Forest cover lessens the impact of drought on streamflow in Puerto Rico
Forest cover lessens the impact of drought on streamflow in Puerto Rico
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DOI：
10.1002/hyp.14551
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发表时间：
2022-03
影响因子：
3.2
通讯作者：
Jazlynn Hall;M. Scholl;Y. Gorokhovich;M. Uriarte
中科院分区：
文献类型：
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作者：
Jazlynn Hall;M. Scholl;Y. Gorokhovich;M. Uriarte
热带地区的森林覆盖率正在迅速丧失，降雨量和降雨时间也在发生变化。这些变化可能会损害径流和供水，突出需要确定森林覆盖如何影响径流发电在降雨量变化的条件下。虽然降雨是径流系统的主要驱动力，但森林的作用不太清楚，特别是在森林损失是一个持续风险的热带地区。森林覆盖损失改变蒸散，降雨入渗和存储，并可能增加河流生态系统的脆弱性，降雨极端。波多黎各是一个森林覆盖率在空间上不均匀、降雨梯度明显的岛屿，预计将更频繁地发生干旱和山洪暴发。使用2005年至2016年期间从20个美国地质调查局流量计收集的15分钟径流数据和3小时多源加权综合降水降雨量估计值，我们利用流量持续时间曲线和线性混合回归模型来研究森林覆盖在调节径流时间和流量方面的作用。混合模型方法有助于考虑流域特征的差异。我们确定了降雨量和森林覆盖对波多黎各溪流的低流量和高峰流量的影响，然后评估了这些关系在干燥和潮湿的前期降雨条件下的变化。高森林覆盖率的流域一直更低，峰值流量比砍伐森林的降雨条件下，虽然效果更显着，在潮湿的前期条件，这表明，峰值流量主要是饱和过量的地表径流的结果。在干燥的前期降雨条件下，高度森林覆盖的流域有较高的径流比砍伐森林，这表明更大的山坡存储和释放也可能在发挥作用。我们的研究结果表明，森林覆盖产生的山坡渗透和存储的净增加，并可能减少干旱对径流在波多黎各的影响。在这一陡峭的山区环境中，有限的蓄水潜力可能限制对长期干旱的恢复能力，突出表明维持森林覆盖是增加渗透的一项重要水管理战略。
Tropical regions are experiencing high rates of forest cover loss coupled with changes in the volume and timing of rainfall. These shifts can compromise streamflow and water provision, highlighting the need to identify how forest cover influences streamflow generation under variable rainfall conditions. Although rainfall is the key driver of streamflow regimes, the role of forests is less clear, particularly in tropical regions where forest loss is an ongoing risk. Forest cover loss alters evapotranspiration, rainfall infiltration and storage, and may increase stream ecosystem vulnerability to rainfall extremes. Puerto Rico, an island with spatially heterogenous forest cover and a marked geographic rainfall gradient, is projected to experience more frequent droughts and flash flooding. Using 15‐min streamflow data collected between 2005 and 2016 from 20 US Geological Survey stream gages and 3‐hourly Multi‐Source Weighted‐Ensemble Precipitation rainfall estimates, we utilized flow‐duration curves and linear mixed regression models to examine the role of forest cover in regulating the timing and volume of streamflow. The mixed model approach helps to account for differences in watershed characteristics. We determined the effects of rainfall and forest cover on low and peak flows in Puerto Rican streams, then evaluated changes in these relationships under dry and wet antecedent rainfall conditions. Watersheds with high forest cover had consistently greater low and peak streamflow than deforested ones under all rainfall conditions, although the effect was more marked during wet antecedent conditions, suggesting that peak flow is largely the result of saturation excess overland flow. During dry antecedent rainfall conditions, highly forested watersheds had higher streamflow than deforested ones, suggesting greater hillslope storage and release may also be at play. Our results demonstrate that forest cover generated a net increase in hillslope infiltration and storage and may lessen drought impacts on streamflow in Puerto Rico. Resilience to prolonged drought may be limited by finite water storage potential in this steep, mountainous setting, highlighting maintenance of forest cover as an important water management strategy to increase infiltration.