India is one of the most drought-ravaged countries in the world and faces at least one drought in one region or another in every 3 years. There is no single reliable approach in characterizing future droughts. To understand future drought risk, potential changes of drought properties and characteristics are analysed in this study. Using Fuzzy c-means clustering approach, homogeneous drought regions are identified in the Godavari river basin and therefore, optimum number of clusters were assigned as four. The 12-month standardized precipitation index (SPI) using precipitation data from India Meteorological Department (IMD) and Global Climate Model (GCM)—MIROC-ESM-CHEM is calculated for the homogeneous regions of the Godavari basin. The best fit copula for observed and simulated severity and duration are: Region 1—Clayton, Regions 2 and 3—Gumbel, Region 4—Frank copula. Severity-duration-frequency (SDF) and severity-area-frequency (SAF) curves were developed and analysed using the best fit copulas. The research findings conclude that moderate and severe droughts are frequently increasing for future periods (2006–2099) compared to the historic period (1962–2005). Droughts with high severity and high mean interarrival time are observed as expected in the future. For the Godavari basin, the SDF curves were concave upwards indicating an increase in severity with an increase in duration. The rate of increase of severity is small for shorter durations compared to that of longer-duration drought. Thus, more prolonged drought events in the 21st century are likely to occur. The SAF curves with steeper slopes and high variability in topographical and hydrological characteristics have been observed over the Godavari basin. From these curves, for a specified percentage of area and return period, the drought severity can be calculated and the information can be used for crop management and agricultural water demands. Overall, the findings of this research offer a view of likely scenarios of drought in the Godavari basin.

中文翻译：

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印度戈达瓦里河流域干旱严重程度-持续时间-频率和严重程度-面积-频率曲线的区域分析

印度是世界上受干旱影响最严重的国家之一，每三年至少在一个地区或另一个地区面临一次干旱。没有单一可靠的方法来表征未来的干旱。为了了解未来的干旱风险，本研究分析了干旱性质和特征的潜在变化。使用模糊 c 均值聚类方法，在 Godavari 河流域中确定了同质干旱区，因此，将最佳聚类数指定为四个。使用来自印度气象局 (IMD) 和全球气候模型 (GCM) 的降水数据的 12 个月标准化降水指数 (SPI) - MIROC-ESM-CHEM 计算了 Godavari 盆地的均质区域。观察到的和模拟的严重性和持续时间的最佳拟合系词是：区域 1-Clayton，区域 2 和 3-Gumbel，区域 4——Frank copula。使用最适合的 copula 开发和分析严重程度 - 持续时间 - 频率 (SDF) 和严重程度 - 面积 - 频率 (SAF) 曲线。研究结果得出结论，与历史时期（1962-2005 年）相比，未来时期（2006-2099 年）中度和重度干旱频繁增加。正如预期的那样，未来将出现严重程度高和平均到达时间长的干旱。对于 Godavari 盆地，SDF 曲线向上凹表示严重程度随着持续时间的增加而增加。与持续时间较长的干旱相比，持续时间较短的严重程度增加率较小。因此，21 世纪可能会发生更长时间的干旱事件。已在戈达瓦里盆地观察到坡度较陡且地形和水文特征变化较大的 SAF 曲线。根据这些曲线，对于指定的面积百分比和重现期，可以计算干旱严重程度，并且可以将信息用于作物管理和农业用水需求。总体而言，这项研究的结果提供了戈达瓦里盆地可能出现的干旱情景的观点。