckling production in May and retain more water through July.

Impacts of Topsoil and Surface Water Salinity on Agriculture: A Study at Paikgachha, Khulna

Studying the structure, intensity and track of tropical cyclone is very important in effective tropical cyclone warning. In this study, an attempt has been made to simulate the Super Cyclone Amphan to reproduce the structure, intensity and track of the storm that occurred over the Bay of Bengal and made landfall over the coastal zone of Sundarban between Western Bangladesh and Eastern West Bengal of India on 20 May 2020. The Weather Research and Forecasting (WRF) Model was run 120 hours from 0000 UTC of 16 May to 0000 UTC of 21 May 2021 with 9 km horizontal resolution to simulate the selected storm. The model simulated intensity and track of the storm were compared with that of best track data of India Meteorological Department (IMD). The results obtained from the WRF model indicated that the intensity of the selected cyclone in terms of Mean Sea Level Pressure (MSLP) and Maximum Sustained Wind speed (MSW) were 905 hPa and 243 kph whereas the observed MSLP and MSW were close to 920 hPa and 241 kph respectively. It was also indicated that the model predicted the track of the cyclone reasonably well and it was quite close to the best track data throughout its path till landfall with very small deviation and the cyclone made landfall at 7-8 hours before the actual landfall with 167.4 km position error. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 8(2), 2019, P 25-32

Integrated Pliocene-Pleistocene magnetostratigraphy and tephrostratigraphy of deep-sea sediments at IODP Site U1424 (Yamato Basin, Japan Sea)

Sediments from the semi-enclosed Japan Sea are sensitive to paleoclimatic perturbations and they offer great opportunities for many regional and global paleoceanographic and paleoclimatic studies. These studies often require a robust chronology. However, due to rare preservation of calcareous microfossils and drastic changes in surface water salinity during glacial lowstands, the construction of a traditional oxygen isotope stratigraphy for Japan Sea sediments is often difficult. Here, we use sediments recovered at Integrated Ocean Drilling Program (IODP) Expedition 346 Site U1424 to build an integrated Pliocene-Pleistocene reference magnetostratigraphy and tephrostratigraphy for sedimentary sequences from the region. Rock magnetic experiments indicate that magnetic remanence of Site U1424 sediments are carried primarily by (titano)magnetite with small contributions from high coercivity minerals (e.g., hematite) and possibly iron sulphides (pyrrhotite and/or greigite). Dark-colored sediments appear to contain less (titano)magnetite probably due to reductive diagenesis under euxinic conditions. Natural remanent magnetization (NRM) of u-channel samples covering a continuous ~ 167.6 m sediment sequence at Site U1424 was repeatedly measured at 1 cm intervals before and after stepwise demagnetization. Despite lower NRM intensity in dark-colored sediments, NRM directional data from both dark- and light-colored sediments are considered suitable for the construction of magnetostratigraphy. Site U1424 sediments clearly recorded the majority of the polarity chrons and subchrons within the last ~ 4.89 Myr, with the Cobb Mountain subchron, the end of Kaena subchron, and the onset of Nunivak subchron less well preserved. Sixteen tephra layers from the site were sampled for chemical composition analyses and the results were correlated to reference tephrostratigraphy of the region. Ages of the identified tephras are consistent with and can be well integrated with the magnetostratigraphy. The resulting age model suggests that sedimentation rates at Site U1424 range between ~ 1.7 and 7.6 cm/kyr with an average of ~ 3.3 cm/kyr. The acquired magnetostratigraphy and tephrostratigraphy at Site U1424 provide a reference chronology that can be correlated with and transferred to other sediment sequences in the region to study paleoceanographic and paleoclimatic changes of the region as well as their links to other regional and global changes. Graphical abstract

The Dominant Climate Change Event for Salinity Intrusion in the GBM Delta

Salinity intrusion through the estuaries in low-lying tide-dominated deltas is a serious threat that is expected to worsen in changing climatic conditions. This research makes a comparative analysis on the impact of salinity intrusion due to a reduced upstream discharge, a sea level rise, and cyclonic conditions to find which one of these event dominates the salinity intrusion. A calibrated and validated salinity model (Delft3D) and storm surge model (Delft Dashboard) are used to simulate the surface water salinity for different climatic conditions. Results show that the effects of the reduced upstream discharge, a sea level rise, and cyclones cause different levels of impacts in the Ganges-Brahmaputra-Meghna (GBM) delta along the Bangladesh coast. Reduced upstream discharge causes an increased saltwater intrusion in the entire region. A rising sea level causes increased salinity in the shallower coast. The cyclonic impact on saltwater intrusion is confined within the landfall zone. These outcomes suggest that, for a tide dominated delta, if a sea level rise (SLR) or cyclone occurred, the impact would be conditional and local. However, if the upstream discharge reduces, the impact would be gradual and along the entire coast.

The distribution of the desalinated waters of the amur estuary in the okhotsk sea according to satellite observations

The distribution of the desalinated waters of the Amur Estuary in the Northwestern ​​Okhotsk Sea during the summer period was analyzed using satellite data on sea level, salinity, temperature and concentrations of suspended organic carbon. There is good agreement between the spatial distribution of surface water salinity (data from the SMAP satellite) and the sea level (AVISO data) in the study area. The identification of the waters of the Amur Estuary by the surface water temperature and the concentration of suspended organic carbon is limited to the Sakhalin Bay and the coastal waters of Sakhalin Island. An increase (decrease) in the flow of the Amur River during the spring-summer flood leads to an increase (decrease) in sea level in the northern part of the Sakhalin Bay in July. Strengthening of the northwestern (southeastern) winds in September reduces (increases) the inflow of waters with low salinity and elevated sea level to the area north of the Sakhalin Bay.