Discharge field collection (DP1.20048.001)

This data product contains the quality-controlled, native sampling resolution data from NEON's stream and river discharge field collection protocol. Individual discharge measurements are conducted by means of surveys that occur in wadeable streams and rivers along permanently benchmarked cross-sections at NEON aquatic sites. At the Toolik Lake site discharge is measured at the lake outflow and inflow locations. At stream sites (and Toolik Lake inflow and outflow), discharge is measured using a handheld flowmeter (when flows are very low) and acoustic Doppler current profiler (ADCP) instrumentation (when flows are at or above baseflow). During flowmeter measurements the waterbody is divided into lateral sub-sections (of which there are typically 20-25 per cross-section). Within each subsection, an instantaneous velocity magnitude is obtained via a handheld flowmeter and transformed to a volumetric discharge magnitude by applying the velocity across the full subsection area. Total stream discharge is then calculated by summing the discrete volumetric discharges for each subsection. During ADCP measurements the ADCP is placed in a trimaran float and pulled back and forth across the channel using a tethered rope system. Velocity, depth, and area data are continuously measured, and discharge is calculated for each transect. Total discharge for a given bout is the mean discharge across all transects. At river sites discharge is measured using ADCPs deployed in remote controlled boats that are driven back and forth across the channel. Discharge is calculated in the same manner as the ADCP method at stream sites, only the deployment method differs. If remote controlled boats are not available a piloted boat method serves as a backup where the ADCP is deployed off the side of a piloted boat. For additional details, see the user guide, protocols, and science design listed in the Documentation section in this data product's details webpage. Latency: The expected time from data and/or sample collection in the field to data publication is as follows, for each of the data tables (in days) in the downloaded data package. See the Data Product User Guide for more information. dsc_fieldData: 30 dsc_individualFieldData: 30 dsc_individualFieldDataADCP: 30

本数据产品包含经质量管控的、保留原生采样分辨率的美国国家生态观测站网络（NEON）溪流与河流径流野外采集协议数据集。径流单点测量通过野外勘测完成，勘测在NEON水生观测站点的永久基准断面处的可涉水溪流与河流中开展。
图利克湖（Toolik Lake）站点的径流在湖泊出流与入流点位开展测量。
溪流站点（含图利克湖入流与出流点位）的径流测量采用两种方式：当流量极低时使用手持式流速仪，当流量达到或高于基流时则使用声学多普勒流速剖面仪（ADCP）。采用手持式流速仪测量时，水体被划分为横向子断面（每个标准断面通常包含20至25个子断面）；在每个子断面内，通过手持式流速仪获取瞬时流速值，并将该流速乘以子断面总面积，换算为体积径流量。最终溪流总径流量通过累加各子断面的体积径流量得到。
采用ADCP测量时，将ADCP安装于三体浮筒上，通过系留绳索系统使其在河道内往复移动；测量过程中持续获取流速、水深与断面面积数据，并为每个测线计算径流量。单次测量周期的总径流量为所有测线径流量的平均值。
河流站点的径流测量采用搭载于遥控船的ADCP，遥控船沿河道往复行进完成测量，径流量计算方式与溪流站点的ADCP测量方法一致，仅布设方式不同。若无法使用遥控船，则采用人工驾驶船只作为备选方案：将ADCP安装于人工驾驶船只的舷侧开展测量。
更多详情请参阅本数据产品详情网页的文档板块中所列的用户指南、技术规程与科学设计方案。
数据滞后性：下载数据包中各数据表的野外数据/样品采集至数据发布的预期时长（单位：天）如下所示，详情请参阅《数据产品用户指南》：
dsc_fieldData：30天；dsc_individualFieldData：30天；dsc_individualFieldDataADCP：30天。