iii Abstract The highway from Huangling to Tongchuan cross the Taoqupo reservoirs and the Qishui River Liuwan water protected areas. Although in the road building programs take full account of the water source protection requirements, the road water source water quality and safety of the operation would cause a potential impact, especially road transport in the sudden pollution incident will paint the Qishui River Liuwan water pose a significant threat. This thesis analyses the environmental impact of highway operation by Investigating and evaluating the topography, the geological conditions and the Water Environment of the second water protected areas. On this basis, it proposes the environmental protection program of water source areas. The same time, the road acrosses the Qishui River many times, which length is about 4.5 km, and set Interchange in K49+580, and the transport of dangerous goods on the water quality of the Qishui River causes potentially dangerous.This thesis uses the degree of risk to evaluate the impact of transport of dangerous goods for the Qishui River Liuwan water source. The results show that the probability is very low about a major accident may cause water pollution which operation of the transport of hazardous chemicals in the waters sections of Qishui River . However, considering the mountainous terrain and traffic in northern Shaanxi energy and heavy chemical base products, as well as the highway increased accidents transporting dangerous goods in recent years, the risk effects of the accident is an objective exist which the road in the operation period of the Qishui River water source. Therefore, it is necessary to take the water of a major pollution emergency treatment plan. According to the preliminary location of the dam site, the study calculate the selected dam site location arrival time to reach the concentration and the need for the capacity used the pollutant dispersion in the mathematical model of the one-dimensional steady-state flow of pollutants. Made TongHuang Highway and the second protected areas of Qishui River water with line segments downstream to a protected area build the accident prevention dam, intercepte sewage to ensure that sewage does not enter the river in order to ensure the iv safety of drinking water in Tongchuan City residents. Provide a theoretical basis for road construction and water source protection and engineering technical support. From the view of water source protection, the pepole should implement this article of the water source protection measures and put forward opinions and suggestions in the construction of a sudden pollution interception dam to effectively control adverse effects of the water source. Key words: Current water environment , Sudden pollution matter, Degree of risk , Risk accidents , Emergency treatment v 目 录 第一章 总论. 1 1.1 . 1 1.2 . 1 1.3 . 2 1.4 . 3 1.5 . 3 1.6 . 4 第二章 区域环境概况. 5 2.1 . 5 2.2 . 5 2.3 . 5 2.4 . 6 2.5 . 7 2.5.1 . 7 2.5.2 . 8 2.5.3 . 8 第三章 水环境现状调查与评价. 10 3.1 . 10 3.1.1 . 10 3.1.2 . 14 3.1.3 .