In: Wagner W., Székely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B 
ilreamftow 
(mm/month) 
• 2003 
1971 
0 1 2 Î 4 5 6 T S 9 10 U 12 
months 
relative % 
difference 
Fig. 7. Monthly hydrographs of historic (1972) and current 
(2003) naturalized Streamflow stations, and relative percentage 
difference of runoff 
5. SUMMARY AND CONCLUSIONS 
Land use and vegetative cover play an important role in 
watershed runoff and streamflow discharge patterns over time, 
including peak flows. Increased human interventions have 
caused rapid transitions in landcover, adversely affecting the 
watershed processes and hydrological cycle in the long run. 
Distributed hydrological modelling offers an efficient solution 
to evaluate the long term hydrological changes by allowing 
quantification of changes in streamflow patterns.The Mahanadi 
river basin covering major portions of Chattisgarh and Orissa 
(India) has been repetitively facing the adverse hydro 
meteorological conditions such as floods, droughts and cyclones 
etc. in the recent times. Frequent occurrence of these events 
indicates a shift in the hydrological response of the basin 
attributed to landcover changes. This study attempts to model 
the hydrology of Mahanadi river basin using physically based, 
distributed VIC hydrological model and assess landcover 
change impacts on streamflows at various locations along the 
river. 
A detailed remote sensing based landcover mapping of the basin 
for years 1972, 1985 and 2003 reveals following changes: 
coefficient of determination before calibration was found 
to be as 0.747, for Mundali. 
• The calibration of the model at Mundali outlet was 
performed for year 2003. Streamflow was found sensitive 
to variables like upper and lower soil layer depth, velocity 
of flow and vegetation parameters. R 2 of 0.836, Ce of 
0.821 and Er of 0.085 was obtained during daily 
simulation. The model performance was found better for 
monthly simulations with Ns of 0.89. 
Streamflows were simulated using VIC model for the year 
1972, 1985 and 2003. Following conclusions can be drawn from 
the analysis carried for predicting changes over years: 
• An increase by 4.53% (24.44 mm) in the annual 
streamflow is predicted at Mundali outlet of the Mahanadi 
basin from 1972 to 2003. It may be concluded that a 
decrease in forest cover by 5.71% in the Mahanadi river 
basin has caused the river flow to increase by 4.53%. This 
is quite a significant amount in terms of volumetric rise 
(3514242122 m 3 ). 
• The relative percentage increase in streamflow was found 
high in the months of May and November in all sub-basins. 
It may be concluded that the impact of landcover changes 
are most pronounced during low flows and that during high 
flows, role of landcover becomes comparatively less. 
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• Total forest cover area has been reduced by 5.71% of the 
total area of the basin from 1972 to 2003. A reduction in 
barren land (0.64%) is followed by an increase in areas of 
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