Sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open-channel
In the semiarid environment, low vegetation cover and deforestation on the banks of rivers represent a strong impact on the flow resistance process, altering the interaction of the flow with the banks, one of the conditioning factors of the morphological balance of the river channel. In extreme hydr...
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| Format: | Article |
| Language: | English |
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Elsevier
2021-06-01
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| Series: | Ecological Indicators |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1470160X21001370 |
| _version_ | 1819130131360251904 |
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| author | Douglas Monteiro Cavalcante Maria Tatiane Leonardo Chaves Gabriella Moreira Campos José Ramon Barros Cantalice Genival Barros Junior |
| author_facet | Douglas Monteiro Cavalcante Maria Tatiane Leonardo Chaves Gabriella Moreira Campos José Ramon Barros Cantalice Genival Barros Junior |
| author_sort | Douglas Monteiro Cavalcante |
| collection | DOAJ |
| description | In the semiarid environment, low vegetation cover and deforestation on the banks of rivers represent a strong impact on the flow resistance process, altering the interaction of the flow with the banks, one of the conditioning factors of the morphological balance of the river channel. In extreme hydrological events, turbulence and high speeds can cause a marked erosion process at the banks, increasing the sediment yield. This study aimed to monitor water and solid discharges through direct hydrosedimentometric measurements, as well as to estimate, using a simplified model based on force balance, the hydraulic roughness coefficients generated by flexible vegetation element of the Ipomoea pes-caprae species under emergent and submerged conditions. The total annual rainfall for 2019 was 748.5 mm year−1, above the historical mean (642.80 mm year−1). The mean depth (h = 0.24 m) and flow (Ql = 0.15 m3 s−1) rates were highly correlated as a power function (R2 = 0.8041). In general, without specifically considering the effect of vegetation, the flow regime was characterized as turbulent and subcritical flow (Re = 66,634.65 dim. and Fr = 0.16 dim.), respectively. The suspended sediment concentration (CSS), suspended sediment (QSS) and bedload (QBed) discharges presented mean values of 409.41 mg L−1, 6.23 t day−1 and 0.069 t day−1, respectively. The total sediment yield (Yt) was 1.90 t km−2 year−1. The vegetation effect was analyzed on the right (RB) and left (LB) banks, where the stems of I. pes-caprae were concentrated between 0.22 and 0.40 m and 0.66–1.20 m from the banks, respectively. On the RB, the shear (1.0 < Sr < 1.95), free flow (0.27 < Sr < 1.0) and the transition (Sr = 1) zones were identified. On the LB, just emergent condition (Sr < 1.0) was indetified. The following relationship were found between vegetation drag coefficient (C′D), stem Reynolds number (Red), plant density Reynolds number (Rev) and Froude number (Fr) on the RB: C′D (1.22–12.46 m−1); Red (567 < Red < 2224), Rev (1305 < Rev < 35,011) and Fr = 0.14; on the LB: C′D (2.10–1168.29 m−1); Red (57 < Red < 1427), Rev (2615 < Rev < 167,534) and Fr = 0.08. These results demonstrate that the aquatic vegetation directly influences the river dynamics; the density vegetation having a hydraulic impact on the flow transport capacity, that is, as the C′D increases, it increases the resistance of the vegetation to the flow and decreases the capacity of transport of sediments. |
| first_indexed | 2024-12-22T08:54:44Z |
| format | Article |
| id | doaj.art-34c683f119ad4cbb874176384f21d0cd |
| institution | Directory Open Access Journal |
| issn | 1470-160X |
| language | English |
| last_indexed | 2024-12-22T08:54:44Z |
| publishDate | 2021-06-01 |
| publisher | Elsevier |
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| series | Ecological Indicators |
