Study On Behaviors Of Water Eutrophication In Three-Gorges Valley Using Complex Networks Theory

The Three-Gorges project had been well known to most people in the world for a long time, which is a huge and famous water hinge conservancy and has obvious economical benefit and engineering functions such as shipping, preventing flood and generating electricity. In the meanwhile, the structure and function of its environment will be deep influenced. Since the Three-Gorges reservoirs begin to intercept water, The self-clarification ability of water have decreased and the water eutrophication aggravated because of the lower velocity of flow, the formation of water-level- fluctuating zone, and the inner tides, causing the ecology and environment of the Yangtze river basin to undergo profound changes. So it's an important and urgent task to do some research on eutrophication prediction along Three-Gorges reservoir.Algal booms is a complex process under multiple factors interaction. The formation, eruption, spread, standing and fluctuating of algae have a complicated, non-linear relationship which are similar to the content of the water eutrophication substance.The synchronization of complex networks with broad universality is a common non-linear phenomenon in nature and it is consistent with the outbreak and real-time characteristic of algal booms. The essence of algal booms is synchronous accumulation of large localized areas in short time. So by using the synchronization of complex networks theory, Kinetics of algal growth and large-scale interactive caculation, a simulation model and the framework that can analyse the overall outbreak of algal booms was constructed to deeply study and describe the inner-rules of Three-Gorge eutrophication and algal blooms.According to the current decade local monitoring data such as total concentrations of nitrogen and phosphorus, water temperatures, a numerical model based on characteristic of alga growth and synchronization of complex networks theory was constructed to reveal inherent dynamic mechanism of algal blooms and describe complex evolution process of algal growth in water area along riversides of Hanjiang river. The scales of gridding above specified algal concentration has been characterized as a criterion to estimate algal bloom and predict the scales, the criticality and the holistic emergency of the algal bloom also verified in a way of synchronization. And revealed the process of algal blooms were the results of synergic action of the whole water valley system. Simulating computation showed if the number of gridding above specified algal concentration exceed the specified scales in the numerical model, the corresponding water valley system would appear algal bloom pollution, and duration of peak states of the gridding was directly proportional to scales of algal bloom.