南水北调中线不同调水方案下的汉江水华发生概率分析

为评估南水北调中线工程对汉江中下游水华的影响，从汉江水华的成因机理分析入手，提出了汉江水华发生概率的计算模型．该模型由河流一维水动力学模型、水体富营养化模型以及随机数生成模型组成，它不仅可以模拟汉江水华的发生机理，而且可以对诱发水华的各种因子进行随机抽样组合，从而求出中线调水不同方案实施后汉江水华的发生概率．计算结果表明，在现状情况下汉江水华的发生概率为9．2％，南水北调中线各调水方案（无引江济汉工程）实施后，汉江水华发生的概率将有一定程度的增加，而如果调水方案与引江济汉工程同时兴建将大大减少汉江水华发生的概率．最后提出建议，汉江自身的水污染治理是减少水华发生概率的最根本措施，而丹江口水库和引江济汉工程的联合调度将会减小汉江水华发生的概率．

Analysis to occurrence probability of water bloom in Hanjiang river under different water transfer schemes of the middle route of China's south-to-north water transfer project

In order to evaluate the effects of the middle route of China's south-to-north water transfer project (mr- snwtp) on the water bloom in the middle-down stream of Hanjiang river, according to the analyzed conclusions about the reasons of Hanjiang's water bloom, the calculating model of probability of water bloom in the Han-jiang River is put forward. The model consists of a one-dimension river hydrodynamic model, a water body eutrophication model and a random generation model. This model not only simulates the generating mechanism of water bloom in Hanjiang River, but also randomly assembles all sorts of factors inducing water bloom, thereby calculates the probability of Hanjiang River's water bloom after implementing different mr-snwtp schemes. The calculative results indicate that the probability of water bloom in Hanjiang river is 9.2% under the present situation, and it will increase on some degree after each scheme of mr-snwtp (without the diversion project from Yangtze river to Hanjiang river) is implemented, but each scheme of mr-snwtp with building the diversion project will markedly decrease the probability of water bloom in Hanjiang river. In the end, the suggestions are put forward that water pollution control of Hanjiang river itself is the most basic measure to reduce the probability of Hanjiang's water bloom and the joint regulation of Danjiangkou reservoir and water transfer project from Changjiang river to Hanjiang river will reduce the probability of Hanjiang's water bloom.