Hydraulic Model Calibration Using CryoSat-2 Observations in the Zambezi Catchment
Hydraulic Model Calibration Using CryoSat-2 Observations in the Zambezi Catchment
复制标题
使用 CryoSat-2 观测在赞比西流域进行水力模型校准
DOI：
10.1029/2020wr029261
复制
发表时间：
2021
影响因子：
5.4
通讯作者：
Kittel C
中科院分区：
文献类型：
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作者：
Kittel C
大地高度计由于其长的重复周期和密集的地面轨迹，提供了对河流表面纵向轮廓的独特观测。这些信息对于校准水力模型参数很有价值，因此，对于洪水预报和河流管理，特别是在仪器设备较差的流域，产生可靠的水位模拟是有价值的。在这项研究中，我们提出了一种基于稳态水力解算器和CryoSat-2观测的水力模型的有效校准方法。为了确保在定标中只考虑相干强迫/观测对，我们首先提出了一种利用水文模型产生的模拟径流对数据稀缺地区的CryoSat-2观测数据进行离群滤波的方法。在水力校准中，稳态求解器计算与CryoSat-2立交桥天数对应的选定流量沿河流的水面高程(WSE)剖面。在合成定标实验中，全局搜索算法通常在有观测数据的河流部分恢复真实参数值，说明了从大地高度计进行密集空间采样的好处。最敏感的参数是床面高程。在用真实的CryoSat-2数据进行的校准实验中，针对哨兵3号WSE和现场记录的验证性能与之前的研究相似，相对于Sentinel-3的均方根偏差在0.43到1.14微米之间，与现场WSE观测的均方根偏差在0.60到0.73之间。在将参数传输到一维流体动力学模型时，性能保持相似。由于该方法计算效率高，可以在高空间分辨率下反演模型参数，以充分利用大地测量CryoSat-2高度计所包含的信息。
Geodetic altimeters provide unique observations of the river surface longitudinal profile due to their long repeat periods and densely spaced ground tracks. This information is valuable for calibrating hydraulic model parameters, and thus, for producing reliable simulations of water level for flood forecasting and river management, particularly in poorly instrumented catchments. In this study, we present an efficient calibration approach for hydraulic models based on a steady‐state hydraulic solver and CryoSat‐2 observations. In order to ensure that only coherent forcing/observation pairs are considered in the calibration, we first propose an outlier filtering approach for CryoSat‐2 observations in data‐scarce regions using a simulated runoff produced by a hydrologic model. In the hydraulic calibration, a steady‐state solver computes the water surface elevation (WSE) profile along the river for selected discharges corresponding to the days of CryoSat‐2 overpass. In synthetic calibration experiments, the global search algorithm generally recovers the true parameter values in portions of the river where observations are available, illustrating the benefit of dense spatial sampling from geodetic altimetry. The most sensitive parameters are the bed elevations. In calibration experiments with real CryoSat‐2 data, validation performance against both Sentinel‐3 WSE and in situ records is similar to previous studies, with Root Mean Square Deviation ranging from 0.43 to 1.14 m against Sentinel‐3 and from 0.60 to 0.73 against in situ WSE observations. Performance remains similar when transferring parameters to a one‐dimensional hydrodynamic model. Because the approach is computationally efficient, model parameters can be inverted at high spatial resolution to fully exploit the information contained in geodetic CryoSat‐2 altimetry.