scholarly journals Responses of soil microarthropod taxon (Hexapoda: Protura) to natural disturbances and management practices in forest-dominated subalpine lake catchment areas

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Maria Sterzyńska ◽  
Julia Shrubovych ◽  
Karel Tajovský ◽  
Peter Čuchta ◽  
Josef Starý ◽  
...  
Keyword(s):  
Management Practices ◽  
Natural Disturbances ◽  
Subalpine Lake ◽  
Catchment Areas ◽  
Lake Catchment ◽  
Soil Microarthropod

scholarly journals Influence of basin connectivity on sediment source, transport, and storage within the Mkabela Basin, South Africa

2012 ◽  
Vol 9 (9) ◽  
pp. 10151-10204 ◽  
Author(s):  
J. R. Miller ◽  
G. Mackin ◽  
P. Lechler ◽  
M. Lord ◽  
S. Lorentz
Keyword(s):  
South Africa ◽  
Best Management Practices ◽  
Management Practices ◽  
Drainage System ◽  
Sediment Source ◽  
Riparian Wetlands ◽  
Valley Bottom ◽  
Sediment Size ◽  
Catchment Areas ◽  
And Storage

Abstract. The management of sediment and other non-point source (NPS) pollution has proven difficult, and requires a sound understanding of particle movement through the drainage system. The primary objective of this investigation was to obtain an understanding of NPS sediment source(s), transport, and storage within the Mkabela basin, a representative agricultural catchment within the KwaZulu-Natal Midlands of southeastern South Africa, by combining geomorphic, hydrologic and geochemical fingerprinting analyses. The Mkabela Basin can be subdivided into three distinct subcatchments that differ in their ability to transport and store sediment along the axial valley. Headwater (upper catchment) areas are characterized by extensive wetlands that act as significant sediment sinks. Mid-catchment areas, characterized by higher relief and valley gradients, exhibit few wetlands, but rather are dominated by a combination of alluvial and bedrock channels that are conducive to sediment transport. The lower catchment exhibits a low-gradient alluvial channel that is boarded by extensive riparian wetlands that accumulate large quantities of sediment (and NPS pollutants). Fingerprinting studies suggest that silt- and clay-rich layers found within wetland and reservoir deposits are derived from the erosion of fine-grained, valley bottom soils frequently utilized as vegetable fields. Coarser-grained deposits within both wetlands and reservoirs result from the erosion of sandier hillslope soils extensively utilized for sugar cane, during relatively high magnitude runoff events that are capable of transporting sand-sized sediment off the slopes. Thus, the source of sediment to the axial valley varies as a function of sediment size and runoff magnitude. Sediment export from the basin was limited until the early 1990s, in part because the upper catchment wetlands were hydrologically disconnected from lower parts of the watershed during low- to moderate flood events. The construction of a drainage ditch through a previously unchanneled wetland altered the hydrologic connectivity of the catchment, allowing sediment to be transported from the headwaters to the lower basin where much of it was deposited within the riparian wetlands. The axial drainage system is now geomorphically and hydrologically connected during most events throughout the study basin. The study indicates that increased valley connectivity partly negated the positive benefits of controlling sediment/nutrient exports from the catchment by means of upland based, best management practices.

scholarly journals Influence of basin connectivity on sediment source, transport, and storage within the Mkabela Basin, South Africa

2013 ◽  
Vol 17 (2) ◽  
pp. 761-781 ◽  
Author(s):  
J. R. Miller ◽  
G. Mackin ◽  
P. Lechler ◽  
M. Lord ◽  
S. Lorentz
Keyword(s):  
South Africa ◽  
Best Management Practices ◽  
Management Practices ◽  
Drainage System ◽  
Sediment Source ◽  
Riparian Wetlands ◽  
Valley Bottom ◽  
Sediment Size ◽  
Catchment Areas ◽  
And Storage

