白洋淀流域气温、降水和径流变化特征及其相互响应关系

运用Mann-Kendall趋势检验、突变检验和小波分析法,对白洋淀流域1957—2012年7个气象站点气温、降水和3个典型水文站点径流量的变化趋势、突变点及周期性变化进行了分析,并探讨了径流与降水和气温的响应关系,以期为该地区生态环境保护和水资源合理利用提供基础数据支持。结果表明,研究区年均气温呈上升的趋势,并在1988年后上升趋势增大,其中,冬季和春季的气温增幅对气温升高贡献较大;降水量变化相对复杂,整体呈波动下降的趋势,其中,夏季降水量减少幅度最大,达1.72 mm·a~(-1)。受气温升高和降水量的直接影响,典型站点径流量呈明显下降趋势,并在年际尺度上与气温呈负相关,与降水变化呈显著正相关;在年内尺度上,则与气温和降水变化呈显著正相关。夏季径流量减少幅度最大,阜平、倒马关和紫荆关站分别下降0.85 m~3·s~(-1)·a~(-1)、0.72 m~3·s~(-1)·a~(-1)和0.66 m~3·s~(-1)·a~(-1)。3个指标的周期性变化都比较明显,其中径流和降水的波动变化基本一致,表明径流对降水的响应比较突出。径流变化不仅受气温和降水的影响,还受到水利工程建设、各类农业措施等多种因素的影响。

Variation trend and response relationship of temperature, precipitation and runoff in Baiyangdian Lake Basin

As the largest freshwater lake in the North China Plain, Baiyangdian Lake is a key hydro-confluence that is critical for flood prevention, sedimentation mitigation, irrigation, water supply and maintenance of ecological balance of the area. Since the 1960s, surface runoff in Baiyangdian Basin has continuously dropped, water quantity greatly reduced and lake-drying frequency increased due to the impact of climate change and human activities. The decreasing water quantity has reduced ecological function of the lake, further affecting socio-economic development and ecological security in the region. Using observed daily temperature and precipitation data at 7 meteorological stations along with monthly runoff data from 3 typical hydrological stations for the period 1957-2012, the change characteristics in temperature, precipitation and runoff in the Baiyangdian Lake Basin were analyzed. In this study, the cumulative anomaly method, Mann-Kendall test and Morlet wavelet analysis method were used to determine the trends and abrupt changes in mean annual temperature, precipitation and runoff. The purpose of this study was to develop data support and reference base for improving ecological environment and reasonable utilization of water resources in the area. The results showed that the climate in the study area had a significant warming trend with an abrupt increase of temperature since 1988. Especially, the increase of temperature in both winter and summer contributed more to temperatures rising. Annual precipitation showed a decreasing trend with obvious fluctuation. The decrease in summer precipitation (1.72 mm·a^-1) was higher than that in the other seasons. Increasing temperature along with decreasing precipitation were the dominant trends, further aggravating dry and hot climatic conditions and lake-drying in the region. There was an obvious decreasing trend in runoff due to the effect of temperature and precipitation. There was a negative correlation between runoff and temperature and a positive correlation between runoff and precipitation at annual scale. At seasonal scale, runoff was positively correlated with temperature and precipitation. Summer runoff in Fuping, Daomaguan and Zijingguan hydrological stations decreased by 0.85 m³·s^-1·a^-1, 0.72 m³·s^-1·a^-1 and 0.66 m³·s^-1·a^-1, respectively. The intervals of change in mean annual temperature, precipitation and runoff were obvious. Also the fluctuations in runoff and precipitation were consistent, suggesting that the response of runoff to precipitation was more prominent. The change in runoff was not only influenced by temperature and precipitation, but also by other climatic factors, water conservancy projects, agriculture and local geological conditions. In future studies, it was needed to further analyze the effect of each factor on the runoff in order to comprehensively understand the driving factors of runoff in the basin.