Obtaining Aquifer Parameter From Groundwater Level Response To Barometric Pressure And Earth Tides

The permeability and structural characteristics of aquifers may change under the influence of tectonic activities and human factors.However,the traditional pumping/injection test methods cannot continuously obtain aquifer parameters,and therefore cannot continuously monitor the aquifer permeability and structural changes.Many studies have shown that groundwater can produce obvious periodic signals under the earth tides and barometric pressure,which can be used for continuous acquisition of continuous aquifer parameters.Such methods have important theoretical and practical significance for obtaining the parameters of aquifers at special sites.In the thesis,the groundwater monitoring wells located in the high-level waste pre-selection area?ALS well?and the coal mining area?J6 well?are selected as the research objects.The tidal and barometric effects recorded by the two wells are analyzed by collecting observation data such as water level and barometric pressure.Applying different tidal and barometric response models,the hydraulic parameters and elastic parameters of the aquifers of the two wells were obtained respectively.?1?Combining the two inversion methods of tidal factor and amplitude,the calculated specific storage ranges from 2.49×10^-61/m?1.25×10^-51/m of J6 well-aquifer system while around 1×10^-61/m?5.4×10^-61/m for the ALS well-aquifer system.?2?The tidal analysis results show that the phase shift of M₂ wave in both wells are positive,based on the vertical flow model under the action of tide,the transmissivity of the aquifer where the two wells are located evolves with time.The result of aquifer transmissivity in J6 well show stable-increase-recovery process during the study period,which may be due to the mining-induced changes.For the ALS well,the transmissivity also show fluctuates periodically?with ranges from 1?7m²/d?,the fluctuation may be related to changes in groundwater runoff in the aquifer where the wellbore is located.?3?Based on the four methods to estimate the barometric efficiency of aquifer,the porosity,Skempton coefficient and rock compressibility are calculated.The results show that the Skempton coefficient estimated by the barometric efficiency method is reasonable,and the porosity obtained is smaller than the measured value,while the compressibility is one order of magnitude different from the measured value.In general,the method based on tide and barometric pressure response has certain reference value for the continuous monitoring of aquifer medium in some specific areas,and it should be paid attention to in related work in the future.