Bunel Raphaël, Lecoq Nicolas, Copard Yoann, Massei Nicolas
Univ Rouen Normandie, Université Caen Normandie, CNRS, Normandie Univ, M2C UMR 6143, F-76000 Rouen, France.
Sci Total Environ. 2023 Dec 10;903:166536. doi: 10.1016/j.scitotenv.2023.166536. Epub 2023 Aug 25.
Runoff and soil erosion are very pronounced in the Western European Loess Belt. In this study, the distributed physically-based model CLiDE is calibrated, validated, and applied to a catchment of this area (Dun, NW, France) to assess the hydro-sedimentary impacts of climate change scenarios. Despite considerable progress over the last decade in the study of runoff and soil erosion in the context of climate change, the effects of changes in the temporal variability of precipitation remain poorly understood, especially at the scale of a river basin. To examine these relationships more closely, we developed a stochastic weather generator to individually adjust the components that structure the temporal variability of rainfall. The climate scenarios considered represent projections to the year 2100 of the temporal variability of rainfall over NW Europe. The scenarios are based on historical daily rainfall records (1990-2012) and 4 exploratory assumptions: a 50 % decrease in the interannual rainfall regime (scenario 6yD), a 100 % increase in the interannual rainfall regime (scenario 6yI), a 50 % increase in the seasonal rainfall regime (scenario 1yI) and a 50 % increase in the synoptic rainfall regime (scenario 3dI). Simulated daily water and sediment discharges and erosion/deposition maps for each scenario are compared to those simulated for the situation without changes in rainfall. The time series were aggregated over different time intervals to allow for a multi-scale analysis of the differences. The results indicate that the model provides a satisfactory prediction of the catchment's water and sediment discharges, especially over the calibration period. Increased climate variability, whether on a synoptic (3dI), seasonal (1yI) or interannual (6yI) scale, leads to increased runoff and erosion. Increasing the synoptic rainfall variability (3dI) leads to the largest increase in mean annual runoff and erosion. Only the reduction of the interannual rainfall variability (6yD) provokes the decrease of these values.
径流和土壤侵蚀在西欧黄土带非常显著。在本研究中，对基于物理过程的分布式模型CLiDE进行了校准、验证，并将其应用于该地区（法国西北部的邓河）的一个流域，以评估气候变化情景下的水沙影响。尽管在过去十年中，气候变化背景下径流和土壤侵蚀的研究取得了显著进展，但降水时间变异性变化的影响仍知之甚少，尤其是在流域尺度上。为了更深入地研究这些关系，我们开发了一个随机天气发生器，以单独调整构成降雨时间变异性的各个组成部分。所考虑的气候情景代表了对欧洲西北部到2100年降雨时间变异性的预测。这些情景基于历史每日降雨记录（1990 - 2012年）和4个探索性假设：年际降雨模式减少50%（情景6yD）、年际降雨模式增加100%（情景6yI）、季节降雨模式增加50%（情景1yI）以及天气尺度降雨模式增加50%（情景3dI）。将每个情景下模拟的每日水沙流量和侵蚀/沉积图与降雨无变化情况下模拟的图进行比较。时间序列在不同时间间隔上进行汇总，以便对差异进行多尺度分析。结果表明，该模型对流域的水沙流量提供了令人满意的预测，特别是在校准期内。气候变异性增加，无论是在天气尺度（3dI）、季节尺度（1yI）还是年际尺度（6yI）上，都会导致径流和侵蚀增加。天气尺度降雨变异性增加（3dI）导致年平均径流和侵蚀增加幅度最大。只有年际降雨变异性降低（6yD）会导致这些值下降。
