A Flood Resilience Strategy for Da Nang

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.title[
# A Flood Resilience Strategy for Da Nang
]
.author[
### Gerardo Ezequiel Martín Carreño, Nikhil Desai, Soki Kimura, Jan Magnszewski, Viktoria Pues, Gavin Rolls
]
.date[
### 22 March 2024
]

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# .h1-background[The City: Da Nang, Vietnam]

.footnote-background[<a name=cite-europeanspaceagencySentinel2024></a>([European Space Agency, 2024](#bib-europeanspaceagencySentinel2024)) ]

---
## City Background

.pull-left[
**Central Vietnam's Largest City**
  * Population: 1,374,562 as of 2019 - <a name=cite-CongBoKet></a>([Đà Nẵng Online, 2024](#bib-CongBoKet)) 
  * Major Port for the Central Coast - <a name=cite-100rcdanangteamResilienceCityNang2016></a>([100RC Da Nang team, 2016](#bib-100rcdanangteamResilienceCityNang2016)) 
  
**Climate**
  * Extremely hot and humid
      * 80% annual average humidity
      * 25.9C˚ mean annual temperature
  * Wet season from September to March - <a name=cite-opitz-stapletonHeatIndexTrends2016></a>([Opitz-Stapleton, Sabbag, Hawley, Tran, Hoang, and Nguyen, 2024](#bib-opitz-stapletonHeatIndexTrends2016))

]

.pull-right-image[
<img src="img/da_nang_centre.jpg" width="75%" style="display: block; margin: auto;" />

.center[Central Da Nang - <a name=cite-vietnamtourismReasonsWhyNang></a>[Vietnam Tourism (2024)](#bib-vietnamtourismReasonsWhyNang)]

.center[Da Nang within Vietnam - <a name=cite-encyclopediabritannicaNangVietnam2024></a>[Encyclopedia Britannica (2024)](#bib-encyclopediabritannicaNangVietnam2024)]
]

---
## The Problem:

### Da Nang's rapid urbanisation puts it at increased risk of flooding

**Development in lowland areas is a key concern** - <a name=cite-huongAnalysisUrbanExpansion></a>([Thi Viet Huong, Nagasawa, and Tsutsui, 2013a](#bib-huongAnalysisUrbanExpansion))

**Floods of all kinds caused £83m in damage from 1998-2020**

.pull-left[
<img src="img/car_flood_da_nang.jpg" width="85%" style="display: block; margin: auto;" />
]

.pull-right[
<img src="img/people_in_water.jpg" width="85%" style="display: block; margin: auto;" />
]

.footnote-cite[Sources: <a name=cite-vnexpressRapidUrbanizationDelivers></a>[VnExpress (2024)](#bib-vnexpressRapidUrbanizationDelivers), <a name=cite-danangtoday000HomesSubmerged2020></a>[Da Nang Today (2024)](#bib-danangtoday000HomesSubmerged2020), <a name=cite-thianFloodVulnerabilityAssessment2022></a>[Thi An, Izuru, Narumasa, Raghavan, Hanh, Van An, Long, Thi Thuy, and Minh (2024)](#bib-thianFloodVulnerabilityAssessment2022)]

---
## Social Impacts

- **Increased Vulnerability:** Lowland communities, often poorer, face heightened flood risks, impacting economic well-being and increasing indebtedness.

- **Education Disruption:** Annual floods lead to school closures, affecting over 200,000 children with long-term absences impacting education, especially in specific wards.

- **Community Cohesion:** Despite challenges, community cohesion reportedly increases post-disasters.

- **Fatalities and Displacement:** Flooding has led to fatalities and significant displacement, with thousands evacuated and schools closed affecting hundreds of thousands of children.

---

## Economic Impacts

.pull-left[

**Income Reduction:**
Households, especially in certain wards, experience up to a 50% decrease in income post-flooding.

**Increased Borrowing:**
Affected households often resort to borrowing, with a significant percentage taking loans from relatives or credit institutions.

**Infrastructure Damage:**
Flooding has caused extensive damage to infrastructure, including crops, power stations, and houses, leading to substantial economic losses estimated in millions of dollars.

]

.pull-right-image[

.center[Economic Zones of Vietnam - <a name=cite-zhouFirmLevelEvidence2021></a>[Zhou and Botzen (2021)](#bib-zhouFirmLevelEvidence2021)]

]

---

## Environmental Impacts

**Water Quality Deterioration:** Post-flood water quality changes adversely affect community health, with a notable percentage of households experiencing poorer water supply quality.

