| The scenic spot known for its karst springs,Xinxiang Baiquan,has been greatly discolored by the long-term dryness of the springs in recent decades,which has greatly reduced the value of tourism resources and worsened the ecological environment,and now the Baiquan springs can only be restored for a short period of time during the abundant water years.Some previous studies have been conducted on the resurgence and protection of Baiquan springs,but there are still problems such as insufficient analysis of the monthly spring flow dynamics,insufficient understanding of the karst groundwater dynamic characteristics of the spring area,and unknown causes of spring breakage.This paper analyzes the dynamic characteristics of the karst water in the Baiquan spring area,establishes a variety of spring flow dynamic prediction models under the monthly time scale,evaluates the exploitable resources of the karst water in the Baiquan spring area,identifies the main reasons for the breakage of the Baiquan spring,and proposes measures for the resumption and protection of the Baiquan spring,which provides a scientific basis for the protection of the Baiquan spring resources,and is also important for the rational use and protection of the karst scenic spring resources in northern Henan and even northern China and the whole country.It is also of great significance to the rational use and protection of karst scenic spring resources in northern Henan and even northern China and the whole country.(1)The Baiquan spring area is a relatively closed hydrogeological unit.According to the differences in its karst water recharge,runoff,drainage,burial conditions and mining status,the Baiquan spring area is further divided into recharge area(divided into exposed and covered);storage area(divided into covered and buried)and drainage area.(2)Based on the monthly spring flow and precipitation in the spring area from January 1964 to December 1978,we found that the regression effect of spring flow is most significant by the monthly precipitation in the current month and the previous 22 months,and the regulating period of precipitation recharge of karst water in the spring area is about 2 years;the flow in the previous January reflects the influence of various factors in the previous January and the previous months,and the regression effect is significant through various schemes.Stepwise regression calculation,determine the main influencing factors of monthly spring flow is the previous January spring flow,the current month precipitation and the previous January precipitation,and establish a stepwise regression model,and its regression effect is significant;based on the results of stepwise regression analysis to establish the spring flow dynamic prediction of the BPNN model,GA-BPNN model and 10-CV-GRNN model.The results show that the stepwise regression model,GA-BPNN model and 10-CV-GRNN model have higher prediction accuracy;based on the spring flow predicted by the three models from January 1964 to December 2022,the P-III curve method is used to evaluate the extraction resources of karst water in the spring area from the perspective of spring preservation must not exceed 1.00 m3/s.(3)Based on the precipitation of spring from 1964 to 2022,groundwater level of spring from 1982 to 2021 and spring flow from 1964 to 2022,the contributions of climate change and human exploitation activities to spring depletion at different stages were quantitatively analyzed,and the main causes of spring depletion were identified.The results show that the water flow of Baiquan spring during 1964-1978 is mainly affected by precipitation,and the effect of artificial mining is little,which reflects the dynamic characteristics under natural conditions.From 1979 to 2004,the contribution of climate change to spring water depletion was 1.063 m3/s,and that of human exploitation was 2.572 m3/s.From 2005 to 2020,the contribution of climate change to spring water depletion is 1.023 m3/s,and the contribution of human exploitation to spring water depletion is 2.881 m3/s.The interrupted flow of Baiquan spring is caused by the improvement of prospecting and sinking technology,the increasing depth and quantity of mining Wells,and the increasing amount of karst water.(4)The basic research work is the premise of the restoration and protection of Baiquan spring,and the policy and regulation are the institutional guarantee of the restoration and protection of Baiquan spring.According to the investigation and exploitation status of karst water in Baiquan spring area,distribution characteristics of regional water resources(including cloud water resources)and existing water conservancy facilities,the author puts forward some measures such as "Formulating karst water protection scheme in Baiquan spring area","making full use of regional water resources and cloud water resources to increase the recharge of karst water",and "strengthening the management of karst water artesian well". |
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