Time of emergence of impacts of climate change on groundwater levels in sub-Saharan Africa
Time of emergence of impacts of climate change on groundwater levels in sub-Saharan Africa
复制标题
气候变化对撒哈拉以南非洲地下水位影响出现的时间
DOI：
10.1016/j.jhydrol.2022.128107
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发表时间：
2022
影响因子：
6.4
通讯作者：
Ascott M
中科院分区：
文献类型：
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作者：
Ascott M
气候变化对地下水的影响没有得到很好的限制，特别是在撒哈拉以南非洲等地区，那里的全球环流模型（GCM）预测降水变化的方向不同。此外，气候变化对地下水的影响何时可以与自然变异性区分开来，这一点尚未量化。在这里，我们第一次估计了气候变化对地下水位影响的出现时间（ToE），使用西非布基纳法索8个地点的时间序列。我们将CMIP 5 GCM的历史和RCP8.5运行的输出数据应用于每个站点的集总地下水模型，并通过计算每个站点和CMIP 5模型的信噪比来估计ToE。我们发现，除了在不同的GCM气候变化影响的方向不一致，有不一致的气候变化信号在未来的地下水位，特别是在干燥的GCM的ToE。在8个地点中，可能的23个CMIP 5大气环流模型中有5（4）到13（13）个显示出与地下水位下降（上升）相关的ToE。CMIP 5大气环流导致地下水位下降（即干燥）的ToE在不同地点和不同大气环流之间差异很大（所有地点的ToE中位数= 2049，四分位距= 48年）。对于产生地下水位上升（即湿润）的CMIP 5大气环流，ToE出现得更早，变异性更小（所有地点的ToE中位数= 2011年，四分位距= 11年）。这些结果强调了在减少GCM不确定性的同时制定无遗憾适应措施的必要性。
The impacts of climate change on groundwater are poorly constrained, particularly in regions such as sub-Saharan Africa where global circulation models (GCMs) project different directions of precipitation change. Moreover, the timing of when climate change impacts on groundwater can be differentiated from natural variability has not been quantified. Here, for the first time, we estimate the time of emergence (ToE) of climate change impacts on groundwater levels, using time series from eight sites across Burkina Faso, West Africa. We apply output data from historical and RCP8.5 runs of CMIP5 GCMs to lumped groundwater models for each site, and estimate ToE by calculating signal to noise ratios for each site and CMIP5 model. We show that in addition to inconsistent direction of climate change impacts across different GCMs, there is inconsistency in the ToE of climate change signals in future groundwater levels, particularly in drying GCMs. Across the eight sites, between 5 (4) and 13 (13) CMIP5 GCMs of a possible 23 show a ToE associated with decreases (increases) in groundwater levels. ToE from CMIP5 GCMs producing decreases in groundwater levels (i.e. drying) is highly variable between sites and GCMs (across all sites, median ToE = 2049, interquartile range = 48 years). For CMIP5 GCMs producing increases in groundwater levels (i.e. wetting), ToE appears to occur earlier and with less variability (across all sites median ToE = 2011, interquartile range = 11 years). These results underline the need for development of no-regrets adaptation measures in parallel with reductions in GCM uncertainty.