**Waste Management Challenges:** A significant number of households report environmental concerns due to flood-related household waste issues.

**Health Risks:** Communities face increased health risks due to polluted environments and limited access to safe drinking water, leading to diseases like cholera, diarrhea, and dengue.

<img src="img/vietnam_floods.jpg" width="40%" style="display: block; margin: auto;" />
.image-caption[
.center[Flooding in Hue - <a name=cite-vuVietnamFloodDeath2020></a>[Vu (2024)](#bib-vuVietnamFloodDeath2020)]
]

---
## Policy Context
.pull-left[
.body-small[
**Global**
- Sustainable Development Goals
- Paris Agreement
- Sendai Framework for Disaster Risk Reduction

**National**
- National Determined Contribution
- National Adaptation Plan
- National Strategy on Natural Disaster Prevention
- Orientation Master Plan 2025

**Local**
- Resilient Da Nang Strategy
- Da Nang Development Plan 2030
]

.footnote-cite[
Sources: <a name=cite-Agenda2023></a>([United Nations, 2015b](#bib-Agenda2023)), <a name=cite-unitednationsParisAgreement2015></a>([United Nations, 2015a](#bib-unitednationsParisAgreement2015)), <a name=cite-undrrSendaiFrameworkDisaster2015></a>([UNDRR, 2015](#bib-undrrSendaiFrameworkDisaster2015)),  <a name=cite-socialistrepublicofvietnamNationallyDeterminedContribution2022></a>([Socialist Republic of Viet Nam, 2022](#bib-socialistrepublicofvietnamNationallyDeterminedContribution2022)), <a name=cite-socialistrepublicofvietnamNationalAdaptationPlan2023></a>([Socialist Republic of Viet Nam, 2023](#bib-socialistrepublicofvietnamNationalAdaptationPlan2023)), <a name=cite-socialistrepublicofvietnamVietnamNationalStrategy2021></a>([Socialist Republic of Viet Nam, 2021](#bib-socialistrepublicofvietnamVietnamNationalStrategy2021)), ([100RC Da Nang team, 2016](#bib-100rcdanangteamResilienceCityNang2016))
]
]

.pull-right-image[
<img src="img/policy.jpg" width="85%" style="display: block; margin: auto;" />
.center[

Da Nang's Flood and Resilience Policy Hierarchy
]
]

---
# Contributions to Policy

<div style="margin-top: -10px; margin-bottom: -30px;">
<h3> Global Policy <h3>
</div>

.pull-left[

**Sustainable Development Goal 11.5**

.pull-left-little[
<img src="img/SDG115.png" width="100%" style="display: block; margin: auto auto auto 0;" />
]

.pull-right-large[

.quote[By 2030, significantly reduce the number of deaths and the number of people affected and substantially decrease the direct economic losses relative to global gross domestic product caused by disasters, including water-related disasters, with a focus on protecting the poor and people in vulnerable situations.]
]
]

.pull-right[

**Sendai Framework**

.pull-left-little[
<img src="img/Sendai.png" width="100%" style="display: block; margin: auto auto auto 0;" />
]

.pull-right-large[

.quote[Priority 3: Investing in disaster risk reduction for resilience]

.body-small[Where is Risk is a combination of vulnerability, exposure, & hazard]

]
]

### National Policy

**Vietnam National Adaptation Plan:** .italics["Reduce Impact of Flooding on Urban Areas"]

---
# Existing Resilience Strategy

.pull-left[
.body-small[
**Climate Risk**  
- Flooding is identified as the main climate risk in the City with adverse impact on people and infrastructure.

**Strategic Objective**
- "Become a prepared City, a City with infrastructure systems which can recover, and be well prepared for challenges in development process."

**Action**
- Assessing flooding risk in new urbanized areas
  - Infrastructure Investment 
  - Planning Restrictions 
  - Resettlement 
]
]

.pull-right-image[
<img src="img/resilience strategy.png" width="85%" style="display: block; margin: auto;" />
.center[

Resilience Strategy for Da Nang - [100RC Da Nang team (2016)](#bib-100rcdanangteamResilienceCityNang2016)
]

]

---
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background-image: url('img/danangflooding.jpg')
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In the context of Da Nang's urban expansion, how can remote sensing be applied to improve urban planning strategies and substantially reduce flood vulnerability?

