Abstract:
ater balance techniques have been extensively used to make quantitative estimates
of water resources and the impact of man's activities on the hydro logic cycle. In this
study, an attempt has been made to describe the methodologies to understand and
assess groundwater potential and irrigation water demand of the Mehoni sub basin.
The ground water is the main resource for irrigation and water supply in the study
area. The approach of this research is centered on quantitative estimation of water
balance component on the area and developing irrigation areas for sustainable use of
the groundwater potential for irrigation. Recharge and discharge components have
been quantified based on inflows, outflows and changes in the aquifer groundwater
storage. Inflow to the system is groundwater recharge from precipitation by
considering that the sub basin is closed. The recharge of the study area is estimated by
water balance technique and each component is calculated separately. The main
components used for estimation of annual recharge in this paper are annual actual
evapotranspiration, surface runoff and rain fall of the study area. The actual
evapotranspiration of the study area was estimated by Thornthwaite and Mather water
balance model and Turc method .The study area is dry basin with no river gauging in
the area. Hence estimation of surface run off in the basin was done using SCS rain
fall runoff method. The irrigation water demand of the study area is estimated by
CROPW A T8 software. Discharge from the system includes groundwater extraction
for irrigation and water supply systems. The result of the study shows that the average
total annual groundwater recharge of the area is 72.9 Min
3
and the total irrigation
water demand is 8.5 l 4Mm
3
annually. The over all net ground water potential of the
study area is 61.784 Mm
3.
By considering the existing situation the ground water
potential of the study area can irrigate up to 5000 ha with out affecting the ground
water level of the study area.