Abstract. The management of sediment and other non-point source (NPS) pollution has proven difficult, and requires a sound understanding of particle movement through the drainage system. The primary objective of this investigation was to obtain an understanding of NPS sediment source(s), transport, and storage within the Mkabela Basin, a representative agricultural catchment within the KwaZulu–Natal Midlands of eastern South Africa, by combining geomorphic, hydrologic and geochemical fingerprinting analyses. The Mkabela Basin can be subdivided into three distinct subcatchments that differ in their ability to transport and store sediment along the axial valley. Headwater (upper catchment) areas are characterized by extensive wetlands that act as significant sediment sinks. Mid-catchment areas, characterized by higher relief and valley gradients, exhibit few wetlands, but rather are dominated by a combination of alluvial and bedrock channels that are conducive to sediment transport. The lower catchment exhibits a low-gradient alluvial channel that is boarded by extensive riparian wetlands that accumulate large quantities of sediment (and NPS pollutants). Fingerprinting studies suggest that silt- and clay-rich layers found within wetland and reservoir deposits of the upper and upper-mid subcatchments are derived from the erosion of fine-grained, valley bottom soils frequently utilized as vegetable fields. Coarser-grained deposits within these wetlands and reservoirs result from the erosion of sandier hillslope soils extensively utilized for sugar cane, during relatively high magnitude runoff events that are capable of transporting sand-sized sediment off the slopes. Thus, the source of sediment to the axial valley varies as a function of sediment size and runoff magnitude. Sediment export from upper to lower catchment areas was limited until the early 1990s, in part because the upper catchment wetlands were hydrologically disconnected from lower parts of the watershed during low to moderate flood events. The construction of a drainage ditch through a previously unchanneled wetland altered the hydrologic connectivity of the catchment, allowing sediment to be transported from the headwaters to the lower basin where much of it was deposited within riparian wetlands. The axial drainage system is now geomorphically and hydrologically connected during events capable of overflowing dams located throughout the study basin. The study indicates that increased valley connectivity partly negated the positive benefits of controlling sediment/nutrient exports from the catchment by means of upland based, best management practices.

scholarly journals Combining sediment Cladocera remains and geochemistry to reveal the role of a large catchment in driving changes in a small subalpine lake (Lake Ledro, N-Italy)

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Manuela Milan ◽  
Richard Bindler ◽  
Monica Tolotti
Keyword(s):  
Body Size ◽  
Catchment Area ◽  
Ice Age ◽  
Lake Productivity ◽  
Cladocera Remains ◽  
Subalpine Lake ◽  
Catchment Areas ◽  
The 1960S ◽  
The Impact ◽  
Large Catchment

<p>Sediment Cladocera remains and geochemistry were analyzed at Lake Ledro, a small subalpine lake with a large catchment area located in northern Italy. The aim of the study was to investigate human, climate and hydrological impacts on the Cladocera community and on the geochemical components during the last few centuries. A sediment core was collected from the deepest point of Lake Ledro and radiometrically dated. Cladocera remains were analyzed to track the trophic lake evolution. The core bottom section revealed the dominance of Bosminidae in concomitance with nutrient pulses entering into the lake during major flood events. The abundance of species preferring cold water temperatures confirmed the deposition of this core section during the Little Ice Age. The flood event occurred in the first half of the 19<sup>th</sup> century produced a drastic increase in littoral species, due to the development of new habitats. The decrease in Cladocera densities during the following lake stage was followed by a rapid increase in planktonic species during the nutrient enrichment after the 1960s. Statistical analyses revealed a clear response of Cladocera community to climate variability during oligotrophic periods, while no relation to temperature changes was recorded during high nutrient levels. A preliminary study on Bosminidae and Daphnidae body size and appendages length was carried out to reconstruct major changes in the lake food web. Only <em>Bosminia</em> spp. revealed clear body size changes: minor shifts were recorded before the 1930s in relation to the low nutrient concentrations, while the major changes occurred during the 1980s were interpreted as related to the appearance of Cladocera invertebrate predators. Geochemical components were studied using X-ray fluorescence spectroscopy (XRF) analysis in order to recognize the impact of the large catchment area and from the lake-level regulations on the lake hydrology. Moreover the Si:Al ratios profile confirmed the increase in lake productivity after the 1960s. Although both Cladocera and geochemical analysis indicate major changes since the 1960s, they also revealed diverse responses to common external and local forcing, thus confirming the value of a multi-proxy approach for disentangling the lake responses to different environmental stressors. Moreover, it outlined the importance of larger catchment areas on small lakes as they are to a larger extent influenced by the modifications occurring in the drainage basin.</p>

