Hydrological modeling to assess water resources resilience towards climate change impacts in Tacloban, Philippines

Tacloban, Philippines, the city most devastated by typhoon Haiyan in 2013, faces severe water supply constraints, particularly on the relocation sites that are expected to accommodate 40% of Tacloban's population by 2018. This region's hydrological system was modeled using QSWAT to evaluate the impacts of climate change, namely, rising temperatures and variation of rainfall patterns, on three rivers (Binahaan, Pongso, and Cabayugan). These rivers are the potential sources of water for the two supply solutions currently being considered. Thus, it is essential to assess their resilience as sources of water. Two climate scenarios were generated for 2020 and 2050 using the Change Factor (CF) method, and the system response was compared to the baseline data (1979–2010).
Results show that, regardless of the chosen supply solution, for certain time periods (most severely for the quarter of March to May), the percentage of days in which the river flows were insufficient to meet the proposed water catchment flows was significant (reaching up to 25%). Outputs also suggest that Binahaan River, where the current water catchment is located, may fail in providing sufficient water to the region for future scenarios. However, it should be noted that Pongso and Cabayugan Rivers in northern Leyte can represent a resilient water source to supply the new resettlement areas.