Dynamic Characteristics Of Groundwater Table And Multivariate Time Series Analysis In Zhaogezhuang Mine

The safety of mine is often threatened by water damage in China.It is difficult to grasp the dynamic laws of the groundwater system for the complexity of the groundwater system.To reduce the threat of mine water damage,it is important to make sure the dynamic relationship between the groundwater system and the influencing factors.The Zhaogezhuang Mine is an example inTangshan City,Hebei Province.The time series as an effective method was used for mine groundwater dynamic research.Then information of rainfall,evapotranspiration,excessive rainfall and groundwater level was collected the time series dynamic model.In the previous study,through groundwater dynamic filtering analysis of groundwater level data and rainfall in the monitoring hole of the area,three types were divided by the response to rainfall,namely: large amplitude-lag type,small amplitude-level lag type,small amplitude-Gradual lag type.These three types belong to the Ordovician limestone fissure water system,strongly weathered marl pore water system,and limestone fissure-pore water transition system.Through principal component analysis and STL(Seasonal and Trend decomposition using Loess)analysis.It was found that excessive rainfall is of great significance to the analysis of groundwater level.In seasonal cycles,long-term trends and random fluctuations,it reflects the strong correlation between excessive rainfall and groundwater level Through the scatter matrix map.It was found that there is no direct linear relationship between the three observation hole sequences,such as rainfall,evapotranspiration,and excessive rainfall,and there may be a complex dynamic relationship.It also reflects the Ordovician limestone fracture water system and the two systems are more closely linked.By applying the univariate time series we find that the forecasting effect of the time series model is related to the modeling length of the sequence,the range of random fluctuation terms and the prediction length.Based on multivariate time series analysis,impulse response function analysis and variance decomposition analysis were conducted on the relationship between precipitation surplus and the groundwater levels of the three observation holes.The largest impulse response is Rongyuan Kong,while the east hole of Shuiyu Kong and the west hole of Kaier Kong are relatively less affected.The cointegration and Granger causality test also show that there is a long-term relationship between precipitation surplus and the groundwater level of the Rongyuan Kong.The prediction effect was improved by using the multivariate time prediction model established with the rainfallexcess sequence.Finally,through comparative analysis,we find that the east hole of Shuiyu Kong belongs to the highly weathered marl pore water system,with the characteristics of slower flow rate and smaller fluctuation,and the range of random fluctuation of its sequence is also relatively small.Therefore,it is the most suitable to choose the seasonal linear model for predicting the highly weathered marl pore water system.Within a certain forecast range,it can obtain high-precision forecast data.The other two types of groundwater system prediction models need further exploration.By the classification of groundwater system and the analysis of time series,we can provide direction for time series in groundwater dynamic analysis and means for preventing and controlling water disaster in mining area.