Download full report in pdf format - Natural Resources Institute

Figure 31 presents information on Gundlur
tank’s surface water balance components during
an eleven year period. This figure gives an
indication of the variability in these components.
It also shows that the potential runoff, tank
inflow and spillage is only loosely correlated with
annual rainfall. Subsequent analysis carried out by
the WHiRL project has shown that the impact of
intensive water harvesting on tank inflows is most
marked in percentage terms in years with low
rainfall.
Figure 32 compares the increase in
groundwater-based irrigation in the tank
catchment areas during the last 12-16 years.
It can be seen that there has been a big increase in
each case with Yapadinne having the largest net
expansion in irrigated area. Figure 32 also shows
the portion of the increased irrigation that could
have come from increased groundwater recharge
that resulted from increased water harvesting in
the tank catchment areas. It can be seen that all the
increase in irrigation in Anabur could, in theory,
be met by the increased groundwater recharge,
whereas in Chapari virtually all the additional
irrigation must rely on “natural” groundwater
recharge.
Figure 31. Gundlur tank surface water balance components
700
600
Rainfall/Runoff (mm/year)
500
400
300
200
100
0
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
Rainfall Runoff Tank inflow Tank spillage
Figure 32. Possible sources of water for increased irrigation in tank
catchment areas during the last 12-16 years
400
350
Change in catchment irrigation (ha)
300
250
200
150
100
50
0
Gundlur Anabur Inchigeri Yapadinne Chapari
Groundwater
Structures
54