GroMoPo Metadata for Iranshahr Aquifer MODFLOW model

Recognitions and predictions of the contamination origin are essential steps in the protective measures to avoid well-water contamination and the first step in managing groundwater resources. In this regard, finite-difference model software (GMS 10.0.6) was used to model the transport path, the origin of contaminants and to determine the wellhead protection area in Iranshahr aquifer. Since contamination transport models require a calibrated groundwater flow model, we first prepared this model. Accordingly, after collecting all geological, meteorological, hydrological and hydrogeological data (based on the maps, geophysical tests and exploratory borehole drilling, rainfall statistics and groundwater level in exploitation wells), a database was constructed in ArcGis10.1 software and a conceptual model was developed by transporting this information to GMS software. Based on the developed model, the aquifer's groundwater level was simulated, calibrated and validated using MODFLOW2000 code in GMS software. The particle transport model in the aquifer was provided to examine and model the transport path and the origin of contaminants through MODPATH module. In the end, the aquifer wells' protection area against contaminants was illustrated. According to the results, contaminant transport path in the wells of central plains is directed from the river to the wells, in forward particle-tracking model; the maximum time taken by particles is 508,952.5 days, the minimum time is 144 days, and the average radius of 50-day wellhead protection area based on the protection against contaminations such as pathogenic bacteria in Iranshahr aquifer was determined to be about 100 m.

识别与预测污染物来源，是规避井水污染的防护措施中的核心环节，同时也是地下水资源管理的首要步骤。为此，本研究采用有限差分模型软件（GMS 10.0.6）对伊朗沙尔含水层的污染物运移路径、污染物来源进行模拟，并确定其水源保护区（wellhead protection area）范围。由于污染物运移模型需以校准后的地下水流模型为基础，因此本研究首先构建了该地下水流模型。据此，研究团队收集了涵盖地图资料、地球物理勘探、探井钻探、降雨统计数据以及开采井地下水位在内的全部地质、气象、水文与水文地质数据，随后在ArcGis10.1软件中搭建数据库，并将相关信息导入GMS软件以构建概念模型。基于所构建的模型，本研究借助GMS软件中的MODFLOW2000模块对含水层地下水位进行了模拟、校准与验证。随后通过MODPATH模块构建含水层粒子追踪模型，用以模拟并分析污染物运移路径与污染物来源。最终明确了该含水层水井的污染物防护区域范围。研究结果显示，在正向粒子追踪模型中，中部平原区域水井的污染物运移路径为从河流指向水井；粒子运移的最长耗时为508952.5天，最短耗时为144天；针对伊朗沙尔含水层内致病菌类污染物的防护需求，50天尺度下的水源保护区平均半径约为100米。