</span>

</div>

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# Objectives

- **Assess Impact**: Evaluate how urban expansion has affected flood vulnerability in Da Nang over the last 20 years using remote sensing.

- **Identify Risks**: Pinpoint current areas at high flood risk due to urban growth.

- **Forecast Future Risks**: Project future urban expansion patterns and their potential impact on flood vulnerability.

- **Develop Strategies**: Recommend measures for mitigation and resilience against future flood risks.

---
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# Methods

---
# Overview & Data Inputs

---

## Land Use / Expansion Analysis

.pull-left[

### Population and Urban Built-up Area

.body-small[
The built up area correlates with the population - an estimate of **181 km<sup>2</sup>** will be required by the year 2035
]
]

.pull-right[
.body-small[
<img src="img/urban_area.png" width="75%" style="display: block; margin: auto;" />
.image-caption[
  .center[Built up area growth of Da Nang.]
]
<img src="img/DaNang_urbanArea.gif" width="75%" style="display: block; margin: auto;" />
.center[
  .image-caption[Change of built up area from 2001-2022. Both images created from dataset by <a name=cite-friedl2022></a>[Friedl and Sulla-Menashe (2022)](#bib-friedl2022)
]
Urban growth model will be applied to extend this prediction to the year 2035
]
]
]

---
## Land Use / Expansion Analysis

.pull-left[

### Methodology
.body-small[
1. Calculate the area of urban built up area using classification of land use from earth observation imagery
2. Calculate the required spread (km<sup>2</sup>) of urban area, using the population prediction as the independent variable
3. Calculate the predicted spread of urban area for various scenarios, including
  - no intervention (cellular automata model of urban sprawl)
  - current masterplan intervention (building up areas designated by planning constraints)
]
]

.pull-right[

### Master Planning

Da Nang Master Plan maps major development plans to be completed by 2030. Areas that will actually be built up can be determined from the projected area for each year.

<img src="https://baodanang.vn/dataimages/202209/original/images1665961_images1665187_Tao_dong_luc2.jpg" width="75%" style="display: block; margin: auto;" />
.center[
  .image-caption[The Da Nang Master Plan, cited from <a name=cite-tung2022></a>[Tung (2022)](#bib-tung2022)]
]
]

---
# Flood Risk Assessment

**Dependent variable**

A proxy of flooded areas will be extracted from the difference in SAR images before and during a flooding event <a name=cite-tripathy2022global></a>([Tripathy and Malladi, 2022](#bib-tripathy2022global)).

.center[
  .image-caption[*Global Flood Mapper* [Tripathy and Malladi (2022)](#bib-tripathy2022global)]
]

---
# Flood Risk Assessment

**Model to predict future extent of flooding**

.pull-left[
A Random Forest pixel-based model will be built, taking as inputs:
- DEM data (flow accumulation),
- RGB bands, indices, like NDBI (impervious surfaces)
- composite of bands calculated e.g. using PCA <a name=cite-munawar2022remote></a>([Munawar, Hammad, and Waller, 2022](#bib-munawar2022remote)),
- Topographic Wetness Index (TWI)
]

.pull-right[
<img src="img/aspect_slope.png" width="90%" style="display: block; margin: auto;" />

.center[
  .image-caption[*Aspect Slope from Sentinel SAR*]
]
]

**Model Deployment**

The model could be deployed before the next expected flood event in the rainy season, to examine if the change in urban expansion will impact which areas are most likely to flood. This could inform appropriate precautionary measures the local government can take.

---
## Outcomes /  Policy Insights

.pull-left[

<img src="img/venn_diagram2.png" width="100%" style="display: block; margin: auto;" />
.center[
  .image-caption[Output illustration of project, indicating policy for each area.]
]
]

.pull-right[

#### Outcomes

- Quantity of land area required for urban expansion
- Areas prone to flood risk

#### Policies

**Future expansion of urban areas** should take place in safer areas or areas with improved flood barriers

**Current urban areas prone to floods** should

- consider relocating to a safer area
- implement flood protective measures to mitigate damage

]

---
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# Project Logistics

---
# Timeline
<img src="img/timeline.png" width="105%" style="display: block; margin: auto;" />
---
# Project Costs

