Dynamics of sedimentary Capibaribe River bed after deepening dredging

ABSTRACT The growth of urban centers in the country are increasingly dependent on the adoption of new mobility options, and before this need was developed and initiated a project to build a river corridor passenger in a part of the Capibaribe River in the city of Recife-PE. For the implementation of a navigation channel deepening are needed dredging to define a geometry of the bed of the river compatible with the needs of ships that will traverse the channel. The monitoring of dredging is done with the constant bathymetric surveys where the information volumes of dredged sediments are removed, aiming to also check the temporal behavior of deposition and erosion processes. In this context, the work aimed to evaluate the geometry of the Capibaribe river bed after the deepening dredging, using data from bathymetric surveys at different times for making longitudinal and transverse profiles, and create digital models of depth to extract information about the deposition/aggradation or erosion/removing sediments and their respective volumes. Early Profile Capibaribe river showed mild slope and heterogeneity in the bottom of the form, especially after kilometer five, with trends of deposition/aggradation downstream of the confluence region with tax arising from the weir Apipucos and upstream of the winding sections in local enlargement of the cross section, and the amount of the fork located at kilometer nine. The scenarios after the dredging to deepen indicate places with predominance of erosion and other sedimentation processes. They compared the longitudinal and transverse profiles of two areas located in western shipping channel, one with 350 meters and over 1000 meters, where it was found that the area 1 to erosion/sediment removal exceeded sedimentation/aggradation, indicating the occurrence of dredging the interval between the two surveys linked to the natural processes. In the study area 2 the sedimentation/aggradation exceeded the removal/erosion, with a volume equivalent to 1 cm thickness. The aggradation occur homogeneously in the navigation channel, while erosion was located on the banks, more intensely on the right bank of the river.

摘要：该国城市中心的发展愈发依赖新型出行方式的应用，基于这一需求，相关部门启动了累西腓市（Recife-PE）卡皮巴里贝河（Capibaribe River）某区段的内河廊道客运工程。为实施航道加深工程，需开展河道疏浚作业以确定适配通航船舶通行需求的河床几何形貌。疏浚作业的监测通过常态化水深测量（bathymetric surveys）开展，一方面核算疏浚泥沙的开挖方量，另一方面同步监测泥沙淤积与侵蚀过程的时空演化特征。在此背景下，本研究旨在依托不同时段的水深测量数据，通过生成纵向与横向剖面，构建水深数字模型，进而分析河床淤积/加积或侵蚀/泥沙开挖过程，并核算对应方量，以此评估疏浚加深后的卡皮巴里贝河河床几何形态。疏浚前的卡皮巴里贝河河床剖面整体坡降平缓，但河床形态存在显著异质性，尤其在5公里航段之后更为突出：与阿皮普库斯堰（Apipucos Weir）支流交汇后的下游区段，以及弯道段上游的局部断面扩宽区域均呈现淤积/加积趋势；9公里航段处的分流岔口区域尤为明显。航道疏浚加深后的监测场景显示，部分区域以侵蚀过程为主，其余区域则以淤积过程为主。研究对比了航道西段两个区域的纵向与横向剖面，两个区域分别长350米和1000余米。结果显示，区域1的泥沙侵蚀/开挖量高于淤积/加积量，表明两次测量间隔期间，除自然演化过程外，还存在疏浚作业的扰动影响。区域2的淤积/加积量则高于侵蚀/开挖量，对应泥沙抬升厚度约1厘米。其中，航道内的加积过程分布相对均匀，而侵蚀作用主要集中于河岸，右岸的侵蚀强度更为显著。