Department of Technology, Shivaji University, Kolhapur, 416004, India.
Department of Civil Engineering, KIT's College of Engineering (Autonomous), Kolhapur, 416234, India.
J Environ Manage. 2024 May;359:121082. doi: 10.1016/j.jenvman.2024.121082. Epub 2024 May 9.
Rainfall is a key hydro meteorological variable. Climate change is disrupting the hydrological cycle and altering the usual cycle of rainfall, which frequently results in long-lasting storms with significant rainfall. A first step in hydrologic design of project is to determine the design storm or rainfall events to be used. For deriving design storm, researchers concluded that instead of using generalized readily available curves or maps, it is better to estimate design storm based on site specific historical rainfall data. The objective of the study is to analyze the rainfall data in the koyna watershed area in order to evaluate the design storm, which will be further used as an input data for HEC-HMS event based hydrological modelling of flood peak attenuation of design storm flow at koyna dam during extreme rainfall event. In this study, 40 years (1982-2021) of rainfall data from 8 rain gauge stations in Koyna Dam Catchment area is used initially for performing trend analysis through statistical and graphical techniques and then for Isopluvial analysis. The Sen's slope test and the Mann-Kendall test are the statistical techniques employed, and Innovative Trend Analysis is the graphical technique used. IDF approach is used for deriving design storm, and using Gumbel's frequency distribution method Isohyetal maps, IDF tables and curves are prepared for 2,10,25,50,75 and 100 year return periods and 6,12,24,48 and 96 h durations. Results obtained from statistical and graphical trend analysis of annual rainfall series are consistent. No statistically significant trend in annual rainfall series is observed, however there is rising and falling trend was observed in annual as well as monthly rainfall series. From the results of design storm study, the design storm hyetograph of 10 years return period and 96 h duration is selected, which gives the rainfall intensity of 10.88 mm/h for the koyna catchment. There are various dams nearby koyna catchment, The Isohyet maps, IDF curves and table output available from this study can be more reliably used during planning and design of hydraulic structure for other areas near by koyna catchment.
降雨是一个关键的水文气象变量。气候变化正在扰乱水文循环，改变通常的降雨周期，这经常导致长时间持续的暴雨和大量降雨。项目水文设计的第一步是确定要使用的设计暴雨或降雨事件。为了推求设计暴雨，研究人员得出结论，最好是根据特定地点的历史降雨数据来估计设计暴雨，而不是使用通用的现成曲线或地图。本研究的目的是分析科伊纳流域的降雨数据，以评估设计暴雨，该暴雨将进一步用作科伊纳大坝在极端降雨事件中基于 HEC-HMS 事件的洪水峰值衰减水文模型的输入数据。在这项研究中，最初使用了科伊纳大坝集水区的 8 个雨量站的 40 年（1982-2021 年）降雨数据，通过统计和图形技术进行趋势分析，然后进行同雨量分析。使用的统计技术是 Sen 斜率检验和 Mann-Kendall 检验，使用的图形技术是创新趋势分析。使用 IDF 方法推求设计暴雨，并使用 Gumbel 频率分布方法生成等雨量线图、IDF 表和曲线，用于 2、10、25、50、75 和 100 年重现期以及 6、12、24、48 和 96 小时历时。从年降雨量序列的统计和图形趋势分析中得到的结果是一致的。在年降雨量序列中没有观察到统计学上显著的趋势，但在年降雨量和月降雨量序列中观察到了上升和下降的趋势。从设计暴雨研究的结果来看，选择了 10 年重现期和 96 小时历时的设计暴雨雨型，该雨型为科伊纳集水区提供了 10.88 毫米/小时的降雨强度。科伊纳集水区附近有各种大坝，本研究提供的等雨量线图、IDF 曲线和表输出可更可靠地用于科伊纳集水区附近其他地区的水力结构规划和设计。
