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

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.

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Evaluation of groundwater recharge sources based on environmental tracers in an arid alluvial fan, NW China

Journal of Radioanalytical and Nuclear Chemistry ◽

10.1007/s10967-018-6272-8 ◽

2018 ◽

Vol 319 (1) ◽

pp. 123-133 ◽

Cited By ~ 2

Author(s):

Wei Xu ◽

Pucheng Zhu ◽

Fengtian Yang

Keyword(s):

Groundwater Recharge ◽

Alluvial Fan ◽

Environmental Tracers ◽

Nw China ◽

Recharge Sources

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Application of Multiple Approaches to Investigate the Hydrochemistry Evolution of Groundwater in an Arid Region: Nomhon, Northwestern China

Water ◽

10.3390/w10111667 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1667 ◽

Cited By ~ 5

Author(s):

Nuan Yang ◽

Guangcai Wang ◽

Zheming Shi ◽

Dan Zhao ◽

Wanjun Jiang ◽

...

Keyword(s):

Stable Isotopes ◽

Qaidam Basin ◽

Groundwater Resources ◽

Atmospheric Precipitation ◽

Northwest China ◽

Major And Trace Elements ◽

Alluvial Fan ◽

Hydrogeochemical Processes ◽

Recharge Sources ◽

Gypsum Precipitation

Groundwater is a critical water resource for human survival and economic development in arid and semi-arid areas. It is crucial to understand the groundwater circulation and hydrochemical evolution for sustainable management and utilization of groundwater resources in those areas. To this end, an investigation of the hydrochemical characteristics of surface water and groundwater was conducted in Nomhon, an arid area located in the Qaidam Basin, northwest China, by using hydrochemical (major and trace elements) and stable isotopes (δD and δ18O) approaches. Stable isotopes and ion ratios were analyzed to determine the recharge sources, hydrochemistry characteristics, and major hydrogeochemical processes. Meanwhile, inverse geochemistry modeling was applied to quantitatively determine the mass transfer of hydrogeochemical processes. The results showed that groundwater in the study area is mainly recharged by atmospheric precipitation in mountainous areas, and the groundwater in the center of basin might originate from ancient water in cold and humid environments. Along the groundwater flow path, the TDS of groundwater increased gradually from fresh to salty (ranging from 462.50 to 19,604.40 mg/L), and the hydrochemical type changed from Cl·HCO3–Na·Mg·Ca to Cl–Na. Groundwater chemical composition and mass balance modeling results indicated that from alluvial fan to lacustrine plain, the main hydrogeochemical processes changed from the dissolution of halite and albite and the precipitation of dolomite and kaolinite to the dissolution of halite and gypsum, precipitation of calcite, redox (SO42− reduction), and cation exchange. This study would be helpful for water resources management in this area and other similar areas.

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Patterning Waterbird Assemblages on Rice Fields Using Self-Organizing Map and Random Forest

Korean Journal of Environmental Agriculture ◽

10.5338/kjea.2015.34.3.26 ◽

2015 ◽

Vol 34 (3) ◽

pp. 168-177 ◽

Cited By ~ 1

Author(s):

Hyung-Kyu Nam ◽

Seung-Hye Choi ◽

Jeong-Chil Yoo

Keyword(s):

Random Forest ◽

Rice Fields ◽

Self Organizing Map ◽

Waterbird Assemblages ◽

Self Organizing

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Feature-based Groundwater Hydrograph Clustering Using Unsupervised Self-Organizing Map-Ensembles

Water Resources Management ◽

10.1007/s11269-021-03006-y ◽

2021 ◽

Author(s):

Andreas Wunsch ◽

Tanja Liesch ◽

Stefan Broda

Keyword(s):

