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、采用原生采样分辨率的数据，源自美国国家生态观测站网络（NEON）的溪流与河流径流量野外采集规程。单次径流量测量依托NEON水生观测站点中经永久基准标记的横断面，在可涉水溪流与河流中通过勘测完成。

在图利克湖（Toolik Lake）观测站点，径流量分别在湖泊出水口与入水口位置开展测量。在溪流观测站点（含图利克湖入水口与出水口），径流量的测量方式分为两种：当流量极低时采用手持式流速仪，当流量达到或高于基流时则采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（每个横断面通常包含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数值，并将该流速应用于整个子断面的过水面积，从而换算得到该断面的体积径流量。最终溪流总径流量通过累加各子断面的体积径流量得出。

采用ADCP测量时，需将ADCP安装于三体浮筒上，通过系留绳索系统将其沿河道往复牵引。系统会持续采集流速、水深与过水面积数据，并针对每个测量断面计算径流量。单次测量作业的总径流量为所有断面径流量的平均值。

在河流观测站点，径流量测量采用搭载于遥控船只上的ADCP，通过遥控船只沿河道往复航行完成数据采集。径流量的计算方式与溪流站点的ADCP测量法一致，仅部署方式有所区别。若无法使用遥控船只，则采用人工驾驶船只作为备用方案：将ADCP安装于人工驾驶船只的舷侧开展测量。

如需了解更多细节，请查阅本数据产品详情网页中“文档”板块所列的用户指南、采集规程与科学设计方案。

数据延迟：
本下载数据包内各数据表从野外数据/样本采集到正式发布的预期时长（单位：天）如下，更多信息请参阅《数据产品用户指南》：
- dsc_fieldData：30天
- dsc_individualFieldData：30天
- dsc_individualFieldDataADCP：30天