( 1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
2. School of Geography and Environmental Sciences, Guizhou Normal University, Guiyang 550001, China)

Abstract: A hydrological and hydrochemical automatic monitoring with high temporal resolution was conducted at the outlet of the Huangzhou River Basin from May 18th to December 3rd, 2018. The Huangzhou River Basin, a typical dolomite catchment in the humid subtropical monsoon climate region, is located in the Shibing World Natural Heritage Site, Guizhou Province. The objective of the study was to understand the hydrological and hydrochemical regime of the typical dolomite catchment with humid subtropical climate. The continuous data of rainfall, discharge, water temperature, electric conductivity, pH and saturation indexes of calcite/dolomite were obtained from the Huangzhou River Outlet. Results showed that: (1) Parameters, pH, electric conductivity, CO2 partial pressure, calcite and dolomite saturation indexes of the outlet river water of the Huangzhou River Basin showed diurnal periodic fluctuations obviously, detailly, the diurnal variation curves of water temperature, pH, calcite and dolomite saturation indexes were similar to those of air temperature, while the diurnal variation curves of electric conductivity and CO2 partial pressure were opposite to those of air temperature. (2) The hydrochemical indexes of the outlet river water in the Huangzhou River Basin had different responding characteristics to different intensities of rainfall, and rainstorm interfered significantly the diurnal periodic fluctuation of the hydrochemical indexes of the river water, the electric conductivity and the partial pressure of CO2 decreased significantly during heavy rainfalls due to the dilution effect. (3) The clear chemostatic behavior was found in the dolomite basin.