Abstract

The long-term spatio-temporal variability in twelve rainfall indices across Tapi basin are investigated for period 1944–2013. The temporal trends in aforesaid indices, representing magnitude, intensity, frequency and duration of rainfall, are analysed using non-parametric tests. The total annual rainfall exhibit uniformly increasing trends over Lower Tapi basin (LTB), while heterogeneous trends are observed across Upper (UTB) and Middle (MTB) Tapi basins. The rainy days portrays decreasing trends at 75% stations in the basin, while rainfall intensity displays increasing trends across LTB and UTB. On other hand, LTB and Purna sub-catchment (in UTB) show coherent increasing trends in extreme rainfall, while decreasing trends are observed over Burhanpur sub-catchment (in UTB) and MTB. A considerable increase in duration of dry spells is reported at 92.5% stations in the basin, indicating a marked shift towards drier climatic regime. Further, Principal Component Analysis (PCA) is carried out to address the space-time variability of rainfall indices. The results of PCA were adopted in cluster analysis to identify the stations exhibiting similar characteristic variations in rainfall trends. The hydroclimatic teleconnections between rainfall indices and large-scale oceanic-atmospheric circulations of the tropical Pacific Ocean (viz., El Niño-Southern Oscillation) revealed the prevalence of wet conditions in the basin during moderate to strong La-Niña, while dry conditions were encountered during moderate to strong El-Niño and weak La-Niña events. The spatial estimates of rainfall indices are derived corresponding to 2-, 10- and 50-year return periods which would be helpful in hydrologic design and risk assessment of rainfall-induced disasters in near future.

中文翻译：

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印度塔皮盆地降水指数的时空变化及其与厄尔尼诺现象-南涛动的遥相关

摘要

研究塔皮河流域1944–2013年期间12个降雨指数的长期时空变化。使用非参数检验分析了代表雨量，强度，频率和持续时间的上述指标的时间趋势。下塔皮盆地（LTB）的年降水总量呈现出均匀增加的趋势，而上塔皮盆地（UTB）和中塔皮（MTB）盆地则观察到非均质趋势。雨天描绘了流域75％站的下降趋势，而降雨强度显示了LTB和UTB的上升趋​​势。另一方面，LTB和Purna子汇水区（在UTB中）显示出一致的极端降雨趋势，而Burhanpur子汇水区（在UTB中）和MTB则观察到下降趋势。据报道，流域中92.5％的气象站的干旱持续时间显着增加，这表明向干旱气候体制的明显转变。此外，进行主成分分析（PCA）以解决降雨指数的时空变化。在聚类分析中采用了PCA的结果，以识别出降雨趋势具有相似特征变化的站点。降雨指数与热带太平洋大范围海洋-大气环流之间的水文气候遥相关（即厄尔尼诺-南方涛动）揭示了在中度至强度拉尼娜期间盆地的湿润条件盛行，而干燥条件是在中度到强烈的厄尔尼诺现象和弱的拉尼娜事件中遇到。得出降雨指数的空间估计值对应于2-，