This study aimed at characterizing the groundwater flow pattern in a semi-arid agricultural area in northern India crossed by an intermittent monsoon-controlled watercourse, the Najafgarh drain. More specifically, it focused on studying the impact of groundwater recharge from the riverbed to the regional aquifer using hydrogeochemical and isotopic data. Significant hydrogeochemical zonation was observed between the northern, central and southern sides of the drain, linked to different mineralization processes and mixings. Northward from the drain, groundwater was mainly brackish (4.1–23.4 mS/cm), due to dissolution of evaporites (halite and anhydrite). Southward from the drain, mostly fresh groundwater was found (from 0.5 to 2.3 mS/cm), revealing notable cation exchange processes. In the vicinity of the drain (central area), mineralization was intermediate (0.7–4 mS/cm) and groundwater showed low geochemical evolution, supposing a distinct origin. Stable isotopes of water (d18O, d2H) confirmed that central groundwater was not a simple mixing between northern and southern groundwater masses, but had a significant component of infiltrated surface water from the drain. Potentiometric data supported these findings and confirmed the contribution of the drain to the recharge of the aquifer, setting up a hydraulic barrier between north and south, despite surface water availability limited to the monsoon season and low hydraulic conductivity of the riverbed. This study demonstrates the value of the geochemical and isotopic analysis of groundwater to characterize groundwater flow pattern in peri-urban agricultural areas, especially surface water–groundwater interactions.

The paper presents semi-analytical mathematical model to estimate unsteady groundwater recharge resulting from variable depth of water in a large water body, influenced by time variant inflows and outflows. The model has been derived by integrating Hantush’s (1967) analytical expression for water table rise due to recharge from a rectangular spreading basin into the water balance equation of the water body. The model has been applied to a test study site in Raipur (India) for assessing viability of Managed Aquifer Recharge (MAR) from a lake located on an area dominated by the massive limestone formation. The components of the water balance equation have been carried out by the comprehensive analysis of the hydrological and hydrogeological aspects of the lake. The hydrological components include

Hydrogeochemical and hydrodynamic surface/groundwater interactions were investigated at the urban floodplain aquifer in Delhi, India. The heavily polluted Yamuna River is in hydraulic contact to the groundwater and river seepage results in a contamination plume. A conceptual redox zonation was developed based on the occurrence or absence of terminal electron acceptors. The redox zonation shows an inverted zonation from sulphate-reducing conditions close to the river over manganese- and iron-reducing conditions to a mixed oxic/suboxic zone. This study shows that the occurrence of problematic substances such as ammonium and arsenic in the groundwater is a consequence of the high load of untreated sewage in the river in combination with losing river conditions. Sequential extraction of aquifer material was performed to obtain information on geochemical availability of arsenic associated with different mineral phases and binding forms. Geogenic and anthropogenic arsenic sources contribute to overall arsenic concentration, and arsenic is found to be attributed mainly to amorphous iron oxide and sulphidic phases in the sediment. The contamination plume at the urban floodplain aquifer makes the groundwater unfit for drinking water purposes.

In Chennai (India) public water supply and agriculture depend on groundwater to various extents, but the valuable resource shows increasing salinity over the past decades due to seawater intrusion. This study aims at identifying major hydrogeological processes which lead to salinity ingress in the main aquifer and investigates the effect of MAR structures such as check dams. Regional hydrochemistry is discussed by a combination of stiff diagrams, Cl/Br ratios, ion exchange diagram and stable isotopes (d18O, dD). The identified hydrogeochemical processes were high saline evolution due to intensive seawater evaporation for commercial salt production and typical ion displacement under refreshening and salinization conditions. Stable isotopes give new insights on (1) mixing processes of different end members (2) occurrence and degree of evaporation in ground- and surface water and (3) isotopical characterisation of groundwater recharge of the region. The identified processes were summarized in a conceptual model of the region. © 2014 Springer-Verlag Berlin Heidelberg.

This report aims at documenting the scientific evidence at 4 managed aquifer recharge (MAR) sites in India after 18 months duration of the EU (European Union) funded project SAPH PANI. The site investigations include compilation of previously existing data, a wide range of field experiments, surface-/groundwater and sediment sampling, data analysis, interpretation and the development of (preliminary) conceptual models. The MAR sites are realised under a wide range of geological and hydrological conditions and the covered aspects can be summarised as:...