人类活动与气候变化对洪湖春旱的影响

Impactanalysis of human activities and climate change on Honghu lake's spring drought

近年来洪湖地区干旱事件频繁发生,对该地区农业生产与生态环境造成了极大影响。利用1960—2011年气候资料、近30年洪湖水文、土地利用资料,采用湖泊水量平衡方法、统计学等方法,研究分析了人类活动和气候变化对洪湖春季干旱的影响。结果表明:伴随全球气候变化该地区年降水和夏季降水呈增加趋势,而春季降水尤其是春季少雨年的降水量减少趋势明显,其减少速率为12.57 mn/10a,达到了α=0.1显著水平;洪湖5月水位高度依赖春季降水,降水对它贡献率为0.36 m/100mm。近20年来,洪湖周边两县市水产养殖面积增加了7倍,在降水偏少时,农业灌溉需水量20a增加了4.14×10~8m^3以上;水产养殖消耗大量春季水资源,对洪湖5月水位的影响率为-0.158 m/10~4hm^2,达到了0.1的显著性水平。人类活动与气候变化是洪湖春旱增多加重两个重要原因,比较它们的变化量与影响率,人类活动对洪湖春旱的影响更大。为维护洪湖生态功能,减轻干旱影响,必须调整农业结构。

In recent years, drought events in Honghu lake have shown a significant increasing trend, which has had a tremendous impact on local ecological and agricultural production. We conducted an analysis based on Honghu＇s hydrology and land-use data over the past 30 years and climate data from 1960 to 2011, using the water balance principle and statistical methods. The results showed that the Honghu water resource is most vulnerable in the spring. The water level at this time of year is just slightly higher-with 2 to 3 times the mean standard error-than that in winter, which leads to frequent and severe drought in Honghu. With global climate change, however, the local annual precipitation is increasing; the rainfall is concentrated in summer and is less in spring, especially in spring drought years, with a decreasing rate of 12.57 mnl/10a, significant at 0.1. The precipitation in summer increases, but it is negatively correlated with the water level in the following spring, which means that an increase in precipitation in summer can aggravate the severity of the spring drought. The Honghu lake water level in May is highly dependent on spring rainfall, with a rate of 0.36 m/100 mm. Over the past 20 years, the agricultural structure in Honghu has changed significantly, with increasing aquaculture areas and decreasing dry crop areas. The aquaculture area of the two counties surrounding Honghu has increased nearly 7 times and, because of this, the agricultural irrigation water requirement has increased by more than 414 million cubic meters in thecase of low rainfall, which is equivalent to 45% of the total water in Honghu lake＇s annual income. Increasing aquaculture consumes much of the water resource in spring and the coefficient between aquaculture and water level of Honghu is about - 0.158 m/10^4 hm^2 with a correlation coefficient of -0.4954, which is significant at 0.1. Human activities, especially excessive aquaculture and climate change, are the main reason for the increasing frequency and severity of spring drought in Honghu, with aquaculture having the greatest impact. In order to maintain Honghu＇s ecological function and reduce the drought effects, measures should be taken to change both the agricultural structure and the way in which land is used.