Chaotic Features of Decomposed Time Series from Tidal River Water Level

This study assessed the characteristics of water-level time series of a tidal river by decomposing it into tide, wave, rainfall-runoff, and noise components. Especially, the analysis for chaotic behavior of each component was done by estimating the correlation dimension with phase-space reconstruction of time series and by using a close returns plot (CRP). Among the time series, the tide component showed chaotic characteristics to have a correlation dimension of 1.3. It was found out that the water level has stochastic characteristics showing the increasing trend of the correlation exponent in the embedding dimension. Other components also showed the stochastic characteristics. Then, the CRP was used to examine the characteristics of each component. The tide component showed the chaotic characteristics in its CRP. The CRP of water level showed an aperiodic characteristic which slightly strayed away from its periodicity, and this might be related to the tide component. This study showed that a low water level is mainly affected by a chaotic tide component through entropy information. Even though the water level did not show chaotic characteristics in the correlation dimension, it showed stochastic chaos characteristics in the CRP. Other components showed stochastic characteristics in the CRP. It was confirmed that the water level showed chaotic characteristics when it was not affected by rainfall and stochastic characteristics deviating from the bounded trajectory when water level rises due to rainfall. Therefore, we have shown that the water level related to the chaotic tide component can also have chaotic properties because water level is influenced by chaotic tide and rainfall shock, thus it showed stochastic chaos characteristics.

Multiple Indicators of Wastewater Contamination to Shellfish Farms Near a Tidal River

Wastewater contamination threatens the shellfish aquaculture industry by posing risks to public health. Multiple indicators of wastewater contamination, including fecal coliforms (fc), male-specific coliphage (MSC), dissolved nutrients, stable isotope ratios, and artificial sweeteners were analyzed to determine possible sources of wastewater to local shellfish farms. Samples were collected at a wastewater treatment plant outfall (WTPO), nonpoint residential, and agricultural areas of a tidal river, and tidal creek inflows adjacent to farms. To capture seasonal variation, we sampled under warm and cold, and wet and dry conditions. Fc ranged < 5–5250 CFU 100 mL−1, NH4+ concentrations ranged up to 9.58 μM, and δ15N ranged 1.4–7.8‰ across all sites and time periods. Fc and NH4+ were higher, and δ15N was lower in the cold wet period and near residential and agricultural areas. Acesulfame and sucralose concentrations ranged 0.004–0.05 μg L−1 and up to > 0.8 μg L−1, respectively, and did not correlate with other indicators but tended to be higher in residential areas and at the WTPO, supporting their value in differentiating human sewage from other sources. Shoreline disturbance during septic system upgrades may have inadvertently contributed bacterial indicators to shellfish farms. Overall, indicator source dominance depended on environmental conditions, with WTPO and residential sources conveying human-specific indicators to farms year-round, while agricultural and industrial sites contributed additional fc during cold wet periods. The use of multiple indicators will aid managers to detect and define wastewater sources, identify targets for monitoring or remediation, and manage shellfish areas in estuaries with a mosaic of land-derived wastewater sources.

Suspended Particular Matter drives the spatial segregation of nitrogen turnover along the hyper-turbid Ems estuary

Estuaries are nutrient filters and change riverine nutrient loads before they reach coastal oceans. They have been extensively changed by anthropogenic activities like draining, deepening, and dredging to meet economic and social demand, causing significant regime changes like tidal amplifications and in some cases to hyper-turbid conditions. Furthermore, increased nutrient loads, especially nitrogen, mainly by agriculture cause coastal eutrophication. Estuaries can either act as a sink or as a source of nitrate, depending on environmental and geomorphological conditions. These factors vary along an estuary, and change nitrogen turnover in the system. Here, we investigate the factors controlling nitrogen turnover in the hyper-turbid Ems estuary (Northern Germany) that has been strongly impacted by human activities. During two research cruises in August 2014 and June 2020, we measured water column properties, dissolved inorganic nitrogen, dual stable isotopes of nitrate and dissolved nitrous oxide concentration along the estuary. Overall, the Ems estuary acts as a nitrate sink in both years. However, three distinct biogeochemical zones exist along the estuary. A strong fractionation (~ 26 ‰) of nitrate stable isotopes points towards nitrate removal via water column denitrification in the hyper-turbid Tidal River, driven by anoxic conditions in deeper water layers. In the Middle Reaches of the estuary nitrification gains in importance turning this section into a net nitrate source. The Outer Reaches are dominated by mixing with nitrate uptake in 2020. We find that the overarching control on biogeochemical nitrogen cycling, zonation and nitrous oxide production in the Ems estuary is exerted by suspended particulate matter concentrations and the linked oxygen deficits.