Selection Process ◽

Groundwater Resources ◽

Regional Scale ◽

Upper Rhine Graben ◽

Self Organizing Map ◽

Cluster Number ◽

Robust Clustering ◽

Homogeneous Groups ◽

Feature Based ◽

Self Organizing

AbstractHydrograph clustering helps to identify dynamic patterns within aquifers systems, an important foundation of characterizing groundwater systems and their influences, which is necessary to effectively manage groundwater resources. We develope an unsupervised modeling approach to characterize and cluster hydrographs on regional scale according to their dynamics. We apply feature-based clustering to improve the exploitation of heterogeneous datasets, explore the usefulness of existing features and propose new features specifically useful to describe groundwater hydrographs. The clustering itself is based on a powerful combination of Self-Organizing Maps with a modified DS2L-Algorithm, which automatically derives the cluster number but also allows to influence the level of detail of the clustering. We further develop a framework that combines these methods with ensemble modeling, internal cluster validation indices, resampling and consensus voting to finally obtain a robust clustering result and remove arbitrariness from the feature selection process. Further we propose a measure to sort hydrographs within clusters, useful for both interpretability and visualization. We test the framework with weekly data from the Upper Rhine Graben System, using more than 1800 hydrographs from a period of 30 years (1986-2016). The results show that our approach is adaptively capable of identifying homogeneous groups of hydrograph dynamics. The resulting clusters show both spatially known and unknown patterns, some of which correspond clearly to external controlling factors, such as intensive groundwater management in the northern part of the test area. This framework is easily transferable to other regions and, by adapting the describing features, also to other time series-clustering applications.

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Multiple‐indicator study of the response of groundwater recharge sources to highly turbid river water after a landslide in the Tedori River alluvial fan, Japan

Hydrological Processes ◽

10.1002/hyp.13796 ◽

2020 ◽

Vol 34 (16) ◽

pp. 3539-3554

Author(s):

Yumi Yoshioka ◽

Kimihito Nakamura ◽

Hiroshi Takimoto ◽

Shinji Sakurai ◽

Takao Nakagiri ◽

...

Keyword(s):

Groundwater Recharge ◽

River Water ◽

Alluvial Fan ◽

Recharge Sources ◽

Multiple Indicator

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

Water Science & Technology Water Supply ◽

10.2166/ws.2021.422 ◽

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.

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Influence of a dual monsoon system and two sources of groundwater recharge on Kofu basin alluvial fans, Japan

Hydrology Research ◽

10.2166/nh.2016.208 ◽

2016 ◽

Vol 48 (4) ◽

pp. 1071-1087 ◽

Cited By ~ 4

Author(s):

Takashi Nakamura ◽

Kei Nishida ◽

Futaba Kazama

Keyword(s):

Mass Balance ◽

Groundwater Recharge ◽

River Water ◽

Isotopic Analysis ◽

Alluvial Fan ◽

Alluvial Fans ◽

Recharge Sources ◽

Balance Analysis ◽

Monsoon System ◽

Mass Balance Analysis

This study investigates the contribution ratios of different groundwater recharge sources and influence of a dual monsoon system in Kofu basin, central Japan, through the hydrogen and oxygen isotopic analysis of precipitation, river water, and groundwater. The study is focused on the area of the Kamanashigawa and Midaigawa alluvial fans, which are formed by two main rivers. Precipitation isotopic content exhibits significant seasonal variability. Also, river water presents d-excess values higher than annual precipitation at plain areas (9 and 10‰), suggesting that two different air-masses contribute to precipitation, corresponding to the monsoon and pre-monsoon periods. The results of this study allow estimation of relative contributions of different sources to groundwater and influence of a dual monsoon system. The mass-balance analysis of the δ18O to identify the groundwater source indicates the river water contributes 38–100% of the recharge, while precipitation contributes 29–62% in Kamanashigawa alluvial fan. In the case of Midaigawa alluvial fan, river water contributes 77–99% in the northern part; in the southern side, 30–93% of contribution comes from precipitation. The mass-balance analysis of the d-excess indicates pre-monsoon precipitation contributes 46–68% and 39–65% to groundwater of the Kamanashigawa and Midaigawa alluvial fans, respectively.

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