GroMoPo Metadata for Algarve coastal aquifer model

The following paper presents a discussion of spatial and temporal distribution of groundwater discharge estimates at a regional scale for two coastal aquifer systems in the Algarve region. A finite element distributed parameter groundwater flow model is applied to analyze the effect of uncertainties regarding definition of model boundary conditions and seasonality on estimated values. Finally, estimates of sustainable yields are provided based on predefined sustainability criteria and the importance of well location is analyzed. Steady-state simulations indicate a range of average annual coastal discharge between 6.5 x 10(6) and 15 x 10(6) m(3)/year from the Albufeira-Ribeira de Quarteira aquifer, and 4.5 x 10(6) and 11.3 x 10(6) m(3)/year from the Quarteira aquifer, as well as significant spatial variation. Transient simulations show that seasonal variability inherent to these systems can lead to inversions of hydraulic head gradient during short periods. Model results indicate that coastal discharge rates are between 1.5 and 2 times higher during the peak winter months than during the minimum in the summer, and as such seasonality has a larger impact on discharge rates than BC conceptualization. Up to 3.31 x 10(6) m(3)/year could be abstracted from existing well fields without causing seawater intrusion problems. Historical levels of abstraction are not within the selected sustainability criteria. However, by placing abstraction further from the coast sustainable yield increases. This work is part of ongoing research that aims to identify and characterize groundwater flow from the coastal strip towards the continental platform, taking into account structural geology, marine geology and the effects of the hydrological/hydrogeologic conditions on the associated ecosystems.

本论文针对阿尔加维（Algarve）地区的两套沿海含水层系统（coastal aquifer systems），开展了区域尺度地下水排泄估算值的时空分布特征研究。研究采用有限元分布参数地下水流模型（finite element distributed parameter groundwater flow model），分析了模型边界条件（model boundary conditions）定义与季节性（seasonality）因素的不确定性对估算结果的影响。最终基于预设的可持续性评价准则给出了可持续开采量（sustainable yields）估算值，并探讨了井位（well location）布局的重要性。稳态模拟（steady-state simulations）结果显示，阿尔布费拉-里贝拉-德-夸特伊拉含水层（Albufeira-Ribeira de Quarteira aquifer）的年均沿海地下水排泄量介于6.5×10⁶ 至15×10⁶ 立方米/年之间，夸特伊拉含水层（Quarteira aquifer）的该数值则介于4.5×10⁶ 至11.3×10⁶ 立方米/年之间，且排泄量存在显著的空间变异（spatial variation）。瞬态模拟（transient simulations）结果表明，这类系统固有的季节性波动可在短时段内引发水头梯度（hydraulic head gradient）反转。模型计算结果显示，冬季峰值时段的沿海地下水排泄速率较夏季最低值高出1.5至2倍，因此季节性因素对排泄速率的影响大于边界条件的概念化设定差异。现有井场的地下水抽取量最高可达3.31×10⁶ 立方米/年，且不会引发海水入侵（seawater intrusion）问题。当前历史地下水开采量（historical levels of abstraction）未达到预设的可持续性评价准则要求。不过，若将开采井布局远离海岸，则可提升可持续开采量。本研究属于一项正在推进的科研工作的一部分，该工作旨在识别并刻画沿海带向大陆架（continental platform）运移的地下水流系统，同时需综合考虑构造地质学（structural geology）、海洋地质学（marine geology）特征，以及水文/水文地质条件（hydrological/hydrogeologic conditions）对相关联生态系统（associated ecosystems）的影响。