Long Term Trend Analysis of Mega Cities in Northern India using Rainfall Data

Abstract

Land use change is occurring rapidly and it has huge impact on the local climate. The study area includes 17 mega cities located within 25°18’00’’N to 34°5’24”N of India. The current study is based on trend of historical rainfall which is analyzed by Mann-Kendall method using monthly rainfall data (1901-2011). Before using this method, pre-whitening method was applied for removing the error from the data. Sen’s Slope estimator is used to derive the magnitude of the data. Standard Normal Homogeneity Test (SNHT) was used for identifying the break point of the data series. Finally true slope of an existing trend and variance of the residuals was calculated for all selected cities using Sen’s method. Increasing trend has been found in Jaipur, Jodhpur, Faridabad, Meerut, Ghaziabad, Delhi, Chandigarh, Ludhiana, Amritsar, Srinagar whereas, Allahabad, Varanasi, Patna, Kanpur, Gwalior, Agra shows decreasing trend. No trend is observed in Kota. Monsoon season depicted decrease in the rainfall magnitude in most of the regions of north India. This result is extremely significant as monsoon rainfall serves the major water demand for agriculture and water resources. Change Percentage for 111 years had shown rainfall variability throughout North India centre’s with the highest increase in Delhi centre’s (32.43 %) and decrease in Patna centre’s (−16.22 %) annually.