scholarly journals Seasonal Variations in Groundwater Level and Salinity in Coastal Plain of Eastern China Influenced by Climate

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Shao-feng Yan ◽  
Shuang-en Yu ◽  
Yu-bai Wu ◽  
De-feng Pan ◽  
Dong-li She ◽  
...  
Keyword(s):  
Seawater Intrusion ◽  
Coastal Plain ◽  
Groundwater Level ◽  
Groundwater Resources ◽  
Eastern China ◽  
Dry Season ◽  
Groundwater Salinity ◽  
Wet Season ◽  
Continuous Precipitation ◽  
River Stage

The coastline of China is approximately 18,000 km long. In most coastal cities, seawater intrusion is a serious threat to groundwater resources. Nine shallow monitoring wells were constructed to study the dynamics of shallow groundwater level and salinity in the coastal plain region of Jiangsu province, China. Results showed that precipitation, evaporation, and river stage affected the groundwater level in our study area. Positive correlations were observed among the groundwater level, precipitation, and river stage; then negative correlation existed between the groundwater level and evaporation. The influencing factors on the groundwater level were in the order precipitation > river stage > evaporation. Sufficient precipitation during the wet season diluted the groundwater salinity. After the dilution, between two continuous precipitation events, the groundwater salinity increased as the groundwater level decreased. During the dry season, the groundwater salinity rapidly increased and reached its peak in December. The groundwater salinity in December was 23 times higher than that in July. The groundwater level and salinity in this study were generally associated with the season. Climate factors led to fluctuation of groundwater levels and salinity during the wet season, and seawater intrusion increased the groundwater salinity during the dry season.

scholarly journals Spatial variability of shallow groundwater level in the Northern Kathmandu Valley

2018 ◽  
Vol 55 (1) ◽  
pp. 45-54
Author(s):  
Manish Shrestha ◽  
Naresh Kazi Tamrakar
Keyword(s):  
Groundwater Level ◽  
Shallow Groundwater ◽  
Soil Surface ◽  
Northern Region ◽  
Dry Season ◽  
Kathmandu Valley ◽  
Wet Season ◽  
Geological Material ◽  
Groundwater Levels ◽  
Shallow Groundwater Level

Groundwater is the water which is present in pore spaces and in the fractures of the geological materials beneath earth surface. Water is incompressible substance and presence of small amount of water in geological material modifies the behavior of geological material under stresses. Determination of engineering behavior of the geological material is almost impossible skipping the role of water. The objective of this study was to map and evaluate shallow groundwater level of the northern Kathmandu Valley covering main rivers such as the Bagmati River, Bishnumati River, Dhobi Khola and the Manahara Khola. These rivers flow from the North to the South across the sand rich sediment zone. Static groundwater levels of 239 wells were measured from different locations of the study area in April/March 2017 (Dry Season) and in August 2017 (Wet Season). Shallow groundwater level was measured from soil surface to water level using well water depth logger (Qin and Li, 1998). The result showed that groundwater level ranged from 0.6 m to 12.5 m in dry season and 0.1 m to 13 m in wet season. The groundwater level increased by average of 34.68% (n = 235) as compared to that in dry season. Increase in the groundwater level suggests recharge of groundwater in wet season of the study area. The flow pattern of groundwater levels from the study shows flow of shallow groundwater towards the major rivers of that particular river watershed. As a consequence, seepage flow and piping erosion is likely along the riverbank slopes. Increase in recharge of groundwater during wet season exhibits that the northern region of the Kathmandu Valley is potential for groundwater recharge and can be used to manage water for the dry period.

