Chiang Mai basin has an escalating population growth resulting in high demand for water consumption. Lack of surface water supply in most parts of the basin gives rise to the increasing use of groundwater which leads to a continuous decline in groundwater level in the past decades. This study is the first long-term groundwater monitoring and modeling study that aims at developing a transient, regional groundwater flow model of heterogeneous unconsolidated aquifers based on the MODFLOW program. Long-term groundwater monitoring data from 49 piezometers were used in model calibration and validation. The pilot points technique was used to account for the spatial variability of hydrogeologic parameters of heterogeneous aquifers. The simulation results and statistics showed that most sensitive and significant model parameters were spatially variable hydraulic conductivities and recharge rates. The Chiang Mai basin’s unconsolidated aquifers do not have high potential. The water table and/or potentiometric surface in the southeast and southwest areas of Chiang Mai city were continuously decreasing with no sign of recovery indicating critical groundwater condition and careful management must be considered. Safe yield calculation, based on a 2-m average drawdown threshold, suggested that unconsolidated aquifers of the Chiang Mai basin can sustain overall abstraction rates up to 51.2 Mm³/y or approximately 214% of the current extraction rates.

中文翻译：

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泰国北部清迈盆地非均质非固结含水层地下水潜力和安全产量评估

清迈盆地人口增长迅速，对水的需求量很大。流域大部分地区缺乏地表水供应，导致地下水使用量增加，在过去几十年中导致地下水位持续下降。这项研究是第一个长期的地下水监测和建模研究，旨在基于MODFLOW程序开发非均质非固结含水层的瞬态区域地下水流模型。来自49个压力计的长期地下水监测数据用于模型校准和验证。先导点技术用于解释非均质含水层水文地质参数的空间变异性。仿真结果和统计数据表明，最敏感和重要的模型参数是空间可变的水力传导率和补给率。清迈盆地未合并的含水层潜力不大。清迈市东南部和西南部地区的地下水位和/或电位计表面在不断减少，没有恢复迹象，表明地下水状况严重，必须考虑谨慎管理。根据平均压降阈值为2 m的阈值进行的安全产量计算表明，清迈盆地的未合并含水层可以维持高达51.2 Mm的总体开采速率 清迈市东南部和西南部地区的地下水位和/或电位计表面在不断减少，没有恢复迹象，表明地下水状况严重，必须考虑谨慎管理。根据平均压降阈值为2 m的阈值进行的安全产量计算表明，清迈盆地的未合并含水层可以维持高达51.2 Mm的总体开采速率 清迈市东南部和西南部地区的地下水位和/或电位计表面在不断减少，没有恢复迹象，表明地下水状况严重，必须考虑谨慎管理。根据平均压降阈值为2 m的阈值进行的安全产量计算表明，清迈盆地的未合并含水层可以维持高达51.2 Mm的总体开采速率³ / y或当前提取率的214％。