Seawater Intrusion Research Articles

Ecohydrological Response of a Tropical Peatland to Rainfall Changes Driven by Intertropical Convergence Zone Variability

ABSTRACTAimTropical peatlands are globally significant carbon stores, increasingly threatened by human activities and climate change. However, their ecohydrological responses to shifting water availability remain poorly understood. In this study, we investigate the connections between climate change, hydrology and vegetation dynamics in a coastal tropical peatland in Panama, aiming to understand the effects of future drying on peatland dynamics.LocationBocas del Toro, Panama (9°22′54″N, 82°21′59″W).TaxonAngiosperms.MethodsHigh‐resolution multiproxy palaeoecological data, including pollen and plant macrofossils (vegetation), testate amoebae (water‐table depth) and physical peat properties, are used to explore the relationships between climate change, hydrology and vegetation in a coastal tropical peatland over the past 700 years. Downscaled climate simulations are integrated with this process‐based understanding to project the likely future responses of this coastal peatland to climate change.ResultsWe identify a clear connection between precipitation variability, driven by shifts in the Intertropical Convergence Zone and water‐table dynamics, which subsequently influence changes in the peatland vegetation mosaic. Historical drier periods are marked by the expansion of shrub communities into the open peatland plain.Main ConclusionsPalaeoecological studies incorporating climate and hydrological proxies are essential for understanding both recent and future ecohydrological dynamics of tropical peatlands. Our findings suggest that in response to future climate change, water tables will lower and shrub communities will expand due to rising temperatures and reduced precipitation. Additionally, future sea‐level rise, combined with declining rainfall, may result in seawater intrusion and significant vegetation shifts in coastal tropical peatlands.

Disaster Induced Agricultural Productivity in Coastal Regions of Bangladesh: A Stochastic Frontier Analysis Approach

The production and technical efficiency of the rice sector in Bangladesh’s coastal areas are vulnerable to a wide range of natural disasters and climate change issues. These regions face recurring threats from climatic events such as salinity intrusion, inundation, rising sea levels, and cyclones, which can significantly disrupt agricultural activities. In this paper, we conduct a comparative analysis of the rice producers’ technical efficiency based on their exposure to disaster-induced impacts over the past five years. Using the Stochastic Frontier Analysis, we examine factors influencing household-level productive efficiency in three coastal districts—Patuakhali, Cox’s Bazar, and Khulna. Our findings reveal that rice-producing households affected by natural disasters between 2014 and 2018 exhibited, on average, an 8.29 percentage point higher productive efficiency compared to unaffected households. When controlling for other confounding variables, such as household characteristics and external conditions, the efficiency gain rises to 19.8%. This suggests that households exposed to adverse climatic events may have adapted their farming practices to become more resilient, thus improving their productive efficiency in the long term. Moreover, our results indicate that a larger household size enhances efficiency by 6.7%. Households where rice farming is the primary occupation also tend to be more efficient, likely because of greater specialization and focus on improving agricultural practices. Finally, the age of the producer is positively associated with efficiency, reflecting the accumulation of farming experience and knowledge over time.

Research on the Patterns of Seawater Intrusion in Coastal Aquifers Induced by Sea Level Rise Under the Influence of Multiple Factors

In the context of global warming, rising sea levels are intensifying seawater intrusion in coastal areas. Due to the complex hydrodynamic conditions and increasing groundwater over-extraction in these regions, understanding the patterns of seawater intrusion is crucial for effective prevention and control. This study employed a sandbox model to investigate both vertical and horizontal seawater intrusion into a coastal unconfined aquifer with an impermeable dam under varying conditions of sea level rise, coastal slope, and groundwater pumping rate. Additionally, a two-dimensional SEAWAT model was developed to simulate seawater intrusion under these experimental conditions. The results indicate that sea level rise significantly increases the extent and intensity of seawater intrusion. When sea level rises by 3.5 cm, 4.5 cm, and 5.5 cm, the areas of the saline wedge reached 362 cm2, 852 cm2, and 1240 cm2, respectively, with both horizontal and vertical intrusion ranges expanding considerably. When groundwater extraction is superimposed, vertical seawater intrusion is notably intensified. At an extraction rate of 225 cm3/min, the vertical intrusion areas corresponding to sea level rises of 3.5 cm, 4.5 cm, and 5.5 cm were 495 cm2, 1035 cm2, and 1748 cm2, respectively, showing significant expansion, and this expansion becomes more pronounced as sea levels rise. In contrast, slope variations had a significant impact only on vertical seawater intrusion. As the slope decreased from tanα = 1/5 to tanα = 1/9, the upper saline wedge area expanded from 525 cm2 to 846 cm2, considerably increasing the vertical intrusion range. Finally, the combined effects of groundwater extraction and sea level rise exacerbate seawater intrusion more severely than either factor alone, presenting greater challenges for coastal water resource management.

