Study on Selection Criteria of Small-Scales Reservoirs for Emergency Action Plan(EAP) Establishment

소규모 저수지 대상 비상대처계획 수립 선정기준 연구

Abstract

This study developed selection criteria of small-scales reservoirs, having under $300,000m^3$ storage capacity, for the Emergency Action Plan(EAP) establishment in order to reduce the disaster risks of the reservoir's failures. Those reservoirs are out of ranges of Korean EAP establishment standard, but have potential risk of disasters as they have often failed by the recent extreme rainfall events and earthquakes, causing economical and life losses. The problem of reservoir aging is also one of the reasons of them. In this study, the developed selection criteria of small reservoirs for EAP establishment are storage capacity, embankment height, reservoir age, heavy rain factor and earthquake factor. These criteria were selected based on the review of the existing EAP establishment guidelines, analysis of the past dam failure cases, and the previous related studies. The quantification of these criteria were conducted for the practical applications in the fields, and applied to 67 previous failures in order to investigate the relation of each criteria with these failures. The earthquake factor found to be the highest relations followed by heavy rain factors, combination of earthquake and heavy rain factors, and reservoir age. The classification was made as observation and review groups for EAP establishments based on overlapping numbers of each criteria. This classifications applied to 354 reservoirs designated as having the potential disaster risk by MOIS, and showed 38.4% of observation and 11.9% of review groups. Anticipatory monitoring and regular inspection should be made by professional facility managers for the observation group, and necessity of EAP establishment should be assessed for the review group based on the downstream status and financial budget.

Fig. 1 Procedure of the study

Fig. 2 Causes of the failures: (a) By dam type, (b) By dam age (MOLIT⋅K-water, 2016)

Fig. 3 Failure records of dams and reservoirs

Fig. 4 Classification of dam and reservoir failures based on storage capacity

Fig. 5 Frequency of damage by heavy rainfall (MOIS, 2014)

Fig. 6 Selection criteria application results for the past failure cases

Fig. 7 Selection criteria application results for the disaster risk reservoirs

Fig. 8 Degree of overlapping criteria on the past failure cases

Table 1 Classification of dam size based on storage capacity and height (CDA, 2017)

Table 2 Classification of dam risk based on design flood (CDA, 2017)

Table 3 Classification of dam risk based on human injury and property damage (CDA, 2017)

Table 4 Selection criteria for EAP establishment in this study

Table 5 Average break width and break time of fill dam (Lee, 1987)

Table 6 Feasibility evaluation criteria for renovation of the disaster risk reservoirs (MOIS, 2016)

Table 7 Over 4 magnitude earthquake occurrence area and earthquake zone of dam design standard (KMA, 2017; KWRA, 2011)

Table 8 Quantification of the reservoir selection criteria for EAP establishment

Table 9 Classification of EAP establishment group based on degree of overlapping criteria

Table 10 Application results of EAP establishment grouping for thedisaster risk reservoirs