Study On Eco-hydrological Effect And Reservoir Ecological Regulation On The Main Yellow River

For meeting the economic and social development demand of water resource, human carried out excessive exploit on many rivers, leading to river eco-hydrological system health situation worsening unceasingly. However, limited scientific and technological development and eco-detection means, people still has no way to take directly a large area of observation to river ecosystem change and evolution process. Therefore, how to use scientific methods to identify the main eco-hydrological factors causing the health status deterioration of the river, and to use targeted measures to gradually restore the river health is a key problem needing to study. In this paper, the Yellow River as the typical river was studied from the. perspective of eco-hydrology approach by combining quantitative analysis and system modeling method. The study focused on the eco-hydrological characteristics changes of the Yellow River, the impact mechanism of reservoirs operation to the river, the eco-hydrological index system and ecological water demand of the Yellow River, and the basic theory and model of reservoir ecological regulation and so on. Main results in the paper are as follows:(1) By discussion and analysis the relationship between ecology and hydrology, it was brought forward that concept of river eco-hydrological system. And based on defining the study content and scope of hydrology and ecology involved in the system, its basic theoretical system was initially built and the definition of its health was given. Then the paper described the eco-hydrological system basic functions, health signs as well as the key eco-hydrological factors to state the eco-hydrological system. All provides a theoretical support to reservoir ecological regulation research.(2) Long series statistic analysis was carried out on run-off, floods, river sediment and fluvial geomorphology on different sections of the main stream of the Yellow River by the different methods such as Mann-Kendall. Furthermore, it were revealed that the long-term evolution rule, mutation characteristics of different ecological indexes and ecological system response mechanism. On the basis of all above research, the key eco-hydrological factors leading to river eco-hydrological system health deterioration were obtained by contrasting different reservoir operation results, which have provided the scientific basis for constructing river eco-hydrological index system.(3) After human activities on the river eco-hydrological system's influence and the function mechanism, the demonstration focus on reservoir damage to river systems. By RVA calculating, quantitative analysis was taken on different reservoirs operations acting on river eco-hydrological system and their inner respond relationship, which made up for past deficiencies with overmuch qualitative research on the thing. Through contrasting the effect to river from single reservoir operation with one from cascade reservoir operation, and comparing between results caused by different functions, the most adverse operating manner damaging river health was given, which would provides a theoretical basis for reservoir ecological regulation.(4) Combined with the actual demand of the Yellow River, the Yellow River eco-hydrological indexes system has been constructed, fully considering regulation demand, flood factor, the abundant or low runoff difference as well as the representation, feasibility and accessibility of the indexes. It divided 7 big kinds,50 eco-hydrology factors. Comparing with other indexes systems, it has more perfect structure, characterization and target.(5) Based on response relationship between keystone species, flow component and hydraulic space on the different river section, ecological flow depth and velocity method was put forward for calculating ecological water demand. The method could consider the required water flow and hydraulic target of keystone species at different life-cycle, then determine the flow range required to maintain the corresponding specie survival on different sections. Combining with Tennant method, the minimum and the suitable ecological flow processes on different sections may be given, which is a new approach to research river ecological water demand.(6) An elementary theory system and research frame about reservoir ecological regulation was constructed, including the concept, connotation, basic principle, regulation type and ways of reservoir ecological regulation and so on. In light of the present existence of rough time scale, spatial scale over-small and difficult issues such as coupling goal, the paper put forward suggestions to solve the coupling problem on time and space scale, and set up a day-scale reservoir multi-objective scheduling model including based on the flow objectives and structure goals. It enriched reservoir ecological regulation research ideas. At the same time, a long-term multi-objective reservoir operation model was built and solved by simulation technology. In real cases to the Yellow River the paper has made the results more reasonable.