Seasonal variation in the microbial quality of shallow groundwater in the Kathmandu Valley, Nepal

2013 ◽  
Vol 14 (3) ◽  
pp. 390-397 ◽  
Author(s):  
Sadhana Shrestha ◽  
Takashi Nakamura ◽  
Rabin Malla ◽  
Kei Nishida
Keyword(s):  
Groundwater Level ◽  
Seasonal Variations ◽  
Shallow Groundwater ◽  
Dry Season ◽  
Kathmandu Valley ◽  
Microbial Quality ◽  
Wet Season ◽  
Groundwater Levels ◽  
E Coli

To develop effective groundwater pollution control strategies for the Kathmandu Valley, Nepal, seasonal variations in microbial quality and their underlying mechanisms must be understood. However, to date, there are no studies that address these topics. In this study, groundwater samples from dug wells were collected during the dry and wet seasons from 2009 to 2012, and Escherichia coli (E. coli) and total coliforms were analysed. Three wells were monitored each month for a year. Microbial concentrations in shallow groundwater were significantly higher during the wet season than during the dry season. Analyses of rainfall and E. coli concentrations in different seasons indicated that a high level of faecal material infiltration during the rainy season may have caused the seasonal variations in microbial quality. A moderate to strong relationship between E. coli concentrations and groundwater level suggested that the rise in groundwater levels during the wet season may be another reason for this variation. This long time-scale survey detected a significant decline in the microbial quality of shallow groundwater during the wet season as compared with the dry season. We propose that the infiltration of contaminants and change in groundwater level are the two probable mechanisms for the observed seasonal differences.

scholarly journals The variation of stygofauna along a gradient of salinization in a coastal aquifer

2015 ◽  
Vol 47 (1) ◽  
pp. 89-103 ◽  
Author(s):  
M. Shapouri ◽  
L. Cancela da Fonseca ◽  
S. Iepure ◽  
T. Stigter ◽  
L. Ribeiro ◽  
...  
Keyword(s):  
Seawater Intrusion ◽  
Coastal Aquifer ◽  
Salinity Gradient ◽  
Groundwater Resources ◽  
Groundwater Salinity ◽  
Low Salinity ◽  
Composition And Structure ◽  
Shallow Wells ◽  
Southern Portugal ◽  
Highly Correlated

We examined the variation of stygofauna composition collected in wells, along a gradient in groundwater salinity/conductivity in a coastal aquifer from southern Portugal. The studied coastal aquifer is considered vulnerable to salinization due to seawater intrusion, caused by overexploitation of the aquifer. Knowing the response of the stygofauna species to present levels of groundwater salinity makes it possible to understand and measure the effects of saltwater intrusion on stygofauna, rendering them potential bioindicators of this environmental pressure. Biotic and abiotic sampling was conducted in six shallow wells located in the fresh–saltwater interface of the Arade estuary along the salinity gradient established in the groundwater from the estuary to inland locations (microSiemens/cm). Groundwater salinity was highly correlated with taxa distribution. The stygobites Eucyclops hadjebensis and Acanthocyclops sensitivus, the cosmopolitan Megacyclops viridis and Cypria ophtalmica were particularly associated with low-salinity conditions, whereas Eucyclops graeteri, Megacyclops brachypus and Daphnia pulicaria were related to high-salinity waters. Multivariate analyses indicated that stygofauna assemblages varied significantly with location. We suggest that stygofauna composition and structure can be a useful complementing tool for monitoring seawater intrusion into coastal aquifers, where reduction or deterioration in groundwater resources is predicted.

scholarly journals Development of Seawater Intrusion Vulnerability Assessment for Averaged Seasonality of Using Modified GALDIT Method

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1820
Author(s):  
Il Hwan Kim ◽  
Il-Moon Chung ◽  
Sun Woo Chang
Keyword(s):  
Sea Level ◽  
Seawater Intrusion ◽  
Groundwater Level ◽  
Anthropogenic Activities ◽  
Groundwater Resources ◽  
Dynamic Parameter ◽  
Management Plan ◽  
Coastal Areas ◽  
Seasonal Characteristics ◽  
Galdit Method

