Browsing by Author "Liu, Pei-Gui"

Now showing 1 - 2 of 2
  • Publication
    Publication
    Environmental impact assessment of risk associated with groundwater overdraft remediation in cone of depression, Jining, China
    (Springer, 2007-01-12) Ong'or, Basil; Shu, Long-cang; Liu, Pei-Gui
    In this paper, a simple scenario and probabilistic approach is used to assess the potential groundwater risk due to proposedoverdraft remedial actions in cone of depression, Jining City, China. Focusing on the concentrations of Chloride ions (Cl−) and total hardness (TH), the impact of artificial recharge and reduced pumping on groundwater quality and quantity is analysedby using the three-dimensional finite difference groundwater flow and transport model, Visual MODFLOW, to simulate groundwaterflow and transport within the study area based on scenarios, and utilizes SURFER software to map risk levels. Although 5,10 or 15% reduced pumping with artificial recharge leads to more decrease in Cl− and TH concentrations than the 25%, less volume increase is achieved for the remediation of land subsidence and other environmentalproblems in the cone of depression. The Cl− concentrations in recovered groundwater are within the desired concentration of 200mg/l; however, TH in some cases are abovethe maximum permissible limit of 500mg/l, with an exceedence probability of about 0.67 for recharge and recharge with reducedpumping at 25%. The presence of fractures and hydrogeological complexity greatly determines impacts of remediation, and the22% reduced pumping with artificial recharge offers an optimum strategy for overdraft remediation in the Jining cone of depression.
  • Publication
    Publication
    Environmental impact assessment using FORM and groundwater system reliability concept: case study Jining, China
    (Springer, 2008-08-01) Shu, Long; Liu, Pei-Gui; Ong'or, Basil
    In this paper, fist-order reliability method (FORM) is used to evaluate the impacts of uncertainties posed by traditionaldeterministic models on the environment in Jining, China. Because of groundwater contamination in shallow aquifer, and anincrease in water demand, the new wells target the confined aquifer with constant pumping rate of 5,000m3/d. Using Theis equation, the groundwater drawdown is analyzed to determine whether the confined aquifer will be contaminated.Although the piezometric level is higher than the phreatic level by 11.0m, the risk of drawdown is still 19.49% when thepumping rate of 5,000m3/d is maintained for 2years. The deterministic model indicates a drawdown of 8.94m which is lower than the maximum tolerancedrawdown of 11.0m. The sensitivity and uncertainty analysis reveal that the model result is more sensitive to transmissivitythan specific yield, while the reliability analysis offers significant information for the decision makers. This approachexposes and minimizes the risk of undesirable consequences such as groundwater contamination.