变化环境下西江流域水文干旱特征及响应机制研究

Under changing environmental conditions caused by climate change and human activities, floods, droughts and environmental issues related to water is becoming increasingly prominent. It is a key scientific problem for water resources management that distinguishing variation characteristics and mechanism of hydrological drought response to climate change and human activities in river basin. A case study is conducted in Xijiang River basin which exhibited high frequency of flood and drought in south china. Based on systems analysis of variation characteristics and mechanism of hydrological factors response to climate change and human activities, the distributed hydrological model is constructed to analyze the effects of climate change and human activities on hydrologic process at different spatial and temporal scales in Xijiang River basin. Comparison between different methods for frequency distribution of meteorological and hydrological data, the standardized precipitation-evapotranspiration index and the standard runoff index is constructed to analyze variation characteristics of the meteorological and hydrologic drought at different spatial-temporal scales in Xijiang River basin. With the improvement of quantitative identification method，the variation characteristics and the mechanism of hydrologic drought respond to climate change and human activities is analyzed quantitatively. The quantitative identification method is employed to distinguish the effects of human activities which include land use, vegetation cover changes, water conservancy construction and water resources utilization. The study will help the government to guarantee the ecological environment protection and the rational exploitation-utilization of water resources.

在气候变化和人类活动引起的全球环境变化驱动下，流域水旱灾害以及与水相关的生态环境问题日益突出。系统识别流域水文干旱对气候变化和人类活动的响应特征和机制，是流域水资源管理亟待解决的关键科学问题。本研究将以我国南方典型水旱灾害多发区西江流域为例，在系统分析变化环境下的流域水文要素演变特征及其影响机制的基础上，构建流域分布式水文模型，模拟分析不同时空尺度下气候变化及人类活动对水文过程的影响。基于多种概率分布模型的比较分析，建立标准降水蒸发指数和标准径流指数模型，对比分析西江流域气象干旱和水文干旱的时空演变规律。通过对定量识别方法的改进，定量识别不同时空尺度下流域径流及水文干旱特征对气候变化和人类活动的响应机制，并进一步细化土地利用、植被变化、水利工程建设、经济社会用水等具体人类活动因素对流域径流及水文干旱的影响机制。以期为流域水资源管理与生态环境保护提供科学依据。

在气候变化和人类活动引起的全球环境变化驱动下，流域水旱灾害以及与水相关的生态环境问题日益突出。系统识别流域水文干旱对气候变化和人类活动的响应特征和机制，是流域水资源管理亟待解决的关键科学问题。近60年来西江干流、郁江年径流量呈现显著性减少的趋势; 西江干流、郁江、黔江、桂江、红水河和北流河年输沙量呈现显著减少的趋势。在泥沙含量发生突变年份的前后时间段内，西江干流、黔江、郁江、红水河、刁江和北流江的挟沙能力明显增强，可侵蚀搬运的沉积物明显减少。SVM模型综合考虑了空间尺度上的降水、蒸散发等产流的关键要素，其模拟和验证效果都比较理想，该模型在西江流域具有较好地适用性。西江流域大部分地区气象干旱强度呈现极显著的加重趋势，气象干旱频率也呈现极显著的上升趋势，在1个月、3个月和6个月的尺度上，SPEI指数整体上低于SPI指数。尤其在冬季和春季各月SPEI指数远远低于SPI指数。西江流域干流年水文干旱出现显著加重的趋势。春季水文干旱变化趋势并不显著，而秋季和冬季水文干旱呈现显著加重的趋势，夏季则出现显著变湿的趋势。气候变化是造成西江流域径流减少的最主要原因，西江流域主要河流降水对径流变化的贡献率在31.4-65.2%， 水利工程建设对年输沙量影响非常显著，其贡献率在29.7-97.8%。深入研究变化环境下河流水文干旱变化及其驱动因素，对流域水资源开发利用、抗旱减灾等具有重大的实际意义。