Hydrochemistry and stable isotopes during salinity ingress and refreshment in surface- and groundwater from the Arani–Koratallai (A–K) basin north of Chennai (India)

Short-term desalination of Pulicat lagoon (Southeast India) due to the 2015 extreme flood event: insights from Land-Ocean Interactions in Coastal Zone (LOICZ) models

“…The river channels (Araniar, Kalangi and Swarnamukhi) are indicated with blue lines. Major dams are marked with black pointers (from Raju et al 2006, Raju et al 2013, Sprenger et al 2015. Entrance of the lagoon into the Bay of Bengal is presently active only near the southern region of the lagoon (marked with a red star).…”

“…However, the upstream dams, reservoirs and 'anicuts' (a local term for check dams) on these rivers ( Fig. 1, Sprenger et al 2015) and managed aquifer recharge structures (Raju et al 2013, Sprenger et al 2015 built to divert/store the runoff from monsoons significantly reduce the surface runoff into the lagoon at various points on the western shore. As a result, there have been few possibilities for monsoonal desalination of the lagoon in the recent times (i.e., from 1960s when the first check dams across the rivers came into existence, source: http://www.indiawris.nrsc.gov.in/wrpinfo/index.php?title=Main_Page) under normal conditions.…”

“…The evaporative outflow (V E ) during the period was negligible due to the high humidity experienced during the event (Mishra 2016). Based on aquifer characteristics and management in the region (described in detail in Raju et al 2013 andSprenger et al 2015), we also considered the contribution from groundwater flow (V G ) and hence the contribution of the salinity of groundwater (S G ) during the period as insignificant compared to the surface flow which was apparently higher during the floods. Maximum freshwater flow (V Q ) was obtained from the flow accumulation procedure described above.…”