Geology Reference
In-Depth Information
INPUT PARAMETERS
Aquifer Characteristics
Horizontal hydraulic conductivity of the sandy aquifer ranges between 25
and 75 m/day. Aquifer lying west of the Buckingham Canal has values
between 45 and 75 m/day. The low K value along west of the canal is
attributed to the presence of sandy clay and clay. The specific yield of the
alluvial aquifer ranges from 0.17 to 0.23. The specific yield of the aquifer
existing between the coast and the canal ranges between 0.21 and 0.23,
while the other portion has values ranging between 0.17 and 0.19.
Groundwater Abstraction
The groundwater of the study area is abstracted for domestic, industrial and
irrigational purposes. The average annual pumping is about 4.25 MGD. This
has been obtained from the government agencies such as the Public Works
Department and Metro Water. Pumping rate by private agencies was estimated
through field visits. The pumping rate of wells that exist within the housing
complexes in the northern part of the study area was also taken into account
and pumping rates from these wells were estimated from well inventory
survey by collecting data on pumping duration in a day. About 90% of the
total pumping occurs within the regions lying between the Buckingham
Canal and the coast. The pumping activity on western side of the canal is
limited only to domestic purposes mainly for drinking and other household
purposes due to poor groundwater quality.
Groundwater Recharge
The rate of rainfall recharge varies within the study area. Two recharge
zones, A and B, have been demarcated based on the soil types, geomorphic
pattern, land use and topography. The rainfall recharge rate in zone A is
around 40-48% and in zone B it is around 25-35% as shown in Table 1. High
recharge occurs in Zone A where sand and sand dunes occur. Recharge rate
in the areas of zone B is quite less due to the presence of sandy clay/clayey
soil.
Table 1.
Recharge value incorporated in the model
Zone
Recharge %
Zone A (Sand)
40-48%
Zone B (Sandy clay/Clayey soil)
25-35%
