scholarly journals Groundwater recharge pathway according to the environmental isotope: the case of Changwu area, Yangtze River Delta Region of China

2021 ◽  
Author(s):  
Liang He ◽  
Junru Zhang ◽  
Suozhong Chen ◽  
Manqing Hou ◽  
Junyi Chen
Keyword(s):  
Groundwater Recharge ◽  
Lake Water ◽  
Yangtze River ◽  
Groundwater Resources ◽  
Yangtze River Delta ◽  
Shallow Aquifer ◽  
Confined Aquifer ◽  
Environmental Isotope ◽  
Groundwater Movement ◽  
Recharge Sources

Abstract Groundwater recharge is an important factor affecting water circulation. As groundwater has slow seepage, directly observing the seepage velocity and recharge path of groundwater in the aquifer is difficult. Environmental isotope technology has become an important means to clarify the mechanism of groundwater movement and the mechanism by which groundwater recharges from the micro and macro perspectives. The Changwu area of Jiangsu Province was taken as an example to identify the recharge sources of groundwater and the recharge paths of groundwater and surface water by using the measured data of isotopes D, 18O, 34S, and T. The results indicated that the shallow aquifer and the I confined aquifer in the Changwu area are mainly recharged by precipitation and surface lake water. The II confined aquifer along the Yangtze River is recharged by modern precipitation. Moreover, the II confined aquifer in the Henglin area was recharged by the ancient Yangtze River before 4,000 years ago, and no recharge relationship exists now. the recharge condition of the II confined aquifer around the northwest of Gehu Lake is in the climate environment of 8,000 years ago and was caused by the surface depression lake water at that time. Additionally, the concealed limestone aquifer is primarily supplied by the II confined aquifer, while the concealed sandstone aquifer supplies the II confined aquifer. Hence, to find out the recharge conditions of groundwater aquifers based on the environmental isotope is conducive to scientific and reasonable evaluation of groundwater resources and to ensure the sustainable development and utilization of groundwater resources.

scholarly journals Application of a Self-Organizing Map of Isotopic and Chemical Data for the Identification of Groundwater Recharge Sources in Nasunogahara Alluvial Fan, Japan

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 278 ◽  
Author(s):  
Takeo Tsuchihara ◽  
Katsushi Shirahata ◽  
Satoshi Ishida ◽  
Shuhei Yoshimoto
Keyword(s):  
Groundwater Recharge ◽  
Groundwater Resources ◽  
Paddy Rice ◽  
Alluvial Fan ◽  
Rice Fields ◽  
Isotopic Ratios ◽  
Self Organizing Map ◽  
Recharge Sources ◽  
Different Origins ◽  
Self Organizing

Paddy rice fields on an alluvial fan not only use groundwater for irrigation but also play an important role as groundwater recharge sources. In this study, we investigated the spatial distribution of isotopic and hydrochemical compositions of groundwater in the Nasunogahara alluvial fan in Japan and applied a self-organizing map (SOM) to characterize the groundwater. The SOM assisted with the hydrochemical and isotopic interpretation of the groundwater in the fan, and clearly classified the groundwater into four groups reflecting the different origins. Two groundwater groups with lower isotopic ratios of water than the mean precipitation values in the fan were influenced by the infiltration of river water flowing from higher areas in the catchments and were differentiated from each other by their Na+ and Cl− concentrations. A groundwater group with higher isotopic ratios was influenced by the infiltration of paddy irrigation water that had experienced evaporative isotopic enrichment. Groundwater in the fourth group, which was distributed in the upstream area of the fan where dairy farms dominated, showed little influence of recharge waters from paddy rice fields. The findings of this study will contribute to proper management of the groundwater resources in the fan.

scholarly journals Construction of spatio-temporal coupling model for groundwater level prediction: a case study of Changwu area, Yangtze River Delta region of China

2021 ◽  
Author(s):  
Liang He ◽  
Manqing Hou ◽  
Suozhong Chen ◽  
Junru Zhang ◽  
Junyi Chen ◽  
...  
Keyword(s):  
Groundwater Level ◽  
Yangtze River ◽  
Prediction Models ◽  
Groundwater Resources ◽  
Temporal Correlation ◽  
Yangtze River Delta ◽  
Dynamic Monitoring ◽  
Yangtze River Delta Region ◽  
Spatio Temporal ◽  
Groundwater Level Prediction

