Assessment of the influence of changes in land use and climate on landslide activity in a Mediterranean environment
Assessment of the influence of changes in land use and climate on landslide activity in a Mediterranean environment
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评估土地利用和气候变化对地中海环境滑坡活动的影响
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发表时间：
2002
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影响因子：
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通讯作者：
L. V. Beek
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作者：
L. V. Beek
在地中海环境中，土地利用和气候的变化通过改变先前的湿度条件和在不稳定的风暴事件期间提供的净降雨量来影响降雨引起的山体滑坡的发生。本研究旨在评估可能发生的土地利用和气候变化对中时间尺度(10-100年)滑坡活动的影响。由于预期环境变化的假设性质，已使用基于物理的模型来评估这种影响。该模型是分布式的，以考虑土地利用模式和水流路径，并将水文模型耦合到边坡稳定性评估中。它已在现有条件下得到验证，并应用于预期环境变化的静态情景。对滑坡活动进行了长达30年的模拟，从中得出了滑坡活动的变化。阿尔科伊(西班牙)附近的一个小流域已被用作案例研究。
在历史时期对水文模型的验证被证明是相当成功的。在有利于滑坡的潮湿条件下，模拟的水文与观测到的含水率比较接近。模拟地下水位的准确性较低，因为它们会在空间和时间上累积误差。稳定性模型的性能已经针对从航空照片中观察到的滑坡事件进行了评估。虽然模拟破坏不能复制观测到的滑坡发生情况，但它反映了不同土地利用类型滑坡活动的差异，因此可以用来评估由于环境变化而造成的滑坡活动的相对差异。
地中海土地利用变化的主要驱动因素是边际农田的废弃和欧盟农业政策提供的激励措施。目前的土地利用变化趋势已被预测为二氧化碳可能翻倍的日期。这导致了三种情况：目前的土地利用、持续的废弃和有限的农业重组。气候条件由两种情景确定：一种是基于缩小尺度的全球气候监测结果，在二氧化碳倍增之日变暖的未来气候；另一种是当前气候。对于这些情景，随机天气发生器提供无偏的、合成的降水量和潜在蒸散量的时间序列。
在假设的情况下，滑坡活动相对于目前的情况有所减少：在放弃后，更广泛的半自然植被产生的更高的蒸散量减弱了对降雨的水文响应。在当前气候条件下，滑坡的时间活动主要受土地利用变化的影响。最大地下水位几乎没有减弱，因此，遭受破坏的地区的降幅很小(约5%)。对于未来气候，土地利用和气候变化的综合影响导致滑坡的时间活动和空间发生较大幅度的减少(5%~25%)。这应该归因于较温暖的气候下较低的前期湿度条件。降幅最大的是较不容易崩塌的斜坡。因此，环境变化对降雨诱发滑坡活动的影响是很大的。在这种情况下，这种影响显然是有利的，尽管在干扰之后继承的景观可能容易进行大的适应
In Mediterranean environments, changes in land use and climate affect the incidence of rainfall-induced landslides by modifying the antecedent moisture conditions and the net rainfall amount delivered during erratic storm events. This study aims to assess the influence of the likely changes in land use and climate on landslide activity on medium temporal scales (10-100 years). Because of the hypothetical nature of anticipated environmental change, a physically based model has been used to assess this influence. The model is distributed to take land use patterns and flow paths into account and couples a hydrological model to a slope stability assessment. It has been validated under present conditions and applied to static scenarios of anticipated environmental change. Landslide activity has been simulated for 30-year periods from which changes in landslide activity have been derived. A small catchment near Alcoy (Spain) has been used as a case study.
Validation of the hydrological model over the historical period has proven to be reasonably successful. Under wet conditions, favourable to landsliding, the simulated hydrology approximates the observed moisture contents adequately. Simulated groundwater levels are less accurate as they accumulate errors over space and time. The performance of the stability model has been evaluated against landslide occurrence as observed from aerial photographs. Although simulated failure does not replicate observed landslide occurrence it reflects the difference in landslide activity between land use types and can consequently be applied to assess relative differences in landslide activity as the result of environmental change.
Mediterranean land use change is mainly driven by the abandonment of marginal fields and by incentives provided by EU agricultural policy. The current trend of land use change has been projected to the likely date of CO2-doubling. This results in three scenarios: present land use, continued abandonment and a limited reorganisation of agriculture. Climate conditions are specified by two scenarios: a warmer, future climate at the date of CO2-doubling, based on downscaled GCM results, and the present one. For these scenarios a stochastic weather generator provides unbiased, synthetic timeseries of precipitation and potential evapotranspiration.
For the hypothetical scenarios, landslide activity decreases relative to the present conditions: after abandonment, the higher evapotranspiration by the more extensive semi-natural vegetation attenuates the hydrological response to rainfall. Under the present climate mainly the temporal activity of landsliding is affected by land use change. The maximum groundwater levels are hardly attenuated and, consequently, the decrease in the area experiencing failure is slight (circa 5%). For the future climate, the compounded effect of land use and climate change leads to larger decreases in the temporal activity and spatial occurrence of landsliding (between 5 and 25%). This should be attributed to the lower antecedent moisture conditions under the warmer climate. The decrease is the largest on slopes that are less susceptible to failure. Thus, the impact of environmental change on the activity of rainfall-induced landslides is large. In this case, the impact is apparently advantageous although the inherited landscape may be prone to large adaptations after disturbance