Approaches and Methods of Quantifying Natural Groundwater Recharge – A Review

Groundwater is the main source of water supply to both urban and rural populations as well as to industry and agriculture. Among various water cycle characteristics, groundwater recharge is the leading hydrologic parameter determining groundwater resources availability and sustainability. Accurate estimation of groundwater recharge is extremely important for proper development and management of the resource. Different approaches and methods are available to quantify groundwater recharge – from direct approaches, inferred from more easily measurable physical and chemical parameters, to simulation models with varying complexity. The methods have their own merits, demerits, and limitations. For proper selection of a method in a particular geo-hydrologic and climatic condition, detail knowledge of the methods along with their applicability/limitations, and the governing factors affecting recharge are essential. This paper presents an overview of the methods along with the theory underlying the methods (physical basis), assumptions, advantages, limitations, and selection procedure under the prevailing situation of technological, hydro-geological, and resource availability; with a view to help proper selection of a method. The overview synthesized and exemplified the above issues, and concludes with discussion of challenges and research needs in this evolving field.