CHANGES OF FLOOD-FORMING FEATURES OF NORTH-WEST CAUCASUS BASINS IN 2000–2014

The rivers of the North West Caucasus are characterized by a flood runoff regime. Floods leading to material damage occur on the rivers of the region every year. However, in the XXI century. the development of both automatic monitoring systems and the capabilities of mathematical modeling of hydrological processes make it possible to fill this gap. After the flood of 2012, a network of automatic level gauges is developing in the region, recording water levels every 10 minutes. Analysis of the accumulated archive of observations allows us to determine the features of the formation and passage of floods on the rivers of the region. Among the features of catchments that determine the transformation of precipitation into runoff in the catchment, vegetation and soil cover are distinguished. When it rains in a multi-layer forest, each layer is sequentially moistened from top to bottom. After the vegetation has been moistened, the precipitated water reaches the soil surface and some of it infiltrates into deeper soil horizons up to the waterproof layers, where it replenishes the groundwater lenses. The vegetation cover of the North West Caucasus in the foothill part is represented mainly by plowed steppes with ravine forests, and in the mountainous part – almost entirely by forests. From west to east of the region, mainly oak forests give way to beech and hornbeam forests with a higher water retention. High forest cover and widespread in the region gray, brown forest and soddy-calcareous soils have a water-holding capacity sufficient to absorb intense precipitation. A large proportion of anthropogenic landscapes in the western part of the region causes a lower capacity for absorbing precipitation and, accordingly, a greater flood hazard. Further decrease in forest cover and development of the region will increase the flood hazard.

Download Full-text

An updated water balance for the Grootfontein aquifer near Mahikeng

Water SA ◽

10.4314/wsa.v44i1.07 ◽

2018 ◽

Vol 44 (1 January) ◽

Author(s):

JE Cobbing

Keyword(s):

Water Balance ◽

Public Interest ◽

Water Levels ◽

Domestic Water ◽

Groundwater Levels ◽

North West ◽

The Public ◽

The North ◽

Increasing Risk ◽

Natural Spring

The Grootfontein Aquifer, part of the important North West dolomite aquifers, supplies about 20% of Mahikeng’s domestic water needs. Over-abstraction caused the large natural spring draining the aquifer to disappear in 1981, and groundwater levels have since fallen nearly 30 m in the vicinity of the former spring. Analysis of water levels and a water balance using recent assessments of groundwater abstractions confirm past work describing the hydrogeological functioning of the aquifer, and suggest that current abstractions need to fall by between 19 and 36 ML/day (7 and 13 Mm3/a) to bring the aquifer back into longterm balance. Continued over-abstraction at Grootfontein implies increasing risk to Mahikeng’s water supply, and illuminates the larger challenge of ensuring groundwater use in the North West dolomites that is sustainable and in the public interest.

Download Full-text

Effects of summer irrigation and trampling in dairy pastures on soil physical properties and earthworm number and species composition

Australian Journal of Agricultural Research ◽

10.1071/a94132 ◽

1997 ◽

Vol 48 (7) ◽

pp. 1059 ◽

Cited By ~ 16

Author(s):

Lisa A. Lobry de Bruyn ◽

T. J. Kingston

Keyword(s):

