Geoscience Reference
In-Depth Information
Fig. 1.
Drainage map of Kunderu basin showing tritium injection sites.
3. Recharge Measurements
Artificial tritium injection experiments have been carried out in Kunderu
river basin with the aim of calculating average recharge and total input to
the shallow groundwater reserves of the basin due to monsoon precipitation.
Tritium (H 3+ ), a radioactive isotope of hydrogen, is a soft β -emitter having
mass 3 and a half-life of 12.26 years. It exists in the form of water molecules
HTO and as such it is an ideal tracer for studying movement of water. The
use of tritium as a tracer in recharge measurement involves injection of triti-
ated water at a certain depth in the soil column and study of the vertically
movement that this tracer undergoes during the hydrological cycle. This
application of tritium in recharge measurements is based on an assump-
tion of the Piston-Flow model, proposed by Zimmermann and others and
Munnich, 3 - 5 assumes that the percolating soil moisture moves downward in
discrete layers and any addition of a fresh layer of moisture at the surface,
would push down an equal amount of water immediately below and so on,
till the moisture of the last such layer in the unsaturated zone is added
to the saturated regime or the water table. The principal steps involved
for calculating recharge have been described by earlier researches. 6 - 9
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