Seepage Characteristics of Karst Water System Using Temperature Tracer Technique

Abstract

In order to reveal the hydrodynamic characteristics of the karst aquifer system, the water temperature dynamic data of a hydrological year in the direct recharge area of Jinan spring area were analyzed using the temperature tracer method, and the runoff intensity of karst water was estimated. The results revealed that, affected by the regional groundwater flow, the vertical temperature profile of the study area consists of four types, a gradual cooling type, a gradual heating type, a temperature‐increasing type, and “S” type. Based on these four geothermal types, three heat transfer models adapted to the region were developed. The inflection point method is used to discriminate the horizontal runoff channels of the three depth segments in the Ordovician strata in the recharge area, and the shallow groundwater horizontal runoff intensity is greater than the deep. According to the calculation of the thermal transport model, the Ordovician limestone in the direct recharge area of the spring area is shallow (at a depth of 100 m), and the vertical flow velocity of the groundwater is around 1.28 × 10−7–3 × 10−6 cm/s, and the flow rate is slow. Based on the field tracer test, the visual flow of the karst water system was found to range between 29.41 and 115.02 m/day, indicating that the karst water is dominated by horizontal motion. Since the method of temperature measurement in the hole is relatively simple, the temperature change signal could be used to reveal the seepage characteristics of the groundwater.

Microbial community structure characteristics among different karst aquifer systems, and its potential role in modifying hydraulic properties of karst aquifers

“…Heat carried by groundwater serves as a tracer to identify flow through fractures, and flow patterns in groundwater basins ( Anderson, 2005 ), and the groundwater flow in the preponderance flow path interferes with the normal temperature distribution of the formation, and the information of groundwater seepage in the formation can be inferred from the anomaly of the temperature curve ( Chi et al, 2020 ). In this study, six boreholes ‘temperature-depth’ profile were used to characterize the hydraulic properties of aquifers, the temperature gradient in B1, B2, B3, B4, B5, and B6 were 4.3, 1.7, 1.5, 0.6, 1.8, and1.0°C/100 m, respectively ( Figure 4 ).…”

Extreme Learning Machine Predicts High-Frequency Stream flow and Nitrate-N Concentrations in a Karst Agricultural Watershed

“…One possible explanation is that soil temperature variability reflects infiltration of influent rainfall and preferential flows, which will impact the extent of transport to the monitored surface channel and hence enable improved understanding of water attenuation by the soil layers. Similarly, for nitrate-N concentrations, soil moisture temperature is a non-conservative tracer (e.g., Chi et al, 2020) and will reflect the extent of mixing of pre-event matrix waters and new water from the event. Therefore, it may have aided in accounting for the time-varying concentration dynamics of the pore waters that are then transported to preferential flow paths during events.…”

Flow Field Fitting Method and Acoustic Doppler Velocity Measurement: A New Approach for Detecting Leakage Pathways in Concrete‐Face Rockfill Dams

“…The MMR method measures the magnetic field by injecting low-frequency current between electrodes A and B; it can detect preferential flow paths (Jessop et al, 2018). Other methods, such as the temperature-field detection method, fluorescent tracer tests and multi-tracer tests (e.g., Battaglia et al, 2016;Chi et al, 2020;Fargier et al, 2014;Haizhou et al, 2016), are used only as auxiliary leakage detection methods and are usually used in combination with other geophysical methods to identify the location of leakages. However, for CFRD, the GPR, the mise à la masse and ERI method are not applicable, because the surface of the CFRD is concrete.…”