Author(s): M. Tsujimura

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Keywords: Groundwater and surface water interaction; Isotopes; Multi tracers approach; Groundwater recharge

Abstract: The hydrological regime is generally affected by the climate change. The global warming is predicted to cause a frequency of extreme phenomena in the hydrological processes. Specifically, it causes drier condition in some semi-arid regions and salinization of fresh water in the coastal area due to sea level rising. Also, the rainfall intensity tends to become higher under the global warming. These characteristics should make the water resources more vulnerable, especially in groundwater recharge and discharge processes. A dependence on the groundwater is dominant in the regions where the water resources are vulnerable, and this trend seems to become more serious under the global warming. The groundwater recharge, that is an input of the water to the groundwater, is one of the most important factors to evaluate the groundwater resource. The groundwater recharge is predicted to decrease, when the rainfall intensity becomes much higher due to the climate change. Because the higher intensity of rainfall with higher impact of raindrops works for infiltration capacity on the ground surface to become lower, the infiltration and percolation in the soil layer becomes lower, leading to decrease of the groundwater recharge. Thus, the groundwater recharge through the vadose zone seems to less dominant under the global warming. Instead, a direct/indirect recharge from the surface water would be more important. We observed that stream water/dam water make a dominant role in the groundwater recharge in the semi-arid regions, Mongolia, Tunisia, China, and humid regions, Japan, Vietnam, by using multi isotope tracers approach (e.g. Tsujimura, et al., 2013). This approach showed that more than50%of the groundwater is recharged by the surface water in those regions. The role of the surface water in the groundwater recharge is expected to be more important under the climate change. We need to consider and monitor the groundwater and surface water interaction in the frame of the hydrological processes under the multiple site conditions. The presentation will show the principles, observed cases and modeled cases of the groundwater and surface water interaction in the regions under the various conditions. Also, the cases in Vietnam will be focused from the view point of future perspectives in the water resources under the climate change.

DOI:

Year: 2014