Role of underground fissure flow in near-surface rainfall-runoff process on a rock mantled slope in the karst rocky desertification area

Karst regions are widely distributed in Southwest China and due to the complexity of their geologic structure, it is very challenging to collect data useful to provide a better understanding of surface, underground and fissure flows, needed to calibrate and validate numerical models. Without characterizing these features, it is very problematic to fully establish rainfall–runoff processes associated with soil loss in karst landscapes. Water infiltrated rapidly to the underground in rocky desertification areas. To fill this gap, this experimental work was completed to preliminarily determine the output characteristics of subsurface and underground fissure flows and their relationships with rainfall intensities (30 mm h−1, 60 mm h−1 and 90 mm h−1) and bedrock degrees (30%, 40% and 50%), as well as the role of underground fissure flow in the near-surface rainfall–runoff process. Results indicated that under light rainfall conditions (30 mm h−1), the hydrological processes observed were typical of Dunne overland flows; however, under moderate (60 mm h−1) and high rainfall conditions (90 mm h−1), hydrological processes were typical of Horton overland flows. Furthermore, results confirmed that the generation of underground runoff for moderate rocky desertification (MRD) and severe rocky desertification (SRD) happened 18.18% and 45.45% later than the timing recorded for the light rocky desertification (LRD) scenario. Additionally, results established that the maximum rate of underground runoff increased with the increase of bedrock degrees and the amount of cumulative underground runoff measured under different rocky desertification was SRD > MRD > LRD. In terms of flow characterization, for the LRD configuration under light rainfall intensity the underground runoff was mainly associated with soil water, which was accounting for about 85%–95%. However, under moderate and high rainfall intensities, the underground flow was mainly generated from fissure flow.

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Forest in Karst Mountain Sinkhole of Southeastern China Provides Refugium for the Preservation of Bryophyte Diversity

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.8944 ◽

2020 ◽

Vol 89 (4) ◽

Author(s):

Xiaofang Li ◽

Zhaohui Zhang ◽

Zhihui Wang ◽

Kuangzheng Shi

Keyword(s):

Diversity Index ◽

Soil Parameters ◽

Available Phosphorus ◽

Forest Species ◽

Key Factors ◽

Karst Rocky Desertification ◽

Southeastern China ◽

Rocky Desertification ◽

Total Potassium

The negative landform of sinkholes provides belowground level refugia for a high diversity of forest species compared to the forests on the surface of surrounding karst plateaus in southeastern China. Bryophyte diversity in sinkhole forests is also likely to be high. In this study, bryophytes of an underground forest sinkhole (UFS), and two forests (Forest Karst Mountain 1; FKM1) and (Forest Karst Mountain 2; FKM2) on the surface of the karst plateau were compared to understand the role of the sinkhole forest in the conservation of bryophyte diversity and the relationships between bryophyte diversity, environmental factors, and soil nutrients. Significantly more bryophyte taxa were recorded from the sinkhole forest (71 taxa, 36 genera, 23 families) than those in the forest on the plateau surface, which was the closest to the sinkhole (FKM1; 29 bryophyte taxa, 16 genera, 12 families), and even fewer bryophytes were found in the forest more distant to the sinkhole (FKM2; 22 taxa, 17 genera, eight families). Twenty-four liverwort taxa were collected from the sinkhole forest, two from the closest surface forest (FKM1) and none from the furthest surface forest (FKM2). Ninety-three percent of the bryophytes in karst mountain sinkhole were not found on surface forest. The diversity index trend was as follows: UFS > FKM1 > FKM2, and the evenness index trend was in the opposite direction as follows: UFS < FKM1 < FKM2. The beta diversity showed that the Jaccard index among the three forests was 0–0.25, reflecting a huge difference between the sinkhole forest and the two surface forests. Canonical correspondence analysis showed that light was the most important factor affecting the distribution of bryophytes in the sinkhole forest, while temperature and humidity were key factors for the distribution of bryophytes in the two surface forests. Further, soil parameters, namely, soil organic carbon, total nitrogen, total phosphorus, total potassium, alkali-hydrolyzed nitrogen, and available phosphorus changed gradually from UFS to FKM1 and to FKM2. The sinkhole forest, located in a landform with the unique negative topography enclosed by cliffs, and with a complex microenvironment, provides a natural refuge for bryophyte species in areas where forests have been negatively impacted by karst rocky desertification.

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Structural variability in the bulk soil, rhizosphere, and root endophyte fungal communities of Themeda japonica plants under different grades of karst rocky desertification

Plant and Soil ◽

10.1007/s11104-021-04969-y ◽

2021 ◽

Author(s):

Ming Tang ◽

Jie Liu ◽

Wenpeng Hou ◽

Reed M. Stubbendieck ◽

Han Xiong ◽

...

