Coastal areas usually gather more population, resources and economy activities thus posing greater water pollution threats, especially to marine ecological reserves. Based on our previous watershed-scale risk assessment for abrupt water pollution accidents, a new version of coastal risk assessment model is completely adapted according to coastal risk profiles such as various waterways, high pollution hazard, and susceptible coastal ecology. The model establish a complete risk chain to evaluate regional risk according to risk formation mechanism, including: sub basin classification, evaluation of risk sources, evaluation of risk receptors, determination of exposure coefficients between risk sources and receptors, determination of effect coefficients between receptors and endpoints, and calculation of sub basin risk. A coastal city in Guangxi Province, China is taken as the case area. The result suggests that the risk scores in RR6, RR4, RR2 and RR3 are 198, 39, 48 and 5, respectively. The resultant risk map indicates that the risk in coastal zones is higher than that in inland zones, in accordance with the more risk sources in coastal zones and susceptible ecological reserves in offshore areas. ©, 2015, Editorial Board of Journal of Basic Science and Engineering. All right reserved.