.body-small[
| Position | Num. Days | Daily Fees | Total
| :--- | :---: | ---: |  ---: |
| Team Leader | 30 | £1,200.00 | £36,000.00 |
| Project Manager | 30 | £700.00 | £21,000.00 |
| Local Project Coordinator | 40 | £400.00 | £16,000.00 |
| Senior Flood Risk Expert | 15 | £1,200.00 | £18,000.00 |
| Flood Risk Expert | 40 | £700.00 | £28,000.00 |
| Senior Remote Sensing Analyst | 15 | £1,200.00 | £18,000.00 |
| Remote Sensing Analysts | 40 | £600.00 | £24,000.00 |
| Data Visualisation Expert | 30 | £600.00 | £18,000.00 |
| Urban Planner |3 | £800.00 | £2,400.00 |
| Urban Infrastructure Expert | 3 | £800.00 | £2,400.00 |
| Capacity Development Expert | 20 | £500.00 | £10,000.00|
| **Total Labour** | **232** | | **£193,800.00** |
| **Total Expenses** | | | **£60,000.00** |
| **Total Project Costs** | | | **£253,800.00** |
]

---

# Project Risks & Limitations

* **Budget Risks**: High or unforseen costs of acquiring and processing advanced remotely sensed data

* **Stakeholder Engagement Risks**: Potential resistance from stakeholders due to potential displacement or poorly articulated project benefits.

* **Data Accuracy Limitations**: Variability in data accuracy and resolution can lead to under or overestimation of flood risk zones.

* **Ongoing Maintenance**: The need for continuous updates and maintenance of the flood risk map to reflect changes in land use, climate and urban development.

---
# Mitigation Actions

* **Budget Mitigations**: Secure funding through a diversity of actors: government grants, partnerships with NGOs and collaborations with research institutions

* **Stakeholder Mitigations**: Develop stakeholder engagement plan, including workshops and transparent communication, to ensure buy-in and support

* **Data Accuracy Mitigations**: Utilise a combination of data sources and validation to enhance the accuracy and reliability

* **Ongoing Maintenance**: Develop a sustainable funding model and operational plan that includes periodic review and updates

---
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### .h1-background[In Summary...]

### .h1-background[We argue that an improved vulnerability asessment strategy which]
### .h1-background[a) Is powered by remote sensing]
### .h1-background[b) Incorporates analysis of urban expansion and flood risk by combining a diverse set of data sources]

### .h1-background[will allow Da Nang to more effectively plan its future development and strategically build infrastructure to prevent flooding where necessary]

---
# References (1/2)

.bibliography[
<a name=bib-100rcdanangteamResilienceCityNang2016></a>[100RC Da Nang
team](#cite-100rcdanangteamResilienceCityNang2016) (2016). _Resilience
Plan for Da Nang City, VietNam_.

<a name=bib-CongBoKet></a>[Đà Nẵng Online](#cite-CongBoKet) (2024).
_Công bố kết quả sơ bộ tổng điều tra dân số 2019: Cả nước có hơn 96,2
triệu người, Đà Nẵng có 1.134.310 người - Đà Nẵng Online_.

<a name=bib-danangtoday000HomesSubmerged2020></a>[Da Nang
Today](#cite-danangtoday000HomesSubmerged2020) (2024). _Over 4,000
homes submerged under water as torrential downpours lash Da Nang_. Vi.

<a name=bib-encyclopediabritannicaNangVietnam2024></a>[Encyclopedia
Britannica](#cite-encyclopediabritannicaNangVietnam2024) (2024). _Da
Nang, Vietnam_. En.

<a name=bib-europeanspaceagencySentinel2024></a>[European Space
Agency](#cite-europeanspaceagencySentinel2024) (2024). _Sentinel 2_.

<a name=bib-friedl2022></a>[Friedl, M. and D.
Sulla-Menashe](#cite-friedl2022) (2022). _MODIS/Terra+Aqua Land Cover
Type Yearly L3 Global 500m SIN Grid V061_.

<a name=bib-munawar2022remote></a>[Munawar, H. S., A. W. Hammad, and S.
T. Waller](#cite-munawar2022remote) (2022). "Remote sensing methods for
flood prediction: A review". In: _Sensors_ 22.3, p. 960.

