Application Of Network RTK Technique Combined With Digital Depth Sounder In Surveying Capacity Of The Lake

The basic situation of rivers and lakes is the main task of the first national waterconservancy survey of the State Council, as part of the first water conservancy surveyworks in Beijing City, the purpose to carry out city lake survey is to accurately graspthe basic situation of the lake in our city, grasp the development, utilization andprotection of water resources,find out the needs of social-economic development towater resources, understand construction capacity of water conservancy,build thebasic water information platform for Beijing City, and provide a reliable basic waterinformation support and guarantee for the economic and social development ofBeijing city. In order to improve the ability of using the water resources to serve theeconomic and social development,achieve the continuable development,utilizationand protection of water resources, our institute join with the relevant departments ofBeijing Municipal Bureau to carry out the survey of some urban important lakes, thereconnaissances include the lowest point positions and elevation, the maximum depthof lakes, the volume of the lakes, the maximum capacity of the lakes and so on.According to the general standard of our country,we need to survey thename,positions,perennial water surface area and numbers of the lakes which haveperennial water surface area above one square kilometer, during this survey of sixlakes only KunMing Lake reached the standard. At the same time, according to therequirements of Beijing municipal water conservancy survey, thename,positions,perennial water surface area and numbers of the lakes which haveperennial water surface area above0.1square kilometer are the object of thesurvey.The TuanCheng Lake,FengChan Lake, LiuYin Park Lake, YuYuanTan Lakeand BaYi West Lake can achieve the general standard of BeiJing City.As capital Beijing is located in the north, water resources are relatively scarce,bound together with technology and local finance resources, scientific and effectivedetection methods have not taken on the survey of lake reservoir capacity. The surveyof city lake mainly used by the sounding rod or sounding ruler of the manualoperation before, the measured points on the map didnotdescribe accurateenough.Work outside largely influenced by the natural environment and long cycle,heavy workload,low precision which limit contribution of the water resources to thedevelopment of economy and society.At present the technology foreign countries used to thelake reconnaissance isGPS and digital depth sounder combined operations,which obtained good results.Thissurvey of the lake is the city of Beijing and the northern region for the first time to usehigh-tech surveying and mapping and geophysical survey on City Lake, reached theinternational advanced level. Through basic informations of the six lakes measured bythe survey, we can find out Beijing city lake resources, provide reliable data for thescientific development and decision-making of the capital and provide advancedexperience for the City Lake survey. This investigation provides a new idea for CityLake survey, can be promoted to use and greatly improve the production efficiency.This is the first time in Beijing to use high-tech surveying and mapping andgeophysical survey on city lake, proposes the use of network RTK techniquecombined with digital depth sounder in the underground water topographic survey andconstruct a new method of the fine3D underground water to calculate the capacity,the main innovation points are as follows: (1) Using network RTK technique combined with digital depth sounder to survey thetopography of underground water, which can make fast acquisition of the highprecision underground water terrain dataThe GPS mobile station antenna is mounted directly above the transducer of echosounder, so that in the process of measurement, GPS measurement point and soundermeasurements of underwater sites in the same plumb line. Network RTK can measureplane coordinate in real-time, at the same time sounding instrument can measure theelevation difference between transducer to the bottom of the water, by using soundinglevel elevation minus sounder draft after subtracting sounder values can obtainmeasuring point height, using this new method can obtain high precision underwaterterrain data.(2) Using high precision underground water terrain data to construct underwater3Dterrain surface, using AutoCAD Civil3D software to accurately calculate the existingwater volume and maximum capacity of the lakeBy using the AutoCAD Civil3D software of Autodesk Inc., we can directly showthe established3D surface, the software can quickly calculate the volume betweenexisting surface and design surface. In the calculation of water volume and capacity ofproduct, using the coordinates and elevation we obtained to establish underwater3Dterrain surface tosimulate the undulating terrainof underground water. Elevationisapproximateas the same surface, which can be understood as a nearly horizontalsurface, the bottom surface of the enclosed horizontal and basin shaped regionis thewater volume of the entire lake; if we improve the level to the lowest point at thewater’s edge, the water surface horizontal and basin shaped area form the reservoircapacity of the lake.The combination of the new mapping technology and the new geophysicalsurveying technology use Beijing CORS network, with network RTK technique anddigital depth sounder, efficiently and accurately get the information of six lakes.Wecan summarize the advanced experience of lake survey, explore the technical processof the city lake survey, so as to provide future reference of city lake survey. Methodsused in this survey greatly reduced the field data collection work time,survey accuracyis greatly improved,influence of the natural environment also weakened, this methodcan be widely used in water conservancy and survey.This paper introduces the network RTK technique combined with digital depthsounder to measure the bottom topography of the lake.We can calculate the watervolume, reservoir volume, maximum water depth and the average depth of characterinformation calculation of six lakes by using AutoCAD Civil3D software through thefield data measured. We can sum up a set of scientific methodsof lake surveytechnology process and survey in this work, and put forward the common solutions ofsome difficulties which can be guidanceto obtain the basic information of the lake.