基于柵格DEM的河網(wǎng)自動提取研究.pdf

1、蘭州大學碩士學位論文基于柵格DEM的河網(wǎng)自動提取研究姓名：許寶榮申請學位級別：碩士專業(yè)：自然地理學指導教師：楊太保20050501ABSTRACTDrainagenetworksmodelingisoneoftheimportantparametersofdistributedhydrologymodelsandthekeydirectionduringthequantitativeresearchbasedOilDigitalElev

2、ationdata(DEMs)inthetraditionalgeomorphologyaswellFurthermore，thelandformoftheearthsurfacecontrolsthedistributionofthesubstanceandenergyonthesurface，andimpactsthehydrological，geomorphologicalandbiologicalprocessesinthela

3、ndscapegreatlyThustheresearchondrainagesystemshasimportanttheoreticalandpracticalsignificanceInthisstudy，takingasubwatershedintheQaidarnasaeaseandusingreliefmaps嘶tllthescaleofhl00000asthedatasources，weanalyzethreeimporta

4、ntaspectsindetail：First，howtochoosethegridscaleduringtheconversionfromspecialscalereliefmapstogridbasedDEM；Second，thecomparisonamongthealgorithmsbasedonthegravitatedwaterflowtheoryinordertodedveterrainspecificinformation

5、abouthydro—geomorphologyfromaDEM；LastlyaphysicallybasedaccumulatedthresholdisdevelopedthroughdistinguishingtheflowbetweenhillslopeandchannelsusinggeomorphologicalknowledgeInthefirststep，weanalyzethequestiontochoosethe鰣ds

6、caleduringtheresamplingprocessesfromthedigitalizedterrainmapstogrid—basedDEMTheslopeoftheterrainisthekeyfactorwhichiIffluencesflowalgorithmsandweusethegeostatificalmethodtodiscusstherelationshipbetweenthedifferent醉dscale

7、DEMandcorrespondingslopeinformationandtodeterminetheappropriateDEMspacingThevariancecoefficientofpredictedslopeatalagofonecellisusedtoanalyzethestabilityoftheregionalinformationinthegridsizeTheresultsshowthattherangeindi

8、catingthespatialcorrelationcausedbytheresamplingincreaseswhenthegridspacingincreases，andforthesamelagdistance，thesemivariogramvaluesdecreasefromfinertocoarsespacing；Thevariancecoefficientsofpredictedslopeatalagofonecella

9、tfirstdecreaserapidlywiththeDEMspacingfrom20mto60m，thenincreasefrom60to150mTheleastvariancecoefficientisfoundedat60mspacingandthe60—nlcell。sizeDEMmaybemoststableamongallthecell—sizeDEMinrepresentingthelandformSothe60mspa