Abstract The dynamic monitoring data of groundwater level is an important basis for understanding the current situation of groundwater development and the utilization and planning of sustainable exploitation. The dynamic monitoring data of groundwater level are typical spatio-temporal sequence data, which have the characteristics of non-linearity and strong spatio-temporal correlation. The trend of dynamic change of groundwater level is the key factor for the optimal allocation of groundwater resources. However, most of the existing groundwater level prediction models are insufficient in considering the temporal and spatial factors and their spatio-temporal correlation. Therefore, construction of a space–time prediction model of groundwater level considering space–time factors and improvement of the prediction accuracy of groundwater level dynamic changes are of considerable theoretical and practical importance for the sustainable development of groundwater resources utilization. Based on the analysis of spatial–temporal characteristics of groundwater level of the pore confined aquifer II of Changwu area in the Yangtze River Delta region of China, the wavelet transform method is used to remove the noise in the original data, and the K-nearest neighbor (KNN) is used to calculate the water level. The spatial–temporal dataset and the long short-term memory (LSTM) are reconstructed by screening the spatial correlation of the monitoring wells in the study area. A spatio-temporal prediction model KNN-LSTM of groundwater level considering spatio-temporal factors is also constructed. The reliability and accuracy of KNN-LSTM, LSTM, support vector regression, and autoregressive integrated moving average model are evaluated by a cross-validation algorithm. Results showed that the prediction accuracy of KNN-LSTM is 20.68%, 46.54%, and 55.34% higher than that of other single prediction models.

scholarly journals Hydrochemical characteristics, hydraulic connectivity and water quality assessment of multilayer aquifers in Western Suzhou City, Northern Anhui Province, China

2021 ◽  
Author(s):  
Jie Ma ◽  
Song Chen ◽  
Songbao Feng ◽  
Diandian Ding
Keyword(s):  
Water Quality ◽  
Ion Exchange ◽  
Groundwater Resources ◽  
Water Quality Assessment ◽  
Unconfined Aquifer ◽  
Shallow Aquifer ◽  
Sodium Absorption ◽  
Confined Aquifer ◽  
Hydrochemical Characteristics ◽  
Reverse Ion Exchange

Abstract The present study focuses on the shallow phreatic aquifer (SA) and the upper confined aquifer (CA) developed in Cenozoic loose strata, which are the major regional groundwater resources for drinking, irrigation, industry and other water-related activities. Seven samples from SA and seventeen samples from CA were analyzed to depict the hydrochemical characteristics, categorize the hydrochemical facies, evaluate the hydraulic connectivity, and appraise the drinking water and irrigation water quality. The abundance of cations is Na+ > Ca2+ > Mg2+ > K+ and the anions is HCO3− > SO42− > Cl− in both aquifers, respectively. Groundwater chemistry is controlled by water-rock interactions such as halite dissolution, ion exchange, reverse ion exchange, silicate weathering, and followed by the dissolution of Glauber's salt. The low connectivity and moderate connectivity between these two aquifers has engendered. The majority of the ion concentrations are within the limit for drinking, only one sample from the shallow aquifer are greater than the limit of 250 mg/L, a total of 29% from the shallow unconfined aquifer and 14% from the confined aquifer were not within the limit of 250 mg/L. The sodium absorption ratio (SAR), residual sodium carbonate (RSC) and soluble sodium percentage (%Na) values reveal that all the samples are appropriate for irrigation uses. The the US salinity laboratory (USSL) diagram shows that sixteen CA samples and all the SA samples fall in the C3S1 zone, implying high salinity hazard and low alkalinity hazard.

scholarly journals Current Status and Temporal Trend of Potentially Toxic Elements Pollution in Agricultural Soil in the Yangtze River Delta Region: A Meta-Analysis

2021 ◽  
Vol 18 (3) ◽  
pp. 1033
Author(s):  
Shufeng She ◽  
Bifeng Hu ◽  
Xianglin Zhang ◽  
Shuai Shao ◽  
Yefeng Jiang ◽  
...  
Keyword(s):  
Yangtze River ◽  
Agricultural Soil ◽  
Toxic Elements ◽  
Temporal Trend ◽  
Meta Analysis ◽  
Yangtze River Delta ◽  
Potentially Toxic Elements ◽  
River Delta ◽  
The Yangtze River ◽  
The Yangtze River Delta