National circumstances in the international circumboreal community

2007 ◽  
Vol 83 (4) ◽  
pp. 539-556 ◽  
Author(s):  
Michael A Wulder ◽  
Celina Campbell ◽  
Joanne C White ◽  
Mike Flannigan ◽  
Ian D Campbell
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Russian Federation ◽  
Boreal Forests ◽  
Management Practices ◽  
Forest Area ◽  
Private Ownership ◽  
Natural Disturbances ◽  
Climate History ◽  
Publicly Owned

Boreal forest nations are often thought to have similar environmental, social, and economic contexts. In this communication we show that boreal forest nations are a disparate grouping, with some similarities and many differences. Highlighting these differing national contexts provides insights into how a given nation utilizes the boreal forests over which it holds stewardship responsibilities. Current national contexts are related to each nation's physiography, climate, history, legacy of past forest management, the timing of transition from natural to plantation forests, population density and distribution, and access to resources and markets. Boreal forests are dominated by pioneer species that are resilient to disturbance and have a demonstrated ability to adapt to past climate changes. National responses to natural disturbances are linked to forest area, ownership, and management intensity. Boreal forests in large nations (e.g., Canada, Russian Federation) are typically publicly owned, and disturbances such as fire are allowed to progress naturally over remote areas. In smaller nations, where there is often a greater proportion of private ownership and a focus on production forestry, natural disturbances are more aggressively controlled (e.g., Sweden, Finland). Large nations with low boreal human population densities have a greater proportion of natural boreal forest, with relatively higher levels of biodiversity when compared to the fully managed forests of some smaller boreal nations. In smaller nations, the combination of limited forest area and private ownership has facilitated the dominance of intensive sustainable forestry management practices (e.g., Finland). Conversely, in nations with more spatially extensive forest assets that are publicly owned and managed to meet multiple objectives, extensive sustainable forest management practices dominate (e.g., Canada, Russian Federation). Key words: boreal forest, global, national circumstances, environmental, social, economic, forestry practices, Canada

scholarly journals A water balance approach for assessing the potential source of water in Dohuk Dam for agricultural, domestic and tourism purposes

Water Policy ◽  
2016 ◽  
Vol 19 (2) ◽  
pp. 322-340
Author(s):  
Mohamad Ali Fulazzaky ◽  
Arien Heryansyah ◽  
Maher Hussain Solaiman ◽  
Zulkifli Yusop
Keyword(s):  
Water Balance ◽  
Flow Rate ◽  
River Discharge ◽  
Management Practices ◽  
Maximum Flow ◽  
Water Transfer ◽  
Potential Source ◽  
Catchment Areas ◽  
Interbasin Water Transfer ◽  
Alternative Scenarios

Water balance approaches have been widely used to stimulate and forecast the average runoff and river discharge in small- and medium-sized basins. The analysis of water balance for Feesh Khabour River and Dohuk Dam catchment areas needs to be verified. This study used 24 alternative scenarios for assessing the robustness of adaptation decisions to water management practices. The discharge of Feesh Khabour River recorded at Zakho station, with a maximum flow rate of higher than 19.6 m cm d−1 and a minimum flow rate of 0.3 m cm d−1, helps ensure that interbasin water transfer remains one of the most attractive alternatives for increasing the amount of water available in the Dohuk Dam for agricultural, domestic and tourism uses.

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