Geoscience Reference
In-Depth Information
scales. Most of the groundwater models are distributed models and param-
eters used are not directly measurable. Recharge estimation using models
based on groundwater level fluctuation method have been discussed in sev-
eral studies.
2
Estimation of groundwater pumping, which is frequently the
least measured water balance component in semi-arid basin with significant
agricultural production is discussed using GIS-based water balance model.
3
The present study attempts to model a regional groundwater system to
analyze groundwater flow in a hard rock aquifer in the Gundal subbasin of
the Kabini river basin, which is very important for groundwater assessment
and management in this area. In this application groundwater modeling is
combined with remote sensing and GIS approaches for parameterization of
the subbasin. A two-dimensional fully distributed groundwater model on
the concept of predominantly lateral flow conceptualized as an unconfined
aquifer has been used in this study for calibration. The model is applied to
study the spatial and temporal variability in the groundwater pumping due
to changing land use practices over a period of 25 years affecting the spatial
and temporal flux distributions within various zones of the subbasin and
the associated controls on the boundary conditions with the neighboring
subbasins.
2. Setting
The Gundal subbasin is located in the south west of Karnataka state. The
location map of study area is shown in Fig. 1. The Gundal subbasin occupies
an area of 1,270 km
2
and it stretches from 76
◦
30
−
76
◦
51
47
longitude and
11
◦
40
13
−
12
◦
7
13
latitude. The study area mainly consists of one major
rock type, which is granitic gneiss. It is observed that the lineaments in this
area are drainage oriented and fracture controlled. Many of the lineaments
in this basin are rectilinear type and trend north-south or NNE-SSW and
range from 2.5 to 7.5 km in length.
4
The vegetation in Gundal watershed is
characterized by agriculture activity. Traditionally, crops are grown during
kharif (monsoon) and rabi (dry) seasons. Main traditional crops are ragi
(finger millet) and pulses, whereas paddy is grown in the command areas
of tanks and canal command areas (northern part of the basin which forms
the discharge area). Since the last two decades, the major source of water
for irrigation in the rest of the subbasin is groundwater, allowing double-
crop cultivation. As a result of increased irrigation by bore wells, irrigated
crops like sugarcane and cash crops replace traditional rainfed crops.
