Loktak Lake is an internationally important wetland in northeast India that provides
valuable goods and services to local communities as well as supporting high
biodiversity. Over the last three decades ecological modifications have occurred, most
notably due to the construction and operation of the Ithai Barrage. The focus on
maximising hydropower generation increased mean lake water levels and reduced their
annual variability. This thesis synthesises hydrometeorological and related data for the
lake and its catchment. Data are employed in coupled hydrological / hydraulic
catchment models (MIKE SHE / MIKE 11) of three gauged sub-catchments, which are
calibrated / validated using observed discharges. Results are used to estimate ungauged
sub-catchment flows. Catchment model results are combined with meteorological data
and current abstractions within a water balance model which successfully simulates
observed lake water levels. A series of barrage operation options are developed using
the water balance model which prioritise the requirements of major stakeholders
(hydropower, agriculture, and the lake ecosystem). A final option is developed, which
shows that it is possible to balance the demands of these stakeholders. The implications
of climate change are assessed by forcing meteorological inputs to the catchment and
water balance models based upon a number of climate scenarios. In the majority of
these scenarios, river inflows increase resulting in higher lake water levels that could
further exacerbate ecological degradation of the lake as well as enhancing flooding of
lakeside communities. The elevated water levels may permit additional irrigation
abstractions however existing infrastructure limits increases in hydropower generation.
The sustainability of the barrage operation options in the face of climate change is
assessed. Results suggest that climate change is likely to limit the ability of barrage
management to satisfy hydropower and agricultural demands whilst at the same time
establishing a more ecologically appropriate lake water level regime
