## 3 Results of the On-Field Evaluations
### Deriving the Problems of the Current Evaluation Method through Field Expert Evaluation  
This section summarizes the results of the interviews and surveys undertaken to increase the consistency and reliability of evaluation results. Currently registered and managed GGSJ sites were selected for the field evaluation. The local government managed these sites, and their selection, evaluation, and management history were unclear. Unlike in foreign countries where GIS-based platforms manage similar structures, it was challenging to identify the sites' exact locations, which made it difficult for the experts to conduct their field evaluations. Various problems occurred during the evaluations owing to the absence of a standard evaluation method. The two procedures which vary among experts in GGSJ evaluations are: (1) the determination of the scope of an evaluation; and (2) the selection of the type of assessment table to be used. Difficulties arise in determining the scope of an evaluation on a large and on a small scale. It is challenging to select the scope of a GGSJ slope on a large scale. The difficulty lies in the criteria for each index of the evaluation table on a small scale, as the existing guidelines for GGSJs do not include a clear definition of steep slopes for the purposes of classification. According to a recent report by the steep slope association, it is appropriate to divide the evaluation around the valley. However, while some of the 16,071 steep slopes being managed are approximately 10-30 m, there are also some which are more than 100 m. However, they are designated and managed under a single management number. Thus, there is no way to distinguish a GGSJ when evaluating and designating it as a registration management target. Therefore, regardless of the length of the GGSJ, a single risk assessment result is derived. Figure 6 shows a GGSJ spanning 500 m, and the evaluation was performed using a single evaluation table. As every meter of the slope has different material properties, it is difficult to determine the point and range to be evaluated  
Figure 5: Slope type selection consistency. during the field evaluation. When performing the evaluation, the state differs depending on where the evaluator is located and the time of viewing. In general, the evaluator scans the entire slope and performs the evaluation. The evaluations by experts and management staff are dependent on their locations at the time of evaluation. Therefore, even with the same slope, there are differences in evaluation results, as shown in Table 2, and the evaluation scores are inconsistent, as shown in Figure 2. Thus, it is necessary to propose a standard evaluation method for various GGS\(\flat\)s.  
The selection of assessment table type is another concern during evaluation. The following question arises when evaluating a complex slope: \"Which evaluation table should be used for the GGS\(\flat\), and which structure and type should be used as data?\" Looking at the evaluation results of the complex slopes among the types in Figure 2, it can be seen that if the assessment table types used in field evaluations differ, the results of steep slope evaluations will differ accordingly. Therefore, since type selection is a significant factor in determining the grade of a slope, different scores and grades are likely to be derived by each evaluator, which is a key point that requires the introduction of a standard. As shown in Figure 7, when a slope is made of one material, the structure may be recorded as rock and evaluated using an artificial assessment table. There is also a problem with evaluating soil and rock simultaneously because there is only one artificial assessment table. Nonetheless, there is no problem with the records of the management ledger. However, as shown in Figure 8, a single type is very rare in GGS\(\flat\)s. As shown in Figures 8-10, there are many complex forms in which rock, soil, concrete embankment and gabion exist together in artificial or natural slopes.