Assessment of direct economic losses of flood disasters based on spatial valuation of land use and quantification of vulnerabilities: a case study on the 2014 flood in Lishui city of China

Detailed and reliable assessment of direct economic losses of flood disasters is important for emergency dispatch and risk management in small- and medium-sized cities. In this study, a single flood disaster in Lishui city in 2014 was taken as an example to study and verify a method for rapid and detailed assessment of direct economic loss. First, based on a field investigation, the inundation data simulated by the one-dimensional hydrodynamic model and geographic information system (GIS) analysis method were verified. Next, the urban land use map and high-resolution land use classifications based on remote sensing data were fused and combined with expert questionnaire surveys, thereby providing the 47 types and values of land use. Then, based on the previous depth–damage function in the past study, the vulnerability curves of 47 types of land use in Liandu district were fitted by the lognormal cumulative distribution function and then calibrated using disaster loss report data. Finally, the distributions of the loss ratio and loss value were estimated by spatial analysis. It is found that the land use data have detailed types and value attributes as well as high resolution. Secondly, the vulnerability curves after function fitting and calibration effectively reflect the change characteristics of land use loss ratio in this area. Finally, except for the three types of land for agriculture, recreational and sports facilities, and green parking spaces, the optimized simulated total loss is CNY 322.6 million, which is 0.16 % higher than the statistics report data. The estimated loss ratio and loss value can reliably reflect the distribution pattern of disaster losses in detail, which can be applied by government and private sectors to implement effective disaster reduction and relief measures.

Assessment of the Direct Economic Losses of Flood Disasters Based on the Spatial Valuation of Land Use and Quantification of Vulnerabilities: A Case Study of the 2014 Flood in Lishui city, China

The refined assessment of the direct economic losses of flood disasters is important for emergency dispatch and risk management in small- and medium-sized cities. There are still great challenges in the accuracy and timeliness of the previous research methods. In this study, a single flood disaster in Lishui city in 2014 was taken as an example to study and verify a method for the rapid and refined assessment of direct economic loss. First, based on a field investigation, the inundation range and submerged depth simulated by the flooding model were verified. Next, the urban land use status map and high-precision remote sensing classification data were fused and combined with expert questionnaire surveys, thereby providing the types and values of disaster-bearing bodies. Then, the existing vulnerability curve database was summarized, and the curves were calibrated by disaster loss reporting. Finally, the spatial distributions of the flood disaster loss ratio and loss value were estimated by spatial analysis. It is found that the constructed land use map has detailed types and value attributes as well as high-precision spatial information. Secondly, the vulnerability curves after function fitting and calibration effectively reflect the change characteristics of land use loss ratio in this area. Finally, the estimated loss ratio and loss value distributions can accurately reflect the spatial pattern of flood disaster loss, which is useful for the government to formulate effective disaster reduction and relief measures.

A Data Augmentation-Based Evaluation System for Regional Direct Economic Losses of Storm Surge Disasters

The accurate prediction of storm surge disasters’ direct economic losses plays a positive role in providing critical support for disaster prevention decision-making and management. Previous researches on storm surge disaster loss assessment did not pay much attention to the overfitting phenomenon caused by the data scarcity and the excessive model complexity. To solve these problems, this paper puts forward a new evaluation system for forecasting the regional direct economic loss of storm surge disasters, consisting of three parts. First of all, a comprehensive assessment index system was established by considering the storm surge disasters’ formation mechanism and the corresponding risk management theory. Secondly, a novel data augmentation technique, k-nearest neighbor-Gaussian noise (KNN-GN), was presented to overcome data scarcity. Thirdly, an ensemble learning algorithm XGBoost as a regression model was utilized to optimize the results and produce the final forecasting results. To verify the best-combined model, KNN-GN-based XGBoost, we conducted cross-contrast experiments with several data augmentation techniques and some widely-used ensemble learning models. Meanwhile, the traditional prediction models are used as baselines to the optimized forecasting system. The experimental results show that the KNN-GN-based XGBoost model provides more precise predictions than the traditional models, with a 64.1% average improvement in the mean absolute percentage error (MAPE) measurement. It could be noted that the proposed evaluation system can be extended and applied to the geography-related field as well.

Building an Awareness Model of Emergency Supplies Dispatching for Tropical Cyclone Disasters in Guangxi

It is found that Guangxi is affected by many tropical cyclones (generally referred to as typhoons in China) every year. According to the statistics of typhoons that entered the inland of Guangxi from 1970 to 2013, 89 typhoons entered Guangxi in 44 years, with an average of 2 typhoons per year (Jing Li, Liyan Qi, 2015). And these tropical cyclone disasters have caused a large number of casualties and economic losses in Guangxi. Typhoon No. 0606 "Prapiroon" entered Guangxi from Yulin city, causing 74 counties (cities and districts) in Guangxi to suffer disasters, affecting 5.76 million people, killing 34 people and causing direct economic losses of 7 billion yuan (Jing Li, et al., 2007). In addition, according to the report of Guangxi Civil Affairs Department, super typhoon No. 1409 "Rammasun" landed in Fangchenggang area of Beibu Gulf, causing 4.3211 million people in 11 cities and 57 counties (cities and districts) including Beihai and Fangchenggang to suffer disaster, affecting 1.456 million hectares of crops, 8,527 farmhouses collapsed, and the direct economic losses reached 13.84 billion yuan. Moreover, the number and intensity of tropical cyclone that caused serious damage to Guangxi increased gradually. The damage caused by tropical cyclone is very huge, the disaster area is widely distributed, and the loss of many people is also very large. How to deliver the emergency supplies to the victims timely at minimum cost becomes the key to disaster relief. But the emergency supplies dispatching involves many problems. Because the displaced people are distributed in different settlements. The extent of the impact varies from place to place and the type and amount of emergency supplies needed. The distance between settlements and distribution centers varies from place to place, as does the connectivity of roads. Therefore, it is necessary to establish an awareness model for emergency supplies dispatching to solve these problems, so that emergency agencies of governments at all levels can make emergency supplies dispatching scheme faster and improve disaster relief effects. Keywords: Emergency Logistics, Tropical Cyclone Disasters, Emergency Supplies Dispatching, Transshipment Problem, Guangxi

A Review Of The Research On Emergency Logistics Of Tropical Cyclone Disasters In Guangxi

It is found that Guangxi is affected by many tropical cyclones (generally referred to as typhoons in China) every year. According to the statistics of typhoons that entered the inland of Guangxi from 1970 to 2013, 89 typhoons entered Guangxi in 44 years, with an average of 2 typhoons per year (Jing Li, Liyan Qi, 2015). And these tropical cyclone disasters have caused a large number of casualties and economic losses in Guangxi. Typhoon No. 0606 "Prapiroon" entered Guangxi from Yulin city, causing 74 counties (cities and districts) in Guangxi to suffer disasters, affecting 5.76 million people, killing 34 people and causing direct economic losses of 7 billion yuan (Jing Li, et al., 2007). In addition, according to the report of Guangxi Civil Affairs Department, super typhoon No. 1409 "Rammasun" landed in Fangchenggang area of Beibu Gulf, causing 4.3211 million people in 11 cities and 57 counties (cities and districts) including Beihai and Fangchenggang to suffer disaster, affecting 1.456 million hectares of crops, 8,527 farmhouses collapsed, and the direct economic losses reached 13.84 billion yuan. Moreover, the number and intensity of tropical cyclone that caused serious damage to Guangxi increased gradually. Keywords: Emergency Logistics, Tropical Cyclone Disasters, Emergency Supplies Requirements, Emergency Supplies Dispatching, Guangxi