Abstract:
Extensive GIS and field studies of Indus delta were conducted during
2005-08 to determine the influence of reduced flow of river Indus on dynamics
of Indus delta changes as well as of its vegetation degradation during 49 years
period from 1953 to 2001. There was huge loss of 67% in dense forests with
slight reduction of 23% in the river flow in initial 25 years period whereas
there was a minor loss of only 9% of dense forests in spite of huge reduction of
57% of river flow in next 24 years period. It was noted that lagged effect
of river water dilution remained variably effective from 5-7 months after
floods.
It was further determined that Indus delta mangrove forests were not
degraded due to higher salinity levels. Comparative figures for different
parameters of forest cover, forest density, annual growth rate as well as
Shannon’s diversity Index H (richness) and E H (evenness) for least flooded
zone (23.12 ppt) and most flooded zone (18.74 ppt) were 60.58 vs. 56.19, 598
vs. 202, 17.46% vs. 18.08%, 0.45 vs. 0.08 and 0.40 vs. 0.07 respectively.
It was determined that reduced flow of river Indus had no adverse effect
on delta erosion, accretion as well as mangrove forest degradation as such. It
was apparent that biological interventions of various nature and magnitude
were responsible for the said degradation.