Potentially toxic elements (PTEs) pollution in the agricultural soil of China, especially in developed regions such as the Yangtze River Delta (YRD) in eastern China, has received increasing attention. However, there are few studies on the long-term assessment of soil pollution by PTEs over large regions. Therefore, in this study, a meta-analysis was conducted to evaluate the current state and temporal trend of PTEs pollution in the agricultural land of the Yangtze River Delta. Based on a review of 118 studies published between 1993 and 2020, the average concentrations of Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni were found to be 0.25 mg kg−1, 0.14 mg kg−1, 8.14 mg kg−1, 32.32 mg kg−1, 68.84 mg kg−1, 32.58 mg kg−1, 92.35 mg kg−1, and 29.30 mg kg−1, respectively. Among these elements, only Cd and Hg showed significant accumulation compared with their background values. The eastern Yangtze River Delta showed a relatively high ecological risk due to intensive industrial activities. The contents of Cd, Pb, and Zn in soil showed an increasing trend from 1993 to 2000 and then showed a decreasing trend. The results obtained from this study will provide guidance for the prevention and control of soil pollution in the Yangtze River Delta.

scholarly journals The Evolution of the Interactive Relationship between Urbanization and Land-Use Transition: A Case Study of the Yangtze River Delta

Land ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 804
Author(s):  
Bo Niu ◽  
Dazhuan Ge ◽  
Rui Yan ◽  
Yingyi Ma ◽  
Dongqi Sun ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
River Delta ◽  
Socioeconomic Factor ◽  
The Yangtze River ◽  
Land Use Transition ◽  
The Yangtze River Delta ◽  
Interaction Relationship

In recent years, the impact of land-use systems on global climate change has become increasingly significant, and land-use change has become a hot issue of concern to academics, both within China and abroad. Urbanization, as an important socioeconomic factor, plays a vital role in promoting land-use transition, which also shows a significant spatial dependence on urbanization. This paper constructs a theoretical framework for the interaction relationship between urbanization and land-use transition, taking the Yangtze River Delta as an example, and measures the level of urbanization from the perspective of population urbanization, economic urbanization and social urbanization, while also evaluating the level of land-use morphologies from the perspective of dominant and recessive morphologies of land-use. We construct a PVAR model and coupled coordination model based on the calculated indexes for empirical analysis. The results show that the relationship between urbanization and land-use transition is not a simple linear relationship, but tends to be complex with the process of urbanization, and reasonable urbanization and land-use morphologies will promote further benign coupling in the system. By analyzing the interaction relationship between urbanization and land-use transition, this study enriches the study of land-use change and provides new pathways for thinking about how to promote high-quality urbanization.

scholarly journals The Spatio-Temporal Analysis of Urban-Rural Coordinated Development and Its Driving Forces in Yangtze River Delta

Land ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 495
Author(s):  
Daizhong Tang ◽  
Mengyuan Mao ◽  
Jiangang Shi ◽  
Wenwen Hua
Keyword(s):  
Influencing Factors ◽  
Yangtze River ◽  
Driving Forces ◽  
Yangtze River Delta ◽  
River Delta ◽  
Urban Agglomeration ◽  
System Level ◽  
Actual State ◽  
Coordinated Development ◽  
Urban Rural

This paper conducts an analytical study on the urban-rural coordinated development (URCD) in the Yangtze River Delta urban agglomeration (YRDUA), and uses data from 2000–2015 of 27 central cities to study the spatial and temporal evolution patterns of URCD and to discover the influencing factors and driving forces behind it through PCA, ESDA and spatial regression models. It reveals that URCD of the YRDUA shows an obvious club convergence phenomenon during the research duration. The regions with high-level URCD gather mainly in the central part of the urban agglomeration, while the remaining regions mostly have low-level URCD, reflecting the regional aggregation phenomenon of spatial divergence. At the same time, we split URCD into efficiency and equity: urban-rural efficient development (URED) also exhibits similar spatiotemporal evolution patterns, but the patterns of urban-rural balanced development (URBD) show some variability. Finally, by analyzing the driving forces in major years during 2000–2015, it can be concluded that: (i) In recent years, influencing factors such as government financial input and consumption no longer play the main driving role. (ii) Influencing factors such as industrialization degree, fixed asset investment and foreign investment even limit URCD in some years. The above results also show that the government should redesign at the system level to give full play to the contributing factors depending on the actual state of development in different regions and promote the coordinated development of urban and rural areas. The results of this study show that the idea of measuring URCD from two dimensions of efficiency and equity is practical and feasible, and the spatial econometric model can reveal the spatial distribution heterogeneity and time evolution characteristics of regional development, which can provide useful insights for urban-rural integration development of other countries and regions.

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