Hydrological connectivity and its controls on hillslope and catchment scale stream flow generation

拟议的项目在1598 CAOS的DFG研究组第一阶段内继续项目G的工作。观察和理解流域内的连通性（包括其空间变异性和组织以及时间动态）是推进水文理解的中心主题之一，可用于预测降雨径流响应、溶质和物质运输以及水量和质量的流内变异性。在这个项目中，我们将重点关注山坡、河岸带和水系网络之间的功能连通性，这是结构（静态）连通性的空间格局如何转化为水、沉积物和溶质的通量和输出的结果。特别是，我们将推进对表面和地下过程中扩散与通道连接的相关性和作用的理解，以及可能的反馈机制。为了观察、理解和预测从河段尺度到中尺度流域的这些不同的功能连通性，我们将开发和应用一系列新的观察和建模技术，在适当的尺度和必要的重复下测量功能连通性，以得出统计上合理的结论。除了第一期（项目G）的46个集落地点和超过20个嵌套集水区内的流量测量地点的宝贵现有设施外，我们建议安装100个定时照相机和饱和度传感器，以跟踪山坡对水系网络的地表贡献，以及水系网络本身的扩张和收缩。将在从河流到山坡样带的嵌套焦点区域观察地下连通性，基于对河流内采样和地球物理观测的快照调查，在近河流和山坡测压网中进行连续测量，并在山坡样带进行选定的示踪实验。最后，河流温度信号将通过遍布阿特尔盆地的密集温度记录仪网络进行监测，将用作山坡-河流连通性的指标和连续混合的示踪剂，但也将作为热平衡和热传输建模的独特数据集，这被认为是单纯的水流建模的重要对应。该项目将对流域过程水文和建模以及CAOS研究单位做出重要贡献，因为对山坡-溪流连通性的系统评估对于将当地尺度动态和径流生成与整体流域响应联系起来至关重要。这种对连通性、其时间动态、空间模式和潜在控制的系统评估将有助于我们对水流和运输的景观组织的理解，并有可能大大改善区域化工作。

The proposed project continues the work of project G within the first phase of the DFG Research Group FOR 1598 CAOS.Observing and understanding connectivity within a catchment (including its spatial variability and organization as well as its temporal dynamics) is one of the central themes in advancing hydrological understanding for predicting rainfall-runoff response, solute and matter transport and in-stream variability of water quantity and quality. In this project, we will focus on functional connectivity between hillslopes, riparian zones and the stream network, which is the result of how spatial patterns of structural (static) connectivity translate into fluxes and export of water, sediment and solutes. In particular, we will advance the understanding of the relevance and role of diffuse vs channelled connectivity for surface and subsurface processes and possible feedback mechanisms. In order to observe, understand and predict these different functional connectivities from the reach scale to the meso-scale watershed, we will develop and apply a range of novel observation and modelling techniques to measure functional connectivity at its appropriate scale and at the necessary repetition to draw statistically sound conclusions. In addition to the invaluable existing installations from phase I (project G) of 46 cluster sites and over 20 streamflow gauging sites within a nested catchment arrangement, we propose to install 100 time-lapse cameras and saturation sensors to track the surface contributions from hillslopes to the stream network as well as the expansion and contraction of the stream network itself. Subsurface connectivity will be observed at nested focus areas from the stream to a hillslope transect, based on snap-shot surveys of in-stream sampling and geophysical observation, continuous measurement in near-stream and hillslope piezometer networks and selected tracer experiments at hillslope transects. Finally, stream temperature signals, which will be monitored with a dense network of temperature loggers across the Attert basin, will be used as indicators of hillslope-stream connectivity and as tracers for consecutive mixing, but will also serve as a unique dataset for heat balance and heat transport modelling which is deemed to be an essential counterpart to the mere modelling of water flows. This project will make an important contribution to catchment process hydrology and modelling and hence to the CAOS research unit, as a systematic assessment of hillslope-stream connectivity is paramount to linking local scale dynamics and runoff generation to overall catchment response. This systematic assessment of connectivity, its temporal dynamics, spatial patterns and the underlying controls will thus add to our understanding of landscape organization of water flow and transport, with the potential to improve regionalisation efforts considerably.