Exploring the Signal Filtering Properties of Idealized Watersheds Using Spectral Analysis
Exploring the Signal Filtering Properties of Idealized Watersheds Using Spectral Analysis
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DOI：
10.1016/j.advwatres.2023.104441
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发表时间：
2023-04
影响因子：
4.7
通讯作者：
Abram Farley;L. Condon
中科院分区：
文献类型：
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作者：
Abram Farley;L. Condon
当水流经地表和地下时，分水岭起着低通过滤器的作用，抑制和衰减气候信号。这是一个很好的观察现象；然而，流域特性控制这种过滤的性质的方式很少得到很好的记录，特别是关于地下水地表水的相互作用。在这里，我们使用一个基于物理的地下水地表水模型来模拟具有不同分水岭属性(坡度、导水率和降雨量)的理想化的山坡集合，以定量地探讨分水岭配置对地表和地下时间过滤的影响。为了限制该系统的复杂性，使用了一个名为-v的理想化结构域。运行了多个十年(95年)的模拟，然后使用功率谱密度和传递函数来量化每个模拟的时间动力学和衰减。总体而言，我们表明，过滤的程度和信号转换的程度由在地下花费的总时间和地下水地表水交换的程度控制。降雨与渗透系数之比控制着入渗和径流的分配。入渗越大，地下的过滤越少，径流中的过滤越多。对于给定的降水电导率，地下水位越深，在5年以下的周期内，径流过滤越大。对于大于5年的时间周期，径流过滤与控制基流动态的水力传导性关系最强。大部分输入信号在地下被过滤不到一年的短周期。对于较长的时间尺度，水力传导性是地下发生的过滤和功率转移的主要控制因素，较大的传导性与较少的过滤和较少的信号转换相关。在饱和存储中，地下水位越深，信号变换越多，而在非饱和存储中，则与滤波无关。这可能是由于较高的电导率(减少过滤)和较深的地下水位深度(增加过滤)的抵消作用。
Watersheds act as low-pass filters, damping and attenuating climatic signals as water moves through the surface and subsurface. This is a well observed phenomenon; however, the ways in which watershed properties control the nature of this filtering are less well documented, especially with respect to groundwater surface water interactions. Here, we use a physically based groundwater surface water model to simulate idealized hillslope ensembles with varying watershed properties (hillslope slope, hydraulic conductivity, and precipitation magnitude) to quantitively explore the impact of watershed configuration on temporal filtering in both the surface and subsurface. To limit the complexities of this system an idealized titled-v domain is used. Multi-decadal simulations (95 years) are run, and then power spectral densities and transfer functions are used to quantify the temporal dynamics and damping of each simulation. Overall, we show that the degree of filtering and the degree of signal transformation is controlled by the total time spent in the subsurface and the degree of groundwater surface water exchanges. The ratio of precipitation to hydraulic conductivity controls the partitioning between infiltration and runoff. Greater infiltration results in less filtering in the subsurface and more filtering in streamflow. For a given precipitation conductivity ratio, deeper water table depths lead to greater streamflow filtering for periods less than 5 years. For time periods greater than 5 years the streamflow filtering is most strongly related to hydraulic conductivity which controls the baseflow dynamics. The majority of the input signal is filtered in the subsurface for short periods less than one year. For longer time scales, hydraulic conductivity is found to be the primary control of filtering and power shift taking place in the subsurface with larger conductivities correlated to less filtering and less of a signal transformation. Deeper water table depths lead to more signal transformation in saturated storage but are not correlated to filtering in unsaturated storage. This is likely due to counteracting effects of higher conductivity (which decreases filtering) and deeper water table depths (which increase filtering).