极端降水条件下华南中小流域暴雨洪水过程对变化环境的响应

Hydrological effects of global environmental change have become a research focus of the international academic community. In recent years, extreme precipitation has triggered intensified and frequent flood disasters in small and middle watershed. Therefore, it is both theoretically and practically significant to construct storm flood models for the flood warning and forecasting. In south China, the heavy precipitation is characterized by high intensity, short duration and small scope, which generate high complexity of storm flood processes in small and middle watershed. This research program seeks to develop a model to simulate storm flood processes under heavy precipitation in small and middle watershed by taking the upstream of the Caojiang watershed as a research area, which is located in one of the rainstorm areas in south China. .Drawing upon materials from the field experiment and historical data about storm flood in the research area, it explores the mechanism of the physical formation of the storm flood process in the small and middle watershed under heavy precipitation in order to identify key factors that affect storm flood processes in the small and middle watershed under heavy precipitation and to examine the relation between them. It then seeks to construct a model of storm flood in the small and middle watershed under heavy precipitation in south China. This model is characterized by its adaptability to environmental change and simple structure. It then analyzes the response of storm flood processes in middle and small watershed under heavy precipitation to changing environment. Based on the simulation of the storm flood processes in middle and small watershed under heavy precipitation in south China, it seeks to discover the rule and characteristics of the storm flood processes in middle and small watershed under heavy precipitation in south China in the condition of changing environment. This research program will contribute to the flood warning and forecasting in middle and small watershed in south China.

全球环境变化产生的水文效应已经成为国际热点，近年极端降水引发中小流域洪水灾害形势严峻，暴雨洪水过程模拟是洪水预警预报的关键环节。本项目针对由于华南暴雨强度大、历时短、范围小等特性使得中小流域快速洪水过程复杂、难以描述的问题，以华南地区暴雨洪水多发区-粤西曹江上游流域为研究区，开展华南中小流域极端降水条件下暴雨洪水过程模拟研究。将用野外实验观测和基于历史场次暴雨洪水资料的机理分析方法；重点研究华南极端降水条件下暴雨洪水过程的物理形成机制，辨识极端降水条件下影响中小流域暴雨洪水过程的关键因子及其关系；分析华南典型中小流域暴雨洪水过程对变化环境的响应；构建既能适应环境变化，又具有简单结构的华南极端降水条件下的中小流域暴雨洪水模型。基于模型对华南强降水条件下中小流域暴雨洪水过程的模拟，实现揭示变化环境下华南中小流域陡涨陡落的快速暴雨洪水特性和规律的目标。为华南中小流域暴雨洪水预报预警提供方法基础。

全球环境变化产生的水文效应已经成为国际热点，近年极端降水引发中小流域洪水灾害形势严峻。暴雨洪水过程模拟是洪水预警预报的关键环节。.本项目围绕变化环境下华南中小流域暴雨洪水特征及产汇流规律，选择鉴江上游曹江流域为典型研究区开展研究，取得以下研究成果：（1）研究了变化环境下华南典型研究区降水和径流等水文气象要素的时空格局变化特征和规律。流域降水具有空间分布不均匀，年值变化相对稳定的特征；流域空间降水变化趋势复杂，流域降水长期变化趋势反应了流域降水将进入增多时期；长序列降水过程具有周期性，且周期与多元ENSO指数存在显著共振周期。（2）进行了野外控制实验，分析了在暴雨条件下各个产流因素对产流期的平均入渗率的影响，结果显示雨强是最主要的影响因素，其次是土壤前期含水量和坡度，而植被覆盖度的影响相对较小；雨强和植被覆盖度与产流期平均入渗率呈现正相关的变化关系，而土壤前期含水量和坡度与产流期平均入渗率呈现负相关的关系。分析了实测暴雨洪水过程中的产流模式，该流域汇流属于蓄满和超渗混合型产流模式，且产流前流域损失量直接影响暴雨洪水过程。进行了数值模拟实验，阐释了流域汇流机制，建立中小流域一维动力波汇流方程的高效率计算方法（HEDWE），提高了汇流动力方程的计算效率：（3）基于前两个研究成果，构建了典型研究区暴雨洪水模型，并对暴雨洪水过程进行模拟。并采用流域实测暴雨洪水资料对模型进行验证，综合效率系数达到0.7以上，取得了较好的预报结果。该成果可以为华南台风暴雨地区洪水灾害预防和治理提供直接依据。.研究成果全面完成了项目预期研究计划，发表项目第一标注论文5篇，其中SCI论文1篇，中文核心论文3篇，申请专利1项，取得软件著作权1项，参加学术会议6人次，开展学术讲座1次。培养硕士研究生2名。