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ABSTRACT: The Nanwenquan (South Hot Spring) and Xiao quan (Small Hot Spring) in the Nanwenquan anticline are well-known attraction for their geothermal water, but currently, the two natural hot springs have hot flow naturally. In order to protect the geothermal water resource, the evolution of hydrodynamic field must be researched for the causation of the hydrodynamic field destroyed. The finite element numerical simulation was adopted and quantitative study on the geothermal water hydrodynamic field. The finite element model was set up to simulate the research sites, the simulated water level was compared with the actual water level, the feasibility of this model was proved when the simulated water level is approximate to actual one, and an applicable finite element model was obtained. The finite element model was used to simulate the evolution of the hydrodynamic field. This paper supplies a basis to exploit adequately and protect effectively the geothermal water resource, at the same time it is proved feasible in practice to apply finite element numerical simulation to quantitative study of the geothermal water. [Copyright &y& Elsevier]

The stable carbon isotopic composition of speleothems is an important but incompletely understood parameter in paleoclimatological and paleoenvironmental reconstruction, recording changes in vegetation and hydrology. This study systematically assesses the influences of karst hydrology, cave environment, and carbon sources on the δ13C values of farmed calcite in Furong Cave, located in Chongqing, southwest China. Six drip sites (MP1-MP5) were monitored between 2009 and 2019, and Δ14C data (Δ14C is the difference in the 14C/12C ratio between a sample and a standard, expressed in permille, ‰) of soil organic matter, drip water and farmed calcite (calcite precipitated on a glass substrate) were obtained. A linear relationship was found between the seasonal variability of p CO 2 in cave air and δ13C Cc of the farmed calcite in "Great Hall" characterised by a relatively stable microenvironment. The growth rate and δ13C Cc values of the farmed calcite was not be affected by the drip rate unless the drip rate decreased to <1 drip/min for a long time, leading to a decrease in growth rate and higher δ13C Cc values because of longer CO 2 degassing. MP2 and MP9 show faster drip rates, higher δ13C DIC and lower Δ14C than MP1 and MP3, which suggests that the "old carbon" in MP9 is derived from the host rock. MP4 and MP5 are characterised by slower drip rates and lower δ13C DIC and δ13C Cc , and the Δ14C values of the farmed calcite are lower than those of MP9. The slow drip rate indicates that less infiltration water reaches MP4 and MP5, and soil CO 2 derived from the decomposition of "old" organic matter enters the fractures that lead to these drip sites. The fast drip rate of MP9 suggests that the fissures feeding this drip site are mostly water-saturated, limiting the exchange between soil CO 2 and CO 3 2− and allowing more "old carbon" from the bedrock to dissolve leading to higher δ13C DIC. This study emphasizes that in addition to changes in the cave environment, the source(s) of the carbon may be a more important factor controlling the δ13C values of drip water (and speleothem) than drip rate. • Carbon isotopic techniques along with 10-year cave monitoring explores multiple carbon sources in drip water and speleothems. • "Old carbon" in drip water feeding by open/close system is from "old" organic matter/bedrock, respectively. • Carbon source is a more important factor to control on δ13C of drip water (and speleothems) than drip rate. [ABSTRACT FROM AUTHOR]