Water injection in aquifers to stabilize water level is a novel method to prevent shaft failure. However, with the progression of water injection, the flow rate of water injection decreases gradually. Through analysis, it is considered that the fine particles in sand migrate to form a dense structure, which hinders the increase of water flow. In order to investigate the migration mechanism of fine particles in the aquifer during water injection, experimental tests and numerical simulations were conducted in the present study. First, the physical experiment was designed, and it was shown that the water pressure difference between the two pressure gauges gradually decreased, while the water flow rate per hour slowly decreased. Furthermore, the permeability coefficient of sand near the outlet became smaller and smaller with the migration of fine particles, which indicated that the fine particles among sand grains migrated gradually from the water injection inlet to the outlet. Additionally, the water flow channels formed slowly. Then, the microscopic mechanism of fine particle migration was studied using particle flow code numerical simulation. During water injection, water pressure and porosity of sand decreased from the water injection inlet to the outlet, while the coordination number of particles increased on the whole. Contact force chain gradually strengthened near the outlet side during water injection. The trends of force chain distribution, the coordination number distributions and the evolution of porosity were consistent, which highlighted the process of fine particles migrating from the injection inlet to the outlet in the aquifer.
相似文献Drought and water scarcity can significantly impair the sustainable development of groundwater resources, a scenario commonly found in aquifers in the Mediterranean region. Water management measures to address these drivers of groundwater depletion are highly relevant, especially considering the increasing severity of droughts under climate change. This study evaluates the potential of managed aquifer recharge (MAR) to offset the adverse effects of drought and water scarcity on groundwater storage. Los Arenales aquifer (central Spain), which was unsustainably exploited for irrigation in the second half of the twentieth century, is employed as a case study. Two neighbouring zones within this aquifer are contrasted, namely, Los Arenales (LA) and Medina del Campo (MC). The primary difference between them in terms of water resources management is the wide-scale implementation of MAR systems in LA since the early 2000s. Several groundwater statistical methods are used. Groundwater-level trend analysis and average piezometric levels show in LA a faster recovery of aquifer storage and less susceptibility to drought compared to MC. On the other hand, standardised precipitation indexes and standardised groundwater level indexes of detrended groundwater-level time series, which do not include the effects of MAR, show that LA can be more negatively affected by drought and groundwater abstraction. The sharper recovery of piezometric levels in LA when considering MAR, and bigger drought impacts observed when the effects of this measure are removed, demonstrate that MAR can effectively alleviate the impacts of water scarcity and drought, providing an adaptation solution to climate change worldwide.
相似文献The progressive electrification of the building conditioning sector in recent years has greatly contributed to reducing greenhouse gas emissions by using renewable energy sources, particularly shallow geothermal energy. This energy can be exploited through open and closed shallow geothermal systems (SGS), and their performances greatly depend on the ground/groundwater temperature, which can be affected by both natural and anthropogenic phenomena. The present study proposes an approach to characterize aquifers affected by high SGS exploitation (not simulated in this work). Characterization of the potential hydro/thermogeological natural state is necessary to understand the regional flow and heat transport, and to identify local thermal anomalies. Passive microseismic and groundwater monitoring were used to assess the shape and thermal status of the aquifer; numerical modeling in both steady-state and transient conditions allowed understanding of the flow and heat transport patterns. Two significant thermal anomalies were detected in a fluvio-glacial aquifer in southern Switzerland, one created by river water exfiltration and one of anthropogenic nature. A favorable time lag of 110 days between river and groundwater temperature and an urban hot plume produced by underground structures were observed. These thermal anomalies greatly affect the local thermal status of the aquifer and consequently the design and efficiency of current and future SGS. Results show that the correct characterization of the natural thermo-hydrogeological status of an aquifer is a fundamental basis for determining the impact of boundary conditions and to provide initial conditions required to perform reliable local thermal sustainability assessments, especially where high SGS exploitation occurs.
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