Application of Multitaper Method (MTM) to Identify the Heterogeneity of Karst Aquifers
Karst aquifers supply drinking water for 25% of population on the earth. Better understanding of the heterogeneity of karst aquifers can help us develop karst groundwater sustainably. Karst hydrological processes include precipitation (rainfall) infiltration, groundwater wave propagation in karst aquifers, and spring discharge. The processes of precipitation signals’ transformation into spring discharge signal are mainly affected by heterogeneity of karst aquifers. Analysis of relations between spring discharge and precipitation can identify heterogeneity of karst aquifers. This paper explores the periodic characteristics of spring discharge and precipitation, and the heterogeneity of karst aquifers in Niangziguan Springs (NS) using multitaper method (MTM). The results show that both spring discharge and precipitation exist in the same period of one year. Cross-correlation function is used to calculate the time lags between the reconstructed spring discharge and precipitation in different areas of the NS basin. The results indicate that the response time of the spring discharge to precipitation is different at different areas. The time lag between the spring discharge and precipitation is 3 months at Pingding County; 4 months at Yu County, Yangquan City, Xiyang County, and Heshun County; and 27 months at Shouyang County and Zuoquan County. The results reflect the heterogeneity of the NS basin and are consistent with the geological structure of the NS basin. MTM is robust in identification of heterogeneity of karst aquifers.
KeywordsMultitaper method (MTM) Cross-correlation function Heterogeneity Time lag
This paper is supported by Natural Youth Science Foundation of China (61501326, 61401310), the National Natural Science Foundation of China (61731006), and Natural Science Foundation of China (61271411). It was also supported by Tianjin Research Program of Application Foundation and Advanced Technology (15JCZDJC31500), Tianjin Natural Science Foundation (18JCZDJC39500), and Tianjin Science Foundation (16JCYBJC16500). This work was also supported by the Tianjin Higher Education Creative Team Funds Program.
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