Runoff Response to Soil Moisture and Micro-topographic Structure on the Plot Scale

Abstract

Structural hydrological connectivity has been proposed to describe the geological structure of the landscape as well as to explain hydrological behaviors. Indices based on the topological or soil condition were developed to interpret their relationships. While previous studies mainly focused on well-instrumented catchments which are narrow in humidity or temperate zone, the hydrological responses to structural connectivity at the plot and hill slope scale as well as in arid or semi-arid climate conditions remain unclear. This study was conducted in the semi-arid mountainous region of northern China in Haihe Basin which is the source of water of about 350 million people. Experiments were conducted during the rainy season in 2012 and 2013 using four runoff plots. Two indices, flow path length (FL) based on topography and integral connectivity scale length (ICSL) based on soil moisture conditions, developed to represent hydrological connectivity structure and the runoff response to rainfall were analyzed. The results showed that the surface runoff coefficient was strongly and positively linearly correlated to FL, and the correlation between subsurface flow and ICSLs was quadratic. Plots with shorter FL required more rainfall to generate surface runoff. In the shallow soil layer, when the ICSLs are relatively low, the soil can store more water and less rainfall feeds subsurface runoff. Further analysis indicated that improved shallow soil connectivity conditions might enhance the water-holding capacity and lead to lower water yields for each event. This study demonstrated that hydrological structure connectivity could explain the mechanism of runoff generation in semi-arid areas while further experiments should be undertaken to find the threshold-like relationship between FL and surface runoff as well as the influence of plant cover on hydrological behaviors.

A novel framework to study the effect of tree architectural traits on stemflow yield and its consequences for soil-water dynamics

“…Ponding could have also been fostered by the hydrophobicity of soil organic matter (Spencer and van Meerveld, 2016), or a higher proportion of silt at the soil surface (unpublished data; Lu and Likos, 2004). The low soil moisture content that we observed, likely reduced the extent of stemflow-derived surface runoff (Liu et al, 2019), that was only noted next to the tree stems (Fig. 2b).…”

Structure from motion photogrammetry in ecology: Does the choice of software matter?

“…However, the differences might not be of practical significance. While centimeter differences are often important for change monitoring (Forsmoo et al, ; Lucieer et al, ) and when modeling processes such as surface runoff based on topographic variability (Mügler et al, ; Thompson, Katul, & Porporato, ), where small differences can lead to important cumulative biases (Liu et al, ; Lucieer et al, ), it is important to acknowledge that for some, if not many, purposes measurement uncertainties at the centimeter magnitude are neglectable. In fact, we would argue that these fine‐grain uncertainties highlight exactly why a user would choose drones over aerial or satellite imagery for change detection.…”

Effect of Hydrological Connectivity on Soil Carbon Storage in the Yellow River Delta Wetlands of China

“…Sedimentation and fork control the fractal dimension of delta river network, which is about 1.2-1.3 (Edmonds et al, 2011). More complicated forked rivers could have more loops, leading to higher hydrology connectivity (Liu et al, 2019). Besides, tidal plays an important role in deltas.…”

“…Studies have shown that the essence of wetlands growth and decline is the destruction of the hydrological cycle with human activities and climate change (Dou et al, 2016;Ala-aho et al, 2018;Higley and Conroy, 2019). The concept of hydrological connectivity has been proposed and evaluated worldwide to describe the process of the hydrological cycle and the relationship between the hydrological and ecological processes (Bracken et al, 2013;Harvey et al, 2019;Liu et al, 2019). The hydrological connectivity refers to the process of transporting water-mediated mass, energy and organisms within or between elements of the hydrolo-gical cycle (Kaller et al, 2015;Thorslund et al, 2018;Conte and Ferro, 2020).…”

“…At present, there are many studies on the mechanism and application of the hydrological connectivity around the world (Covino, 2017;Singh and Sinha, 2019). Attention has been given to the evaluation method, spatialtemporal scale assessment, application in habitat restoration and management (Thorslund et al, 2018;Liu et al, 2019). The research on mechanism between hydrological connectivity and the biochemical cycle is on early stage, and the relationship between hydrological connectivity and carbon storage is still unclear (Cui et al, 2016a;Zhang et al, 2019).…”