Sedimentary heterogeneity conditions of Catania Plain quaternary aquifer (CPQA), the wider alluvial multi-aquifer system of Sicily, were rebuilt to simulate and quantify groundwater flow. Transition probabilities base...Sedimentary heterogeneity conditions of Catania Plain quaternary aquifer (CPQA), the wider alluvial multi-aquifer system of Sicily, were rebuilt to simulate and quantify groundwater flow. Transition probabilities based on a Markov Chain (MC) and Sequential Indicator Simulation (SIS) are the structure-imitating simulators utilized for generating stochastic distributions of hydraulic conductivity fields of CPQA, basing on borehole data: plausible equiprobable solutions of the complex geological structure of the CPQA were simulated. This study highlights that the choice of geostatistical simulation method plays a fundamental role in predictive scenarios for groundwater resources managing of CPQA. Indeed, simulated characteristics of the sedimentary heterogeneity constituted the basis of finite difference models for simulating the groundwater flow of CPQA. In heterogeneous systems such as CPQA, SIS may be inadequate for reproducing the macrostructures. Instead, MC adequately reproduced spatial connection of lithofacies, representing a more realistic solution dealing to the proposed geological model of CPQA. MC and SIS models were utilized to both assess the uncertainty of the generated hydraulic conductivity fields of CPQA and predictions about its behavior under normal stress conditions induced by urbanization. The calibration of CPQA groundwater flow models based on MC and SIS simulations allowed to achieve a realistic feedback about the quality of the geostatistical reconstructions of the geological heterogeneity field.展开更多
Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of wa...Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of water is not uniform across different localities and uses. As a result, circumstances have given many Sacramento Valley rice farmers the option to sell their water to users elsewhere, in lieu of using it themselves. Because the sold water is typically surface water that would normally help recharge local aquifers when applied to a field;it is reasonable to suspect that transferring that water elsewhere could adversely affect local aquifers since that recharge would be reduced. This study performs numerical experiments using the United States Geological Survey’s Central Valley Hydrologic Model (CVHM) to better understand the temporal effects of a set of land idling scenarios. CVHM is capable of modeling the entire Central Valley, which encompasses the Sacramento and San Joaquin Valleys, and of representing rice field idling on a large scale. These experiments were executed using historical data to contrast recently typical amounts of rice field idling with scenarios reflecting varying degrees of hypothetical, increased idling. In doing so, this study aims to characterize the nature and potential magnitude of idling rice fields on groundwater storage in the Sacramento Valley. The impact of these scenarios on groundwater storage was quantified relative to an unaltered baseline model scenario. The results of this research show rice field idling will reduce recharge and groundwater storage levels;these results may provide useful information for future policy decisions and provide a basis for future study.展开更多
文摘Sedimentary heterogeneity conditions of Catania Plain quaternary aquifer (CPQA), the wider alluvial multi-aquifer system of Sicily, were rebuilt to simulate and quantify groundwater flow. Transition probabilities based on a Markov Chain (MC) and Sequential Indicator Simulation (SIS) are the structure-imitating simulators utilized for generating stochastic distributions of hydraulic conductivity fields of CPQA, basing on borehole data: plausible equiprobable solutions of the complex geological structure of the CPQA were simulated. This study highlights that the choice of geostatistical simulation method plays a fundamental role in predictive scenarios for groundwater resources managing of CPQA. Indeed, simulated characteristics of the sedimentary heterogeneity constituted the basis of finite difference models for simulating the groundwater flow of CPQA. In heterogeneous systems such as CPQA, SIS may be inadequate for reproducing the macrostructures. Instead, MC adequately reproduced spatial connection of lithofacies, representing a more realistic solution dealing to the proposed geological model of CPQA. MC and SIS models were utilized to both assess the uncertainty of the generated hydraulic conductivity fields of CPQA and predictions about its behavior under normal stress conditions induced by urbanization. The calibration of CPQA groundwater flow models based on MC and SIS simulations allowed to achieve a realistic feedback about the quality of the geostatistical reconstructions of the geological heterogeneity field.
文摘Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of water is not uniform across different localities and uses. As a result, circumstances have given many Sacramento Valley rice farmers the option to sell their water to users elsewhere, in lieu of using it themselves. Because the sold water is typically surface water that would normally help recharge local aquifers when applied to a field;it is reasonable to suspect that transferring that water elsewhere could adversely affect local aquifers since that recharge would be reduced. This study performs numerical experiments using the United States Geological Survey’s Central Valley Hydrologic Model (CVHM) to better understand the temporal effects of a set of land idling scenarios. CVHM is capable of modeling the entire Central Valley, which encompasses the Sacramento and San Joaquin Valleys, and of representing rice field idling on a large scale. These experiments were executed using historical data to contrast recently typical amounts of rice field idling with scenarios reflecting varying degrees of hypothetical, increased idling. In doing so, this study aims to characterize the nature and potential magnitude of idling rice fields on groundwater storage in the Sacramento Valley. The impact of these scenarios on groundwater storage was quantified relative to an unaltered baseline model scenario. The results of this research show rice field idling will reduce recharge and groundwater storage levels;these results may provide useful information for future policy decisions and provide a basis for future study.
