Quantifying the Effect of Driving Factors on Spring Discharge in an Industrialized Karst Watershed

Identifying the footprint of controlling factors on the spring discharge is challenging under the impacts of human activities and climate change. The challenge can be addressed by (1) exploring the temporal scaling features of spring discharge; and (2) disentangling and quantifying the effects of latent factors on the spring discharge. Taking an example of the Niangziguan Spring in China, the study explores the spring discharge over a 49-year (1959-2007) time window. The results show that the spring discharge is controlled by the positive feedback mechanism before the beginning of groundwater exploitation, while human activities cause variability in spring discharge. The effects of latent factors on the spring discharge characterize the obvious temporal scale-dependent. The quantitative analysis indicates that the local recharge of groundwater possesses the largest contribution (43%) to spring discharge on the temporal scale of 4-16 months. The western North Pacific monsoon (WNPM) and Indian Summer monsoon (ISM) cause the smallest effect (3%) on spring discharge. Human activities have become one of the most important factors (27%) in controlling spring discharge. The results are useful to predict or simulate the groundwater dynamic processes in the study reported here considering that spring discharge is a natural outlet of groundwater.