Quantitative identification of Conduit flow and crack flow based on the spring hydrograph analysis

Karst aquifers contain irregular networks of pores,fissures,fractures and conduits of various sizes and forms.Such structure with significant physical and geometrical heterogeneity causes complex hydraulic conditions and spatial and temporal variability of hydraulic parameters.To solve this problem,the composi-tion transfer function for karst aquifers is established by the analysis of the spring hydrograph.This hydro-graph is composed of the accumulative storage rainfall,channel flow,and quick flow based on the character-istic of the karstic aquifer.A linear convolution integral model is applied to distinguish the quick flow and slow flow components of a karst spring hydrograph.This method is tested by a case application to the Houzhai underground river in southwestern China.Simulation of the data of the spring flow and the rainfall using this approach shows that the accumulative storage capacity increases from the upstream to the down-stream,and the proportions of conduit flow are 0.84,0.6 and 0.48,respectively.It means that the increas-ing networks of fissures develop to downstream of the river basin.The NSE from the model calculation is o-ver 90% compared with the real measurement values.