桉树因生长速度快、适应能力强、经济效益高等特点,广泛种植于我国南方湿润地区。大面积种植桉树人工林对水资源量和洪水的影响已成为学者关注的焦点问题之一。以广东省流溪河水库流域为例,采用具有物理机制的分布式水文模型,应用情景分析方法,模拟不同桉树人工林种植下垫面条件对流域径流的影响。结果表明:相对一般树种(天然混交林等),大面积种植桉树人工林将减少流域年水资源量,桉树人工林面积每增加1万hm²,年水资源量减少约2 200万m³;大面积种植桉树人工林对场次洪水影响较小,不同桉树种植条件下的洪水过程线比较相近,洪峰流量变化相对较大;每种植1万hm²桉树人工林,洪峰流量可增加约10 m³/s。总体来看,大面积种植桉树人工林加剧了水资源量流失,提高了洪峰流量,从而增加了水旱灾害防御的风险。

Eucalyptus is widely planted as an economic forest in the humid regions of southern China due to its fast growth rate, adaptability, and high economic benefits. However, the impact of large-scale eucalyptus plantations on water resource amout and floods has become a major concern. To examine this issue, a distributed hydrological model with physical mechanisms was constructed for the Liuxihe reservoir watershed in Guangdong Province. Scenario analysis method was applied to simulate the impact of land surface pattern under different eucalyptus plantation scenes on water resource amout in the watershed. The study found that large-scale eucalyptus plantation reduces annual water resource amout compared to common tree species such as natural mixed forest. For every additional 10 000 hectares of eucalyptus plantation, the annual water resource amout can be reduced by approximately 22 million m³. Although the impact on floods is less pronounced and the flood process under different eucalyptus planting scenes are basically the same, the flood peak flow changes are relatively significant. For every 10 000 hectares of eucalyptus plantation, the flood peak flow can be increased by approximately 10 m³/s. Overall, the large-scale planting of eucalyptus aggravates the loss of water resources, increases the peak flow of floods, and raises the risk of flood and drought disaster prevention.