scholarly journals The role of biocrust-induced exopolymeric matrix in runoff generation in arid and semiarid zones – a mini review

2021 ◽  
Vol 69 (4) ◽  
pp. 360-368
Author(s):  
Giora J. Kidron
Keyword(s):  
Green Algae ◽  
Extracellular Polymeric Substances ◽  
Overland Flow ◽  
Runoff Generation ◽  
Semiarid Regions ◽  
Current Review ◽  
Infiltration Excess ◽  
Arid And Semiarid

Abstract Although playing an important role in shaping the environment, the mechanisms responsible for runoff initiation and yield in arid and semiarid regions are not yet fully explored. With infiltration-excess overland flow, known also as Hortonian overland flow (HOF) taking place in these areas, the uppermost surface ‘skin’ plays a cardinal role in runoff initiation and yield. Over large areas, this skin is composed of biocrusts, a variety of autotrophs (principally cyanobacteria, green algae, lichens, mosses) accompanied by heterotrophs (such as fungi, bacteria, archaea), which may largely dictate the infiltration capability of the surface. With most biocrust organisms being capable of excreting extracellular polymeric substances (EPS or exopolymers), and growing evidence pointing to the capability of certain EPS to partially seal the surface, EPS may play a cardinal role in hindering infiltration and triggering HOF. Yet, despite this logic thread, great controversy still exists regarding the main mechanisms responsible for runoff generation (runoff initiation and yield). Elucidation of the possible role played by EPS in runoff generation is the focus of the current review.

scholarly journals Response of the parameters of excess infiltration and excess storage model to land use cover change

2020 ◽  
Vol 68 (2) ◽  
pp. 99-110 ◽  
Author(s):  
Yuexiu Wen ◽  
Caihong Hu ◽  
Guodong Zhang ◽  
Shengqi Jian
Keyword(s):  
Land Use ◽  
Overland Flow ◽  
Yellow River ◽  
The Yellow River ◽  
Model Parameters ◽  
Runoff Generation ◽  
The Loess Plateau ◽  
Infiltration Capacity ◽  
Infiltration Excess ◽  
Generation Mechanisms

AbstractThe Loess Plateau is the main source of water in Yellow River, China. After 1980s, the Yellow river water presented a significant reduction, what caused the decrease of the Yellow river discharge had been debated in academic circles. We proceeded with runoff generation mechanisms to explain this phenomenon. We built saturation excess runoff and infiltration excess runoff generation mechanisms for rainfall–runoff simulation in Jingle sub-basin of Fen River basin on the Loess Plateau, to reveal the influence of land use change on flood processes and studied the changes of model parameters under different underlying conditions. The results showed that the runoff generation mechanism was mainly infiltration-excess overland flow, but the flood events of saturation-excess overland flow had an increasing trend because of land use cover change (the increase of forestland and grassland areas and the reduction of cultivated land). Some of the model parameters had physical significances，such as water storage capacity (WM), infiltration capacity (f), evapotranspiration (CKE), soil permeability coefficient (k) and index of storage capacity distribution curve (n) showed increasing trends, and index of infiltration capacity distribution curve (m) showed a decreasing trend. The above results proved the changes of runoff generation mechanism from the perspective of model parameters in Jingle sub-basin, which can provide a new perspective for understanding the discharge reduction in the Yellow River basin.

The role of run-on for overland flow and the characteristics of runoff generation in the Loess Plateau, China

2012 ◽  
Vol 57 (6) ◽  
pp. 1107-1117 ◽  
Author(s):  
Dengfeng Liu ◽  
Fuqiang Tian ◽  
Hongchang Hu ◽  
Heping Hu
Keyword(s):  
Loess Plateau ◽  
Overland Flow ◽  
Runoff Generation ◽  
The Loess Plateau

scholarly journals The Role of Urban Planning and Landscape Tools Concerning Flash Flood Risk Reduction Within Arid and Semiarid Regions

2021 ◽  
pp. 283-316
Author(s):  
Karim I. Abdrabo ◽  
Sameh A. Kantosh ◽  
Mohamed Saber ◽  
Tetsuya Sumi ◽  
Dina Elleithy ◽  
...  
Keyword(s):  
Urban Planning ◽  
Risk Reduction ◽  
Land Use Planning ◽  
Flood Risk ◽  
Urban Areas ◽  
Mitigation Measures ◽  
Semiarid Regions ◽  
Flood Risk Reduction ◽  
Arid And Semiarid

