1960—2013年昭通市极端降雨时空演变规律研究

气候变化引起的极端降雨量级和频次变化已经引起了广泛的关注,极端降雨演变规律的研究对于区域防洪减灾和水资源管理具有重要意义。基于昭通市及其周边的16个气象站点1960—2013年共54 a的降雨数据,选取世界气象组织推荐的6个极端降雨指数,采用线性趋势分析、Mann-Kendll法和滑动T检验等方法分析了昭通市的极端降雨时间演变规律,并基于ArcGIS10.2采用反距离插值法(IDW)分析了昭通市极端降雨指数的空间分布格局。结果表明:在趋势演变方面,昭通市的总降雨量PRCPTOT有下降趋势;而反映极端降雨量级的3项指数SDII,RX5day,R95p均呈上升趋势,其中RX5day上升趋势显著;而R10mm和CWD这2项反映极端降雨频率的指数均呈下降趋势,其中R10mm下降趋势显著。在空间分布方面,昭通市6项极端降雨指数具有较高的空间异质性,东北部降雨量级和频率较高,中部趋缓,而西南部总体上相对较低。相关分析的结果表明昭通地区极端降雨指数与高程呈现负相关关系,极端降雨主要发生在低海拔地区。研究成果有助于加深对该区域极端降雨发生规律的认识,为区域防洪减灾和水资源管理提供参考。

Spatio-temporal Variations of Extreme Rainfall in Zhaotong from 1960 to 2013

Changes in the magnitude and frequency of extreme rainfall caused by climate change have attracted wide attention around the world. Researching the evolution law of extreme rainfall is of great significance for regional flood control and water resources management. According to rainfall data in 54 years (1960-2013) at 16 meteorological stations in Zhaotong, Yunnan Province and its surrounding areas, we analyzed the spatial evolution of six extreme rainfall indicators recommended by the World Meteorological Organization by linear trend analysis, Mann-Kendall method, and moving-t test, and the spatial distribution pattern by inverse distance interpolation method based on ArcGIS10.2. Results manifest that total rainfall volume indicator PRCPTOT presented a downward trend; three indices reflecting the magnitude of extreme rainfall, namely, SDII, RX5day, and R95p, displayed increasing trends, among which RX5day increased significantly; R10mm and CWD, which reflect the frequency of extreme rainfall, both showed decreasing trends, of which R10mm decreased apparently in particular. In terms of spatial distribution, the six indicators are of high spatial heterogeneity: the magnitude and frequency of rainfall were high in northeast Zhaotong, but alleviated in central Zhaotong, and relatively low in the southwest. In addition, extreme rainfall indicators were negatively correlated with elevation: extreme rainfall mainly happened in area of low altitude.