scholarly journals Gully controlling practices associated with soil geotechnical properties in the subhumid Ethiopian highlands

2021 ◽  
Vol 8 (3) ◽  
pp. 2719-2729
Author(s):  
Meseret Belachew Addisie ◽  
Hailu Menale WAS
Keyword(s):  
Rainy Season ◽  
Clay Content ◽  
Bank Erosion ◽  
Gully Erosion ◽  
Soil Erodibility ◽  
Longitudinal Gradient ◽  
Check Dams ◽  
The Status ◽  
In The Beginning ◽  
Business As Usual

Check dams are business as usual practices used to avert gully erosion development and sedimentation in the downstream areas of the humid highlands of Ethiopia. We investigated the status of check dams and their relationship with geotechnical soil properties in the sub-humid Fogera floodplain. The density of gullies in the area was more sever having about 3.6 km km-2 which shows the severity of gully erosion. Thirty-two dams constructed and monitored over one rainy season. In the beginning of the rainy season, all the dams filled up with sediments, and at the end of the monitoring period ninety five percent of them had destroyed and the remainings had partially destroyed and had sediments accumulated on one side of the gully bank. The longitudinal gradient of streams above the dams decreased due to sedimentation. The morphological change of the gully showed an increase in width-depth ratio, gully bank erosion, and sediment aggradation in the gully bed. We found that the amount of sediments deposited behind the dams were higher than the amount of eroded material. The higher clay content and Atterberg limits increased soil erodibility once the gully channel formed. The erodibility and saturation in these soils were highly contributing to gully development and reducing the effectiveness of check dams. In conclusion, it is better to adopt an integrated novel practice to control gullying than solely using check dams.

The Humdrum Use of Ultimate Authority: Defining and Analysing Chapter VII Resolutions

2009 ◽  
Vol 78 (3) ◽  
pp. 309-342 ◽  
Author(s):  
Patrik Johansson
Keyword(s):  
Cold War ◽  
United Nations ◽  
Security Council ◽  
Security Council Resolution ◽  
Post Cold War ◽  
Standard Definition ◽  
The Status ◽  
Definition Of ◽  
The Cold War ◽  
Business As Usual

AbstractUnder Chapter VII of the Charter of the United Nations, the Security Council has the unique authority to make decisions that are binding on member states. However, the lack of a standard definition of what makes a Security Council resolution "a Chapter VII resolution" has caused disagreement regarding the status of several resolutions. This is unfortunate as the international community should never have to doubt whether a Security Council resolution is in fact adopted under Chapter VII or not. It is also unnecessary. This article addresses this problem by proposing a definition of Chapter VII resolutions, based on two criteria referred to as "Article 39 determinations" and "Chapter VII decisions". On the basis of the proposed definition, the article describes and analyses a dramatic increase in the use of Chapter VII during the post-Cold War era. It concludes that as Chapter VII has come to constitute the majority of Security Council resolutions in recent years, the resort to Chapter VII no longer signifies exceptional determination and resolve, which it did during the Cold War; instead Chapter VII today implies business as usual. An appendix lists all Chapter VII resolutions from 1946–2008.

scholarly journals Physically-based modelling of hydrological processes in a tropical headwater catchment (West Africa) – process representation and multi-criteria validation

2006 ◽  
Vol 10 (6) ◽  
pp. 829-847 ◽  
Author(s):  
S. Giertz ◽  
B. Diekkrüger ◽  
G. Steup
Keyword(s):  
Soil Moisture ◽  
Rainy Season ◽  
Overland Flow ◽  
Soil Layer ◽  
Hydrological Processes ◽  
Runoff Generation ◽  
Field Investigations ◽  
Physically Based ◽  
In The Beginning ◽  
Headwater Catchment

