Identifying rainfall trends in highly urbanized area is extremely important for various planning and implementation activities, including designing, maintaining and controlling of water distribution networks and sewer networks and mitigating flood damages. However, different available methods in trend analysis may produce comparable and contrasting results. Therefore, this paper presents an attempt in comparing some of the trend analysis methods using one of the highly urbanized areas in Sri Lanka, Colombo. Recorded rainfall data for 10 gauging stations for 30 years were tested using the MannKendall test, Sen’s slope estimator, Spearman’s rho test, and innovative graphical method. Results showcased comparable findings among three trend identification methods. Even though the graphical method is easier, it is advised to use it with a proper statistical method due to its identification difficulties when the data scatter has some outliers. Nevertheless, it was found herein that Colombo is under a downward rainfall trend in the month of July where the area receives its major rainfall events. In addition, the area has several upward rainfall trends over the minor seasons and in the annual scale. Therefore, the water management activities in the area have to be revisited for a sustainable use of water resources.

中文翻译：

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确定斯里兰卡科伦坡降雨趋势的不同分析技术的比较

确定高度城市化地区的降雨趋势对于各种规划和实施活动极为重要，包括设计，维护和控制配水管网和下水道管网以及减轻洪水灾害。但是，趋势分析中不同的可用方法可能会产生可比较的对比结果。因此，本文提出了一种尝试，使用斯里兰卡科伦坡的一个高度城市化地区，比较一些趋势分析方法。使用MannKendall检验，Sen的斜率估算器，Spearman的rho检验和创新的图形化方法测试了10个测量站30年的记录降雨数据。结果显示了三种趋势识别方法之间的可比结果。即使使用图形方法比较容易，由于数据散布有一些异常值，由于识别困难，建议使用适当的统计方法使用它。然而，在这里发现科伦坡在该地区接收到主要降雨事件的7月份处于降雨下降趋势。此外，该地区在短季节和年尺度上都有几种向上的降雨趋势。因此，必须重新考虑该地区的水资源管理活动，以实现水资源的可持续利用。在短季节和年尺度上，该地区降雨呈上升趋势。因此，必须重新考虑该地区的水资源管理活动，以实现水资源的可持续利用。在短季节和年尺度上，该地区降雨呈上升趋势。因此，必须重新考虑该地区的水资源管理活动，以实现水资源的可持续利用。