GroMoPo Metadata for Covey Hill MODFLOW model

In the context of climate change, it is important to understand possible future projections and historical trends of groundwater recharge, flow, and discharge to surface reservoirs. Knowledge of a vast range of possible conditions is required to fully appreciate the variability of the hydrologic cycle and hence the long-term vulnerability of groundwater-dependent habitats. This research investigates historical trends for a groundwater-surface water interacting system that supports a fragile ecosystem in southern Quebec. A transient model was developed using MODFLOW to simulate site-wide groundwater flow for the study area. The model was used to simulate past hydrogeological conditions (1900-2010) using a new data set of available precipitation (rain and snowmelt) and temperature. This data set was used to simulate the overall groundwater budget and to determine groundwater discharge (river baseflow and spring flow) in the study area. This allows for the quantification of century-long trends in flow data, as well as the extreme maximum and minimum flows over 110 years. Recharge was variable, ranging from 41 to 197 mm/year over the study period. Lower recharge rates from 1950 to 1965 induced marked effects on spring flow. Although the trend is not statistically significant, there appears to be, for the second half of the study period (1966-2010), a tendency towards a reversal to an increase for recharge, hydraulic heads, spring flow and baseflows. A longer time series would be necessary to confirm this tendency. The simulated historical trends are compared with flow projections for future scenarios (2041-2070). The confirmation that the natural system has been subjected to a wide range of climatic conditions over the last century helps to inform about its resilience. This study highlights the utility of groundwater flow modeling using historical climate data sets to gain a better understanding of long-term trends for climate change-related hydrogeological and ecohydrological studies.

在气候变化研究的背景下，明晰地下水补给、径流以及向地表水库的排泄量的未来可能情景与历史演变趋势，具有重要意义。唯有掌握海量潜在情景的相关知识，方能充分认知水文循环的变异性，进而明确依赖地下水的生境的长期脆弱性。本研究针对魁北克南部一处维系脆弱生态系统的地表水-地下水交互系统，开展历史演变趋势分析。研究团队采用MODFLOW构建了研究区全域地下水径流瞬态模型，依托一套包含实测降水（降雨与融雪）与气温的全新数据集，对研究区1900年至2010年的水文地质条件进行了模拟。借助该数据集，研究人员模拟了研究区的地下水总均衡，并核算了地下水排泄量（含河道基流与泉水流量），借此可量化径流数据的百年演变趋势，以及110年间的极端最大与最小径流量。研究期内地下水补给量波动显著，区间为41毫米/年至197毫米/年；1950年至1965年间较低的补给速率，对泉水流量产生了显著影响。尽管该趋势未达到统计学显著性水平，但在研究期后半段（1966年至2010年），补给量、地下水位水头、泉水流量与基流均呈现回升趋势，需借助更长时间序列的数据方可验证这一趋势。研究将模拟得到的历史演变趋势，与未来情景（2041年至2070年）下的径流预测结果进行了对比。经证实，该自然系统在过去一个世纪中经历了多样的气候条件，这一结论有助于明确其气候恢复力。本研究凸显了依托历史气候数据集开展地下水流模拟的应用价值，可为气候变化相关水文地质与生态水文研究中对长期演变趋势的深入认知提供支撑。