The Application Of Design Method Of Unsteady Flow Theory For Small Cropland Drainage Engineering

Flood is one of the most frequent disaster in the word and it’s also quite often in China.In recent years, influenced by the global climate change,the flood disaster has caused significant damage to agricultural production because of its suddenness and abnormality.In order to eliminate the farmland waterlogging and improve the production and living conditions of the rural population as well as promote the healthy development of rural economy,the government attaches great importance to the small drainage engineering construction which has experienced great progress. Although it has played a large role in ensuring the development of national economy and social stability,we are still faced with many problems,such as lack of reasonable planning,slow construction, aging and out of repair facilities and so on.These conditions has gradually become the obstacles of agricultural production and rural economic development in our country.Small farmland drainage engineering,which plays an important component in little-scale irrigation works,usually refers to small-scale water conservancy engineering whose controlling drainage area within 30,000-acre.With the further development of basic farmland construction,the engineering construction standardization has gradually become problems urgently to be solved in small irrigation and water conservancy construction.At present,in the current system of the water conservancy industry technical standards,we are still lacking technical standards or specifications specifically for the small water conservancy project and little technical data is also available for reference. These work is often determined by designers’ experience.For some complex situation,the results,calculated by the specification formula,are often inconsistent with actual conditions.It cannot meet design requirement,which restricts its practical usage.On the basis of reading many related information, this paper is carried out to study theapplication of unsteady flow theory to design the small irrigation and drainage engineering.This paper includes eight chapters,and the details are as follows:Firstly, this article introduces the research background and significance as well as objectives of this thesis.The research progress of unsteady open channel flow theory and the present application of MIKE 11 software at home and abroad are summarized. On this basis, it proposes the content and the technical route of this research.Secondly,survey of research region is introduced.Combination of the basic data and field survey data,this chapter introduces the basic situation of the research region,including natural survey, topography and landform,agricultural performance,current situation of irrigation works, main construction contents and drainage method as well as storm data.Thirdly,based on basic features of flow movement, this paper contrasts and analyzes the theories and formulas of steady uniform flow,steady ununiform flow and unsteady flow.It is concluded that the differences and relations between the three theories.Moreover,it exports the basic data to calculate and the results are obtained.With checking the flow velocity, it ensures the section size of ditch.Finally,the accuracy of results is analyzed.By collecting the measured hydrographic data, this paper contrasts and analyzes the results of three different theories,then getting conclusion of accuracy verification.The whole work in this paper is summed up and further research work is prospected.