Simulating the Hydraulic Effects of Climate Change on Groundwater Resources in a Selected Aquifer in the Philippines Using a Numerical Groundwater Model

Climate change can negatively impact groundwater resources due to its influence on the hydrologic cycle. In view of the Philippines’ heavy reliance on groundwater resources, it is important to quantify these effects to serve as basis for sustainable groundwater resources management. This study aimed to simulate and predict the effects of climate change on groundwater levels on selected productive shallow aquifer system in Bay, Laguna, Philippines, using a numerical groundwater model. Model simulations using various climate change scenarios, based on the lower and upper limits of predicted air temperature from the Intergovernmental Panel on Climate Change’s (IPCC) Third Assessment Report, indicated that groundwater levels generally decline as temperature increases and as precipitation decreases. In a low temperature condition, the model showed that groundwater levels will decline at an average rate of 0.10785 m, 0.11286 m and 0.11294 m per decade of 0, 10, and 20 percent decrease in annual precipitation, respectively. This could mean that by the end of 2050, groundwater levels are likely to decrease by 0.43138 m, 0.45143 m and 0.45177 m if rainfall decreases by 0, 10, and 20 percent. Using the high temperature increase scenario, the model predicted a 0.43924 m, 0.45 m, and 0.45439 m decrease in groundwater levels under 0, 10 and 20 percent annual precipitation reduction scenarios, respectively. This corresponds to a decadal groundwater decline of 0.10981 m, 0.11250 m and 0.11360 m. This study generated quantitative results that could be used as basis for further research in aid of formulation or refinement of policies addressing climate change and water resources sustainability.