{"title":"The coupling effects of grass and shrub with biological crust on the overland flow hydrodynamic characteristics","authors":"","doi":"10.1016/j.catena.2024.108281","DOIUrl":null,"url":null,"abstract":"<div><p>Biological crust (BSC) is a common kind of ground cover that affects overland flow together with vegetation. It is important to understand the hydrodynamic mechanism of slope covered by both vegetation and BSC to clarify the water erosion dynamics. However, the coupling effects of vegetation and BSC on overland flow characteristics are still unclear. In this study, simulated rainfall was employed to explore the effects of different combinations of grasses, shrubs and BSC on the hydrodynamic characteristics of flow. The results showed that grasses, shrubs, BSC and vegetation combinations significantly reduced the flow velocity. Compared with the control check (CK), the flow velocities of the more BSC (MBSC), grass cover (GC) and shrub cover (SC) treatments were reduced by 50 %, 32 % and 14 %, respectively. The detention coefficient of different treatments increased with increasing BSC coverage. This result indicated that BSC played a dominant role in slowing the flow velocity under low-cover vegetation. The Froude number (<em>Fr</em>) of CK, GC, SC, and SC+GC were > 1 during rainfall, indicating supercritical flow. The average <em>Fr</em> of the other treatments was < 1, but <em>Fr</em> > 1 was found in the less BSC (LBSC) and SC+LBSC treatments. The total flow resistance under different vegetation combinations did not conform to the simple linear stacking relationship. The interaction effect between different covers generated additional resistance, which varied among different ground cover combinations. The relationship between resistance coefficient (<em>f</em>) and Reynolds number (<em>Re</em>) gradually changed from a negative correlation for bare slopes to a positive correlation when vegetation or BSC existed, indicating that form resistance played a dominant role. It was concluded that BSC had a dominant effect on the hydraulic characteristics of overland flow in all ground cover treatments. This research provides a theoretical basis for the mechanism of erosion dynamics on slopes with combined vegetation and BSC.</p></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":null,"pages":null},"PeriodicalIF":5.4000,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Catena","FirstCategoryId":"97","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0341816224004788","RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Biological crust (BSC) is a common kind of ground cover that affects overland flow together with vegetation. It is important to understand the hydrodynamic mechanism of slope covered by both vegetation and BSC to clarify the water erosion dynamics. However, the coupling effects of vegetation and BSC on overland flow characteristics are still unclear. In this study, simulated rainfall was employed to explore the effects of different combinations of grasses, shrubs and BSC on the hydrodynamic characteristics of flow. The results showed that grasses, shrubs, BSC and vegetation combinations significantly reduced the flow velocity. Compared with the control check (CK), the flow velocities of the more BSC (MBSC), grass cover (GC) and shrub cover (SC) treatments were reduced by 50 %, 32 % and 14 %, respectively. The detention coefficient of different treatments increased with increasing BSC coverage. This result indicated that BSC played a dominant role in slowing the flow velocity under low-cover vegetation. The Froude number (Fr) of CK, GC, SC, and SC+GC were > 1 during rainfall, indicating supercritical flow. The average Fr of the other treatments was < 1, but Fr > 1 was found in the less BSC (LBSC) and SC+LBSC treatments. The total flow resistance under different vegetation combinations did not conform to the simple linear stacking relationship. The interaction effect between different covers generated additional resistance, which varied among different ground cover combinations. The relationship between resistance coefficient (f) and Reynolds number (Re) gradually changed from a negative correlation for bare slopes to a positive correlation when vegetation or BSC existed, indicating that form resistance played a dominant role. It was concluded that BSC had a dominant effect on the hydraulic characteristics of overland flow in all ground cover treatments. This research provides a theoretical basis for the mechanism of erosion dynamics on slopes with combined vegetation and BSC.
期刊介绍：
Catena publishes papers describing original field and laboratory investigations and reviews on geoecology and landscape evolution with emphasis on interdisciplinary aspects of soil science, hydrology and geomorphology. It aims to disseminate new knowledge and foster better understanding of the physical environment, of evolutionary sequences that have resulted in past and current landscapes, and of the natural processes that are likely to determine the fate of our terrestrial environment.
Papers within any one of the above topics are welcome provided they are of sufficiently wide interest and relevance.
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