Little change in hydrogen and oxygen isotopic composition of rivulet before and after 921 earthquake in paikangchi and nankangchi river basin implied that the earthquake stress might just force the groundwater stored in soil or strata to flow out but did not change the water sources of the two basins 因其氢、氧同位素组成在921地脓前、后并未发生变化，因此北港溪和南港溪流域在地震之后所显示的异常水源，可能是地震的应力迫使原涵蓄于土壤或地层中之地下水流溢出，而并未改变其原集水型态。
