Orthomosaic Image and Digital Surface Model for the South Fork Serpentine River Beaver Dams and Ponds, Seward Peninsula, Alaska, 31 March 2022

Emergence of beavers as ecosystem engineers in the New Arctic project focuses on establishing field sites at tundra beaver ponds to study the implications of beaver engineering on hydrology and permafrost. Drones are being used to collect baseline data and track beaver dam building and pond evolution over time. This dataset consists of an orthomosaic and digital surface model (DSM) derived from drone surveys on 31 March 2022 at the South Fork Serpentine River site on the Seward Peninsula, Alaska. 1,072 digital images were acquired from a DJI Phantom 4 Real-Time Kinematic (DJI P4RTK) quadcopter with a DJI D-RTK 2 Mobile Base Station. The mapped area was around 155 hectares (ha). The drone system was flown at 120 meters (m) above ground level (agl) and flight speeds varied from 8-9 meters/second (m/s). The orientation of the camera was set to 90 degrees (i.e. looking straight down). The along-track overlap and across-track overlap of the mission were set at 80% and 70%, respectively. All images were processed in the software Pix4D Mapper (v. 4.7.5) using the standard 3D Maps workflow and the accurate geolocation and orientation calibration method to produce the orthophoto mosaic and digital surface model at spatial resolutions of 5 and 10 centimeters (cm), respectively. Elevation information derived over waterbodies is noisy and does not represent the surface elevation of the feature. A Leica Viva differential global positioning system (GPS) provided ground control for the mission and the data were post-processed to WGS84 UTM Zone 3 North in Ellipsoid Heights (meters).“‘新北极地区海狸作为生态系统工程师’研究项目以苔原（tundra）海狸池塘为野外样地，旨在探究海狸工程活动对水文与永久冻土的影响。本研究采用无人机采集基线数据，并长期追踪海狸水坝建造与池塘演化过程。本数据集包含2022年3月31日于美国阿拉斯加州苏厄德半岛蛇河南支样地开展的无人机测绘所生成的正射影像镶嵌图（orthomosaic）与数字表面模型（digital surface model, DSM）。数据采集使用搭载DJI D-RTK 2移动基站的大疆精灵4实时动态差分（DJI Phantom 4 Real-Time Kinematic, DJI P4RTK）四旋翼无人机，共获取1072张数码影像。测绘区域总面积约155公顷（hectare, ha）。无人机飞行高度设定为距地面120米（meters, m，agl），飞行速度区间为8~9米每秒（meters per second, m/s）。相机拍摄角度固定为90度，即垂直向下拍摄。本次任务的航向重叠度与旁向重叠度分别设置为80%与70%。所有影像均采用Pix4D Mapper（v.4.7.5）软件，通过标准三维地图工作流与精准地理定位及姿态校准方法进行处理，最终生成空间分辨率分别为5厘米（centimeters, cm）与10厘米的正射影像镶嵌图与数字表面模型。水体区域提取的高程信息存在噪声，无法反映对应地物的真实地表高程。本次任务采用徕卡Viva差分全球定位系统（differential global positioning system, GPS）布设地面控制点，并将数据后处理至WGS84坐标系UTM北3区，采用椭球高（单位：米）。”