Simulation of water hyacinth growth area based on multi-source geographic information data: An integrated method of WOE and AHP

Predicting the suitable growth areas (SGAs) of WH under different environmental scenarios are important for sustainable management of water hyacinth (WH) which is more severe than ever due to increased water pollution caused by human activities. Based on an integrated method of Weight-of-Evidence (WOE) and Analytical Hierarchy Process (AHP), this study developed habitat adaptability index (HAI) to predict the SGA under four environmental scenarios using 412 WH events and 15 environmental variables in Guangdong of South China, which has significantly meteorological and hydrological characteristics of annual average (AAS), April to September (high flow season, HFS), October to March (low flow season, LFS), and December or next January (the coldest month, CMS). In each scenario, multi-classified environmental variables (i.e., topography, meteorology, socioeconomics, land cover, and urban sewage treatment) of WH events were firstly weighted by the WOE model. Then, the WOE weights were further input to AHP as data matrix for calculating the final weights which were used to analyze the impact of environmental variables on WH growth. The integrated WOE-AHP method under four scenarios performs well with the area under the curve (AUC > 0.85) of Receiver Operating Characteristic (ROC). Under different scenarios, the risk simulation of WH disaster shows the following distribution law: HFS > LFS > AAS > CMS. More than 54% of water areas in the study area is suitable for the growth of WH. WH density increased from north to south (or upstream to downstream) along rivers while the density decreased from central to both east and west wings of Guangdong province. The most WH-prone occurrence regions are located at elevation < 50 m, slope < 2 degrees, gross industrial production > RMB 10, 000 million yuan, people > 5 million persons, air temperature between 25.4 degrees C and 27.7 degrees C, precipitation between 1575 mm and 1864 mm, and annual average evapotranspiration between 904 mm and 1,065 mm. The Pearl River Delta, Zhanjiang-Maoming regions of western Guangdong, and Teochew area of Eastern Guangdong are three major risk areas. Under the background of global warming and serious deterioration of the aquatic environment, the SGA of WH is expanding northward. Based on the location of the water system in Guangdong province, we proposed two WH management strategies for rural and urban water systems. Given macroscopic and rapid advantages of WOE-AHP in simulating WH's SGA, this method can be applied to other areas invaded by WH, and the scenario setting and selection criteria of environmental factors can provide important reference for adopting targeted WH management measures.