Assessment of rainfall recharge using rainfall infiltration factor method and empirical equations

Abstract

The rainfall recharges of subsurface and ground water is through the artificial application and natural geology. The rainfall recharge occurring through geology features is natural which is mainly based on the process of infiltration where infiltrated water percolates from the surface and subsurface to the bed of the aquifer. Recharge plays a vital role in rabi and zaid season, especially for agricultural purposes. The average annual rainfall of Chhattisgarh is higher than India’s annual rainfall, but most of the regions have drought condition during off monsoon. In this study, an attempt has been made to assess the recharge from rainfall in Mandri river watershed, Kanker district, Chhattisgarh, India. Rainfall recharge calculated using four different methods such as Rainfall Infiltration Factor (RIF) method, Chaturvedi equation, Water level fluctuation method and an empirical equation developed by National Geophysics Research Institute (NGPRI). The above methods were mostly used in recharge by rainfall. The RIF method and NGPRI equation is based on geological classification. Rainfall recharge is computed by all the four methods and compared at study area of Kanker district in Chhattisgarh. It was found that RIF and NGPRI methods gave well-defined and closed results to the water table fluctuation method as compared to empirical equation. Also, it can be concluded that the equation should be region specified, based on the specific infiltration factor of that region-specific rock. Rainfall recharge is significant in those areas where geology strata are Vesicular, Jointed Basalt, Semi- consolidated sandstone, Weathered Granite etc. The ten-year average recharge value using RIF method is 890.22 ha-m, whereas using NGPRI method is 1036.25 ha-m, Water level fluctuation method gives 1079.ha-mand Chaturvedi equation was found to yield the highest value i.e. 1349.38 ha-m.