Analysis Of Precipitation Characteristics With Respect To The Urban Flood Control And Drainage In Lujiang County

As the rapid development of urbanization in China in the recent decades, a lot of cities are experiencing urban flooding problems to some extend because the capacity of their urban drainage systems can not meet the rapid development of urbanization. As a result of this, urban flood has affected the everyday life of the citizens, ever their life. It has also hindered the development of the cities in terms of both economics and urbanization.Lujiang County is located in mid-south of Anhui Provence where is one of the sub-catchments of the Yangtze River with area of2347km2. The characteristics of the precipitation between1952and2009in the county were analyzed in different scales using a couple of statistic approaches. Time series analysis of the non-uniformity coefficient, complete adjustment coefficient, concentration degree and period, and variation of amplitude of the precipitation was also monthly analyzed. The results showed that the precipitation was non-uniformly distributed from month to month. Most of it concentrated in May, June, July, and August and its total amount varied significantly from year to year. Wet and dry years occurred rotationally, which were11dry years happened in the60’s,9near-dry years happened in the60’s as well, and22average years happened in the50’s,70’s,80’s,90’s, and the21st century among the analyzed period.Mann-Kendall trend test, R/S analysis, and Empirical Mode Decomposition (EMD) were applied to analyze the mutability, constancy, and periodicity of the precipitation. The results demonstrated that the precipitation declined from the year1952to196, then fluctuated within a small range until2009. EMD analysis showed that IMF of the precipitation represented in the variation cycle of1-3years,3-6years,5-8years,9-12years, and17-21years. R/S analysis showed that the precipitation indicated negative change, meaning that the precipitation might decline slightly in the near future. Therefore, the forecasted precipitation by Markov approach for the year of2010might be kept as an average.Based on the analysis above, the designed flood was calculated, which in turn the flood control planning was worked out. According to the current situation and the planed urban development planning, the urban area was divided into22self-drainage and7power-drainage sub-areas. The amount of the flood within the sub-areas was calculated. The results would assistant the regional precipitation analysis and the urban flood control planning.