Assessment of landslide behaviour in colluvium deposit at Doi Chang, Thailand

AbstractThe paper presents the case study of the recurrent slope movement in colluvium deposits at Doi Chang, Thailand. A thorough site investigation confirmed the slope movement rate corresponding to slow creep during dry season, while in the rainy season, its velocity remarkably increased. Despite frequent repair, the movement rate was sufficient to result in the recurrent damage of infrastructures like roads and buildings, causing economic loss and public concerns. Furthermore, surface mapping revealed that the hill's topography led to the concentration of flowing water in a particular area. This resulted in a high level of groundwater table, especially during the rainy season. The inclinometer installed in that area suggested an average movement rate of 20.5 mm/month in the wet season. In contrast, during the dry season, it was limited within 2 mm/month, indicating that the increase in the rate of slope movement in the colluvium deposit was primarily due to the rising groundwater table. Field and laboratory tests were conducted to determine the properties of the colluvium deposit. Landslide susceptibility assessment was performed using infinite slope model and later integrated with GIS to evaluate the factor of safety (FS) over a large area. The FS decreased below 1 when the groundwater level rose to 0.3 cm below the ground surface, and using GIS, based on infinite slope model, the potential risk zone were delineated.

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Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

Physical Science International Journal ◽

10.9734/psij/2019/v23i430161 ◽

2019 ◽

pp. 1-11

Author(s):

Adekunle Titus Adediji ◽

Joseph Babatunde Dada ◽

Moses Oludare Ajewole

Keyword(s):

Rainy Season ◽

Annual Variation ◽

Ground Surface ◽

Local Effect ◽

Dry Season ◽

Radio Link ◽

Wet Season ◽

Annual Variations ◽

Microwave Radio

In this study, four years in-situ measurements of atmospheric parameters (pressure, temperature and relative humidity) were carried out. The measurement was by placing an automatic weather station at five different heights: ground surface, 50, 100, 150 and 200 m respectively on a 220 m Nigeria Television Authority TV tower in Akure, South Western Nigeria. The four years Data collected (January 2007 to December 2009 and January to December 2011) were used to compute radio refractivity and its gradient. The local effect of a location/ region cannot but looked into when designing effective radio link, hence the diurnal, seasonal and annual variations of the radio refractivity gradient were studied. Results showed that refractivity gradient steadily increases inthe hour of 8:30 and 9:30 to 18:00 during dry season throughout the years investigated, and decreases two hours in the rainy season than the dry season. The record shows that at 50 m altitude, the maximum and minimum values are 158 N-unit/km around 14:30 and - 286 N-unit/km around 13:30 to 14:00 hrs, LT during the dry and rainy season respectively. Seasonally, refractivity gradient is steeper with greater variability in the dry season months than in the wet season months.

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Spatial and temporal variability of canopy cover and understory light in a Cerrado of Southern Brazil

Brazilian Journal of Biology ◽

10.1590/s1519-69842010000100005 ◽

2010 ◽

Vol 70 (1) ◽

pp. 19-24 ◽

Cited By ~ 12

Author(s):

JP. Lemos-Filho ◽

CFA. Barros ◽

GPM. Dantas ◽

LG. Dias ◽

RS. Mendes

Keyword(s):

Rainy Season ◽

Light Availability ◽

Canopy Cover ◽

Dry Season ◽

Photon Flux ◽

Photon Flux Density ◽

Spatial And Temporal Variability ◽

Wet Season ◽

Area Index ◽

Understory Plants

Canopy cover has significant effects on the understory environment, including upon light availability for seedling growth. The aim of the present study was to verify spatial heterogeneity and seasonal changes in the canopy cover of a dense Cerrado area, and their relationship to understory photosynthetic active radiation availability. Leaf area index (LAI) values in the rainy season varied from 0.9 to 4.83, with 40% of the values ranging from 4.0 to 5.0, while in the dry season LAI varied from 0.74 to 3.3, with 53% of the values oscilating from 2.0 to 3.0. Understory light (Qi ) and the Lambert-Beer ratio (Qi/Qo) were taken around noon on sunny days (between 11:00 AM and 1:00 PM). They were also statistically different (p < 0.01) between the dry and wet seasons, with 72% of sampled points in the rainy season presenting photosynthetic photon flux density (PPFD) values lower than 250 μmol.m-2/s around noon, whereas in the dry season, most PPFD values varied from 1500 to 1817 μmol.m-2/s , thus providing high light availability for understory plants. In most of the studied sites, understory plants did not even receive enough light for 50% of their photosynthetic capacity in the wet season. In contrast during the dry season, Qi/Qo values of 0.8 to 1.0 were observed in more than 50% of the points, thereby allowing for photosynthetic light saturation. Thus, light variability around noon was higher during the dry season than in the wet season, its heterogeneity being related to spatial complexity in the canopy cover.

