Integrated surface-subsurface model to investigate the role of groundwater in headwater catchment runoff generation: A minimalist approach to parameterisation
Integrated surface-subsurface model to investigate the role of groundwater in headwater catchment runoff generation: A minimalist approach to parameterisation
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DOI：
10.1016/j.jhydrol.2017.02.023
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发表时间：
2017-04
影响因子：
6.4
通讯作者：
P. Ala‐aho;C. Soulsby;Hailong Wang;D. Tetzlaff
中科院分区：
文献类型：
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作者：
P. Ala‐aho;C. Soulsby;Hailong Wang;D. Tetzlaff
了解地下水对源头流域径流产生的作用是水文学中的一个挑战，特别是在数据稀缺的地区。完全集成的地表-地下建模已显示出增强径流生成过程理解的潜力，但高数据要求和模型校准困难通常被认为妨碍了它们在流域规模研究中的使用。我们使用完全集成的地表-地下水文模拟器来增强对具有丰富经验数据背景的水源流域地下水相关过程的理解。为了建立模型，我们使用了可以合理预期任何实验流域存在的最少数据。我们方法的一个新颖之处是使用简化的模型参数化，并在自动模型校准中包括来自所有模型域（地表、地下、蒸散）的参数。校准的目的不仅是为了提高模型拟合度，而且是为了测试校准目标函数中使用的观测数据（水流、遥感蒸散量、地下水位中值）的信息内容。我们确定了所有模型域（地下、地表、蒸散量）中的敏感参数，证明模型校准应包含来自这些不同模型域的参数。将地下水数据纳入校准目标改进了模型对地下水位的拟合，但即使在校准后，模拟也无法很好地再现遥感蒸散时间序列。空间明确的模型输出提高了我们对地下水如何主要通过饱和过量地表流量来维持水流生成的理解。稳定的地下水输入在谷底河岸泥炭地创造了饱和条件，即使在干旱时期也会导致地表径流。山坡上的地下水对降雨的响应更加动态，扩大了饱和面积范围，从而促进了暴雨期间饱和过量的地表径流。我们的工作展示了使用集成的地表-地下建模以及严格的模型校准的潜力，即使在数据集有限的情况下，也可以更好地理解和可视化地下水在径流生成中的作用。
Understanding the role of groundwater for runoff generation in headwater catchments is a challenge in hydrology, particularly so in data-scarce areas. Fully-integrated surface-subsurface modelling has shown potential in increasing process understanding for runoff generation, but high data requirements and difficulties in model calibration are typically assumed to preclude their use in catchment-scale studies. We used a fully integrated surface-subsurface hydrological simulator to enhance groundwater-related process understanding in a headwater catchment with a rich background in empirical data. To set up the model we used minimal data that could be reasonably expected to exist for any experimental catchment. A novel aspect of our approach was in using simplified model parameterisation and including parameters from all model domains (surface, subsurface, evapotranspiration) in automated model calibration. Calibration aimed not only to improve model fit, but also to test the information content of the observations (streamflow, remotely sensed evapotranspiration, median groundwater level) used in calibration objective functions. We identified sensitive parameters in all model domains (subsurface, surface, evapotranspiration), demonstrating that model calibration should be inclusive of parameters from these different model domains. Incorporating groundwater data in calibration objectives improved the model fit for groundwater levels, but simulations did not reproduce well the remotely sensed evapotranspiration time series even after calibration. Spatially explicit model output improved our understanding of how groundwater functions in maintaining streamflow generation primarily via saturation excess overland flow. Steady groundwater inputs created saturated conditions in the valley bottom riparian peatlands, leading to overland flow even during dry periods. Groundwater on the hillslopes was more dynamic in its response to rainfall, acting to expand the saturated area extent and thereby promoting saturation excess overland flow during rainstorms. Our work shows the potential of using integrated surface-subsurface modelling alongside with rigorous model calibration to better understand and visualise the role of groundwater in runoff generation even with limited datasets.