Flood Risk And Cost Optimization Research Of Long Distance Water Transfer Project

It is very often that long distance water transfer engineering was destroyed by flood due to too many rivers to cross. So synthese flood risk analysis is needed. According to stochastic characteristics of hydrology, geology, geograghy and structure, we present synthese flood risk assessment method of crossing structures along water transfering engineering based on realibility analysis theory. The method was applied in South to North Water Transfer Project Middle Route in Hebei province. Results show that the flood risk of the system is between 4.6% to 1.5%,the average risk is about 3.1%. The break points in this thesis are following:1. According to stochastic characteristics of hydrology, geology, geograghy and structure, synthese flood risk assessment method of crossing structures along South to North Water Transfer Projcet Middle Route was established based on realibility analysis theory.2. This paper proposes the use of the two-dimension Gumbel mixed model, the bivariate extreme value distribution model with Gumbel marginals,to analyze the joint probability distribution of two hydrology stochastic variables. Based on the marginal distributions of these random variables, the joint distributions, the conditional probability functions, and the associated return periods are derived. It is helpful to solve the multi-variations hydrology problem.3. Traditional flood risk assessment method only appropriate to one river from hydrology view. This thesis establishing risk assessment model of long distance series system with Ditlevsen boundary and two dimensions Gumbel mixed model to avoid the nightmare of establishment of n-dimenssions joint probability distribution. The flood risk of South to North Water Transfer Project Middle Route in Hebei province is calculated as an example.4. Traditional flood risk assessment method is not real flood risk assessment. It is because traditional flood risk assessment method is based on annual maximum flow sample. But there is not only one flood process in one year. So it is often that second maximum flow in one year is larger than that of other year. Traditional method neglect many other hydrology information. The real flood risk assessment model is established on the base of time and spatial varying load reliability principle to make full ues of flood information.5. Crossing Structure Reliability of Water Transfer Project is determined by stochastic characteristics of hydrology, material, geology and structure. All of these aspects impact cost of engineering indirectly or directly. How to resolve the dilemma between cost and reliability is focus in engineering planning phase. This thesis present relation between cost and reliability of Water Transfer Project and optimize the engineering cost under the restriction of engineering reliability.