| spelling | doaj.art-34c683f119ad4cbb874176384f21d0cd2022-12-21T18:31:53ZengElsevierEcological Indicators1470-160X2021-06-01125107472Sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open-channelDouglas Monteiro Cavalcante0Maria Tatiane Leonardo Chaves1Gabriella Moreira Campos2José Ramon Barros Cantalice3Genival Barros Junior4Rural Technology Department, Environmental Engineering Graduate Program, Federal Rural of Pernambuco University, Dom Manuel Medeiros avenue, N/A, 52171-900 Recife, PE, Brazil; Environmental Engineering Graduate Program, UFRPE, PNPD/CAPES Brazilian Program, Dom Manuel Medeiros Street, N/A, 52171-900 Recife, PE, Brazil; Corresponding author at: Environmental Engineering Graduate Program, Federal Rural of Pernambuco University, Dom Manoel de Medeiros Street, 52171-900 – Recife/PE, Brazil.Rural Technology Department, Environmental Engineering Graduate Program, Federal Rural of Pernambuco University, Dom Manuel Medeiros avenue, N/A, 52171-900 Recife, PE, BrazilRural Technology Department, Environmental Engineering Graduate Program, Federal Rural of Pernambuco University, Dom Manuel Medeiros avenue, N/A, 52171-900 Recife, PE, BrazilRural Technology Department, Environmental Engineering Graduate Program, Federal Rural of Pernambuco University, Dom Manuel Medeiros avenue, N/A, 52171-900 Recife, PE, BrazilRural Technology Department, Environmental Engineering Graduate Program, Federal Rural of Pernambuco University, Dom Manuel Medeiros avenue, N/A, 52171-900 Recife, PE, BrazilIn the semiarid environment, low vegetation cover and deforestation on the banks of rivers represent a strong impact on the flow resistance process, altering the interaction of the flow with the banks, one of the conditioning factors of the morphological balance of the river channel. In extreme hydrological events, turbulence and high speeds can cause a marked erosion process at the banks, increasing the sediment yield. This study aimed to monitor water and solid discharges through direct hydrosedimentometric measurements, as well as to estimate, using a simplified model based on force balance, the hydraulic roughness coefficients generated by flexible vegetation element of the Ipomoea pes-caprae species under emergent and submerged conditions. The total annual rainfall for 2019 was 748.5 mm year−1, above the historical mean (642.80 mm year−1). The mean depth (h = 0.24 m) and flow (Ql = 0.15 m3 s−1) rates were highly correlated as a power function (R2 = 0.8041). In general, without specifically considering the effect of vegetation, the flow regime was characterized as turbulent and subcritical flow (Re = 66,634.65 dim. and Fr = 0.16 dim.), respectively. The suspended sediment concentration (CSS), suspended sediment (QSS) and bedload (QBed) discharges presented mean values of 409.41 mg L−1, 6.23 t day−1 and 0.069 t day−1, respectively. The total sediment yield (Yt) was 1.90 t km−2 year−1. The vegetation effect was analyzed on the right (RB) and left (LB) banks, where the stems of I. pes-caprae were concentrated between 0.22 and 0.40 m and 0.66–1.20 m from the banks, respectively. On the RB, the shear (1.0 < Sr < 1.95), free flow (0.27 < Sr < 1.0) and the transition (Sr = 1) zones were identified. On the LB, just emergent condition (Sr < 1.0) was indetified. The following relationship were found between vegetation drag coefficient (C′D), stem Reynolds number (Red), plant density Reynolds number (Rev) and Froude number (Fr) on the RB: C′D (1.22–12.46 m−1); Red (567 < Red < 2224), Rev (1305 < Rev < 35,011) and Fr = 0.14; on the LB: C′D (2.10–1168.29 m−1); Red (57 < Red < 1427), Rev (2615 < Rev < 167,534) and Fr = 0.08. These results demonstrate that the aquatic vegetation directly influences the river dynamics; the density vegetation having a hydraulic impact on the flow transport capacity, that is, as the C′D increases, it increases the resistance of the vegetation to the flow and decreases the capacity of transport of sediments.http://www.sciencedirect.com/science/article/pii/S1470160X21001370Submerged vegetationEmergent vegetationForce balanceVegetation drag coefficientReynolds number |
| spellingShingle | Douglas Monteiro Cavalcante Maria Tatiane Leonardo Chaves Gabriella Moreira Campos José Ramon Barros Cantalice Genival Barros Junior Sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open-channel Ecological Indicators Submerged vegetation Emergent vegetation Force balance Vegetation drag coefficient Reynolds number |
| title | Sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open-channel |
| title_full | Sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open-channel |
| title_fullStr | Sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open-channel |
| title_full_unstemmed | Sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open-channel |
| title_short | Sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open-channel |
| title_sort | sediment transport and roughness coefficients generated by flexible vegetation patches in the emergent and submerged conditions in a semiarid alluvial open channel |
| topic | Submerged vegetation Emergent vegetation Force balance Vegetation drag coefficient Reynolds number |
| url | http://www.sciencedirect.com/science/article/pii/S1470160X21001370 |
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