Though metrics that quantify the long‐term water balance of a catchment have been known to influence the statistics of flood frequency data, little has been done to understand exactly what the substantive links are that causes baseflow to impact instantaneous annual maximum flows (IAMF). As abrupt changes to baseflow can occur via climate change and human disturbances, understanding the effects of baseflow on IAMF behavior can provide insight into how groundwater alterations and climate change can impact flood risk assessment, particularly for regional data aggregation. We thus seek to quantify baseflow impacts across the flood frequency curve considering a top down approach enumerating the differential impacts of baseflow (as Baseflow Index) across the IAMF flood frequency curve and then analyzing the impact of baseflow at the event‐scale. Results show that baseflow exerts significant influence over the entire flood frequency curve, showing a slight increase in effect with higher return period flows. At the event‐scale, the permeability of the catchment (proxied by baseflow rate during rising limb), significantly impacted the variability in IAMF and had more of an effect than antecedent moisture of the catchment (proxied by antecedent discharge). Furthermore, the effects of each of the event‐scale variables changed across climate regions and return periods, suggesting that changes to climate and groundwater abstractions would greatly affect the flood frequency curve.

中文翻译：

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量化洪水频率曲线上的长期和事件尺度基流影响

尽管量化流域长期水平衡的度量标准已知会影响洪水频率数据的统计数据，但几乎没有做过什么来确切了解导致基流影响瞬时年最大流量（IAMF）的实质性联系。由于基本流量的突然变化可能是由于气候变化和人为干扰而发生的，因此了解基本流量对IAMF行为的影响可以洞悉地下水变化和气候变化如何影响洪水风险评估，特别是对于区域数据汇总。因此，我们考虑采用自上而下的方法来枚举整个IAMF洪水频率曲线上基础流量的差异影响（作为基础流量指数），然后在事件尺度上分析基础流量的影响，从而寻求量化整个洪水频率曲线上的基础流量影响。结果表明，基本流量对整个洪水频率曲线都具有显着影响，并且随着较高的返回期流量，效果略有增加。在事件规模上，集水区的渗透性（由上升肢体的底流率所代理），显着影响了IAMF的可变性，并且比集水区的前期水分（由前期排放量代理）具有更大的影响。此外，每个事件尺度变量的影响在整个气候区域和返回期之间都发生了变化，这表明气候和地下水抽取的变化将极大地影响洪水频率曲线。集水区的通透性（由上升肢体的底流率所代理），显着影响了IAMF的可变性，并且比集水区的前期水分（由前期排放量代理）具有更大的影响。此外，每个事件尺度变量的影响在整个气候区域和返回期之间都发生了变化，这表明气候和地下水抽取的变化将极大地影响洪水频率曲线。集水区的通透性（由上升肢体的底流率所代理），显着影响了IAMF的可变性，并且比集水区的前期水分（由前期排放量代理）具有更大的影响。此外，每个事件尺度变量的影响在整个气候区域和返回期之间都发生了变化，这表明气候和地下水抽取的变化将极大地影响洪水频率曲线。