| Abstrakt: |
The wet‐dry tropics of Central America are characterized by long dry seasons, during which communities often struggle for water. High interannual rainfall variability, driven in parts by the El Niño Southern Oscillation (ENSO), increases these challenges. Further, climate change projections indicate that the region will likely become drier. However, research on impacts on water resources at the watershed scale is limited in the region—yet this information is essential for water managers. Therefore, in this research, we quantified the potential impacts of ENSO and four different climate change scenarios on water resources in two watersheds in the wet‐dry tropics of Guanacaste, Costa Rica, using a hydrological model (Water Evaluation and Planning Tool [WEAP]). Given that the watersheds are human used, we also explored different water demand scenarios. Modeling results indicated that an extreme El Niño can reduce groundwater recharge and streamflow by ∼60% relative to ENSO neutral. For 2075–2100, modeling results indicated that while potential evapotranspiration increases, actual evapotranspiration decreases due to limited water availability. Further, climate change may lead to reductions of mean annual streamflow and groundwater recharge by 40%–45% and 26%–28%, respectively, in comparison to the historical baseline. Importantly, high population growth could further hasten potentially irreversible groundwater storage declines. On the other hand, reduction of per‐capita water demand could slow down, or even reverse, the decline of groundwater storage. Plain Language Summary: In the wet‐dry tropics of Costa Rica, communities often struggle for water during the long dry season. Climate variability is high in the region, and in some years, rainfall is reduced, mostly due to El Niño (an ocean‐atmosphere circulation). With climate change, it might become drier in the future. In this research, we assessed the potential impacts of El Niño and four future climate change scenarios on surface water and groundwater supplies and found that during an extreme El Niño, streamflow and groundwater recharge are ∼60% reduced. Climate change at the end of the 21st century may lead to reductions of mean annual streamflow and groundwater recharge by 40%–45% and 26%–28%, respectively, in comparison to the historical baseline. We also considered increasing domestic water demand and found that a growing population with increasing water demands can lead to potentially irreversible groundwater supply decline. On the other hand, reduction of domestic water demand due to effective water management can potentially slow down, or even reverse, such a decline of groundwater supplies. Key Points: Watershed‐based analysis of climate change and water demand impacts on streamflow and groundwater in wet‐dry tropics of Central AmericaEl Niño and climate change may substantially impact streamflow and groundwater recharge, especially with high population growthReductions in domestic water demand may be able to slow down, or reverse, groundwater storage declines [ABSTRACT FROM AUTHOR] |
Plný text