SSF SUBSURFACE CONTROLS: Non-invasive identification and characterization of the subsurface structures and their control on SSF processes

水文相关土壤参数的空间异质性是全面理解SSF过程中的主要挑战之一。它从流动过程的最初想法开始，进而对流动和输运过程进行数值模拟，这是定量预测SSF所必需的。这种异质性不仅涉及参数值在几个数量级上的可变性，而且还涉及组织严密的模式。该项目解决了目前在将地下结构的实验识别与其数值参数化联系起来方面的局限性，这是更大尺度数值模式所需的。中心假设是，非均质的、但组织严密的地下结构在理解SSF中起着关键作用。这一假设反映在以下研究问题中：(1)试验点的地质土壤学背景是什么？(2)土壤的小尺度非均质性和相关模式对SSF的发生起到了什么作用？(3)土壤的小尺度非均质性可以在多大程度上用非侵入性方法绘制？(4)我们能否有效地将关于局部土壤非均质性的信息推广到流域尺度，以改进流域尺度的径流过程预测？该项目结合了实验、理论和数值工作。虽然经典的土壤制图将是起点，但重点将放在非侵入性地球物理方法的地下勘探上。将应用几种方法(特别是电阻率层析成像、电磁感应法和探地雷达)。测量将包括对所有实验点的静态探索和延时测量，以发现优先流型。作为最后一步，将制定一个能够解释这种多源信息的业务框架，并以新兴的理论概念为支撑，将物理参数扩大到集水范围更大的领域。

The spatial heterogeneity of the hydrologically relevant soil parameters is one of the major challenges on the way towards a comprehensive understanding of SSF. It starts from the first ideas on the flow processes and proceeds to the numerical simulation of the flow and transport processes which are finally needed for a quantitative prediction of SSF. This heterogeneity involves not only a variability of the parameter values over several orders of magnitude, but also strongly organized patterns.The project addresses the current limitations in linking the experimental identification of subsurface structures to their numerical parameterization as required by numerical models working at larger scales. The central hypothesis is that the heterogeneous, but strongly organized subsurface structures play a key role in understanding SSF. This hypothesis is reflected in the following research questions:(1) What is the geo-pedological setting of the experimental sites? (2) Which role do the small-scale heterogeneity and the related patterns of the soil play for the occurrence of SSF? (3) To what extent can the small-scale heterogeneity of the soil be mapped using non-invasive methods?(4) Can we effectively generalize the information about the local soil heterogeneity to the catchment scale towards an improved catchment-scale prediction of the runoff processes?The project combines experimental, theoretical and numerical work. While classical soil mapping will be the starting point, focus will be on subsurface exploration by non-invasive geophysical methods. Several methods (in particular, electrical resistivity tomography, electromagnetic induction methods, and ground-penetrating radar) will be applied. The measurements will involve both static explorations of all experimental sites and time-lapse measurements in order to detect preferential flow patterns. As a final step, an operational framework capable of accounting for such multi-source information will be developed, supported by emerging theoretical concepts for up-scaling the physical parameters to the catchment-larger domain.