Agriculture land suitability of tidal swampy area at Palingkau Irrigation Area in Central Kalimantan Province for national food estate program

Agriculture plays an important role in Indonesia development. Between the years 2020 - 2024, the government targets food security on sustainable development goals. Food estates have been made in several areas. However, there are constraints such as peatland and low elevation. Various irrigation systems developed by inhabitants and government called Handil, the traditional water management system applied to irrigate rice fields using tidal river system. One of the Handil in Central Kalimantan is called Handil Rakyat Palingkau in Kapuas which can control irrigation area for around 1397 ha. Agricultural land suitability analysis is needed to ensure land suitability based on land quality in requirements and planning. In this study, land analysis was determined using FAO parameters which were analyzed based on temperature, soil type, soil nutrient retention, hydro-topography, safe from flooding, and water quality. The results showed that the relevant aspects for rice were salinity, peat thickness, inundation, TDS, pyrite depth, and hydro topography. However, some aspects are unsuitable for rice that need more attention, such as pH, temperature, and soil nutrient retention.

ENVIRONMENTAL IMPACTS OF SHRIMP FARMING IN CHAKARIA UPAZILA OF COX’S BAZAR IN BANGLADESH

Aquaculture has become one of the fastest-growing economic sub-sectors of the Bangladesh economy, providing protein-rich food, the source of employment and foreign currency earnings. Therefore, shrimp farming is very much common in the brackish water which affects the coastal natural ecosystem and livelihood of the coastal communities, prticularly in Chakaria Upazila of Cox’s Bazar district. Due to rapid and unplanned growth of this farming, socio-ecological systesms has been changing. This study aims to assess shrimp farming’s environmental, social, and economic impacts in Chakaria upazila in Bangladesh. Soil sample was collected to determine the environmental impacts of shrimp farming. Besides, we selected the shrimp farmers, rice producers, and alternative shrimp-rice producers through simple random sampling. Purposive sampling was conducted to choose the other stakeholders. A semi-structured questionnaire was developed for interviewing different stakeholders. We found that, because of the high economic benefit, high production rate in short time, and availability of brackish water, the people in this Upazila are attracted to continue the shrimp farming. As a result, mangrove forest and agricultural land converted into shrimp farming. Our soil analysis showed that organic matter content in was low (0.25-3.56%). In addition to this, most people suffer from water-borne diseases during the flooding period. We also found clear evidene of shortage of safe drinking water due to salinity intrusion in grounwater. The tendency of raring livestock such as cow, goat, and buffalo decreased due to insufficient grazing land. The study also revealed that some internal conflicts exist between different stakeholders in Chakararia Upazila. Most local shrimp fry collectors collect fry from the tidal river and use an unscientific traditional method which was harmful for the other aquatic fish population. Poor quality of larvae supply from hatchery caused various diseases in cultivated ghers and ponds. The findings from this study provide useful information for sustainable coastal zone management in Bangladesh to build a more resilient coastal communities.

Freshwater Composition and Connectivity of the Connecticut River Plume During Ambient Flood Tides

The Connecticut River plume interacts with the strong tidal currents of the ambient receiving waters in eastern Long Island Sound. The plume formed during ambient flood tides is studied as an example of tidal river plumes entering into energetic ambient tidal environments in estuaries or continental shelves. Conservative passive freshwater tracers within a high-resolution nested hydrodynamic model are applied to determine how source waters from different parts of the tidal cycle contribute to plume composition and interact with bounding plume fronts. The connection to source waters can be cut off only under low-discharge conditions, when tides reverse surface flow through the mouth after max ambient flood. Upstream plume extent is limited because ambient tidal currents arrest the opposing plume propagation, as the tidal internal Froude number exceeds one. The downstream extent of the tidal plume always is within 20 km from the mouth, which is less than twice the ambient tidal excursion. Freshwaters in the river during the preceding ambient ebb are the oldest found in the new flood plume. Connectivity with source waters and plume fronts exhibits a strong upstream-to-downstream asymmetry. The arrested upstream front has high connectivity, as all freshwaters exiting the mouth immediately interact with this boundary. The downstream plume front has the lowest overall connectivity, as interaction is limited to the oldest waters since younger interior waters do not overtake this front. The offshore front and inshore boundary exhibit a downstream progression from younger to older waters and decreasing overall connectivity with source waters. Plume-averaged freshwater tracer concentrations and variances both exhibit an initial growth period followed by a longer decay period for the remainder of the tidal period. The plume-averaged tracer variance is increased by mouth inputs, decreased by entrainment, and destroyed by internal mixing. Peak entrainment velocities for younger waters are higher than values for older waters, indicating stronger entrainment closer to the mouth. Entrainment and mixing time scales (1–4 h at max ambient flood) are both shorter than half a tidal period, indicating entrainment and mixing are vigorous enough to rapidly diminish tracer variance within the plume.