Stable nutrient removal from wastewater with fluctuating seawater content ensured by an adaptable aerobic granular sludge microbiome

Seawater intrusion in coastal regions can alter the wastewater composition, threatening the microbial communities in wastewater treatment processes. An aerobic granular sludge (AGS) system was challenged by fluctuations in wastewater salinity levels promoted by seawater intrusion events for 286 days, divided into two stages. During stage I, the seawater content in wastewater increased stepwise, and over stage II the seawater content in wastewater oscillated throughout the day. Most of the time, the AGS effectively removed COD during the anaerobic phase, regardless of the wastewater salt content. Ammonium removal was slightly unstable (ca. 75 ± 19 %) during stage I, with nitrite release in the effluent. Over stage II, the ammonium content in the wastewater was fully removed. The nitrite content in the effluent decreased, and nitrate became the main nitrogen form released. Phosphate removal was quite unstable at the beginning, improving over time with complete removal achieved during stage II (ca. 98.4 ± 1.1 %). Taxa involved in nitrogen and phosphorous removal were identified in the AGS microbiome at both stages but with superior abundance in the latter stage. A diverse core microbiome, mainly composed of extracellular polymeric substances-producing bacteria (Thauera, Flavobacterium, Paracoccus) and denitrifying bacteria (Thiotrix, Azoarcus, Aequorivita) was identified in stage II. The AGS system efficiently managed daily oscillating seawater levels in wastewater, corroborated by the effective removal performance that seemed to be sustained by an adaptable AGS microbiome.

Identifying periods impacted by sewer inflow and infiltration using time series anomaly detection

Accurate diagnosis of sewer inflow and infiltration (I/I) is crucial for ensuring the safe transportation of sewage and the stability of wastewater treatment processes. Identifying periods impacted by I/I is essential for I/I diagnosis, but current methods lack a standard criterion and require adaptation to specific conditions, resulting in low accuracy, complexity, and limited generalizability. This paper proposes a novel approach to distinguish I/I periods from time series of sewer measurements based on anomaly detection theory through an iterative use of a time-series reconstruction model. This method eliminates the need for external data such as rainfalls and avoids intensive manual data analysis. Operating directly on in-sewer data, it enhances accuracy compared to existing approaches and is applicable to various external factors such as rainfall, snowmelt, and seawater intrusion. The method can be applicable to a broad range of monitoring data, including flow rate, temperature, and conductivity. Validated through simulation studies and demonstrated via real-life applications, this method offers an efficient solution for I/I detection, facilitating further I/I diagnosis, including I/I quantification and location identification.

Temporal dynamics of soil salinization due to vertical and lateral saltwater intrusion at an onshore aquaculture farm

Temporal dynamics of soil salinization due to vertical and lateral saltwater intrusion at an onshore aquaculture farm

Seasonal nitrogen sources and its transformation processes revealed by dual-nitrate isotopes in Xiamen Bay, China

The eutrophication load in coastal waters is gradually increasing due to excessive nitrate (NO3−) input caused by intense human activities. The tracing of NO3− sources as well as their biogeochemistry is crucial for the development of effective measures to alleviate the eutrophication load. In this study, seasonal seawater samples from Xiamen Bay were investigated to explore the sources and fates of NO3− using dual nitrate isotopes. The results indicated that the NO3− is less affected by biological processes and mainly influenced by the terrestrial sewage discharges (48%) during rainy seasons. Contrarily, as runoff input decreases and external seawater intrusion increases, the assimilation of phytoplankton dominates the process of nitrate removal during dry seasons. This study suggests that the increase in the input of terrestrial sewage nutrients is responsible for the increase in eutrophication in Xiamen Bay, providing a basis for controlling water eutrophication and regional environmental governance.