Soil Surface ◽

Sampling Period ◽

Study Data ◽

Lumbricus Rubellus ◽

Research Station ◽

Pasture Production ◽

North West ◽

The North ◽

Main Plot ◽

On Farm

In 1989 a replicated split-plot trial on a Krasnozem soil was established at Elliott Research Station (ERS) in the north-west of Tasmania, as well as 14 on-farm trials in newly irrigated pastures on 3 different soil types (Alluvial, Podzolic, Krasnozem) in the dairy districts of Scottsdale, Smithton, and Deloraine. There were 3 main treatments at ERS: irrigated before grazing, irrigated after grazing, and grazed and not irrigated. Part of each main plot was fenced to prevent trampling but still allowed grazing. Effects of summer irrigation and trampling by dairy cows were examined for pasture production, and soil chemical and structural properties. Summer irrigation at ERS and on-farm trials has led to a decline in soil structure indicated by slower ponded water in filtration rates on irrigated plots compared with the dryland plots. The decline in ponded water in filtration rates suggests a reduction in macroporosity, especially in the soil surface. However, other indicators for soil structural change in the top 100 mm|percentage water-stable aggregates (>2·5 mm) and bulk density|revealed no significant variation between the irrigated and dryland paddocks. There were, however, higher water in filtration rates and lower bulk densities in the untrampled areas than the trampled areas at ERS. Pasture production at ERS was about 50% more with irrigation in each of the 2 years of the study. Data collected at ERS in autumn and spring on the numbers of Aporrectodea caliginosa(Savigny) and Lumbricus rubellus (Hoffmeister) earthworms showed that they respond quite differently to irrigation. After 2 irrigation seasons, A. caliginosa numbers in irrigated plots dropped by over 50%, whereas in the dryland plots densities of this earthworm have remained around 390 earthworms/m 2. In contrast the densities of L. rubellus at ERS rose under irrigation practices, especially in the autumn{winter sampling period. Therefore, with the advent of summer irrigation at ERS, there was a shift in earthworm composition from a fauna dominated by A. caliginosa to a fauna with an increasing proportion of L. rubellus and a decreasing number of A. caliginosa. The typical dairy pasture in the on-farm trials recorded 2 main species, A. caliginosa (70%) and L. rubellus (30%). Total earthworm densities were highest in the north-west (Smithton) region of the State (293{351 earthworms/m 2) regardless of soil type, and the lowest densities were recorded in the Alluvial soils of Deloraine (96 earthworms/m 2). The north-west area also had the most diverse earthworm fauna, with 5 species recorded in one site: A. caliginosa, A. longa, Allolobophora chlorotica, L. rubellus, and O. cyaneum. Summer irrigation effects after 2 seasons on earthworm composition and abundance on dairy farms caused no significant change in A. caliginosa numbers, but there was a 45% increase in the numbers of L. rubellus in irrigated treatments. L. rubellus was considerably more active over summer in irrigated paddocks (25 earthworms/m 2) than in non-irrigated paddocks (7 earthworms/m 2). In contrast the number of A. caliginosa recorded in dryland paddocks was not statistically different to the irrigated paddocks, but the A. caliginosa in dryland paddocks were mostly inactive 8-20 mm from the soil surface.

Download Full-text

MONITORING OF FLOODING EVENTS ON THE RIVERS OF THE NORTH-WESTERN CAUCASUS IN 2014–2020

Ecology Economy Informatics System analysis and mathematical modeling of ecological and economic systems ◽

10.23885/2500-395x-2021-1-6-185-190 ◽

2021 ◽

Vol 1 (6) ◽

pp. 185-190

Author(s):

I.V. Sheverdyaev ◽

◽

А.V. Kleschenkov ◽

S.А. Misirov ◽

Keyword(s):

Water Levels ◽

Winter Period ◽

Floodplain Vegetation ◽

The North ◽

Northwestern Caucasus ◽

Catchment Areas ◽

Runoff Regime ◽

Flooding Events ◽

North Western ◽

Automatic Level

The rivers of the Northwestern Caucasus between Anapa and Tuapse are characterized by a flood runoff regime. Floods leading to material damage occur on the rivers of the region every year. After the 2012 flood, a network of automatic level gauges is developing in the region, recording water levels every 10 minutes. During the expeditions of the SSC RAS in the winter period 2019-2020 the analysis of the installation sites of 69 level gauges was carried out. The features of level gauges influencing the collection of observations are identified: the installation options, floodplain vegetation, the features of the channel, floodplain and river valley. The analysis of the accumulated for 2014–2020 database of level observations on rivers with catchment areas from 1.4 km2 to 1245 km2 was carried out. 34 778 periods of growth, 70 135 periods of stagnation, 39 485 periods of decline and 42 032 gaps were identified. Of these, 3398 flood situations were considered. More than 100 flood events were recorded on 11 level gauges: on the rivers Abin, Shebsh, Psekups, Pshish (3 gauges), Nechepsukho, Dzhubga, Vulan, Pshada and Mezyb. Less than 10 flood situations were recorded on 14 level gauges. To increase the efficiency of the network of automatic level gauges, it is necessary to expand it to the watersheds between rivers Abin and Khable, as well as on Pshish on the northern macroslope and on the watersheds of Pshada, Nechepsukho and Tuapse on the southern macroslope.

Download Full-text

Urban nature conservation: vegetation of natural areas in the Potchefstroom municipal area, North West Province, South Africa

Koedoe ◽

10.4102/koedoe.v42i1.218 ◽

1999 ◽

Vol 42 (1) ◽

Cited By ~ 9

Author(s):

S.S. Cilliers ◽

E. Van Wyk ◽

G.J. Bredenkamp

Keyword(s):

South Africa ◽

Plant Communities ◽

Soil Depth ◽

Research Programme ◽

Soil Surface ◽

Management Plan ◽

Natural Areas ◽

North West ◽

The North ◽

North West Province

This study on the natural and degraded natural vegetation of natural areas in the Potchefstroom Municipal Area, forms part of a research programme on spontaneous vegetation in urban open spaces in the North West Province, South Africa. Using a numerical classification technique (TWINSPAN) as a first approximation, the classification was refined by applying Braun-Blanquet procedures. The result is a phytosociological table from which 6 plant communities were recognised, which are subdivided in sub-communities and variants, resulting in 18 vegetation units. Some of these vegetation units are similar to communities described previously in natural areas. The presence of degraded natural communities suggests huge anthropogenic influences in certain areas. An ordination (DECORANA) scatter diagram shows the distribution of the plant communities along gradients which could be related to vegetation structure, altitude, soil depth, rockiness of soil surface, wetness or dryness of the habitat and number of introduced species. This study contributes to the compilation of a guideline for a conservation orientated management plan for the area, but also created a wealth of new knowledge of the reaction of indigenous plant species under disturbed conditions.

