In accordance with the technical requirements for sudden water environment risk assessment and early warning, a complete water environment risk assessment and early warning technical system of "risk source identification and evaluation-environmental risk monitoring-rapid simulation of environmental risks-emergency assessment of pollution accidents-emergency control of characteristic pollutants" has been established. system. In terms of risk source identification and assessment, a risk source identification technology based on the coupling of risk source characteristics of water ecological functional zoning and water environment sensitive targets is proposed to provide "goals" for water environment risk early warning. In terms of environmental emergency monitoring technology, we will build technical methods for early warning and monitoring of water pollution sources and water environment quality to realize the transformation of environmental monitoring from "post-event monitoring" to "early warning monitoring". In terms of simulation of the impact of sudden water pollution accidents, rapid simulation technology for sudden environmental risks has been developed, which has achieved rapid and accurate judgment of sudden water environment risks and gained time for emergency decision-making. In terms of assessing the impact of sudden water pollution accidents, a technology for determining emergency control threshold for sudden water pollution accidents is proposed to provide a scientific basis for the reasonable disposal of pollution incidents. In terms of on-site emergency response technology for water pollution accidents, we have developed on-site emergency treatment and disposal technology for chemicals in pollution accidents to provide tools for emergency response. In terms of river basin water environment risk assessment and early warning information platform construction technology, a multi-source data access adapter has been developed and a universal database of river basin water environment information has been built to provide technical support for the construction of river basin water environment risk and early warning information platform. In accordance with the overall design concept of the "Five Ones", a technical platform for water environment risk assessment and early warning in the Three Gorges Reservoir Area has been built. Since its operational operation in 2010, the platform has realized the intelligence of the water environment monitoring and emergency management system in the Three Gorges Reservoir Area and greatly improved work efficiency.