Experimental Study of Seawater Intrusion in Stratified Layers with Sloping Ocean–Aquifer Boundary

Experimental Study of Seawater Intrusion in Stratified Layers with Sloping Ocean–Aquifer Boundary

Coastal vertical land motion across Southeast Asia derived from combining tide gauge and satellite altimetry observations

Vertical land motion (VLM) is complex in Southeast Asia because this region is subject to a range of natural processes (e.g., earthquakes) and anthropogenic activities (e.g., groundwater withdrawal) that can change land heights. To aid in coastal management, long-term observations of VLM are as crucial as observations for climate-induced sea surface height changes; however, such long-term observations are sparse for Southeast Asian coasts. To fill this observational gap, here we derive monthly VLM time series from 1993 to 2020 at 50 coastal sites across Southeast Asia by combining tide-gauge records and newly generated satellite altimetry observations. These altimetry observations are reproduced sea-level products using new altimetry standards and more accurate geophysical corrections. Our 27-year-long VLM dataset shows high spatial variability and non-linear temporal changes in VLM across Southeast Asia. We identify several major sources that dominate the regional land-height changes, which include large subsidence due to groundwater extraction in Manila and Bangkok, land uplift in Indonesia and subsidence in Thailand from postseismic deformation resulting from the sequence of large Sumatran earthquakes since 2004, and land subsidence as a result of sediment compaction in Malaysia. Those signals are quantitatively or qualitatively consistent with observations from other sources. This VLM dataset can be used to advance our understanding of the physical mechanisms behind land-height changes and to improve sea level projections in the region.

A method for estimating maximum safe installable power for groundwater extraction with application to Africa

New groundwater development is a likely way to meet growing global water demand but needs careful management. To help inform the sustainable development of groundwater resources, a novel method based on the maximum safe installable power for water pumping systems and the maximum safe remaining installable power (considering current abstraction) is developed. The proposed model couples energy, technology and hydrogeological parameters, and is then developed to compute the maximum power that can be safely installed per km2 without exceeding a maximum annual pumpable volume, calculated through available recharge and storage. The model is applied to estimate the maximum safe installable power across Africa with a 0.2-degree resolution, using available energy and hydrogeological data. Constrained by recharge (considering that 25 % of the annual recharge is available for utilization), the maximum safe installable power ranges between 0 and 9960 W/km2 across Africa with regions such as the Congo Basin (~340 W/km2), and western Africa between the Ivory Coast and Nigeria (~230 W/km2) identified as having high potential for sustainable pumping system development. Constrained by storage (considering that 0.1 % of storage can be withdrawn per year), it ranges between 0 and 13,425 W/km2 highlighting the ability to harness storage for pumping system development in the large aquifers of Northern Sahara (~8720 W/km2). When considering limitations posed by both groundwater recharge and aquifer storage (considering that 25 % of the annual recharge and 0.1 % of storage can be withdrawn per year), along with current groundwater withdrawal, 93 % of the maximum safe installable power remains still installable on average across Africa. Nevertheless, 2 % of the locations are estimated to be already experiencing overexploitation, particularly in Sudan, northern Africa, and northeastern South Africa. These findings provide a novel and adaptable way to examine water security, which can assist institutions in targeting investments to meet water demand sustainably.

Utilizing deep learning to investigate the impacts of climate change on groundwater dynamics and pumping variability

Climate change occasionally leads to unprecedented groundwater level decline. This study investigates the impacts of climate change on groundwater level and pumping electricity consumption concurrently over an agricultural region in Central Taiwan. A hybrid deep learning model i.e., CNN-LSTM was employed to predict future groundwater level and pumping electricity using monthly precipitation and average temperature as exogenous inputs from 2007 to 2021. We adopted future projections for these climate inputs from the latest CMIP6 climate models spanning 15 years (2022–36) for shared socioeconomic pathways (SSPs) scenarios (SSP245 and SSP585). Results revealed that the groundwater level fluctuations in the region are indirectly influenced by climate-induced pumping, as evidenced by exacerbated energy consumption for groundwater extraction during periods of high temperatures and reduced precipitation. Future projections imply that pumping electricity is expected to rise by 2.5–5 % while groundwater level may decline by more than 1 m due to a reduction in average precipitation of about 50–150 mm and a rise in temperature of about 0.7–1.3 °C, respectively over the next 15 years (2022–36). Most notable impacts are witnessed for irrigation-intensive regions such as mid and distal fans. This study necessitates the need to collect and involve pumping along with climate information for a more pragmatic assessment of future groundwater level that may indirectly threaten the food and water security in the region through proficient management of groundwater resources.

