Rainfall is an vital hydro-climatic element at the helm of that heads the hydrological cycle and water availability in a specific region. In current years, significant deviances have been observed in rainfall patterns on a global as well as local scale. Several analyses have established that any study of hydro-climatic variables must be handled and executed on different micro-scales rather than regional scale because the trends and their effects may differ widely from station to station. In the current investigative study, the urban rainfall variation in the Koraiyar basin between the years 1975-2010 is examined to study the trend of precipitation. The non-parametric test is used in this study because the data outliers can be avoided easily. The Mann-Kendall (M-K) method is adopted to analyze the trend, and Sen’s slope is used to estimate the linear trend. To detect the change in trends, the CUSUM test is applied. The coefficient of variance (CV) is applied for variability analysis. From the analysis, it is noted that there is an unpredictable increasing and decreasing trend in the yearly and periodic rainfall patterns in the basin.

中文翻译：

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降雨数据趋势研究：以泰米尔纳德邦科赖亚尔盆地为例

降雨是影响特定地区水文循环和水供应的重要水文气候要素。近年来，在全球和地方范围内的降雨模式中都观察到了明显的偏差。多项分析已经确定，任何水文气候变量研究都必须在不同的微观尺度而不是区域尺度上进行和执行，因为趋势及其影响可能因站而异。在目前的调查研究中，考察了1975-2010年间科赖亚尔盆地的城市降水变化，以研究降水趋势。本研究中使用非参数检验，因为可以轻松避免数据离群值。采用Mann-Kendall（MK）方法分析趋势，Sen的斜率用于估计线性趋势。为了检测趋势的变化，应用了CUSUM测试。方差系数（CV）用于变异性分析。从分析中可以看出，流域的年降水量和周期性降水量存在不可预测的增减趋势。