Evaluating the Use of the Penman–Monteith and Priestley–Taylor Algorithms for Modelling Peatland Evapotranspiration Using the Cold Regions Hydrological Model

IF 2.5 3区环境科学与生态学 Q2 ECOLOGY

Ecohydrology Pub Date : 2024-09-05 DOI:10.1002/eco.2714

Brandon Van Huizen, Richard M. Petrone, Xing Fang, John W. Pomeroy

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Abstract

Methods used to quantify evapotranspiration (ET) from Sphagnum‐dominated peatlands often assume that soil moisture is not a limiting factor; actual ET (AET) equals potential ET (PET). However, soil moisture can become limiting as peatlands dry, lowering AET below PET and necessitating the use of a surface resistance term in AET estimations. Quantifying and calculating surface resistance is a challenge for the non‐vascular plant surfaces such as those dominated by Sphagnum moss. This paper explores and quantifies the ecohydrological processes that drive Sphagnum resistance to ET. It is hypothesized that a relationship exists between the Sphagnum moss resistance and the ratio of unsaturated to saturated hydraulic conductivity (K‐ratio) for boreal peatlands, where the K‐ratio is a proxy for the hydrophysical properties of the porous medium. An empirical relationship between Sphagnum moss resistance and the K‐ratio was developed from data collected from a boreal peatland and implemented in the cold regions hydrological model. Empirically modelled resistance values (0–800 s m−1) did not match well with estimates from inverting observations and the Penman–Monteith (PM) algorithm (0–5000 s m−1). Difficulties in validating resistance values were possibly due to lack of moisture limiting conditions although this is seemingly contradicted by the alpha value being less than 1. Priestley–Taylor (PT) and PM algorithms in CRHM were used to estimate AET and compared with each other and with observations from an onsite eddy covariance (EC) system. The PT algorithm, using a site‐specific alpha value (0.75) performed the best with a mean difference of 9.4% (±12.0%) when compared to EC measurements of AET. The PM algorithm consistently overestimated EC measurements with a mean difference of 68.4% (±50.0%), even with a moss resistance incorporated into its use. The performance of PM algorithm is impeded by the uncertainty in quantifying Sphagnum resistance. Reducing this uncertainty should be a focus of future studies, as it does not require the use of a site‐specific alpha value.

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评估使用寒区水文模型建立泥炭地蒸散模型的彭曼-蒙蒂思算法和普利斯特里-泰勒算法的使用情况

用于量化以泥炭藓为主的泥炭地蒸散量（ET）的方法通常假定土壤水分不是限制因素；实际蒸散量（AET）等于潜在蒸散量（PET）。然而，泥炭地干燥时，土壤水分会成为限制因素，使实际蒸散发低于潜在蒸散发，因此在估算实际蒸散发时必须使用地表阻力项。对于非维管束植物表面（如以泥炭藓为主的表面）而言，量化和计算表面电阻是一项挑战。本文探讨并量化了驱动泥炭藓抵抗蒸散发的生态水文过程。假设北方泥炭地的泥炭藓阻力与非饱和与饱和导水率之比（K-ratio）之间存在关系，其中 K-ratio代表多孔介质的水物理特性。根据从北方泥炭地收集的数据，建立了泥炭藓阻力与 K 比率之间的经验关系，并将其应用于寒冷地区水文模型。根据经验模拟的阻力值（0-800 s m-1）与通过观测数据和彭曼-蒙蒂斯（PM）算法（0-5000 s m-1）反演得出的估算值不太吻合。CRHM 中的 Priestley-Taylor（PT）和 PM 算法被用来估算 AET，并与其他算法以及现场涡度协方差（EC）系统的观测结果进行了比较。使用特定站点α值（0.75）的 PT 算法性能最佳，与 EC 测量的 AET 相比，平均差异为 9.4% (±12.0%)。PM 算法始终高估了导电率测量值，平均差为 68.4%（±50.0%），即使在使用该算法时加入了苔藓阻力。PM 算法的性能受到泥炭藓抗性量化不确定性的影响。减少这种不确定性应该是未来研究的重点，因为它不需要使用特定地点的阿尔法值。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Ecohydrology 环境科学-生态学

CiteScore

5.10

自引率

7.70%

发文量

116

审稿时长

24 months

期刊介绍： Ecohydrology is an international journal publishing original scientific and review papers that aim to improve understanding of processes at the interface between ecology and hydrology and associated applications related to environmental management. Ecohydrology seeks to increase interdisciplinary insights by placing particular emphasis on interactions and associated feedbacks in both space and time between ecological systems and the hydrological cycle. Research contributions are solicited from disciplines focusing on the physical, ecological, biological, biogeochemical, geomorphological, drainage basin, mathematical and methodological aspects of ecohydrology. Research in both terrestrial and aquatic systems is of interest provided it explicitly links ecological systems and the hydrologic cycle; research such as aquatic ecological, channel engineering, or ecological or hydrological modelling is less appropriate for the journal unless it specifically addresses the criteria above. Manuscripts describing individual case studies are of interest in cases where broader insights are discussed beyond site- and species-specific results.