Harrington Glenn A, Cook Peter G, Herczeg Andrew L
CSIRO Land and Water, Glen Osmond, SA, Australia.
Ground Water. 2002 Sep-Oct;40(5):518-27. doi: 10.1111/j.1745-6584.2002.tb02536.x.
Two environmental tracer methods are applied to the Ti-Tree Basin in central Australia to shed light on the importance of recharge from floodouts of ephemeral rivers in this arid environment. Ground water carbon-14 concentrations from boreholes are used to estimate the average recharge rate over the interval between where the ground water sample first entered the saturated zone and the bore. Environmental chloride concentrations in ground water samples provide estimates of the recharge rate at the exact point in the landscape where the sample entered the saturated zone. The results of the two tracer approaches indicate that recharge rates around one of the rivers and an extensive floodplain are generally higher than rates of diffuse recharge that occurs in areas of lower topographic relief. Ground water 2H/1H and 18O/16O compositions are all depleted in the heavier isotopes (delta2H = -67 per thousand to -50 per thousand; delta18O = -9.2 per thousand to -5.7%o) compared with the long-term, amount-weighted mean isotopic composition of rainfall in the area (delta2H = -33.8 per thousand; delta18O = -6.3 per thousand). This indicates that recharge throughout the basin occurs only after intense rainfall events of at least 150 to 200 mm/month. Finally, a recharge map is developed to highlight the spatial extent of the two recharge mechanisms. Floodout recharge to the freshest ground water (TDS <1,000 mg/L) is approximately 1.9 mm/year compared with a mean recharge rate of approximately 0.2 mm/year to the remainder of the basin. These findings have important implications for management of the ground water resource.
两种环境示踪方法被应用于澳大利亚中部的钛树盆地，以阐明在这个干旱环境中，季节性河流洪水泛滥补给的重要性。利用钻孔中地下水的碳 - 14浓度来估算从地下水样本首次进入饱和带的位置到钻孔之间这段时间间隔内的平均补给速率。地下水样本中的环境氯化物浓度可估算出样本进入饱和带时所在景观确切位置的补给速率。这两种示踪方法的结果表明，其中一条河流和广阔洪泛区周围的补给速率通常高于地形起伏较小地区发生的弥散补给速率。与该地区降雨的长期、水量加权平均同位素组成（δ²H = - 33.8‰；δ¹⁸O = - 6.3‰）相比，地下水的²H/¹H和¹⁸O/¹⁶O组成中较重同位素均有所贫化（δ²H = - 67‰至 - 50‰；δ¹⁸O = - 9.2‰至 - 5.7‰）。这表明整个盆地只有在月降雨量至少为150至200毫米的强降雨事件之后才会发生补给。最后，绘制了一张补给图，以突出两种补给机制的空间范围。对最新鲜地下水（总溶解固体 < 1000毫克/升）的洪水泛滥补给约为每年1.9毫米，而盆地其余部分的平均补给速率约为每年0.2毫米。这些发现对地下水资源的管理具有重要意义。
