| There are many factors to affect the soil erosion,while the rain is direct one for the appearance of sand by erosion.Accurate measurement for the analysis of characters of rainfall is the foundation of the establishment of return simulation equation,as well as the development for the quantitative investigation of the rule in soil erosion and the effective prevention methods against soil erosion. The time-frequency localization characteristic in wavelet analysis could display the exact structure of climate time series,and it also provides a new way to analyse variation characteres of climate in much time scale,which is the basement of further climate compution,as well as the forcast of rainfall and water erosion.The establishment of the national conservation of water and soil foundation database is the guarance for dynamic monitoring and forcast in the soil erosion.The substation of water and soil conservation,as the front of national monitoring net,takes the responsibility for monitoring, experimenting,gathering and analysing of data.In nowadays,it is a long time to establish the nationwide,united monitoring network information system of water and soil conservation.Therefore, it is necessary to establish the database management system that fits for the basic conservation of water and soil,while the monitoring network information system of water and soil conservation has not been completed and the monitoring data hasn't been well managed.This article is maily divided into two parts:The first part is the the value characteristic analysis on rainfall amount based on the yearly rainfall data of the Chongqing typical area(county),through SPSS for routine ananlysis,as well as the deviation coefficient Cv and tendency coefficient r.The mutiple time criterion characters of the rainfall amount in 35years have been studied by the duplicate value Morlet wavelet.The results are followed:(1)There are obivious annual differences between the yearly raifall of 5 areas(county,)in Chongqing in 35years and the annual rainfall ammount is in the normal distribution.The high flow years are not correlated with low flow years in each area,but some of which are corresponded.The appearance of extreme rainfall amount is not regular.(2)There are obvious annual and age changes between yearly rainfall amount in 35years.In macroscale,the fluctuating cycle is quite different in each area,which is also not general. In microscale,in the research area 5 areas(county),the point of discontinuity in rainfall is increasing,the number,time and place of which is not same under different time criterion.(3)From the value of WA,the highest value of Kai Xian appears in the section of 10-15 years,which is also general,and the center point is about 1983.Those in other areas are not as obvious as that in Kai Xian.The second part is about the establishment of database management system for basic monitoring station of water and soil censervation based on Delphi and SQL.Taking the establishment of database management system for Suining water and soil canservation station as the example,the methods of object-oriented promgram plan is dicussed,which is under visual environment,as well as the feasibility of the construction of database management system for basic monitoring station of water and soil censervation based on Delphi and SQL.This research mainly explored the database management system,which satisfies with the needs from the basic monitoring station of water and soil censervation,whose explorement includes the establishment maintenance for backstage database,as well as the front application procedure.As for the backstage,the database must be uniformed,safe in data and integrated.And the front should be usible and functionally complete.According to current data manegement situation of the basic monitoring station of water and soil conservation,the research consider the character of monitor data that is vast and long-lasting and the practical needs for sort management and sending achievement. Delphi 7.0 has been used to develop the system software,with Windows,as the platform,and SQL Server 2000,as supporting relation database,so that the ananlysis of demands and model for management system of database could be accomplished,as well as thedivision of function module. And then the structure and application of the database could be designed.The function of this system includes three parts:1)it enables the basic monitoring stations of water and soil conservation to wholly manage their data;2)to provide convient inquiry;3)to output the chart.Before the national monitoring network of water and soil conversation is finished,this system,as the transition for data management of the basic monitoring station of water and soil conservation,has been proved to be practical and feasible. |
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