Geoscience Reference
In-Depth Information
Fig. 1.
Location map of Gundal subbasin in Cauvery river basin.
The thematic layers of land use and structure are prepared from the
remote sensing and are shown in Fig. 2. It may be observed from the
two-season land use map (Fig. 2(a)) that substantial double crop areas
(kharif + rabi) exist not only in the discharge zone but also in the recharge
areas of the subbasin. The double crop areas in the recharge zone are man-
aged by groundwater pumping. It may be noted that sustained pumping
for both kharif and rabi crops in these zones are possible due to the good
yields in these areas, which are correlated to the presence of several lin-
eaments and structural control of groundwater in these parts. Figure 2(b)
shows the structural map of the subbasin, which shows the reasons for the
sustainability of double crop in some of the recharge and intermediate zones
of the subbasin. These thematic layers along with the hydrogeomorphology,
soil and transmissivity (obtained from pump tests) maps are combined to
produce an integrated composite zonation map (Fig. 2(c)), which delin-
eates nine homogeneous zones. Each of the zones contains one observation
well (OW) which is referred with the corresponding zone number (i.e. OW7
refers to well in zone 7). Figure 2(c) shows also the locations of the mon-
itoring network stations for the rainfall and groundwater level data used
for carrying out the analyses in the subbasin during the period 1977-2000.
The draft has been increasing in this subbasin beginning 1975. A detailed