Abstract. The aim of the study was to test the applicability of a physically-based model to simulate the hydrological processes in a headwater catchment in Benin. Field investigations in the catchment have shown that lateral processes such as surface runoff and interflow are most important. Therefore, the 1-D SVAT-model SIMULAT was modified to a semi-distributed hillslope version (SIMULAT-H). Based on a good database, the model was evaluated in a multi-criteria validation using discharge, discharge components and soil moisture data. For the validation of discharge, good results were achieved for dry and wet years. The main differences were observable in the beginning of the rainy season. A comparison of the discharge components determined by hydro-chemical measurements with the simulation revealed that the model simulated the ratio of groundwater fluxes and fast runoff components correctly. For the validation of the discharge components of single events, larger differences were observable, which was partly caused by uncertainties in the precipitation data. The representation of the soil moisture dynamics by the model was good for the top soil layer. For deeper soil horizons, which are characterized by higher gravel content, the differences between simulated and measured soil moisture were larger. A good agreement of simulation results and field investigations was achieved for the runoff generation processes. Interflow is the predominant process on the upper and the middle slopes, while at the bottom of the hillslope groundwater recharge and – during the rainy season – saturated overland flow are important processes.

scholarly journals A small rainfall simulator for the determination of soil erodibility.

1987 ◽  
Vol 35 (3) ◽  
pp. 407-415 ◽  
Author(s):  
A. Kamphorst
Keyword(s):  
Organic Matter ◽  
Soil Conservation ◽  
Standard Procedure ◽  
Organic Matter Content ◽  
Clay Content ◽  
Matter Content ◽  
Soil Erodibility ◽  
Rainfall Simulator ◽  
Highly Sensitive

A small rainfall simulator is described, which can be used in the field as well as in the laboratory for the determination of infiltration and erosion characterisitcs of soils. It is particularly suitable for soil conservation surveys, as it is light to carry and easy to handle in the field. A description is given of a standard procedure for the determination of topsoil erodibilities in the field and some results are presented. The method appears to be highly sensitive to soil properties influencing soil erodibility, such as clay content, organic matter content and soil pH. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Spatio-temporal dynamics of erosion and deposition in a partially restored valley-bottom gully

2021 ◽  
Author(s):  
Alberto Alfonso-Torreño ◽  
Álvaro Gómez-Gutiérrez ◽  
Susanne Schnabel
Keyword(s):  
Temporal Dynamics ◽  
Land Use Changes ◽  
Degradation Process ◽  
Gully Erosion ◽  
Aerial Images ◽  
Negative Consequences ◽  
Valley Bottom ◽  
Erosion And Deposition ◽  
Check Dams ◽  
Spatio Temporal

<p>Soil erosion by water is a frequent soil degradation process in rangelands of SW Spain. The two main erosive processes in these areas are sheetwash erosion in hillslopes and gully erosion due to concentrated flow in valley bottoms. Land use changes and overgrazing play a key role in the genesis and development of gullies and gully erosion is a frequent process with negative consequences at the valley bottoms of these landscapes.</p><p>The development of new techniques allows monitoring of gully dynamics with an increase at spatial and temporal resolutions. Here we present a detailed study of a valley-bottom gully in a Mediterranean rangeland with a savannah-like vegetation cover that was partially restored in February 2017. Restoration activities included check dams (gabion weirs and fascines) and livestock exclosure by fencing. The objectives of this study were: (1) to analyze the effectiveness of the restoration measures, (2) to study erosion and deposition dynamics before and after the restoration activities, (3) to examine the role of micro-morphology on the observed topographic changes and (4) to compare the current and recent channel dynamics with previous studies conducted in the same study area through different methods and spatio-temporal scales, quantifying medium-term changes. Topographic changes were estimated using multi-temporal high-resolution DEMs produced using Structure-from-Motion (SfM) photogrammetry and aerial images acquired by a fixed-wing Unmanned Aerial Vehicle (UAV). DEMs and orthophotographs with a Ground Sampling Distance of 0.02 m were produced by means of SfM photogrammetric techniques. The average Root Mean Square Error (RMSE) estimated during the SfM processing was 0.03 m.</p><p>The performance of the restoration activities was satisfactory to control gully erosion. Check dams were effective favoring sediment deposition and reducing lateral bank erosion. Nevertheless, erosion was observed immediately downstream in 9% of the check dams. Livestock exclosure in the most degraded area promoted the stabilization of bank headcuts and revegetation. The sediments retained behind check dams reduced the longitudinal slope gradient of the channel bed and established a positive feedback mechanism for channel revegetation.</p><p><strong>Keywords</strong>: gully erosion, restoration, topographic change, UAV+SfM, rangeland.</p>

scholarly journals Population biology of Trichomycterus sp. (Siluriformes, Trichomycteridae) in Passa Cinco stream, Corumbataí River sub-basin, São Paulo State, southeastern Brazil

