## 5 Conclusions  
In the design and planning of groundwater-related projects, hydraulic test data are usually used to obtain hydraulic conductivity. This study used the existing hydraulic test data in the mountainous area of Taiwan, for the application of fracture network system identification. The main conclusions can be summarized as follows:  
1. Constant-head hydraulic test data combined with [PERSON]'s general radial flow model successfully carried out the disclosure of flow dimension \(n\). The disclosure of the n parameter was used to describe the geometry of the groundwater flow in the fractured rock mass and to estimate its fracture network density around each test section. The related results have preliminarily established an economical and effective method of discovering fracture network patterns.
2. Five proposed hydrogeological indices, namely RQD, FA, FD, hydraulic conductivity, and \(\mathrm{K_{f}}/\mathrm{K_{m}}\) ratio, were used to investigate the correlation between n and each index. The results show that, the larger the \(n\) value, the smaller the RQD, the higher the FD,  
Figure 11: Histogram of log(\(\mathrm{K_{f}}/\mathrm{K_{m}}\)) for two types of lithology (sedimentary and metamorphic rock).  
the larger the FA, the larger the hydraulic conductivity, and the greater the K\({}_{\rm f}\)/K\({}_{\rm m}\) ratio. All hydrogeological indices have high correlations with the flow dimension \(n\) values. Based on the successful verifications, the proposed method for the interpretation of fracture network patterns is feasible.
* The results of the flow-dimension \(n\) values have two other additional contributions to the study area: (a) The relation between n and depth showed that a higher \(n\) value appears at the shallower depth, which is based on the reference of 100 m borehole. This finding gives information about groundwater availability or a drilling depth for maximizing profits concerning the water supplies available; (b) the relation between n and lithology show that the \(n\) values of both sedimentary and metamorphic rocks vary considerably. In addition, the average \(n\) value of flow dimension of metamorphic rocks is slightly larger than that of sedimentary rocks, which means that the fracture network of fractured rocks is denser than that of sedimentary rocks.
* Finally, based on the result of the K\({}_{\rm f}\)/K\({}_{\rm m}\) ratio correlated with different lithologies, the metamorphic rocks in Southern and Central Taiwan have a higher chance of having high permeability ratios than the sedimentary rocks. In other words, the metamorphic rocks are fragmented relative to sedimentary rocks, and the groundwater flow is dominated by fractures.  
Conceptualization, supervision, project administration, and funding acquisition, S.-M.H.; methodology, formal analysis, and investigation, S.-M.H., C.-M.C. and H.-L.L.; resources, C.-C.K.; writing--original draft preparation, S.-M.H.; writing--review and editing, C.-Y.K.; visualization, S.-M.H., C.-Y.K. and C.-C.K. All authors have read and agreed to the published version of the manuscript.  
This work was partially supported by the Ministry of Science and Technology of Taiwan (MOST 108-2116-M-019-003-). The authors express their gratitude to the Central Geological Survey, Ministry of Economic Affairs (MOEA) of Taiwan, for offering hydrogeological raw data used in this study.  
The authors declare no conflict of interest.