Assessing Chinese flood protection and its social divergence

Shiqiang Du,Paolo Scussolini,Dan Wang

doi:10.5194/nhess-21-743-2021

Shiqiang Du, Paolo Scussolini + Show 1 more

Open Access

https://doi.org/10.5194/nhess-21-743-2021

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Abstract

Abstract. China is one of the most flood-prone countries, and development within floodplains is intensive. However, flood protection levels (FPLs) across the country are mostly unknown, hampering the present assertive efforts on flood risk management. Based on the flood-protection prescriptions contained in the national flood policies, this paper develops a dataset of likely FPLs for China and investigates the protection granted to different demographic groups. The new dataset corresponds to local flood protection designs in 91 (53.2 %) of the 171 validation counties, and in 154 counties (90.1 %) it is very close to the designed FPLs. This suggests that the policy-based FPLs could be a valuable proxy for designed FPLs in China. The FPLs are significantly higher than previously estimated in the FLOPROS (FLOod PROtection Standards) global dataset, suggesting that Chinese flood risk was probably overestimated. Relatively high FPLs (return period of ≥50 years) are seen in 282 or only 12.6 % of the evaluated 2237 counties, which host a majority (55.1 %) of the total exposed population. However, counties with low FPLs (return period of <50 years) host a disproportionate share (52.3 %) of the exposed vulnerable population (children and elders), higher than their share (44.9 %) of the exposed population. These results imply that to reduce social vulnerability and decrease potential casualties, investment in flood risk management should also consider the demographic characteristics of the exposed population.

Highlights

Flood protection level (FPL) is the degree to which a flood-prone location is protected against flooding (Scussolini et al, 2016)
Scussolini et al (2016) developed FLOPROS (FLOod PROtection Standards), a global database of FPLs based on information included in protection design documents and in protection policy documents, in addition to FPL estimates based on flood risk modeling
Flood protection policies provide an opportunity to establish a large-scale FPL dataset (Mokrech et al, 2015), as they generally contain information on how a region should be protected from floods, some authors suggest that the actual protection levels could differ from the policy-prescribed protection standard (Jonkman, 2013)

Summary

Introduction

Flood protection level (FPL) is the degree to which a flood-prone location is protected against flooding (Scussolini et al, 2016). It is a key determinant of flood risk, making its quantification a prerequisite to reliable risk assessment (Ward et al, 2013). Hallegatte et al (2013) created an FPL dataset for coastal cities by combining design information of flood defenses and expert estimates to improve coastal flood risk assessment. Scussolini et al (2016) developed FLOPROS (FLOod PROtection Standards), a global database of FPLs based on information included in protection design documents and in protection policy documents, in addition to FPL estimates based on flood risk modeling Jongman et al (2014) estimated the FPLs in major European river basins by assuming that high-risk areas have high FPLs. Hallegatte et al (2013) created an FPL dataset for coastal cities by combining design information of flood defenses and expert estimates to improve coastal flood risk assessment. Scussolini et al (2016) developed FLOPROS (FLOod PROtection Standards), a global database of FPLs based on information included in protection design documents and in protection policy documents, in addition to FPL estimates based on flood risk modeling

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