Trend Analysis of Groundwater Levels in Kalpathypuzha Sub-Basin of Bharathapuzha, Kerala in India

Groundwater is one of the most precious and significant sources of water in the world. The understanding of groundwater level variability and trend is crucial for water resources planning in a region. The present study was conducted in the Kalpathypuzha sub-basin of Bharathapuzha. The variability of ground water levels was analyzed using various descriptive statistics such as mean, standard deviation, coefficient of variation, skewness and kurtosis. The groundwater level trend was estimated using the Mann-Kendall test and Sen’s slope estimator. Twelve observation wells evenly distributed in the blocks of Kuzhalmannam, Palakkad, Malampuzha and Chittur blocks of Palakkad districts in Kerala were selected for the study. The results of variability analysis showed that, the highest mean monthly groundwater level of 139.1 m was found for the well 139 of Chittur block in September and the lowest mean monthly groundwater level of 61.5 m was found for the well 129 of Palakkad block in September. The highest mean annual groundwater level was 138.9 m in the year 2007 for the well 139 of Chittur block and the lowest was 62.1 m in the year 2016 for the well 129 of Palakkad block. The results of trend analysis showed a decreasing pre-monsoon groundwater level trend in three wells viz. well 129 of Palakkad block and wells 133 and 142 of Malampuzha block while decreasing post-monsoon groundwater level trend was observed in well 139 of Chittur block. There was no significant trend in the rest of the wells for both the pre-monsoon and post-monsoon periods.