2009 ◽  
Vol 69 (3) ◽  
pp. 925-934 ◽  
Author(s):  
GR. Rondineli ◽  
AL. Carmassi ◽  
FMS. Braga
Keyword(s):  
Rainy Season ◽  
Population Biology ◽  
Stomach Contents ◽  
Sampling Period ◽  
Southeastern Brazil ◽  
Longitudinal Gradient ◽  
Temporal Dimension ◽  
Paulo State ◽  
Males And Females ◽  
Electric Fishing

The aim of this work was to characterise the population of Trichomycterus sp. in Passa Cinco stream, regarding length structure, sex ratio, diet and reproductive aspects, in accordance with drought and rainy season periods and longitudinal gradient, as well as to analyse its corporal condition in a temporal dimension. Six samplings were accomplished with the use of electric fishing equipment in three different sites in Passa Cinco stream, contemplating sites of order two, three and four, during the months of May, July, September and November of 2005; and January and March of 2006. Three hundred and forty one individuals were captured, composed of 203 males, 99 females and 39 immatures. The smallest captured individual, an immature, presented 28 mm of standard length and the largest, a male, 85 mm. There was not significant variation in repletion degree and accumulated fat in the visceral cavity of the individuals analysed during the considered periods. Eleven different food items were found in the stomach contents. Considering the whole sampling period, immature Diptera was a preferential item and other items were found as occasionally ingested. Spearman and Friedman tests did not find significant differences in the diet of Trichomycterus sp. in the periods and sampling sites, respectively. The average of absolute fecundity was of 73 oocytes, and the parceled type of spawning was performed. Both males and females of Trichomycterus sp. presented significant differences in their corporal conditions in the considered periods, and in the rainy season, these fishes were in better condition.

scholarly journals Rewetting strategies to reduce nitrous oxide emissions from European peatlands

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Haojie Liu ◽  
Nicole Wrage-Mönnig ◽  
Bernd Lennartz
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Bulk Density ◽  
Peat Soil ◽  
Soil Bulk Density ◽  
Nitrous Oxide Emissions ◽  
The Status ◽  
Suggested Strategy ◽  
Peatland Rewetting ◽  
Business As Usual

Abstract Nitrous oxide (N2O) is approximately 265 times more potent than carbon dioxide (CO2) in atmospheric warming. Degraded peatlands are important sources of N2O. The more a peat soil is degraded, the higher the N2O-N emissions from peat. In this study, soil bulk density was used as a proxy for peat degradation to predict N2O-N emissions. Here we report that the annual N2O-N emissions from European managed peatlands (EU-28) sum up to approximately 145 Gg N year−1. From the viewpoint of greenhouse gas emissions, highly degraded agriculturally used peatlands should be rewetted first to optimally reduce cumulative N2O-N emissions. Compared to a business-as-usual scenario (no peatland rewetting), rewetting of all drained European peatlands until 2050 using the suggested strategy reduces the cumulative N2O-N emissions by 70%. In conclusion, the status of peat degradation should be made a pivotal criterion in prioritising peatlands for restoration.

scholarly journals Diversity and habitat preference of aquatic insects along the longitudinal gradient of the Macaé River basin, Rio de Janeiro, Brazil

2001 ◽  
Vol 61 (2) ◽  
pp. 249-258 ◽  
Author(s):  
D. F. BAPTISTA ◽  
D. F. BUSS ◽  
L. F. M. DORVILLÉ ◽  
J. L. NESSIMIAN
Keyword(s):  
River Basin ◽  
Aquatic Insects ◽  
Habitat Preference ◽  
Rainy Season ◽  
Rio De Janeiro ◽  
Dry Season ◽  
Longitudinal Gradient ◽  
Order Stream ◽  
Surber Sampler ◽  
Janeiro State

