气候变化下典型山区森林干扰和水电开发对径流过程的累积影响研究

In large forested watersheds, climate change, forest disturbance and hydroelectric development are commonly recognized as major drivers interactively influencing hydrology in mountain river basin. Human activities including forest disturbance and hydroelectric development are typically cumulative over time and space in basin. The Upper Minjiang River will be selected as typical basin, which is very sensitive to climate change, has been greatly influenced by forest disturbance and hydroelectric development, has the most important strategic position, Impact of cumulative forest disturbance and hydroelectric development on runoff will be analyzed and separated coupling with modeling and approaches, based on finding out the spatial and temporal evolution features of hydro-moteorological elements in the basin. A concept “equivalent disturbed area”(EDA) will be applied to replace traditionally forest cover measures as the former considers hydrological recovery process during forest re-establishment following disturbance, and the attribution model of water resources evolution under changing environment will be also brought forward, the range of variability approach(RVA) will be used to study the quantitative cumulative variation of hydrological conditions in time and space caused by forest disturbance and hydroelectric development. The causes and mechanisms of annual runoff decrease, especially an inflow decrease in spring and autumn and earlier appearance and longer duration of the low-flow season will be investigated.

气候变化、森林干扰、水电开发是山区河流水循环最主要的驱动影响因子。人类活动(森林干扰、水电开发)对流域水文的影响在时间和空间上具有累积性。项目选取对气候变化非常敏感、森林干扰强烈、水电开发程度高、具有重要战略地位的岷江上游流域为典型流域，在明确流域水文气象要素时空演变特征的基础上，应用建模和统计分析方法研究和区分气候变化和人类活动对径流量的影响。构建EDA指标代替传统森林覆盖率计算方法，研究森林植被景观格局对径流分配格局的影响，提出了变化环境下流域水资源演变的归因方法，并运用水文变异法分别对森林干扰和水电开发所导致的时空累积变异进行定量化评价。分析了岷江上游年径流量减少，尤其是春、夏季来水减少、枯水期提前并且持续时间增长的内在机理成因。

研究人类活动对流域水文的时间和空间上的影响，对流域生态系统可持续发展、土地管理及策略制定具有重要意义。本项目选取的岷江上游流域和金沙江流域，具有自然梯度明显，森林干扰强烈，水电开发程度高，以及具有重要战略意义等特点。通过对流域长序列水文气象数据研究，明确了水循环及气象特征的时空分布。构建流域SWAT模型，结合回归分析、主成分分析等统计方法，定量区分了人类活动和气候变化对流域水资源的影响。运用均化系数法，水文变化指标法等统计方法对研究区域梯级电站对水文情势的累积效应进行了分析。结果表明，气候变化和土地覆被共同产生了相同的负向的水文效应，造成流域年径流量减少。通过构建流域土地利用生态格局指数，进一步模拟并分析了岷江上游流域年径流量减少的原因，结果表明其中草甸的减少导致植被优势度降低，以及耕地和居民地的大幅度增加导致的景观丰富度和破碎化程度高，是土地覆被影响流域流量减少的主要方式。草地植被的恢复、城市和农业用水应当是流量恢复的主要关注焦点。随着电站不断建设，只有描述河流涨水率、落水率和反转次数的水文指标随着梯级水库的运行有逐渐减小的趋势，其余指标改变度均呈现逐渐增加的趋势，高流量值减少，低流量值增加。极大值减少，极小值增加，流量变化的改变率及频率趋缓。项目资助发表论文13篇，其中SCI论文1篇，EI期刊论文1篇，EI会议论文1篇，中文核心8篇，国内会议论文2篇。培养博士生1名，硕士8名，其中5名取得硕士学位。