基于实测资料和古水文沉积记录的珠江流域长序列洪水频率分析

The increased flooding risk caused by climate change is one of the major challenges for human survival. The assumption of stationarity is a basic premise behind conventional flood frequency analysis for hydrological design of water resources projects. Under changing environments, hydrological series in many rivers have been found to exhibit nonstationarity. Due to the non-uniformity and shortage of the existing hydrological data, there is a large uncertainty involved in the extension of the design flood frequency curve. In this proposal, the slackwater deposit and peat deposit in the tributaries of the Pearl River Watershed will be studied by interdisciplinary, such as Geomorphology and Sedimentology. Using particle size, magnetic susceptibility analysis and high resolution scanning interpret paleo-flood information, detect the period of time and quantity levels and discuss the sedimentary characteristics of flood events and its responding to climate change. What’s more，by analyzing the temporal and spatial characteristics of hydrographical features in Pearl River Watershed，reconstructing “observed flood-history flood-paleoflood” orders, conducting multi scales analysis of flood frequency and discussing the applicability and uncertainty of paleo-flood events on flood frequency analysis, a longer time scale flood evolution pattern compared with sensor data could be revealed, and which can also help to provide useful reference for regional flood control and disaster reduction planning and design, and optimal management of water resources.

洪灾是人类面临的主要自然灾害之一，在变化环境下这一问题更为突出，加强对洪水的研究具有重要意义。水文观测资料短缺及序列非一致性是影响设计洪水精度的一个主要因素，它会导致外延洪水频率曲线求解设计洪水存在很大不确定性，如何扩大使用信息量是目前洪水频率分析的难点。本项目拟选取古水文研究薄弱的珠江流域为研究区，以河流洪水沉积为载体，采用河流地貌学、沉积学和水文学多学科交叉的方法，通过沉积结构、粒度、高分辨率元素扫描等手段，获取古洪水的信息，延长洪水序列；基于变化环境下水文序列重构，融合“实测洪水+历史洪水+古洪水”多段数据，开展洪水频率分析，计算大洪水的发生频率/重现期，揭示珠江流域长时间尺度上洪水演变规律，并结合多源古气候代用指标，探讨洪水事件对全球气候变化的响应，以期为现代洪水演变供历史“相似型”，为未来气候变化的预测提供“源数据”。

在全球变暖过程中，降水、洪涝灾害、干旱化等事件的频率和强度也在发生变化。识别不同时间尺度水文极值事件演变规律是防灾减灾的重要基础。本研究利用气象监测、遥感等多源数据，揭示了近50年来区域非平稳水文序列变异特征、洪旱灾害演变趋势及时空分布规律。利用沉积学和地球化学的技术手段，研究了典型剖面洪水沉积记录特征，初步探究了古洪水信息解译方法及其物理成因机制。洪水过程中水动力参数发生变化，不同沉积物空间分异明显，漫滩相洪水平流沉积记录，以泥和粉砂为主，洪水高位期沉积。基于小样本信息扩散原理，利用改进的内集-外集模型揭示了洪水灾害的随机性和模糊性，提升了洪峰流量特大或洪水样本集中的情况下洪水事件预测精度。通过三年研究，我们在保证质量前提下完成预期目标，已发表10篇学术研究论文，其中被SCI检索9篇，中文核心1篇，其中以第一作者或通讯作者发表SCI论文6篇，同时也启发我们继续在洪水记录方面开展进一步研究。