Abstract:
To understand the interaction of surface water and groundwater it is important to know the
mixing of various sources of water like precipitation or evaporated or storage water bodies
and releases from them or recharge to aquifers to understand the man’s influence on streams
and aquifers. It can help plan or prevent deterioration of water quality by salinization and
pollution. The environmental isotopic methods provide a valuable approach to understand the
complex phenomena of rainfall - surface water - groundwater interactions. The application of
the environmental isotope methods to understand the origin of sources of surface and
groundwater with respect to its recharge is based on the spatial and temporal variability of the
isotopic contents of water. Errakalva river drains West Godavari district for about 180 km
and joins the Upputeru river, which takes off from the Kolleru lake falls into Bay of Bengal.
Errakalva enters the Godavari western delta, after draining an area of including that of
upstream catchment of 2330.10 km2, near Nandamuru aqueduct of Tadepalligudem Mandal
and emerges as Yenamadarru drain and debauches in to Bay of Bengal through Upputeru
major creek. In this study, as part of IWRM project in Errakalva Pilot basin, variation of
measurement of stable isotopes of Deuterium and Oxygen i.e, D and 18O in the water
samples of precipitation, canal water, stream water, tank water and groundwater collected in
the Yanamadurru drain, discharging from 394.93 km2 in deltaic plain is studied and analysed.
The variation of stable isotope 18O16 in the surface and ground waters of the lower part of
Errakalva basin called Yanamadurru drain or Y Drain system is discussed to understand the
proportion of mixing of sources waters in surface water and groundwater at different
locations.