Download Full-text

Geotechnical Investigations Of Calcareous Soils On The North West Shelf, Australia

10.4043/3772-ms ◽

1980 ◽

Cited By ~ 3

Author(s):

R.W. King ◽

W.R. van Hooydonk ◽

H.F. Kolk ◽

D.W. Windle

Keyword(s):

Calcareous Soils ◽

North West ◽

The North ◽

Geotechnical Investigations

Download Full-text

Variability assessment of flood hazard indicators on the North Caucasus

10.5194/egusphere-egu2020-11512 ◽

2020 ◽

Author(s):

Anastasiia Mironenko ◽

Ekaterina Rets ◽

Natalia Frolova

Keyword(s):

Flood Hazard ◽

Maximum Amplitude ◽

Water Levels ◽

The Black Sea ◽

North Caucasus ◽

Main Research ◽

Variability Analysis ◽

The North ◽

Maximum Water ◽

Hazard Levels

The result of maximum water levels variability analysis along with the information of the frequency of adverse and dangerous hydrological phenomena exceeding levels and fluctuations maximum amplitude of water levels are presented in this research. There are two periods of comparison of the water levels recorded at 146 hydrological gauges &#8211; 1926-1975 and 1976-2015. Statistical analysis of databases was selected as the main research method including agreement criteria with parametric and nonparametric criteria of homogeneity.The recent rise in mathematical expectation of maximum water levels is a characteristic for all the North Caucasian rivers. Maximum water levels dispersion have a tendency to decrease in the south of the Black Sea Caucasian coast, the Psheha and the Belaya rivers, the Sulak and the Fortanga rivers, the Baksan upstream. The remaining gauges recorded an increase in water levels dispersion, which is the predominant trend for the North Caucasian rivers.The frequency of the adverse events exceeding water levels reaches 50% on the Afips, the Belaya, the Kuma, the Laba, the Mzymta, the Ubinka and the Vulan rivers. By the number of hazard levels exceeded, the areas adjacent to the Kuma, the Laba, the Psekups, the Pshish and the Ubinka are most susceptible to the floods.Another part of the framework was connected with potential flood-affected region mapping over the North Caucacus. Thus, a map of potential flood zones caused by North Caucasian rivers was created according to maximum water levels recorded at 232 hydrological gauges.This study was funded by RFBR according to the research project &#8470; 20-35-70024.

Download Full-text

An improved Victorian erosivity map

Soil Research ◽

10.1071/sr02030 ◽

2003 ◽

Vol 41 (1) ◽

pp. 141 ◽

Cited By ~ 12

Author(s):

G. J. Sheridan ◽

C. J. Rosewell

Keyword(s):

Rainfall Intensity ◽

Soil Surface ◽

Water Runoff ◽

Contour Map ◽

North West ◽

Erosion Processes ◽

The North ◽

Forested Areas ◽

The Individual ◽

The Impact

The impact of raindrops on the soil surface and surface water runoff are two of the agents of soil detachment and sediment transport. The magnitude of these erosion processes is a function of the erosive potential, or erosivity of a rainstorm. The erosivity of rainfall is commonly quantified using the R factor developed for the universal soil loss equation. R is the average of the annual sum of the individual storm erosivity values and can be estimated from published relationships between the storm energy and the rainfall intensity. Currently the most likely source of R-values in Victoria is a hand-drawn contour map produced more than 20 years ago by an expert panel and published in an out-of-print handbook. A new R-value contour map for Victoria is presented, developed from current empirical relationships between rainfall intensity–frequency–duration and R. The R contours vary in value across the state by about a factor of 4, from <800 MJ.mm/ha.h.year in the north-west, to >2700 MJ.mm/ha.h.year in the eastern ranges. The new map improves the resolution and accuracy of erosivity values for Victoria, especially in steeper, forested areas, and will assist in the prediction and modelling of erosion and water quality.

Download Full-text

SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157838 ◽

1990 ◽

Vol 48 (3) ◽

pp. 58-59

Author(s):

Daryl A. Cornish ◽

George L. Smit

Keyword(s):

Morphological Characteristics ◽

Oreochromis Mossambicus ◽

Breeding Cycle ◽

Limited Information ◽

North West ◽

The North ◽

Sem And Tem ◽

Sperm Development ◽

Ultrastructural Characteristics ◽

The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

Download Full-text