Climate change and anthropogenic activities are necessitating accurate diagnoses of seawater intrusion (SWI) to ensure the sustainable utilization of groundwater resources in coastal areas. Here, vulnerability to SWI was assessed by classifying the existing GALDIT into static parameters (groundwater occurrence (G), aquifer hydraulic conductivity (A), and distance from shore (D)) and dynamic parameters (height to groundwater-level above sea-level (L), impact of existing status of seawater intrusion (I), and aquifer thickness (T)). When assessing the vulnerability of SWI based on observational data (2010–2019), 10-year-averaged data of each month is used for GALDIT dynamic parameter for representing the seasonal characteristics of local water cycles. In addition, the parameter L is indicated by the data observed at the sea-level station adjacent to the groundwater level station. The existing GALDIT method has a range of scores that can be divided into quartiles to express the observed values. To sensitively reflect monthly changes in values, the range of scores is divided into deciles. The calculated GALDIT index showed that the most vulnerable month is September, due to relatively low groundwater level. The proposed method can be used to apply countermeasures to vulnerable coastal areas and build water resources management plan considering vulnerable seasons.

scholarly journals The precipitation variability of wet and dry season at the interannual and interdecadal scales over eastern China (1901–2016): The impacts of the Pacific Ocean

2020 ◽  
Author(s):  
Tao Gao ◽  
Fuqiang Cao ◽  
Li Dan ◽  
Ming Li ◽  
Xiang Gong ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Climate Variability ◽  
Southern Oscillation ◽  
Eastern China ◽  
Dry Season ◽  
Spatiotemporal Variability ◽  
Climatic Research Unit ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Wet Season

Abstract. The spatiotemporal variability of rainfall in dry (October–March) and wet (April–September) seasons over eastern China is examined based on gridded rainfall dataset from University of East Angela Climatic Research Unit during 1901–2016. Principal component analysis is employed to identify the dominant variability modes, wavelet coherence is utilized to investigate the spectral characteristics of leading modes of precipitation and their coherences with the large-scale modes of climate variability, and Bayesian dynamical linear model is adopted to quantify the time-varying correlations between climate variability modes and rainfall in dry and wet seasons. Results show that first and second principal components (PCs) account for 34.2 % (16.1 %) and 13.4 % (13.9 %) of variance in dry (wet) season, and their changes are roughly coincident with phase shifts of the El Niño–Southern Oscillation (ENSO) in both seasons. The anomalous moisture fluxes responsible for the occurrences of precipitation events in eastern China are asymmetry during high and light rainfall years in dry (wet) season. ENSO has a 4- to 8-year signal of the statistically positive (negative) association with rainfall during dry (wet) season in eastern China. The statistically significant positive (negative) associations between Pacific Decadal Oscillation (PDO) and precipitation are found with 9- to 15-year (4- to 7-year) signal. The impacts of PDO on rainfall in eastern China exhibit multiple time scales as compared to ENSO episodes, while PDO triggers a stronger effect on precipitation in wet season than dry season. The interannual and interdecadal variations in rainfall over eastern China are substantially modulated by drivers originated from Pacific Ocean, the finding has meaningful implications for regional hydrologic predictability and water resources management.

scholarly journals Development of monthly seawater intrusion vulnerability assessment method using GALDIT

2021 ◽  
Author(s):  
Il hwan Kim ◽  
IL-Moon Chung ◽  
Sun Woo Chang
Keyword(s):  
Sea Level ◽  
Seawater Intrusion ◽  
Groundwater Level ◽  
Groundwater Resources ◽  
Assessment Method ◽  
Coastal Areas ◽  
Dynamic Parameters ◽  
Groundwater Occurrence ◽  
Monthly Changes ◽  
Galdit Method

Accurate diagnoses of vulnerability of seawater intrusion (SWI) into aquifers are required to ensure sustainable utilization of groundwater resources in coastal areas. GALDIT was selected to assess the SWI vulnerability on western coastal areas of South Korea. Climate change trends are updated every year. The existing GALDIT method has various scores to express the changing observed values. However, they are limited because of their sensitivity in the assessment of regional characteristics or climatic change due to low weight flexibility. Therefore, this study assessed vulnerability to SWI by classifying the existing GALDIT into static and dynamic parameters. The static parameters include groundwater occurrence (G), aquifer hydraulic conductivity (A), and distance from the shore (D), whereas the dynamic parameters include height to groundwater level above sea level (L), impact of existing status of seawater intrusion (I), and aquifer thickness (T). The monthly mean was used as the dynamic index to reflect monthly variations. To indicate the temporal trend of parameter L was calculated based on the data observed at the sea level station adjacent to the groundwater level station. To sensitively reflect the monthly changes in values, the range of scores was divided into 10 parts. The calculated GALDIT index showed that the most vulnerable month was September. In the progress of SWI, vulnerability was assessed monthly to highlight the differences in parameters that fluctuate seasonally. The proposed method can be used to apply intensive countermeasures to vulnerable sites and build an operation plan considering the vulnerability period.

