气候变化对鄱阳湖赣江流域水文情势影响的实证研究

An empirical study on the impact of climate change on the hydrological situation of Ganjiang River in Poyang Lake Basin

为了解气候变化对鄱阳湖赣江流域不同区域水文情势的影响,选择栋背、吉安、峡江、外洲等代表性水文站,将赣江流域进一步划分为赣江上游、坝吉区间、吉峡区间、峡外区间等4个子区域,结合长系列的水文资料,从气候变化下的降雨演变、径流演变、洪水时空分布演变、干旱及旱涝急转事件发生频率演变4个方面进行实证研究,并提出相应的对策建议。结果表明:气候变化对赣江流域不同区域的水文情势影响有一定区别。(1)相比于1960—2001年,赣江上游、吉峡区间、峡外区间2002—2020年的年平均降水量和年降雨天数均有减少;而坝吉区间的年降雨天数有一定减少,但年平均降水量则增大了6.4%。(2)降水方面,4个区域的年均降雨天数都处于减少状态。相比于1960—2001年,赣江上游的年平均流量和大于2 a一遇洪水的发生频率均有大幅下降;而中下游的峡江站和外洲站年平均流量则分别增加了3.6%和1.0%。除此之外,大于5 a一遇的典型洪水来水区域和主雨带总体也呈由上游向下游转移的趋势。(3)相比于1960—2001年,2002—2020年流域级旱涝急转事件频率由2.5%上升至10.5%;但赣江上游的气象干旱频率变化不大,而中下游吉安、南昌的气象干旱频率有明显提升。

To reveal the influence of climate change on the hydrological situation of different regions of Ganjiang River in Poyang Lake Basin, 4 representative hydrological stations including Dongbei, Ji’an, Xiajiang and Waizhou are selected. And then, the Ganjiang River Basin is further divided into 4 sub-regions: the upper reaches, the Baji region, the Jixia region and the Waizhou region. Combined with the long series of hydrological data, empirical research is carried out from 4 aspects of rainfall evolution: runoff evolution, flood spatial and temporal distribution evolution, drought and drought-flood abrupt change events evolution, and corresponding countermeasures are proposed. The result shows that climate change has different effects on the hydrological regime in 4 areas of Ganjiang River Basin.(1) Compared with 1960-2001, the average annual precipitation and the number of days of annual rainfall in the upper reaches, Jixia region and the Waizhou region decrease in the period of 2002-2020. The annual rainfall days in Baji region also decreases to a certain extent, but its annual average precipitation increases by 6.4%.(2) In terms of precipitation, all the average annual precipitation days in the 4 regions decrease. Compared with 1960-2001, the average annual flow and frequency of floods with return period larger than 2 years in the upper reaches of Ganjing River decrease significantly in the period of 2002-2020. However, the average annual flow in the middle and lower reaches increase by 3.6% and 1.0%, respectively. In addition, the inflow area and main rain belt of typical flood with return-period more than 5 years also show a general trend of shifting from the upstream to the downstream.(3) Compared with the period of 1960-2001, the frequency of sudden floods and droughts at the basin level increase from 2.5% to 10.5% in the period of 2002-2020.The frequency of meteorological droughts in the upper reaches of the Ganjiang River has not changed much, while the frequency of meteorological droughts in Ji’an and Nanchang in the middle and lower reaches have increased significantly.