Keyword(s):

Fungal Communities ◽

Bulk Soil ◽

Karst Rocky Desertification ◽

Rocky Desertification ◽

Root Endophyte ◽

Structural Variability ◽

Soil Rhizosphere

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Applications of Energy Beams in Material and Device Processing

MRS Proceedings ◽

10.1557/proc-23-25 ◽

1983 ◽

Vol 23 ◽

Author(s):

G.J. Galvin ◽

L.S. Hung ◽

J.W. Mayer ◽

M. Nastasi

Keyword(s):

Ion Beam ◽

High Energy ◽

Ion Beams ◽

Traditional Role ◽

Near Surface ◽

Device Processing ◽

Composition Modification ◽

Directed Energy ◽

Transistor Fabrication

ABSTRACTEnergetic ion beams used outside the traditional role of ion implantation are considered for semiconductor applications involving interface modification for self-aligned silicide contacts, composition modification for formation of buried oxide layers in Si on insulator structures and reduced disorder in high energy ion beam annealing for buried collectors in transistor fabrication. In metals, aside from their use in modification of the composition of near surface regions, energetic ion beams are being investigated for structural modification in crystalline to amorphous transitions. Pulsed beams of photons and electrons are used as directed energy sources in rapid solidification. Here, we consider the role of temperature gradients and impurities in epitaxial growth of silicon.

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A warm jet in a cold ocean

Nature Communications ◽

10.1038/s41467-021-22505-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jennifer A. MacKinnon ◽

Harper L. Simmons ◽

John Hargrove ◽

Jim Thomson ◽

Thomas Peacock ◽

...

Keyword(s):

The Arctic ◽

Bering Strait ◽

Near Surface ◽

Ice Melt ◽

Beaufort Gyre ◽

The Pacific ◽

Climate Simulations ◽

Initial Evolution ◽

Forecast Models

AbstractUnprecedented quantities of heat are entering the Pacific sector of the Arctic Ocean through Bering Strait, particularly during summer months. Though some heat is lost to the atmosphere during autumn cooling, a significant fraction of the incoming warm, salty water subducts (dives beneath) below a cooler fresher layer of near-surface water, subsequently extending hundreds of kilometers into the Beaufort Gyre. Upward turbulent mixing of these sub-surface pockets of heat is likely accelerating sea ice melt in the region. This Pacific-origin water brings both heat and unique biogeochemical properties, contributing to a changing Arctic ecosystem. However, our ability to understand or forecast the role of this incoming water mass has been hampered by lack of understanding of the physical processes controlling subduction and evolution of this this warm water. Crucially, the processes seen here occur at small horizontal scales not resolved by regional forecast models or climate simulations; new parameterizations must be developed that accurately represent the physics. Here we present novel high resolution observations showing the detailed process of subduction and initial evolution of warm Pacific-origin water in the southern Beaufort Gyre.

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Hillslope Contribution to the Clark Instantaneous Unit Hydrograph: Application to the Seolmacheon Basin, Korea

Water ◽

10.3390/w13121707 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1707

Author(s):

Chulsang Yoo ◽

Huy Phuong Doan ◽

Changhyun Jun ◽

Wooyoung Na

Keyword(s):

Peak Flow ◽

Peak Time ◽

Rainfall Runoff ◽

Maximum Rainfall ◽

Rainfall Events ◽

Storage Coefficient ◽

Channel Velocity ◽

Linear Reservoir ◽

Mountainous Basin

In this study, the time–area curve of an ellipse is analytically derived by considering flow velocities within both channel and hillslope. The Clark IUH is also derived analytically by solving the continuity equation with the input of the derived time–area curve to the linear reservoir. The derived Clark IUH is then evaluated by application to the Seolmacheon basin, a small mountainous basin in Korea. The findings in this study are summarized as follows. (1) The time–area curve of a basin can more realistically be derived by considering both the channel and hillslope velocities. The role of the hillslope velocity can also be easily confirmed by analyzing the derived time–area curve. (2) The analytically derived Clark IUH shows the relative roles of the hillslope velocity and the storage coefficient. Under the condition that the channel velocity remains unchanged, the hillslope velocity controls the runoff peak flow and the concentration time. On the other hand, the effect of the storage coefficient can be found in the runoff peak flow and peak time, as well as in the falling limb of the runoff hydrograph. These findings are also confirmed in the analysis of rainfall–runoff events of the Seolmacheon basin. (3) The effect of the hillslope velocity varies considerably depending on the rainfall events, which is also found to be mostly dependent upon the maximum rainfall intensity.

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