scholarly journals Investigating Groundwater Condition and Seawater Intrusion Status in Coastal Aquifer Systems of Eastern India

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1952
Author(s):  
Subrata Halder ◽  
Lingaraj Dhal ◽  
Madan K. Jha
Keyword(s):  
Groundwater Quality ◽  
Seawater Intrusion ◽  
Groundwater Level ◽  
Coastal Aquifer ◽  
Quality Data ◽  
Confined Aquifer ◽  
Groundwater Levels ◽  
Post Monsoon ◽  
Aquifer Systems ◽  
Sustainable Water Supply

Providing sustainable water supply for domestic needs and irrigated agriculture is one of the most significant challenges for the current century. This challenge is more daunting in coastal regions. Groundwater plays a pivotal role in addressing this challenge and hence, it is under growing stress in several parts of the world. To address this challenge, a proper understanding of groundwater characteristics in an area is essential. In this study, spatio-temporal analyses of pre-monsoon and post-monsoon groundwater-levels of two coastal aquifer systems (upper leaky confined and underlying confined) were carried out in Purba Medinipur District, West Bengal, India. Trend analysis of seasonal groundwater-levels of the two aquifers systems was also performed using Mann-Kendall test, Linear Regression test, and Innovative Trend test. Finally, the status of seawater intrusion in the two aquifers was evaluated using available groundwater-quality data of Chloride (Cl−) and Total Dissolve Solids (TDS). Considerable spatial and temporal variability was found in the seasonal groundwater-levels of the two aquifers. Further, decreasing trends were spotted in the pre-monsoon and post-monsoon groundwater-level time series of the leaky confined and confined aquifers, except pre-monsoon groundwater-levels in Contai-I and Deshpran blocks, and the post-monsoon groundwater-level in Ramnagar-I block for the leaky confined aquifer. The leaky confined aquifer in Contai-I, Contai-III, and Deshpran blocks and the confined aquifer in Nandigram-I and Nandigram-II blocks are vulnerable to seawater intrusion. There is an urgent need for the real-time monitoring of groundwater-levels and groundwater quality in both the aquifer systems, which can ensure efficient management of coastal groundwater reserves.

scholarly journals The seasonal changes of the gut microbiome of the population living in traditional lifestyles are represented by characteristic species-level and functional-level SNP enrichment patterns

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xue Zhu ◽  
Jiyue Qin ◽  
Chongyang Tan ◽  
Kang Ning
Keyword(s):  
Gut Microbiome ◽  
Seasonal Changes ◽  
Dry Season ◽  
Urban Setting ◽  
Snp Analysis ◽  
Wet Season ◽  
Human Gut ◽  
Human Gut Microbiome ◽  
Genome Level ◽  
Prevalent Species

