现代浅水三角洲分流河道宽度自动提取及沉积模式重构:以赣江三角洲为例OA

The channel network structure of shallow delta is complex.In the previous studies on the morphological characterization of distributary channels,there was a lack of quantitative data support for the spatial continuity of river width.This paper focuses on the quantitative characterization of channel morphological parameters and studies the spatial continuous variation characteristics of the width of the distributary channels in the Ganjiang Delta,aiming to provide constraints on the spatial variation of channel width for reservoir configuration research,and then improve the reservoir configuration characterization method system.Based on the Google Earth Engine big data cloud computing platform,this paper improves the RivWidthCloud river width extraction algorithm,realizes the automated extraction of continuous width data of the Ganjiang Delta distributary channel,and reveals the spatial continuous variation law of the width of the distributary channel in the shallow delta plains.The results show that:(1)the river width data extracted after algorithm optimization have significant correlation with the measured values(R2=0.84),which verifies the reliability and applicability of this method in river morphology monitoring;(2)the seasonal variation of the width of the main branch of Gan River is significant(the average river width in the dry season is 444.85 m,and the average river width in the rainy season is 650.75 m,an increase of 46％),which is significantly higher than that of the other two tributary channels;(3)There is a significant spatial coupling relationship between channel width and bifurcation frequency:the width of the upstream section of the bifurcation mouth increases sharply,and the width of the secondary channel decreases significantly after bifurcation;(4)According to the continuous channel width curve(the trend line of continuous river width data points),the width data of the distributary channels has an overall decreasing trend towards the downstream of the delta,but still shows an oscillating change with multiple levels of fluctuations.(5)70％of the quasi-central-bar development areas present a width variation pattern of"wide beach head,narrow beach neck,and wider beach tail",and the corresponding river channel width curve shows a three-stage feature of"high-low-higher".The continuous river width quantification method provides a new tool for the study of modern delta sedimentation.The law of distributary channels scale variation revealed by it can provide a quantitative basis for fine characterization of the scale of distributary channels,geometric constraints for reservoir architecture modeling,compilation of small-scale sedimentary facies maps.