Assessment of Aquifer Resistivity, Depth, and Thickness using Vertical Electrical Sounding (VES) in Parts of Bori Metropolis for Groundwater Exploration

Groundwater exploration is vital to guaranteeing a reliable water supply in both urban and rural locations. In Bori Metropolis, the growing demand for potable water necessitates a thorough examination of the aquifer system. Therefore, the purpose of this study is to determine the groundwater potential in Bori Metropolis by assessing aquifer resistivity, depth, and thickness using Vertical Electrical Sounding (VES). A total of 13 VES surveys were completed in the study region using the Schlumberger array. The apparent resistivity measurements were analyzed using 1D inversion techniques to determine aquifer depth and thickness. The results showed that aquifer resistivity values ranged from to at depths ranging from to . Aquifer thicknesses ranged from to , indicating a high groundwater potential in the area. The results indicate that the Bori Metropolis area comprises a well-defined aquifer system with a high potential for groundwater extraction. These findings give important information for future water resource management in the region.

Climate-Induced Saltwater Intrusion in 2100: Recharge-Driven Severity, Sea Level-Driven Prevalence.

Saltwater intrusion is a critical concern for coastal communities due to its impacts on fresh ecosystems and civil infrastructure. Declining recharge and rising sea level are the two dominant drivers of saltwater intrusion along the land-ocean continuum, but there are currently no global estimates of future saltwater intrusion that synthesize these two spatially variable processes. Here, for the first time, we provide a novel assessment of global saltwater intrusion risk by integrating future recharge and sea level rise while considering the unique geology and topography of coastal regions. We show that nearly 77% of global coastal areas below 60° north will undergo saltwater intrusion by 2100, with different dominant drivers. Climate-driven changes in subsurface water replenishment (recharge) is responsible for the high-magnitude cases of saltwater intrusion, whereas sea level rise and coastline migration are responsible for the global pervasiveness of saltwater intrusion and have a greater effect on low-lying areas.

Simulation of Seawater Intrusion and Upconing Processes in Mediterranean Aquifer in Response to Climate Change (Plana de Castellón, Spain)

Simulation of Seawater Intrusion and Upconing Processes in Mediterranean Aquifer in Response to Climate Change (Plana de Castellón, Spain)

Integrated impacts of mariculture on nitrogen cycling processes in the coastal groundwater of Beihai, southern China

Groundwater nitrogen (N) contamination in coastal zones is becoming an increasingly serious global issue. Mariculture, as a major anthropogenic activity, has profound impacts on coastal groundwater and constitutes an important source of coastal N contamination. However, a comprehensive understanding of the impact of mariculture on N cycling (especially N removal) is still lacking. Taking the Daguansha mariculture region in southern China as the study area, we aimed to investigate the environmental impact of mariculture on coastal groundwater and identify N cycling processes influenced by mariculture using hydrogeochemistry, multiple isotopes, coupled with 16S rRNA gene sequencing, and the quantitative polymerase chain reaction (qPCR) experiments. The results showed that the combined effects of seawater intrusion and seepage from land-based mariculture ponds have led to localized groundwater salinization in the region. Meanwhile, mariculture promotes nitrification and anammox processes in groundwater. The dominance of ammonia-oxidizing and anammox bacteria in the upper aquifer is attributable to local salinization, N and organic carbon input, as well as anoxic to suboxic conditions induced by seepage from aquaculture ponds. In addition, the gene abundances of ammonia oxidation (dominated by AOA) and denitrification were positively correlated, indicating their cooperative interaction. This study provides deeper insight into N cycling in coastal groundwater systems affected by extensive mariculture.

Enhancing Water Productivity under Climate Change Scenarios: Indian Perspective

The scarcity of water has grown into a significant obstacle to ecosystem preservation, food production for the expanding population, and social security and health maintenance. Our ecology is also threatened by water logging and salinity in numerous canal commands, seawater intrusion along the coast, wetland drying up, low stream flows, etc. Water supplies have suffered as a result of climate change. The issue of water shortage and agricultural production are made worse by the regular occurrence of catastrophic events like drought and floods. The problems facing a large nation like India include the temporal and geographical variability of floods and droughts as well as the stark spatial differences in the growing irrigated area. The irrigated agro-ecosystem faces several obstacles. The new challenges confronting the country include geographic variations in groundwater development, low usage and filtration of wastewater for irrigation, poor irrigation efficiency, particularly for canal irrigation, and spatial disparities in the country's growing irrigated area. One of the best ways to establish a favorable water regime for improved crop development and production in a rainfed argo-ecosystem is to save rainwater in various land forms and use it effectively. The most difficult places to manage are those that are prone to flooding and waterlogging. However, a number of technologies are available to help with the difficulties. In broadest sense, water productivity reflects the objectives of producing more food, income, livelihoods and ecological benefits at less social and environmental cost per unit of water.

