Rainfall interception - Localization of water storage and evapotranspiration in forests

降雨截留 - 森林储水和蒸散的局部化

• 批准号: 324915082
• 负责人: Professor Dr. Christian Bernhofer
• 金额: --
• 依托单位: Professur für Meteorologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/324915082?language=en
• 关键词: Rainfall; interception; Localization; water; storage

Interception of precipitation has a significant influence on the availability of water in ecosystems. Especially in forest ecosystems evaporates up to 50 % of precipitation via interception which is not available to plants. The process is highly variable and is not yet described by models satisfactorily. Statistical methods for the determination of model parameters, and conceptual approaches describing the processes incompletely, produce significant uncertainty in the quantification of interception. In particular the statistical parameterization and the weak consideration of the structure and properties of vegetation stands prevent the transfer of experimental findings to other sites. However, this is mandatory to account for effects of changing rainfall patterns and land use on the future water budget.The aim of the proposed project is the considerable reduction of uncertainties in interception assessment and modelling by investigation and parameterization of the small spatial variability of the process. It is known that rain events with low intensity are intercepted by the outer layers of forest stands which are characterized by strong atmospheric coupling and effective evaporation. In comparison, rain events with high intensity exceed the storage capacity and also produce wet layers, which dry very slowly. This nonlinear behavior is still not sufficiently included in interception models due to a limited consideration of the vegetation structure. In the project, the mechanisms of water storage and interception within the canopy shall be examined on the basis of detailed measurements (micrometeorological, hydrological and via laser scanning), and new approaches will be developed and tested which parameterize the dependencies with regard to vegetation structure. Standard interception estimates of forests are based on throughfall collected through spatially distributed precipitation gauges or large troughs and on model results without taking the three-dimensional spatial heterogeneity of the stands into account adequately. The resulting error in the parameters and model outcome has not been investigated and quantified yet. The new modeling approach with high spatiotemporal resolution will allow the assignment of the simulation results to individual throughfall collectors, as well as the comparison with micrometeorological measurements of evapotranspiration. The required detailed vegetation model is provided from terrestrial laser scanning. Therefore, the simulation of the interception process will be conducted with a spatial-temporal resolution of 1 m³ and 1 min in a range of 600 m × 600 m around a well suited Fluxnet tower, which provides a unique set of almost 20 years of micrometeorological and hydrological measurements. By this combination of experiments and modelling it is expected to generate a step-change in understanding of interception.

降水截留对生态系统中水的有效性有重要影响。特别是在森林生态系统中，高达50%的降水是通过截留蒸发的，这是植物所不能获得的。这个过程是高度多变的，目前还没有得到令人满意的模型描述。确定模型参数的统计方法和不完全描述过程的概念性方法在截获的量化方面产生了很大的不确定性。特别是，统计参数和对植被林分结构和性质的考虑薄弱，妨碍了将实验结果转移到其他地点。然而，考虑到降雨模式和土地用途的变化对未来水收支的影响，这是强制性的。拟议项目的目标是通过调查和对过程的微小空间变异性进行参数化，大大减少截流评估和建模中的不确定性。众所周知，低强度的降雨事件被具有强大气耦合和有效蒸发特征的林分外层截留。相比之下，高强度的降雨超过了存储能力，也会产生湿层，干燥速度非常慢。由于对植被结构的考虑有限，这种非线性行为在截留模型中仍然没有得到充分的考虑。在该项目中，将在详细测量(微气象、水文和激光扫描)的基础上研究树冠内的蓄水和截水机制，并将开发和测试新的方法，将与植被结构的相关性参数化。森林的标准截留量估计是基于通过空间分布的雨量计或大雨槽收集的穿透雨量和模型结果，而没有充分考虑到林分的三维空间异质性。由此产生的参数和模型结果的误差还没有被调查和量化。这种具有高时空分辨率的新模拟方法将允许将模拟结果分配给各个穿透雨收集器，并与蒸散量的微气象测量进行比较。所需的详细植被模型由陆地激光扫描提供。因此，拦截过程的模拟将在一个非常合适的FLUXNET塔周围的600 m×600 m的范围内以1 m³1分钟的时空分辨率进行，该塔提供了一套独特的近20年的微气象和水文测量。通过这种实验和模型的结合，预计将在对拦截的理解上产生阶段性的变化。