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| Titel |
The spatial geochemical characteristics of groundwater and surface in the
Tuul River basin, Ulaanbatar, Mongolia |
| VerfasserIn |
Odsuren Batdelger, Maki Tsujimura, Byambasuren Zorigt, Enkhjargal Togtokh |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140814
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| Publikation (Nr.) |
 EGU/EGU2017-4252.pdf |
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| Zusammenfassung |
| The capital city, Ulaanbaatar, is located along the Tuul River and its water supply totally
dependent on the groundwater, which comes from the aquifer of the Tuul River. Due to the
rapid growth of the population and the increasing human pressures in this basin, water quality
has been deteriorating and has become a crucial issue for sustainable environmental and
socio-economic development.
Hydro-chemical and stable isotope tracing approaches were applied into the groundwater
and surface water in order to study geochemical characteristics and groundwater and surface
water interaction. The Tuul River water was mostly characterized by the Ca-HCO3 type,
spatially variable and it changed into Ca-Na-HCO3 type in the downstream of the city after
wastewater (WW) meets the river. Also, electrical conductivity (EC) values of Tuul River are
increasing gradually with distance and it increased more than 2 times after WW meets the
stream, therefore anthropogenic activities influence to the downstream of the river. The
dominant hydro-chemical facies of groundwater were the Ca-HCO3 type, which
represents 83% of the total analyzed samples, while Ca- HCO3-Cl-NO3, Na-HCO3,
Ca-HCO3-SO4 each represent 4%, and Ca-mixed and Ca-Mg-HCO3 each represent 2%
of the total samples. This suggests that groundwater chemistry is controlled by
rock-water interaction and anthropogenic pollution. The floodplain groundwater chemical
characteristics were similar to Tuul River water and showing lowest EC values.
Groundwater far from floodplain showed higher EC (mean value of 498 μs/cm) values than
river waters and floodplain groundwater. Also, different kinds of hydro-chemical
facies were observed. The stable isotopic compositions revealed less evaporation
effect on the groundwater and surface water, as well as an altitude effect in the river
water. The similarity of stable isotopes and chemical characteristics of floodplain
groundwater and river water suggests that alluvial groundwater is recharged by Tuul River
water in the study area. The cluster analysis (CA) clearly indicated a connection
between floodplain groundwater and river water, and also the effect of anthropogenic
activities (such as canal and WW) in the system. The analysis results show that CA is
a useful approach for future spatial sampling strategy in an optimal manner and
offers a reliable classification of sampling stations in the region, especially along
Tuul River. Therefore, the number of sampling stations in the monitoring network
could be optimized without losing any significant information and saving cost. |
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