南水北调中线工程对汉江中下游水华的影响及对策研究(Ⅰ)——汉江水华发生的关键因子分析

为了评估南水北调中线工程对汉江中下游水华的影响,在广泛现场监测、资料收集、调查论证工作的基础上,应用水动力学模型和富营养化动力学模型对汉江水华发生的成因和关键因子进行了分析。汉江水华发生的主要原因有3个:汉江中游进入城区的排污量日趋增大,藻类等生物所需的氮、磷等营养物质严重过量(此乃根本原因);汉江水枯同时长江水位增高使汉江流速变缓,产生类似于湖泊的水流特性;春季气温偏高。在已满足藻类生长需求的营养条件下,流量和流速是制约汉江水华发生的关键(敏感)因子,南水北调中线工程对汉江中下游水华的影响将主要体现在水文因子上。

Research into the effects of the middle route of China' south-to-north water transfer project on water bloom in the middle-down stream of Hanjiang Riverand the countermeasures Part Ⅰ:An analysis of the key factors generating water bloom in Hanjiang River

In order to evaluate the effects of the middle route of China's south-to-north water transfer project(MR-SNWTP)on water bloom in the middle-down stream of Hanjiang River, ba- sed on monitoring data,collected information and investigation work,the reasons and key factors for Hanjiang's water bloom are analyzed by applying hydrodynamic model and dynamic model of eutrophication.There are three major reasons accountable for the generation of Hanjiang water bloom.The first and main one is that there are more and more polluted drainage from the middle stream to the down stream of Hanjiang River and excessive nutrition material needed by algae such as nitrogen,phosphorus,etc.The second one is that the water velocity in Hanjiang slows down when Hanjiang River has low water level and Yangtze River has high water level,and Hanjiang River has the flow characteristics like lakes.The third one is higher temperature in spring.Under the nutrition condition needed for algae growth,the discharge and water velocity are the key factors to restrict water bloom in Hanjiang River.The effects of MR-SNWTP on the water bloom in the middle-down stream of Hanjiang River will embody mainly on hydrological factors.