# Design Flood Estimation: Exploring the Potentials and Limitations of Two Alternative Approaches

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## Abstract

**:**

## 1. Introduction

## 2. Methodology

## 3. Example Application

#### 3.1. Hydraulic Modelling

#### 3.2. Rating Curve

^{3}/s to 1000 m

^{3}/s with steps of 100 m

^{3}/s, followed by simulations of discharge ranging from 1000 m

^{3}/s to 13,000 m

^{3}/s with steps of 1000 m

^{3}/s. After that, the estimated rating curve was assessed by fitting the synthetic data pairs $\left(Q,h\right)$ using a power law relationship between the water level and river flow. Data pairs $\left(Q,h\right)$ for the statistical fit are discharge data ranging from 1000 m

^{3}/s to 6000 m

^{3}/s (with steps of 1000 m

^{3}/s) and their corresponding stages derived from the hydraulic simulations. The power law relationship is expressed as:

#### 3.3. Parent Distribution

#### 3.4. Probability Model

#### 3.5. Application of the Simulation Framework

## 4. Results

## 5. Discussion

## 6. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**Virtual experiment proposed in this study. Graphical representation of the simulation framework to compare the estimation of design flood levels based on two alternative approaches.

**Figure 2.**Synthetic and estimated rating curves derived using the Hydrologic Engineering Center’s River Analysis System (HEC-RAS) model and the power law models for two cross-sections located 58 km (

**A**) and 68 km (

**B**) downstream of Cremona (Po River, Italy).

**Figure 3.**Boxplots of error estimates for the two approaches with Gumbel distribution used for design flood level estimation at cross-sections (

**A**,

**B**). The red lines represent the median (50th percentile), the lower and upper ends of the blue box represent the 25th and 75th percentile, respectively. Outliers are represented by red dots.

Various Aspects and Applications | Common Approach (Flood Discharges) | Alternative Approach (Flood Levels) |
---|---|---|

Sources of uncertainty | − | + |

Computational time | − | + |

Data requirement | − | + |

Changes in the river channel (e.g., erosion) | + | − |

Hydraulic effects on the channel (e.g., backwater) | + | − |

Design of levees | − | + |

Design of flood-control reservoirs | + | − |

Regionalization methods | + | − |

Hydrogeomorphic methods | − | + |

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**MDPI and ACS Style**

Okoli, K.; Breinl, K.; Mazzoleni, M.; Di Baldassarre, G.
Design Flood Estimation: Exploring the Potentials and Limitations of Two Alternative Approaches. *Water* **2019**, *11*, 729.
https://doi.org/10.3390/w11040729

**AMA Style**

Okoli K, Breinl K, Mazzoleni M, Di Baldassarre G.
Design Flood Estimation: Exploring the Potentials and Limitations of Two Alternative Approaches. *Water*. 2019; 11(4):729.
https://doi.org/10.3390/w11040729

**Chicago/Turabian Style**

Okoli, Kenechukwu, Korbinian Breinl, Maurizio Mazzoleni, and Giuliano Di Baldassarre.
2019. "Design Flood Estimation: Exploring the Potentials and Limitations of Two Alternative Approaches" *Water* 11, no. 4: 729.
https://doi.org/10.3390/w11040729