<a name=bib-opitz-stapletonHeatIndexTrends2016></a>[Opitz-Stapleton,
S., L. Sabbag, K. Hawley, et
al.](#cite-opitz-stapletonHeatIndexTrends2016) (2024). "Heat index
trends and climate change implications for occupational heat exposure
in Da Nang, Vietnam". In: _Climate Services_ 2-3, pp. 41-51.

<a
name=bib-socialistrepublicofvietnamVietnamNationalStrategy2021></a>[Socialist
Republic of Viet
Nam](#cite-socialistrepublicofvietnamVietnamNationalStrategy2021)
(2021). _Vietnam: National strategy on natural disaster prevention,
response and mitigation to 2030, vision to 2050 PreventionWeb_. En.

<a
name=bib-socialistrepublicofvietnamNationallyDeterminedContribution2022></a>[Socialist
Republic of Viet
Nam](#cite-socialistrepublicofvietnamNationallyDeterminedContribution2022)
(2022). _Nationally Determined Contribution_.

<a
name=bib-socialistrepublicofvietnamNationalAdaptationPlan2023></a>[Socialist
Republic of Viet
Nam](#cite-socialistrepublicofvietnamNationalAdaptationPlan2023)
(2023). _National Adaptation Plan for the period 2021-2030, with a
vision to 2050 United Nations Development Programme_.

<a name=bib-thianFloodVulnerabilityAssessment2022></a>[Thi An, T., S.
Izuru, T. Narumasa, et
al.](#cite-thianFloodVulnerabilityAssessment2022) (2024). "Flood
vulnerability assessment at the local scale using remote sensing and
GIS techniques: a case study in Da Nang City, Vietnam". In: _Journal of
Water and Climate Change_ 13.9, pp. 3217-3238.
]

---
# References (2/2)

.bibliography[
<a name=bib-huongAnalysisUrbanExpansion></a>[Thi Viet Huong, D., R.
Nagasawa, and K. Tsutsui](#cite-huongAnalysisUrbanExpansion) (2013a).
"Analysis of urban expansion and flood risk change in Da Nang city in
Central Vietnam". In: _Journal of the Japanese Agricultural Systems
Society_, pp. 123-134.

<a name=bib-tripathy2022global></a>[Tripathy, P. and T.
Malladi](#cite-tripathy2022global) (2022). "Global Flood Mapper: a
novel Google Earth Engine application for rapid flood mapping using
Sentinel-1 SAR". In: _Natural hazards_ 114.2, pp. 1341-1363.

<a name=bib-tung2022></a>[Tung, T.](#cite-tung2022) (2022). _Momentum
created for Da Nang development from urban zoning planning_.
http://baodanang.vn/english/business/202209/momentum-created-for-da-nang-development-from-urban-zoning-planning-3921322/.

<a
name=bib-undrrSendaiFrameworkDisaster2015></a>[UNDRR](#cite-undrrSendaiFrameworkDisaster2015)
(2015). _Sendai Framework for Disaster Risk Reduction 2015-2030_.

<a name=bib-unitednationsParisAgreement2015></a>[United
Nations](#cite-unitednationsParisAgreement2015) (2015a). _Paris
Agreement_. UN Treaty

<a name=bib-Agenda2023></a>[United Nations](#cite-Agenda2023) (2015b).
_Transforming our world: the 2030 Agenda for Sustainable Development_.
General Assembly

<a name=bib-vietnamtourismReasonsWhyNang></a>[Vietnam
Tourism](#cite-vietnamtourismReasonsWhyNang) (2024). _4 Reasons Why Da
Nang is Vietnam’s Most Livable City_.

<a
name=bib-vnexpressRapidUrbanizationDelivers></a>[VnExpress](#cite-vnexpressRapidUrbanizationDelivers)
(2024). _Rapid urbanization delivers Da Nang's worst flooding ever -
VnExpress International_. En.

<a name=bib-vuVietnamFloodDeath2020></a>[Vu,
K.](#cite-vuVietnamFloodDeath2020) (2024). _Vietnam flood death toll
rises to 23 as storm Nangka set to dump more rain_. En. Section: News.

<a name=bib-zhouFirmLevelEvidence2021></a>[Zhou, F. and W.
Botzen](#cite-zhouFirmLevelEvidence2021) (2021). "Firm Level Evidence
of Disaster Impacts on Growth in Vietnam". In: _Environmental and
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]