基于耦合协调模型的复合干旱研究——以汉江中下游流域为例

Characteristics of compound drought based on coupling coordination model—a case study of the middle and lower reaches of Hanjiang River

近年来,流域干旱逐年加剧,城市规模扩大和人口增加,使得水资源供需矛盾突出。因此,研究气象干旱与水文干旱之间的关系对水资源的影响以及评估不同城市对干旱的脆弱性至关重要。本文提出了复合干旱概念及判别标准;基于汉江中下游1973一2020年逐月降水、径流数据,利用标准化降水指数和借助粒子群优化算法改进的标准化径流指数分析了汉江中下游气象干旱与水文干旱的时空变化;结合耦合协调度模型探究了复合干旱之间的关系及时空分布特征。结果表明:(1)时间上,汉江中下游春季干旱由水文干旱主导;夏季整体无旱;秋季干旱由气象干旱主导;冬季由气象干旱和复合干旱主导。(2)时间上,1973一2020年汉江中下游气象干旱与水文干旱整体耦合程度以较强(0.75<C≤1)为主,协调程度以中协调(0.5<D≤0.7)为主。空间上,2013年前汉江中下游各地区耦合度大小为:仙孝都市圈>荆门市>襄阳市>武汉市>天潜都市圈;2013年后各地区耦合度大小为:武汉市>天潜都市圈>襄阳市>荆门市>仙孝都市圈。(3)汉江中下游气象干旱与水文干旱耦合协调关系以高耦合中协调为主,且在研究期内耦合协调关系呈减弱状态,整体下降了7.8%。2013年以后汉江中下游流域天潜都市圈、武汉市干旱防治最为紧迫。本文提出的基于耦合协调模型研究复合干旱的思路和方法可为流域的干旱防治与发展提供理论依据,从而实现城市可持续发展。

In recent years,the drought in the basin has intensified year by year,the expansion of urban scale and the increase of population have made the contradiction between supply and demand of water resources prominent.Therefore,it is important to study the impact of relationship between meteorological drought and hydrological drought on water resources and to assess the vulnerability of different cities to drought.In this paper,the concept and criterion of compound drought are proposed.Based on the monthly precipitation and runoff data of the middle and lower reaches of the Hanjiang River(MLHR)from 1973 to 2020,the standardized precipitation index and the standardized runoff index improved by particle swarm optimization algorithm were used to analyze the spatial and temporal changes of meteorological drought and hydrological drought in MLHR.Combined with the coupling coordination degree model,the relationship between compound droughts and their spatial and temporal distribution characteristics were explored.Results showed that:(1)On the seasonal scale,the spring drought in MLHR was mainly dominated by hydrological drought;there was no drought in summer;autumn drought was mainly dominated by meteorological drought;winter was mainly dominated by meteorological drought and compound drought.(2)In terms of time,the overall coupling degree of meteorological drought and hydrological drought in MLHR from 1973 to 2020 was mainly strong(0.75<C≤1),and the coordination degree was mainly moderate(0.5<D≤0.7).In terms of space,the coupling coordination degree of the MLHR before 2013 was:Xianxiao metropolitan area>Jingmen city>Xiangyang city>Wuhan city>Tianqian metropolitan area;after 2013,the coupling coordination degree of each region was:Wuhan>Tianqian metropolitan area>Xiangyang>Jingmen>Xianxiao metropolitan area.(3)The coupling and coordination relationship between meteorological drought and hydrological drought in MLHR was mainly based on high coupling and medium coordination,and the coupling and coordination relationship was weakened during the study period,with an overall decrease of 7.8%.After 2013,the prevention and control of drought in Tianqian metropolitan area and Wuhan in MLHR was most urgent.The idea and method of studying compound drought based on coupling coordination model proposed in this paper can provide a theoretical basis for drought prevention and development in the basin,so as to achieve sustainable urban development.