Abstract Background Most studies investigating human gut microbiome dynamics are conducted on humans living in an urban setting. However, few studies have researched the gut microbiome of the populations living traditional lifestyles. These understudied populations are arguably better subjects in answering human-gut microbiome evolution because of their lower exposure to antibiotics and higher dependence on natural resources. Hadza hunter-gatherers in Tanzania have exhibited high biodiversity and seasonal patterns in their gut microbiome composition at the family level, where some taxa disappear in one season and reappear later. Such seasonal changes have been profiled, but the nucleotide changes remain unexplored at the genome level. Thus, it is still elusive how microbial communities change with seasonal changes at the genome level. Results In this study, we performed a strain-level single nucleotide polymorphism (SNP) analysis on 40 Hadza fecal metagenome samples spanning three seasons. With more SNP presented in the wet season, eight prevalent species have significant SNP enrichment with the increasing number of SNP calling by VarScan2, among which only three species have relatively high abundances. Eighty-three genes have the most SNP distributions between the wet season and dry season. Many of these genes are derived from Ruminococcus obeum, and mainly participated in metabolic pathways including carbon metabolism, pyruvate metabolism, and glycolysis. Conclusions Eight prevalent species have significant SNP enrichments with the increasing number of SNP, among which only Eubacterium biforme, Eubacterium hallii and Ruminococcus obeum have relatively high species abundances. Many genes in the microbiomes also presented characteristic SNP distributions between the wet season and the dry season. This implies that the seasonal changes might indirectly impact the mutation patterns for specific species and functions for the gut microbiome of the population that lives in traditional lifestyles through changing the diet in wet and dry seasons, indicating the role of these variants in these species’ adaptation to the changing environment and diets.

scholarly journals Seasonal Climate Impacts on Vocal Activity in Two Neotropical Nonpasserines

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 319
Author(s):  
Cristian Pérez-Granados ◽  
Karl-L. Schuchmann
Keyword(s):  
Air Temperature ◽  
Daily Rainfall ◽  
Climatic Conditions ◽  
Dry Season ◽  
Climate Impacts ◽  
Calling Behavior ◽  
Wet Season ◽  
Focal Species ◽  
Calling Activity ◽  
Vocal Activity

Climatic conditions represent one of the main constraints that influence avian calling behavior. Here, we monitored the daily calling activity of the Undulated Tinamou (Crypturellus undulatus) and the Chaco Chachalaca (Ortalis canicollis) during the dry and wet seasons in the Brazilian Pantanal. We aimed to assess the effects of climate predictors on the vocal activity of these focal species and evaluate whether these effects may vary among seasons. Air temperature was positively associated with the daily calling activity of both species during the dry season. However, the vocal activity of both species was unrelated to air temperature during the wet season, when higher temperatures occur. Daily rainfall was positively related to the daily calling activity of both species during the dry season, when rainfall events are scarce and seem to act as a trigger for breeding phenology of the focal species. Nonetheless, air temperature was negatively associated with the daily calling activity of the Undulated Tinamou during the wet season, when rainfall was abundant. This study improves our understanding of the vocal behavior of tropical birds and their relationships with climate, but further research is needed to elucidate the mechanisms behind the associations found in our study.

scholarly journals Inorganic Nitrogen Production and Removal along the Sediment Gradient of a Stormwater Infiltration Basin

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 320
Author(s):  
Qianyao Si ◽  
Mary G. Lusk ◽  
Patrick W. Inglett
Keyword(s):  
Removal Efficiency ◽  
N Mineralization ◽  
Inorganic Nitrogen ◽  
Dry Season ◽  
Pollutant Removal ◽  
Net N Mineralization ◽  
Wet Season ◽  
Inorganic N ◽  
N Removal ◽  
Stormwater Infiltration

Stormwater infiltration basins (SIBs) are vegetated depressions that collect stormwater and allow it to infiltrate to underlying groundwater. Their pollutant removal efficiency is affected by the properties of the soils in which they are constructed. We assessed the soil nitrogen (N) cycle processes that produce and remove inorganic N in two urban SIBs, with the goal of further understanding the mechanisms that control N removal efficiency. We measured net N mineralization, nitrification, and potential denitrification in wet and dry seasons along a sedimentation gradient in two SIBs in the subtropical Tampa, Florida urban area. Net N mineralization was higher in the wet season than in the dry season; however, nitrification was higher in the dry season, providing a pool of highly mobile nitrate that would be susceptible to leaching during periodic dry season storms or with the onset of the following wet season. Denitrification decreased along the sediment gradient from the runoff inlet zone (up to 5.2 μg N/g h) to the outermost zone (up to 3.5 μg N/g h), providing significant spatial variation in inorganic N removal for the SIBs. Sediment accumulating around the inflow areas likely provided a carbon source, as well as maintained stable anaerobic conditions, which would enhance N removal.

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