10:45 〜 11:00
[AHW20-01] Groundwater and surface water interaction revealed by multi-tracer method in Klang River Watershed, Kuala Lumpur, Malaysia
キーワード:マルチトレーサー手法、酸素・水素安定同位体比、複雑な地質構造
The δ18O of river water increases with a decrease of sampling altitude from 70 to 26 m, however, it reaches the maximum value at the elevation of 26 m, then decreases with the flow toward downstream. The elevation of 26 m corresponds to the boundary of geology between sedimentary rocks and alluvial deposits. The shallow groundwater table contour lines constructed by observation of the static water level show a clear change from the losing stream to the gaining stream at an elevation of approximately 26 m. This suggests that the discharge of groundwater with higher δ18O seems to cause a maximum value of δ18O in the river at the elevation of approximately 26 m.
The deep groundwater shows a lower δ18O than the volume-weighted mean of rainwater and higher inorganic ions concentrations, whereas the shallow groundwater shows a higher δ18O and lower inorganic ions concentrations. This suggests that the deep groundwater with low δ18O seems to be recharged in the mountainous area with an altitude ranging from 70 to 1421 m. This shows that the deep groundwater in the downstream area is recharged mainly in the mountainous areas with the highest altitude of 1421 m, and the shallow groundwater is recharged partly in the hilly areas with the highest altitude of 250 m.