50-Characteristics of Groundwater Hydrographs in Diverse Hydrogeological Setup of Madhya Pradesh, India

Abstract

The state of Madhya Pradesh encompasses diverse setup of geological rock formations. The type of rock formation mainly controls the ground water occurrence and movement. Although, the sub-surface geology has been established by geophysical surveys and exploratory drilling by the Central Ground Water Board, to better comprehend the nature of the aquifer tapped by a well and changes of groundwater regime with time, it is imperative to monitor the groundwater levels regularly. Manual monitoring, especially high frequency monitoring of groundwater levels is a very tedious practice. High frequency monitoring of ground water level is being carried out by Digital Water Level Recorders, fitted in piezometers tapping different aquifers in diverse hydrogeological setups in Madhya Pradesh. Hydrographs produced by high frequency water level monitoring are of immense use. The shape, size and amplitude of a hydrograph will be different in different geological formation. Hydrographs are as useful to a hydrogeologist as an electro cardiogram to a heart specialist. The shape, size and amplitude of hydrograph can be utilized as indirect indicator of aquifer material beneath earth surface. In case of thick and highly permeable aquifers (high transmissivity), flatter shape of hydrograph indicates coarse grained consolidated or unconsolidated rocks and alluvium. Flatter shape of hydrograph may also be indicative of aquifers with low recharge and low permeability. The slope of rising limb as well as the falling limb of the hydrograph is steep in the case of confined aquifer and gradual and gentle in the case of unconfined aquifer. A gradual slope of the rising limb and slow dissipation or gentle slope of the falling limb is indicative of a weathered aquifer material, while a very steep slope of the rising limb and gradual dissipation or gradual slope of the falling limb is indicative of a fractured aquifer material. Amplitude is indicative of amount of recharge and thereby rainfall. Higher precipitation is evinced by higher amplitude and lower precipitation will reflect in lower peak.