Diversity and habitat preference of macroinvertebrates were studied in Macaé River basin, Rio de Janeiro State, Brazil, along its longitudinal gradient. We selected stream reaches corresponding to 1st, 2nd, 4th, 5th and 6th orders. A Surber sampler was used to collect four macroinvertebrates samples of each substrate (sand, litter in pool areas, stones, and litter in riffle areas) during the three sampling periods, defined based on the rain regime: April (end of the rainy season), July (dry season), and October (beginning of the rainy season). We identified 46,431 specimens corresponding to 117 taxa. Analysis of diversity numbers (both for family or genus level) indicated that all insect taxonomic orders had higher numbers on 2nd order stream reach, except for Ephemeroptera, on 4th order. However when considering morph-species taxonomic level, the higher diversity number occurred on 4th order stream. The highest richness and diversity numbers were found at the dry season. Considering habitat preference, both litter in pool areas and litter in riffle areas had the highest faunal richness.

scholarly journals Further studies on bluetongue and bluetongue-related Orbiviruses in the Sudan

1990 ◽  
Vol 105 (3) ◽  
pp. 619-632 ◽  
Author(s):  
M. E. H. Mohammed ◽  
P. S. Mellor
Keyword(s):  
Rainy Season ◽  
Bluetongue Virus ◽  
Population Densities ◽  
Seasonal Incidence ◽  
Central Sudan ◽  
Culicoides Imicola ◽  
The Status ◽  
Haemorrhagic Disease ◽  
First Time ◽  
Virus Isolates

SUMMARYThe seasonal incidence of bluetongue virus (BTV) in Central Sudan is related primarily to fluctuations in the prevalence of the vector, Culicoides imicola. Population densities of this midge begin to rise with the onset of precipitation and peak during October, before falling sharply at the end of the rainy season in November. These are also the months of BTV transmission. Populations of C. schultzei, the commonest midge in Central Sudan, are also related to the rainy season but this species does not seem to be involved with BTV transmission.BTV serotype 2 was isolated from C. imicola confirming the status of this midge as a known vector but a second isolate of the same serotype was made from a mixed pool of Culicoides not including C. imicola. This suggests that BTV transmission in the Sudan may involve more than one species of Culicoides. Epizootic haemorrhagic disease virus (EHDV) serotype 4 and a palyam virus were isolated from C. schultzei which indicates that this species may be involved in the transmission of BT-related viruses. Seven further virus isolates from sentinel calves at Shambat (Khartoum) confirmed the presence of BTV serotypes 1, 4 and 16, and an untyped EHDV (designated 318) in the Sudan. All of the viruses isolated and identified during the course of this work are recorded from the Sudan for the first time.

scholarly journals The Effect of a Period of Aquatic Therapy Exercise on the Quality of Life and Depression in Aged Males Suffering from Chronic Physical Pains

2015 ◽  
Vol 56 ◽  
pp. 127-137
Author(s):  
Y. Khanjari ◽  
R. Garooei
Keyword(s):  
Quality Of Life ◽  
Mental Condition ◽  
Control Group ◽  
Aquatic Therapy ◽  
The Status ◽  
Physical Diseases ◽  
Different Dimensions ◽  
In The Beginning ◽  
And Control

Aging is a stage of life that increases the risk of physical diseases, some of which are chronic and can affect different dimensions of life’s quality and the status of psychological factors in these patients. In addition to medical supports, it is essential to provide sport complexes in accordance with the physical and mental condition of these patients. The aim of this study was to evaluate the effect of a period of aquatic therapy exercise on the quality of life and depression in aged males suffering from chronic physical pains.In a semi-experimental study, 30 aged males who voluntarily referred to Niyayesh health center of Shiraz were selected. They were randomly divided in to two groups; experimental (n=15) and control (n=15). Subjects of aquatic therapy exercise were involved in an 8-week-activity in water; 3 sessions per week each lasting approximately 50 to 70 minutes. At the same time, the control group was only followed-up and was not engaged in any exercise during this period. The variables of the quality of life and depression among the patients were measured by standard questionnaires in the beginning and end of the eight-week-aquatic therapy exercise. Results of this study showed that aquatic therapy exercise can be used as an effective and helpful method to promote public health in aged males suffering from chronic physical pains because it leads to the improvement of multi-dimensional variables of quality of life and depression in the patients.

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