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has increased by 63% over two decades (1979-1999). In spite of these large
inflows, the storage change in this zone shows a significant decline during
drought periods (1984-1989 and after 1999) due to lower recharge from
rainfall in this zone as well as correspondingly reduced inflows from the
adjacent zones. On the contrary during good rainfall periods (1991-1993)
an increase in the groundwater storage is observed. In the zone 9, the draft
is quite small and is approximately 30% of the recharge. The pumping is
not much changed in this zone as considerable part of this zone lies in the
forested region. The outflows from this recharge zone have increased by
about 35% during 1979-1999. Further inflows into this zone have increased
considerably by 60% during 1984-1999 to sustain the requirements of zone
7. These inflows might have occurred from the adjacent region of Bandipur
national park located in the Nugu basin. Due to these inflows, the storage
change in this zone shows an interesting trend of increasing water levels in
spite of high pumping occurring in adjacent zone 7.
4. Conclusions
The Gundal subbasin, which is located in a semi-arid portion of the Cauvery
river basin, is intensively cultivated through irrigated canal command in its
Northern part and groundwater in the recharge and intermediate zones.
Significant part of the recharge zones is part of the ecologically sensi-
tive Bandipur National Sanctuary. It was found that the evaluation of the
impact of groundwater based agriculture needs to be carried out at the scale
of the whole system. The most salient feature of the study is the necessity of
analyzing groundwater balance at a regional scale, due to the importance of
lateral fluxes, which are generally neglected in hard rock aquifers. The lat-
eral groundwater flow appears to be controlled by the geological structures
in the vicinity of high pumping zones. As a consequence, the assessment
of the sustainability of agricultural practices in the high pumping areas
located in the recharge zones of the subbasin, must take into account the
impact on the neighboring zones, including the protected forested areas.
The study indicates that water levels in the excessive groundwater deple-
tion zones are sustained at the present level due to the inflows from the
adjacent Nugu river basin. This might result in decline of water levels in
the region of Bandipur national park.
Acknowledgments
This work was carried out through the support received from Indian Insti-
tute of Science, the French Institute of Research for Development and
