Integrated hydrogeological modelling of hard-rock semi-arid terrain: supporting sustainable agricultural groundwater use in Hout catchment, Limpopo Province, South Africa
Integrated hydrogeological modelling of hard-rock semi-arid terrain: supporting sustainable agricultural groundwater use in Hout catchment, Limpopo Province, South Africa
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DOI：
10.1007/s10040-019-01957-6
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发表时间：
2019-03
影响因子：
2.8
通讯作者：
G. Ebrahim;K. Villholth;M. Boulos
中科院分区：
文献类型：
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作者：
G. Ebrahim;K. Villholth;M. Boulos
利用遥感、降雨径流建模和三维 (3D) 动态模型开发了一种适用于半干旱数据稀缺非洲硬岩含水层的综合水文地质建模方法。综合建模方法应用于南非林波波省的豪特流域，这是一个重要的农业地区，1968 年至 1986 年间，用于灌溉的地下水抽取量增加了一倍。自 20 世纪 60 年代以来，灌溉区的地下水位出现了长期下降，但由于十年间重大降雨事件或时期的影响，地下水位部分或全部恢复。基于一水水文流量模型 (MODFLOW-OWHM) 的集成动态 3D 水文地质流量模型有助于了解补给和流量过程，并为水的利用和管理提供信息。灌溉取水量是根据陆地卫星归一化植被指数 (NDVI) 描绘的灌溉作物面积和作物需水量估算的。使用地下水位数据，对模型进行了校准（2008-2012 年）和验证（2013-2015 年）。估计的平均扩散补给（年降雨量的 3.3±2.5%）与降水径流建模系统模型的估计值相比较。补给和地下水储存量显示出显着的年际变化。人们发现，这条短暂的河流正在流失，含水层的平均净流量（集中补给）约为年降雨量的 1.1%。结果表明，一个脆弱的人类自然系统依赖于小规模但高度可变的补给，通过可变抽水传播到更加可变的存储，使得组合系统容易受到气候和人为变化的影响。综合建模对于理解可持续管理地下水资源所需的关键参数的时空变化至关重要。
An integrated hydrogeological modelling approach applicable to hard-rock aquifers in semi-arid data-scarce Africa was developed using remote sensing, rainfall-runoff modelling, and a three-dimensional (3D) dynamic model. The integrated modelling approach was applied to the Hout catchment, Limpopo Province, South Africa, an important agricultural region where groundwater abstraction for irrigation doubled during 1968–1986. Since the 1960s, groundwater levels in irrigated areas have displayed extended periods of decline with partial or full recovery in response to major decadal rainfall events or periods. The integrated dynamic 3D hydrogeological flow model, based on the One-Water Hydrologic Flow Model (MODFLOW-OWHM), helped to understand recharge and flow processes and inform water use and management. Irrigation abstraction was estimated based on irrigated crop area delineated using the Landsat Normalized Difference Vegetation Index (NDVI) and crop water requirements. Using groundwater level data, the model was calibrated (2008–2012) and validated (2013–2015). Estimated mean diffuse recharge (3.3 ± 2.5% of annual rainfall) compared well with estimates from the Precipitation Runoff Modelling System model. Recharge and groundwater storage showed significant inter-annual variability. The ephemeral river was found to be losing, with mean net flux to the aquifer (focused recharge) of ~1.1% of annual rainfall. The results indicate a delicate human-natural system reliant on the small but highly variable recharge, propagating through variable pumping to an even more variable storage, making the combined system vulnerable to climate and anthropogenic changes. The integrated modelling is fundamental for understanding spatio-temporal variability in key parameters required for managing the groundwater resource sustainably.