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首页> 外文期刊>Australian Journal of Earth Sciences >Impact of change in vegetation cover on groundwater recharge to a phreatic aquifer in Western Australia: assessment of several recharge estimation techniques
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Impact of change in vegetation cover on groundwater recharge to a phreatic aquifer in Western Australia: assessment of several recharge estimation techniques

机译：植被变化对西澳大利亚潜水层地下水补给的影响：几种补给估算技术的评估

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摘要

Groundwater levels in a deep phreatic aquifer in the northern Perth Basin, Western Australia have risen between 10 and 55 cm/y over the last three decades due to the replacement of deep-rooted native vegetation with pasture and annual crops, This has sparked debate over increasing groundwater allocation limits to meet growing demand. Estimates of recent and historical rates of groundwater recharge are needed to manage the resource effectively. The Parmelia Formation, composed predominantly of sandstone, supplies domestic, stock and production bores for rural towns. Groundwater recharge was estimated using several recharge estimation techniques including the water-table fluctuation method and tracer techniques; groundwater chloride, chlorofluorocarbons (CFCs) and C-14, Vertical fluxes of soilwater under pasture and native vegetation were determined using chloride as a tracer, Apparent groundwater ages determined using CFCs and carbon-14 are generally younger than 40 years in piezometers that are screened within a few metres of the water-table from recharge under pasture, while groundwater is older than several thousand years in bores that are screened well below the water-table, and mixed waters occur at discharge areas. Recharge-rate estimates obtained under native vegetation are mainly < 12 mm/y, whereas after replacement with pasture and annual crops, recharge rates are generally 20-50 mm/y. The presence of thick clay lenses in some areas may be responsible for observed delays of approximately one decade in the water-table response to land-use change. The study highlighted the fact that several recharge estimation techniques are required for better understanding of recharge processes and evaluation of recharge.
机译：在过去的三十年里，由于牧场和一年生作物取代了根深蒂固的原生植被，西澳大利亚州珀斯盆地北部深水潜水层的地下水位上升了10至55厘米/年。这引发了关于增加地下水分配限制以满足不断增长的需求。为了有效管理资源，需要估算近期和历史地下水补给率。 Parmelia组主要由砂岩组成，可为农村城镇提供家庭，库存和生产钻孔。地下水补给利用几种补给估算技术进行估算，包括地下水位波动法和示踪剂技术。地下水氯化物，氯氟碳化合物（CFCs）和C-14，使用氯化物作为示踪剂确定了草场和天然植被下土壤水的垂直通量，使用氯氟化碳和碳14确定的表观地下水年龄在压滤仪中一般小于40岁在距草场补给水位几米以内的地方，地下水的筛孔远低于地下水位，井孔中的地下水已经存在了几千年，并且在出水区出现了混合水。在天然植被下获得的补给率估计值主要<12 mm / y，而在以牧场和一年生作物替代后，补给率通常为20-50 mm / y。在某些地区，厚黏土镜片的存在可能是造成地下水位对土地利用变化的响应大约延迟了十年的原因。该研究强调了一个事实，即需要几种充电估算技术来更好地了解充电过程和评估充电。

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