Research into global water resources is challenged by the lack of ground-based hydrometric stations and limited data sharing. It is difficult to collect good quality, long-term information about river discharges in ungauged regions. Herein, an approach was developed to determine the river discharges of 24 rivers in ungauged regions on the Tibetan Plateau on a long-term scale. This method involved coupling the Manning–Strickler formula, and data from an unmanned aerial vehicle (UAV) and the Gaofen-2, SPOT-5, and Sentinel-2 satellites. We also compared the discharges calculated by using the three satellites’ data. Fundamental information about the rivers was extracted from the UAV data. Comparison of the discharges calculated from the in-situ measurements and the UAV data gave an R² value of 0.84, an average NSE of 0.79, and an RMSE of 0.11 m³/s. The river discharges calculated with the GF-2 remote sensing data and the in-situ experiments for the same months were compared and the R², RMSE, and the NSE were 0.80, 1.8 m³/s, and 0.78, respectively. Comparing the discharges calculated over the long term from the measured in-situ data and the SPOT-5 and Sentinel-2 data gave R² values of 0.93 and 0.92, and RMSE values of 2.56 m³/s and 3.16 m³/s, respectively. The results showed that the GF-2 and UAV were useful for calculating the discharges for low-flow rivers, while the SPOT-5 or the Sentinel-2 satellite gave good results for high-flow river discharges in the long-term. Our results demonstrate that the discharges in ungauged tributaries can be reliably estimated in the long-term with this method. This method extended the previous research, which described river discharge only in one period and provided more support to the monitoring and management of the tributaries in ungauged regions.

中文翻译：

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组合和比较无人机和多颗遥感卫星，以计算青藏高原空旷水源区的长期河道流量

缺乏地面水文测站和有限的数据共享，对全球水资源的研究面临挑战。很难收集有关未开垦地区河流排放的高质量，长期信息。在此，开发了一种方法来长期确定青藏高原未开垦区的24条河流的河流量。该方法涉及耦合曼宁-斯特里克勒公式和无人飞行器（UAV）以及高分2号，SPOT-5和Sentinel-2卫星的数据。我们还比较了使用三颗卫星的数据计算出的流量。有关河流的基本信息是从无人机数据中提取的。通过现场测量和UAV数据计算出的排放量的比较得出R ²值为0.84，平均NSE为0.79，RMSE为0.11 m ³ / s。比较了用GF-2遥感数据和当月进行的原位实验计算出的河流流量，R ²，RMSE和NSE分别为0.80、1.8 m ³ / s和0.78。比较从实测数据和SPOT-5和Sentinel-2数据得出的长期排放量，得出R ²值为0.93和0.92，RMSE值为2.56 m ³ / s和3.16 m ³/ s。结果表明，GF-2和UAV可用于计算低流量河流的流量，而长期来看SPOT-5或Sentinel-2卫星对于高流量河流的流量效果良好。我们的结果表明，使用这种方法可以长期可靠地估算未支流支流的流量。这种方法扩展了先前的研究，该研究仅描述了一个时期的河流流量，并为无支配地区的支流监测和管理提供了更多支持。