# Evaluating the Cost of Failure Risk: A Case Study of the Kang-Wei-Kou Stream Diversion Project

^{1}

^{2}

^{3}

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^{†}

## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Study Area

^{2}. According to government sources, the downstream flood area includes residential and industrial areas in the vicinity of the freeway bridge, and average flood damage causes New Taiwan Dollars (TWD) 516 million loss per year (Water Resources Agency, Taichung, Taiwan, 2009). In an effort to mitigate damage from flooding, the government constructed a new floodway to guide the flow from the upstream catchment into the river, to release flood pressure in the downstream area.

#### 2.2. HEC-RAS Simulation

^{3}/s under events with a 25-year return period. At the point where the KWK Diversion connects to the Er-Jen river, the water stages corresponded to the following event return periods: 10 years (9.46 m), 25 years (9.73 m), and 100 years (10.41 m). The boundary conditions used for the original design plan included the upstream flowrate and downstream water depth (the larger value of the normal depth and the 25-year return period water stage of the Er-Jen river) [58]. Note that the boundary conditions, which are crucial to the risk of failure, were varied throughout the stochastic simulations rather than assigning a fixed number, as in previous planning reports. HEC-RAS simulations were used to derive hydrodynamic features, including water level, velocity, and energy gradient in various section of the KWK Diversion.

#### 2.3. Hydrologic Conditions

## 3. Results

## 4. Discussion

- Scenario A: concrete lined channel (alternative plan)
- Scenario B: concrete retaining wall for riverbanks only (original plan)

## 5. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 7.**One of the output sets from 1000 experiments by HEC-RAS, EG: energy gradient line, WS: water surface, Crit: critical depth.

**Figure 8.**The histogram of the magnitudes and locations of 75 hydraulic jumps produced by simulation. (

**a**) Magnitude; (

**b**) Location.

Return period (year) | 2 | 5 | 10 | 20 | 25 | 50 | 100 |

Discharge (m^{3}/s) | 121.65 | 152.89 | 168.00 | 178.65 | 181.00 | 186.58 | 188.24 |

Water surface elevation (m) | 7.90 | 8.80 | 9.46 | 9.55 | 9.65 | 9.91 | 10.41 |

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**MDPI and ACS Style**

Liang, C.-Y.; Wang, Y.-H.; You, G.J.-Y.; Chen, P.-C.; Lo, E. Evaluating the Cost of Failure Risk: A Case Study of the Kang-Wei-Kou Stream Diversion Project. *Water* **2021**, *13*, 2881.
https://doi.org/10.3390/w13202881

**AMA Style**

Liang C-Y, Wang Y-H, You GJ-Y, Chen P-C, Lo E. Evaluating the Cost of Failure Risk: A Case Study of the Kang-Wei-Kou Stream Diversion Project. *Water*. 2021; 13(20):2881.
https://doi.org/10.3390/w13202881

**Chicago/Turabian Style**

Liang, Chung-Yuan, Yuan-Heng Wang, Gene Jiing-Yun You, Po-Chun Chen, and Emilie Lo. 2021. "Evaluating the Cost of Failure Risk: A Case Study of the Kang-Wei-Kou Stream Diversion Project" *Water* 13, no. 20: 2881.
https://doi.org/10.3390/w13202881