Recharge systems for protecting and enhancing groundwate

V
Infiltration mechanism
of artificial recharge of groundwater –
A case study at Pingtung Plain, Taiwan
C.-S. Ting, C.H. Lee, C.Y. Lin, S.H. Chen and K.C. Chang
Abstract
This paper discusses the artificial groundwater recharge effect of high-infiltration basins. Hydrogeological
parameters of the study area are collected in order to construct a conceptualized physical model. Numerical
simulation software, TOUGH2, is then used to simulate the infiltration behavior of an artificial recharge into
an underground aquifer. Four wells (MW-1, MW-2, MW-3, and MW-4) are observed at the field site and the
groundwater levels are compared with the simulation results. It is found that good agreement exists between
the observed and numerical data for wells MW-1 and MW-2. However, the observed groundwater level in MW-3 is
higher than the simulated level. MW-3 is located at the edge of the artificial recharge lake, and the high groundwater
level may well be the result of a portion of the infiltration load following the well border into the well
screen. Conversely, the groundwater level in MW-4 is found to be lower than in the simulated well due to local permeability
in the well location. Finally, the numerical results predict that the groundwater level will attain a steady
state at approximately 47 hours after the beginning of infiltration.
Keywords
Infiltration, artificial recharge of groundwater, Taiwan.
INTRODUCTION
Taiwan is located in a sub-tropical region and hence receives a very high annual rainfall. However, the amount of
rainfall received varies significantly over the course of the year. According to measurement data, 90% of the annual
precipitation falls during the rainy season (i.e. May to September) while only 10% of the rainfall occurs during
the dry season (October to April). This imbalance in the monthly rainfall presents planners involved in the conservation
and utilization of water resources in Taiwan with a major problem.
The flourishing development of inland aquaculture along the coastal areas of southwestern Taiwan relies on an
abundant freshwater supply. Groundwater represents the primary source of fresh water for aquacultural water diluting
and flushing. Furthermore, the swelling population in these regions has also led to an increase in the domestic
water consumption. To meet these increased water demands, groundwater pumping schemes have been implemented
extensively along the coastal areas. However, this has resulted in a significant fall in the groundwater level,
and in severe cases has been directly responsible for environmental and geological hazards, including land subsidence,
soil salinization, and seawater intrusion. In order to address these problems, local government initiatives
have been launched to investigate the potential for exploiting new water resources and developing artificial groundwater
recharge schemes.
Artificial groundwater recharging has developed into a major element of Taiwan’s integrated water resource
exploitation policy over recent decades. However, much work remains to be done in developing effective means to
transfer excess surface water into an aquifer during the rainy season in order that this water can be conserved for
use in the dry season.
10 – 16 June 2005, Berlin ■ 5th International Symposium ■ AQUIFER RECHARGE ■ ISMAR 2005