Study On The Water Transparency Numerical Model And Its Application On Submerged Plant Restoration

The primary requirement of submerged plant community restoration is to improving the water transparency. Light field below water surface is a significant factor of aquatic ecosystem, which has direct effects on the growth of aquatic plants. The low water transparency will hinder the photosynthetic activity and ulteriorly lead aquatic plants dead. Therefore, the basis and prerequisite for aquatic plant restoration is to understanding the main factors affecting water transparency and the efficient control measures, to researching the complicated dynamic mechanism of water transparency and its quantitative influence on submerged plant growth. The study will provide the theoretical and practical support on hydrophyte restoration and water environmental remediation.This dissertation takes Neijiang River as the research object, centered on the transparency and makes research on the following aspects:1. Research the mutual influence of submerged plant and environmental factor in laboratory. On one hand, studies the aquatic plant's capability of nutrients adsorption and water quality purification; According to the experimental result, obtains the quota parameter of sediment and water quality purification affected by aquatic plant. On the other hand, studies the submerged plant's growth rhythm under the condition of different transparency through the experiment, according to the experimental result, establishes quota relations of the transparency and the aquatic plant growth parameter. The experiment provides parameters for the transparency numerical model.2. Water transparency is an essential parameter which describes the optical characteristic in water body. With the on-site monitoring data, the main environmental factors affecting the transparency in Neijiang are determined which are sediment, algae and soluble organic matter. Then, the multiple regression equation of transparency and the sediment content, the permanganate index and the chlorophyll-a is established. Taking the sediment, the algae and the soluble organic matter's complicated transportation and variation into consideration, based on the analysis of hydrology characteristics, the sediment motion and the water quality variation in Neijiang, it separately establishes the sediment transportation model, the water quality model and the eutrophication model in Neijiang. Coupling the three models and combing the transparency regression equation, it establishes the transparency model in Neijiang.3. After the controlling of water level in Neijiang by the regulating check, the habitat condition in Neijiang will be changed, under the new habitat condition, some submerged plant which does not exist in Neijiang at present has the possibility to restore. This dissertation bases on natural restoration idea, according to the light depth of compensation, studies the feasibility of the submerged plant's restoration in Neijiang. The light depth of compensation is related to the light coefficient of attenuation and the aquatic plant's photosynthesis characteristic. It applies the transparency model to calculate the distribution of transparency after the implementation of project in Neijiang. According to quota relations of the transparency and the light coefficient of attenuation which obtained from experiment, it has...