School of Water Resources and Hydropower Engineering, North China Electric Power University, Beijing, 102206, China; State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, 210029, China.
National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural, Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.
Environ Res. 2022 Nov;214(Pt 4):113976. doi: 10.1016/j.envres.2022.113976. Epub 2022 Aug 20.
Vegetation patterns play an important role in precipitation partitioning into hydrological components, especially evapotranspiration and runoff. However, few studies focus on their competitive relationship and the influence of the vegetation on them. In this study, a vegetation threshold was postulated to prevent further decrease of runoff by determining a new hydrological component continuing evapotranspiration (partitioned from total and initial evapotranspiration) through a novel model coupled with the Budyko model (dimensional form) and two-stage partitioning model (nondimensional form) in the semi-arid watershed. The results showed significant correlations between model parameters ε (underlying surface index), λ (ratio of initial evapotranspiration) and vegetation coverage (M) (R = 0.95 and 0.97, p < 0.01) b Based on the modified Budyko model and λ. The nondimensional model showed high-precise estimations of K (Horton index Fraction), K (Baseflow Fraction), K (evapotranspiration Fraction), K (runoff Fraction), and K (continuing evapotranspiration Fraction) (R > 0.98, p < 0.01) as a function of a new aridity index φ. K, K, K, K, showed symmetrical patterns correlated with φ both at between-subwatershed and between-year scale based on the dimensional model and λ. However, K showed asymmetrical different correlation with M and φ (K/M ∼ φ: in between-subwatershed: R = 0.92, p < 0.01; and between-year scale: R = 0.74, p < 0.01). Based on the solution of continuing evapotranspiration, the vegetation threshold has been solved with M = 0.73 (+0.09/-0.02) to prevent further decreasing runoff. The framework presented can be applied in other semi-arid watersheds worldwide to better protect the sustainability of the hydro-ecosystems.
植被格局在将降水分配为水文分量（特别是蒸散发和径流量）方面起着重要作用。然而，很少有研究关注它们的竞争关系以及植被对它们的影响。本研究提出了植被阈值的概念，以通过耦合新模型与布地模型（维度形式）和两阶段分配模型（无量纲形式），在半干旱流域中防止径流量进一步减少，该模型通过确定一个新的水文分量（通过总蒸散发和初始蒸散发的划分）来防止进一步的径流量减少。结果表明，模型参数 ε（下垫面指数）、λ（初始蒸散发比）和植被覆盖率 M 之间存在显著相关性（R=0.95 和 0.97，p<0.01）。基于改进的布地模型和 λ。无量纲模型对 K（霍顿指数分数）、K（基流分数）、K（蒸散发分数）、K（径流量分数）和 K（持续蒸散发分数）的高精度估算（R>0.98，p<0.01）作为新干旱指数 φ 的函数。基于维度模型和 λ，K、K、K、K 表现出与 φ 对称的相关模式，无论是在子流域之间还是在年际之间。然而，K 与 M 和 φ 之间的相关性不对称（K/M∼φ：在子流域之间：R=0.92，p<0.01；在年际尺度上：R=0.74，p<0.01）。基于持续蒸散发的解，解决了植被阈值，当 M=0.73（+0.09/-0.02）时，可以防止径流量进一步减少。本研究提出的框架可应用于世界其他半干旱流域，以更好地保护水生态系统的可持续性。