Groundwater salinization and suitability assessment in the coastal aquifer of the Thiruvallur district, India

ABSTRACT This study was conducted to assess the groundwater suitability for drinking and irrigation and to recognize the comprehensive controls of groundwater salinization in the coastal regions of the Thiruvallur district. For this purpose, groundwater from 54 dug and bore wells at locations covering most of the coastal aquifer within 10 km was sampled and analyzed for various physicochemical parameters. The analytical results expose that the groundwater in the study area is slightly alkaline to alkaline, moderately fresh to highly saline, and very high in hardness. The dominance of significant ion concentrations was found in the following order: Na+ > Ca2+ > Mg2+ > K+ = Cl− > HCO3− > SO42− > NO3− >PO43− > F–. The Water Quality Index (WQI) map shows that 70% of the groundwater samples are unsuitable for drinking due to the enhanced levels of TDS, salinity, and significant major ionic concentrations. However, the rest of the groundwater samples are in excellent to good condition. The Hydrochemical Facies Evaluation Diagram (HFE-D) reveal that many samples show the overlapping in the mixing line between fresh groundwater and saltwater caused by seawater intrusion.

Unveiling subsidence patterns: Time series analysis for land deformation investigation in the west-Qurna oil field, Iraq

Land subsidence is a worldwide geological and environmental risk caused by natural occurrences and human actions. Its effects include a range of socio-economic, environmental, and hydrogeological consequences, such as damage to infrastructure like buildings, roads, bridges, and pipelines, as well as increased flooding and reduced groundwater storage capacity. Due to these diverse impacts, it is crucial to monitor the spatial and temporal scope of land subsidence. This study presents an investigation into land subsidence within the West-Qurna oil field, a large oil reservoir situated in Iraq's Basrah governorate. The study employs Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) analysis from the European Space Agency Sentinel 1A over six years, from June 2017 to May 2023. The Stanford Method for Persistent Scatterers (StaMPS) has been utilised to assess the scale and magnitude of land deformations in this region. Results revealed a notable subsidence within the central urban area of the oil field, forming an ellipsoidal subsidence bowl spanning 86 km2. The peak subsidence rate is identified at −13.2 ± 0.4 mm/yr within this bowl, with a cumulative vertical displacement of 75 mm throughout the six-year observation period. Furthermore, uplifting phenomena are also detected at the study area's peripheries, reaching a maximum rate of 12 ± 0.4 mm/yr and a cumulative shift of 54 mm. Temporal analysis showcases a significant alteration in subsidence rates, with rates of −18 mm/yr observed between 2017 and 2020, followed by −5 mm/yr post-2020. This change is attributed to COVID-19-related oil production reductions enacted by the government to boost prices. Our analysis points toward oil extraction as a probable primary driver of subsidence in the studied area, although a deeper probe into the impact of groundwater extraction for reservoir injection remains essential.

Influence of River Discharge and Tides on the Salinity Structure at the Magdalena River Estuary

The salinity structure in the Magdalena River estuary results from a massive river discharge and a micro-tidal regime over a narrow-deep channel. Both environmental forcings are analyzed here to assess their effects on the temporal and spatial variability of the estuarine system. We investigated long-term (seasonal to interannual) and short-term (diurnal) changes in salinity structure and circulation through in situ measurements and a 3D hydrodynamic model ensemble (21 model runs). The measurements cover low (below 10th percentile) and mean river discharge conditions. Results show that the Magdalena River estuary (MRE) behaves as a strongly stratified system during the dry season (February to April) and as a vertically homogeneous one during the wet and transitional seasons when the river plume exhibits a lift-off regime at the mouth. A river discharge threshold has been found for the estuary to lift-off regime transition, corresponding to the 30th percentile (5200 m3/s). At the seasonal scale, the salinity intrusion length in the MRE shows more reactivity to river discharge variability than other reported strongly stratified estuaries; it is reflected in the scaling factor n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n$$\\end{document} in the relationship L∼Q-n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$L\\sim {Q}^{-n}$$\\end{document}. A n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n$$\\end{document} value of 3.9 is the best fit for the MRE; nevertheless, it follows the Schijf and Schönfeld theoretical model solution for a prismatic flat configuration. Micro tides modulate the salinity intrusion on the diurnal cycle with a more significant effect on salinity intrusion and water exchange than previously reported, particularly during low discharge conditions. The findings from measurements and model scenarios for the MRE can be broadly applied and stand for an exemplary tropical, micro-tidal, anthropogenic intervened system.

Impacts of salinity intrusion on agriculture in the coastal region of Bangladesh

Impacts of salinity intrusion on agriculture in the coastal region of Bangladesh