This study analyses the changes in the runoff of forested experimental catchments in south-central Chile, to determine to what extent observed trends can be attributed to effects of intensive forestry and/or climate change. For this, we applied the distributed TETIS® model to eight catchments (7.1−413.6 ha) representative of the land uses and forestry activities in this geographical area. Rainfall and runoff data collected between 2008 and 2015 were used for modelling calibration and validation. Simulation of three land uses (current cover, partial harvest and native forest) and 25 combinations of climatic scenarios (percentage increases or decreases of up to 20% of rainfall and evapotranspiration relative to the no-change scenario applied to input series) were used in each calibration. We found that changes in land use and climate had contrasting effects on runoff. Smaller catchments affected by the driest climatic scenarios experienced higher runoff when the forest cover was lower than under full forest cover (plantations or native forests). In contrast, larger catchments under all climatic scenarios yielded higher runoff below the full forest cover than under partial harvest and native forest. This suggests that runoff can be influenced, to a great extent, by rainfall decrease and evapotranspiration increase, with the model predicting up to a 60% decrease in runoff yield for the dry’s climatic scenario. This study proves to be relevant to inform ongoing discussions related to forest management in Chile, and is intended to minimize the impact of forest cover on runoff yield under uncertain climatic scenarios.

中文翻译：

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模拟森林覆盖和气候变化对智利中南部源头集水区水文的影响

本研究分析了智利中南部森林试验集水区径流的变化，以确定观察到的趋势在多大程度上可以归因于集约化林业和/或气候变化的影响。为此，我们将分布式 TETIS® 模型应用于代表该地理区域土地利用和林业活动的八个集水区（7.1-413.6 公顷）。2008 年至 2015 年期间收集的降雨和径流数据用于建模校准和验证。模拟三种土地利用（当前覆盖、部分采伐和原生林）和 25 种气候情景组合（相对于应用于输入序列的无变化情景，降雨量和蒸发量的增加或减少百分比高达 20%）每次校准。我们发现土地利用和气候的变化对径流有不同的影响。当森林覆盖率低于完全森林覆盖率（人工林或原生林）时，受最干燥气候情景影响的较小集水区会经历更高的径流。相比之下，在所有气候情景下，较大的集水区在完全森林覆盖下产生的径流高于部分收获和原生林下的径流。这表明径流可以在很大程度上受到降雨量减少和蒸散量增加的影响，模型预测干旱气候情景下径流产量减少高达 60%。事实证明，这项研究有助于为智利正在进行的与森林管理相关的讨论提供信息，并旨在在不确定的气候情景下最大限度地减少森林覆盖对径流产量的影响。当森林覆盖率低于完全森林覆盖率（人工林或原生林）时，受最干燥气候情景影响的较小集水区会经历更高的径流。相比之下，在所有气候情景下，较大的集水区在完全森林覆盖下产生的径流高于部分收获和原生林下的径流。这表明径流可以在很大程度上受到降雨量减少和蒸散量增加的影响，模型预测干旱气候情景下径流产量减少高达 60%。事实证明，这项研究有助于为智利正在进行的与森林管理相关的讨论提供信息，并旨在在不确定的气候情景下最大限度地减少森林覆盖对径流产量的影响。当森林覆盖率低于完全森林覆盖率（人工林或原生林）时，受最干燥气候情景影响的较小集水区会经历更高的径流。相比之下，在所有气候情景下，较大的集水区在完全森林覆盖下产生的径流高于部分收获和原生林下的径流。这表明径流可以在很大程度上受到降雨量减少和蒸散量增加的影响，模型预测干旱气候情景下径流产量减少高达 60%。事实证明，这项研究有助于为智利正在进行的与森林管理相关的讨论提供信息，并旨在在不确定的气候情景下最大限度地减少森林覆盖对径流产量的影响。