Assessing the impact of climate change on soil erosion in East Africa using a convection-permitting climate model
Assessing the impact of climate change on soil erosion in East Africa using a convection-permitting climate model
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DOI：
10.1088/1748-9326/ac10e1
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发表时间：
2021-08-01
影响因子：
6.7
通讯作者：
Marsham, John H.
中科院分区：
文献类型：
--
作者：
Chapman, Sarah;Birch, Cathryn E.;Marsham, John H.
东非高度依赖农业，土壤侵蚀率高，这对农业产量产生了负面影响。气候预测表明，东非的降雨强度将增加，这可能会增加土壤侵蚀。土壤侵蚀估算需要有关降雨侵蚀力的信息，而降雨侵蚀力是利用次日风暴特征计算出来的，而已知在传统的参数化对流气候模式中存在偏差。允许对流的气候模式以更高的分辨率运行，不需要对流参数化，通常能更好地代表降雨强度和频率。我们使用一种新的允许对流的泛非区域气候模型（CP4A）来估计坦桑尼亚和马拉维的降雨侵蚀力，并将其与参数化的对应模型（P25）进行比较，以确定使用允许对流的气候模型来研究降雨侵蚀力是否有好处。我们使用8年历史和世纪末（RCP8.5）气候模拟，基于CP4A和P25对修正通用土壤流失方程的降雨侵蚀力估算，研究了气候变化对坦桑尼亚和马拉维土壤侵蚀的影响。并对土壤保持措施的效果进行了评价。P25的降雨侵蚀力低于CP4A，即使经过偏置校正，与观测风暴特征的匹配也较差。这些结果表明，参数化的对流区域和全球气候模式可能低估了降雨侵蚀力和相关的土壤侵蚀。在CP4A中，我们发现坦桑尼亚和马拉维山区的当前侵蚀值很高。在气候变化条件下，由于CP4A降水强度的增加，土壤侵蚀高风险区域扩大。梯田在减少未来土壤侵蚀风险方面不如现在有效，可能需要更广泛的土壤管理来管理土壤侵蚀并减少土壤侵蚀对农业的负面影响。
East Africa is highly reliant on agriculture and has high rates of soil erosion which negatively impact agricultural yields. Climate projections suggest that rainfall intensity will increase in East Africa, which is likely to increase soil erosion. Soil erosion estimates require information on rainfall erosivity, which is calculated using sub-daily storm characteristics that are known to be biased in traditional parameterized convection climate models. Convection-permitting climate models, which are run at higher resolution to negate the need for convection parameterization, generally better represent rainfall intensity and frequency. We use a novel convection-permitting pan-Africa regional climate model (CP4A) to estimate rainfall erosivity in Tanzania and Malawi, and compare it to its parameterized counterpart (P25), to determine if there is a benefit to using convection-permitting climate models to look at rainfall erosivity. We use eight year historical and end-of-century (RCP8.5) climate simulations to examine the impact of climate change on soil erosion in Tanzania and Malawi based on rainfall erosivity estimates from CP4A and P25 applied to the Revised Universal Soil Loss Equation. The effectiveness of soil conservation measures was also evaluated. Rainfall erosivity was lower in P25 than in CP4A and was a poorer match to observational storm characteristics, even after bias-correction. These results suggest that parameterized convection regional and global climate models might under-estimate rainfall erosivity, and the associated soil erosion. We found high values of present day erosion in mountainous regions in Tanzania and Malawi in CP4A. Under climate change, areas at high risk of soil erosion expanded due to increases in rainfall intensity in CP4A. Terracing was less effective at reducing soil erosion risk in the future than in the present day, and more extensive soil management may be required to manage soil erosion and reduce the negative impacts of soil erosion on agriculture.