Why does a conceptual hydrological model fail to correctly predict discharge changes in response to climate change?
Why does a conceptual hydrological model fail to correctly predict discharge changes in response to climate change?
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DOI：
10.5194/hess-24-3493-2020
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发表时间：
2020-07-13
影响因子：
6.3
通讯作者：
Parajka, Juraj
中科院分区：
文献类型：
--
作者：
Duethmann, Doris;Bloeschl, Guenter;Parajka, Juraj
一些研究表明，水文模型在应用于气候条件与模型校准期间不同的时期时表现不佳。这对这些模型在气候变化影响研究中的应用具有重要意义。然而，仅在少数研究中调查了对气候条件变化的可转移性低的原因。在这里，我们重新审视了在奥地利的一项研究，证明了一个概念性的半分布式HBV型模型无法模拟所观察到的排放响应增加降水和空气温度。本文的目的是阐明这些模型问题的原因。我们建立了假设的可能原因之间的不匹配的观察和模拟的变化，放电和评估这些使用模拟与修改的模型。在基线模型中，1978-2013年期间模拟和观测排放量的趋势在所有156个集水区的平均差异为每35年95 +/- 50毫米/年（-1）。在计算参考蒸发量时，考虑到从卫星植被指数得出的植被动态变化，可以解释模拟排放量趋势与观测排放量趋势之间每35年36 +/- 9毫米的差异。降水量数据的不均匀性，由不同数量的站点造成的，解释了39 +/- 26毫米每35年（-1）的这种差异。将校准期从5年延长到25年，在目标函数中包括每年汇总的排放数据或积雪数据，或用Penman-Monteith而不是Blaney-Criddle方法估计蒸发量，对模拟排放趋势的影响很小（每35年或更少5 mm yr（-1））。降水数据问题突出了在研究水文变化时使用基于固定输入站网络的降水数据的重要性。植被动力学的模型结构问题可能与瞬态气候中广泛的区域有关，并对气候变化影响研究具有重要意义。
Several studies have shown that hydrological models do not perform well when applied to periods with climate conditions that differ from those during model calibration. This has important implications for the application of these models in climate change impact studies. The causes of the low transferability to changed climate conditions have, however, only been investigated in a few studies. Here we revisit a study in Austria that demonstrated the inability of a conceptual semi-distributed HBV-type model to simulate the observed discharge response to increases in precipitation and air temperature. The aim of the paper is to shed light on the reasons for these model problems. We set up hypotheses for the possible causes of the mismatch between the observed and simulated changes in discharge and evaluate these using simulations with modifications of the model. In the baseline model, trends of simulated and observed discharge over 1978-2013 differ, on average over all 156 catchments, by 95 +/- 50 mm yr(-1) per 35 years. Accounting for variations in vegetation dynamics, as derived from a satellite-based vegetation index, in the calculation of reference evaporation explains 36 +/- 9 mm yr(-1) per 35 years of the differences between the trends in simulated and observed discharge. Inhomogeneities in the precipitation data, caused by a variable number of stations, explain 39 +/- 26 mm yr(-1) per 35 years of this difference. Extending the calibration period from 5 to 25 years, including annually aggregated discharge data or snow cover data in the objective function, or estimating evaporation with the Penman-Monteith instead of the Blaney-Criddle approach has little influence on the simulated discharge trends (5 mm yr(-1) per 35 years or less). The precipitation data problem highlights the importance of using precipitation data based on a stationary input station network when studying hydrologic changes. The model structure problem with respect to vegetation dynamics is likely relevant for a wide spectrum of regions in a transient climate and has important implications for climate change impact studies.