# A Modeling of Human Reliability Analysis on Dam Failure Caused by Extreme Weather
## 3 PSFs Analysis
### Performance Shaping Factors (PSFs) in Dam Failure Accidents  
The concept of PSF, Performance Shaping Factor, was first introduced by [PERSON] [35] in the construction of THERP. With the profound study of human reliability, it was realized that human error is not only caused by the person's own reasons but is triggered by all the factors in the situational environment in which the person is located, which means that the situational environmental factors are the root causes of human error. PSF is a characterization of situational environmental factors, like PIF (Performance Influencing Factor), CPC (Common Performance Condition), EPC (Error Producing Condition), etc., the essence of which is the same. Successful inter-combination of PSFs decreases the probability of human error and increases human reliability, and vice versa. [PERSON] categorized PSFs into three groups, namely external PSFs, outside of personal factors; internal PSFs, personnel's own factors; and stress levels. The traditional THERP method does not consider task characteristics when considering PSFs, the HCR (Human Cognitive Reliability) method removes available task time, and the ATHEANA (A Technique for Human Error Analysis) method includes all factors except power plant conditions as PSFs. Some scholars argued that all three should fall under the category of PSFs since they belong to situational environmental factors that would have an impact on people [36]. Combining the set of influences above and the effect of each on the pattern of errors, the following PSF categorization was established, as shown in Table 2.  
The PSFs are divided into five main categories, considering the five factors of operator, technology, organization, environment, and task, and contain a total of 49 specific elements in 13 subcategories, which in general cover the situational environmental factors affecting people during operations. The main separate considerations in software facilities are water condition measurement, safety monitoring facilities and Intelligent decision-making technology, due to the fact that the completeness of these three has a great impact on operator reliability in the case of extreme weather-driven dam failures. From the four nodes on the basic path in the previous section, combined with the relationships identified in the causality diagram and the model of human error in complex organizational accidents, the model of human error in dam failure accidents is obtained, and is shown in Figure 8. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Work Process** & **Reasons for Errors** & **Failure Mode** \\ \hline Monitoring and awareness & Observation of targeting error & Target error \\  & Failure to detect in time & Time error \\ State diagnosis & Delayed diagnosis & Time error \\  & Wrong diagnosis & Target error \\  & Irrational distribution of tasks & Behavior error \\ Plan formulation & Unreasonable planning & Sequence/target error \\  & Excessive decision time & Time error \\ Operation execution & Failure of operation & Behavior/Sequence/target \\  & Insufficient teamwork & Behavior error \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Causes of human errors. Figure 7: Causality diagram for the basic path of human error. The main human factors that influence the dam failure events caused by overtopping are hardware like gates, engineering, professional skills, internal atmosphere, and risk awareness. When leakage problems lead to dam failure, human factors are mainly daily management, software such as monitoring systems, professional skills, responsibility, and supervision efforts. In the case of dam failure due to defects in engineering quality, the main human factors of influence are software such as monitoring systems, supervision efforts, risk awareness, daily management, and experience. Dam failures in China are divided into three main periods: 1950 to 1980, 1980 to 2000, and after 2000.