AbstractThis chapter highlights some substantial questions inquired by researchers to comprehend the flood risks (FRs) that occur in their cities as follows: (1) What is the impact of flooding on urban areas? (2) what effect does urbanization have on FR? (3) What are the existing nonstructural and structural mitigation measures for urban flooding? and (4) What is the role of urban planning and landscape tools in flood risk reduction (FRR) for cities as well as their inhabitants? The main messages in this chapter could be summarized as follows: (1) Comprehension of both the sources and types of flooding is vital if proper FRR measures are to be determined, (2) Unplanned urban growth could seriously put lives and properties at high risk (3) Land use planning and regulation, and Sustainable infrastructure for stormwater management through landscape architecture are fundamental measures for future FRR (4) The application of the urban planning approach for FRR in arid and semiarid regions has not yet received adequate attention and facing many challenges for its implementation, and finally (5) the combination of structural and nonstructural mitigation measures in spatial planning could be much more effective than using one type of measure alone.

scholarly journals The dominant runoff processes on grassland versus bare soil hillslopes in a temperate environment - An experimental study

2019 ◽  
Vol 67 (4) ◽  
pp. 297-304 ◽  
Author(s):  
Gabriel Minea ◽  
Gabriela Ioana-Toroimac ◽  
Gabriela Moroşanu
Keyword(s):  
Overland Flow ◽  
Bare Soil ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Rainfall Events ◽  
Natural Rainfall ◽  
Antecedent Precipitation ◽  
Temperate Environment ◽  
The Relationship

Abstract This paper aimed to investigate the dominant runoff processes (DRP’s) at plot-scale in the Curvature Subcarpathians under natural rainfall conditions characteristic for Romania’s temperate environment. The study was based on 32 selected rainfall-runoff events produced during the interval April–September (2014–2017). By comparing water balance on the analyzed Luvisol plots for two types of land use (grassland vs. bare soil), we showed that DRP’s are mostly formed by Hortonian Overland Flow (HOF), 47% vs. 59% respectively. On grassland, HOF is followed by Deep Percolation (DP, 31%) and Fast Subsurface Flow (SSF, 22%), whereas, on bare soil, DP shows a higher percentage (38%) and SSF a lower one (3%), which suggests that the soil-root interface controls the runoff generation. Concerning the relationship between antecedent precipitation and runoff, the study indicated the nonlinearity of the two processes, more obvious on grassland and in drought conditions than on bare soil and in wet conditions (as demonstrated by the higher runoff coefficients). Moreover, the HOF appeared to respond differently to rainfall events on the two plots - slightly longer lag-time, lower discharge and lower volume on grassland - which suggests the hydrologic key role of vegetation in runoff generation processes.

scholarly journals Hillslope-scale experiment demonstrates the role of convergence during two-step saturation

2014 ◽  
Vol 18 (9) ◽  
pp. 3681-3692 ◽  
Author(s):  
A. I. Gevaert ◽  
A. J. Teuling ◽  
R. Uijlenhoet ◽  
S. B. DeLong ◽  
T. E. Huxman ◽  
...  
Keyword(s):  
Land Surface ◽  
Overland Flow ◽  
Subsurface Flow ◽  
Water Dynamics ◽  
Natural Environments ◽  
Wetting Front ◽  
Runoff Generation ◽  
Hillslope Scale ◽  
Saturation Excess

Abstract. Subsurface flow and storage dynamics at hillslope scale are difficult to ascertain, often in part due to a lack of sufficient high-resolution measurements and an incomplete understanding of boundary conditions, soil properties, and other environmental aspects. A continuous and extreme rainfall experiment on an artificial hillslope at Biosphere 2's Landscape Evolution Observatory (LEO) resulted in saturation excess overland flow and gully erosion in the convergent hillslope area. An array of 496 soil moisture sensors revealed a two-step saturation process. First, the downward movement of the wetting front brought soils to a relatively constant but still unsaturated moisture content. Second, soils were brought to saturated conditions from below in response to rising water tables. Convergent areas responded faster than upslope areas, due to contributions from lateral subsurface flow driven by the topography of the bottom boundary, which is comparable to impermeable bedrock in natural environments. This led to the formation of a groundwater ridge in the convergent area, triggering saturation excess runoff generation. This unique experiment demonstrates, at very high spatial and temporal resolution, the role of convergence on subsurface storage and flow dynamics. The results bring into question the representation of saturation excess overland flow in conceptual rainfall-runoff models and land-surface models, since flow is gravity-driven in many of these models and upper layers cannot become saturated from below. The results also provide a baseline to study the role of the co-evolution of ecological and hydrological processes in determining landscape water dynamics during future experiments in LEO.

