当前世界环境

干旱是影响自然资源和环境的长期缺水的最广泛的水文气象模式。然而，它在不同地区有着明显不同的特征。泰米尔纳德邦遭受包括干旱在内的各种灾害的折磨。一般来说，降雨量与长期平均值的偏差仍然是广泛采用的干旱强度评估指标。这一指标的应用受到其依赖平均值的固有性质的严重限制。因此，克服这些限制的标准化程序成为一种基本需要。此外，近年来降雨的稳定性是不稳定的，因此使用降水比(PR)来了解历年降雨的稳定性。为了进一步了解泰米尔纳德邦南部地区的干旱气候，采用了标准化降水指数(SPI)。公关研究历时30年(1981-2010)，覆盖7个地点。1981-90年期间，大部分地区的降雨量保持稳定，此后降雨量逐渐下降，证实了近10年的极端天气。 SPI had an annual range from +2.69 to -4.94 while Monsoon period had +2.41 to -3.43 and +2.69 to -3.14 respectively for Southwest and Northeast monsoon seasons. As per SPI index, Southern zone is prone to moderate drought followed by severe and extreme drought category. Among the periods studied (Annual, SWM and NEM) number of moderate drought occurrences had no much variation while in severe and extreme drought category, variations could be observed. In particular, during NEM period there was almost no occurrence of extreme drought.