scholarly journals Hydrological heterogeneity in Mediterranean reclaimed slopes: runoff and sediment yield at the patch and slope scales along a gradient of overland flow

2011 ◽  
Vol 8 (6) ◽  
pp. 9927-9959
Author(s):  
L. Merino-Martín ◽  
M. Moreno-de las Heras ◽  
S. Pérez-Domingo ◽  
T. Espigares ◽  
J. M. Nicolau
Keyword(s):  
Overland Flow ◽  
Field Research ◽  
Bare Soil ◽  
Thymus Vulgaris ◽  
Runoff Generation ◽  
Community Types ◽  
Vegetation Patches ◽  
Overland Flow Routing ◽  
Continental Climate

Abstract. Hydrological heterogeneity is recognized as a fundamental ecosystem attribute in drylands controlling the flux of water and energy through landscapes. Therefore, mosaics of runoff and sediment sinks and source patches are frequently identified in these dry environments. There is a remarkable scarcity of studies about hydrological spatial heterogeneity in restored slopes, where ecological succession and overland flow are interacting. We conducted a field research to study the hydrological role of patches and slopes along an overland flow gradient in three reclaimed slopes coming from mining reclamation in a Mediterranean-continental climate. We found that runoff generation and routing in non-rilled slopes showed a pattern of source and sink areas of runoff. Such hydrological microenvironments were associated to seven vegetation patches (characterized by plant community types and cover). Two types of sink patches were identified: shrub Genista scorpius patches could be considered as a "deep sink", while patches where the graminoids Brachypodium retusum and Lolium perenne dominate were classified as "surface sinks" or "runoff splays". A variety of source patches were also identified spanning from "extreme sources" (Medicago sativa patches; equivalent to bare soil) to "poor sources" (areas scattered by dwarf-shrubs of Thymus vulgaris or herbaceous tussocks of Dactylis glomerata). Finally, we identified the volume of overland flow routing along the slope as a controlling major factor of hydrological diversity: when overland flow increases at the slope scale hydrological diversity diminishes.

scholarly journals Hillslope experiment demonstrates role of convergence during two-step saturation

2014 ◽  
Vol 11 (2) ◽  
pp. 2211-2232 ◽  
Author(s):  
A. I. Gevaert ◽  
A. J. Teuling ◽  
R. Uijlenhoet ◽  
P. A. Troch
Keyword(s):  
Land Surface ◽  
Overland Flow ◽  
Wetting Front ◽  
Runoff Generation ◽  
Biosphere 2 ◽  
Soil Moisture Sensors ◽  
Water Tables ◽  
Gravity Driven ◽  
Saturation Excess

Abstract. A continuous and intense rainfall experiment on an artificial hillslope at the Landscape Evolution Observatory in Biosphere 2 resulted in saturation excess overland flow and gully erosion in the convergent hillslope area. An array of 496 soil moisture sensors revealed a two-step saturation process. First, the downward movement of the wetting front brought soils to a relatively constant but still unsaturated moisture content. Second, soils were brought to saturated conditions from below in response to rising water tables. Convergent areas responded faster than upslope areas, due to contributions from lateral subsurface flow. This led to the formation of a groundwater ridge in the convergent area, triggering saturation excess runoff generation. This unique experiment demonstrates, at very high spatial and temporal resolution, the role of convergence on subsurface storage and flow dynamics. The results bring into question the representation of saturation excess overland flow in conceptual rainfall-runoff models and land-surface models, since flow is gravity-driven in many of these models and upper layers cannot become saturated from below.

Sign in / Sign up

Export Citation Format

Share Document