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Hydrogeological, hydrochemical, and natural isotopes evaluation of groundwater and surface water interactions in the alluvial plain, tropical region of southeastern Brazil

10.22541/au.163534840.02185492/v1 ◽

2021 ◽

Author(s):

Waldilene Correa ◽

Sueli Pereira ◽

Joaquim Ernesto Bernardes ◽

Paulo Ricardo Pereira

Keyword(s):

Surface Water ◽

Groundwater Flow ◽

Rainy Season ◽

Dry Season ◽

Alluvial Plain ◽

Morphological Features ◽

Southeastern Brazil ◽

Wet Season ◽

Natural Isotopes ◽

Abandoned Meanders

Groundwater-Surface water interactions in alluvial plains facing morphological features are the subject of the study. Considered transitions zones, alluvial plains have different morphological features interfering with groundwater flow and hydrochemistry. The alluvial plain of Mogi Guaçu river (southeastern Brazil) presented topography-controlled groundwater flow, nevertheless, natural levees, wet fields, oxbow lakes, and abandoned meanders can control local flow and interfere in discharges points of the main river. Two sampling water campaigns were done in the dry and wet season for physicochemical and natural isotopes analysis, collecting in total 44 groundwaters samples from monitoring wells and eight water samples from the river, creek, and lake. The groundwaters in wet fields and terraces, and surface waters from creek and lake presented low mineralization (EC from 8 to 37 μS.cm), pH acidic (4.98 to 5.8), and essentially Ca and Na-HCO composition. River waters samples presented pH between 5.92 e 7.69 (acidic in the rainy season and basic in the dry season), and EC from 24.2 and 181.1 μS/cm (lower values in the wet season), Na-HCO and Na-HCO-SO (dry season) and Ca-HCO and Na-HCO (rainy season) compositions. In dry season groundwaters composition showed evolution from sodium mixed (SO – HCO) to bicarbonate waters and higher mineralization; in wet season waters varied from Ca to Na-HCO composition and low mineralization, denoting dilution due to rainwater infiltration. Closer to the river margins, in abandoned meanders and oxbows, the groundwaters have increased values of EC and major ions indicating GW-SW mixtures, and effluent-influent changes (descendent and ascendent flux) in wet and dry seasons, respectively. Natural isotopes in groundwaters imply meteoric origin, without evaporation during recharge and high d-excess can be influenced by continental air masses and Amazonia Basin low-level jet. Shallow water table, permeable silty-sand material of vadose zone, flat terrain, and pristine conditions can contribute to direct infiltration of rainwaters, recharging the shallow aquifer.

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Avian Communities of a Mixed Mopane-Acacia Savanna in the Cuvelai Drainage System, North-Central Namibia, During the Dry and Wet Season

Vestnik Zoologii ◽

10.2478/vzoo-2014-0040 ◽

2014 ◽

Vol 48 (4) ◽

pp. 333-338 ◽

Cited By ~ 1

Author(s):

G. Kopij

Keyword(s):

Rainy Season ◽

Diversity Index ◽

Drainage System ◽

Dry Season ◽

Line Transect ◽

Wet Season ◽

North Central ◽

Numida Meleagris ◽

Dominance Structure ◽

Shannon’S Diversity Index

Abstract Studies were conducted by means of the Line Transect Method in late rainy season (March), in the middle of dry season (July) and at beginning of rainy season (November).Th e total length of all transects was c. 11 km. In total, 70 resident and 13 nonresidentspecies were recorded. Th e number of species in dry season was significantly lower than in rainy season (x2-test: 14.1; p < 0.01). Th e highly significant seasonal differences in abundance were recorded for the following species: Streptopelia senegalensis, Streptopelia capicola, Uraeginthus angolensis, Cisticola juncidis, Upupa africana, Cynniris mariquensis, and Numida meleagris. In overall, five species have been classified as dominants: Streptopelia senegalensis, Streptopelia capicola, Uraeginthus angolensis, Plocepasser mahali and Cypsiurus parvus. They comprised together 43.9 %. Significant variations in the dominance structure between the wet and dry season have been evidenced. Granivores were much more numerous in the dry than in the wet season, while for the insectivores the reverse was true. Although Sorensen Coefficient was much the same between all three seasons, the Shannon’s Diversity Index was lower in July than in March and November.

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Ground Surface Features Attributable to Feral Buffalo, Bubalus bubalis I. Their Distribution relative to Vegetation Structure and Plant Lifeform

Wildlife Research ◽

10.1071/wr9840303 ◽

1984 ◽

Vol 11 (2) ◽

pp. 303 ◽

Cited By ~ 15

Author(s):

JA Taylor ◽

GR Friend

Keyword(s):

Leaf Litter ◽

Vegetation Structure ◽

Ground Surface ◽

Bubalus Bubalis ◽

Dry Season ◽

Northern Australia ◽

Wet Season ◽

Surface Features ◽

Dense Vegetation ◽

Lower Elevation

Relationships among ground surface features attributable to feral buffalo (viz. wallows, trails, pug marks and dung pats), vegetation structure, and lifeform spectrum were examined in both dry and wet seasons in a tropical monsoonal area of northern Australia. In the dry season, the frequency of pug marks was negatively correlated with the number of trails and dung pats, and positively correlated with the number of wallows. In the wet season only dung pats and wallows were significantly correlated. In the dry season, wallows were not associated with any vegetation structure or lifeform attribute, but in the wet season they were associated with dense foliage <1 m high. Trails occurred in areas of low dense vegetation (<0.5 m) in the dry season, but in the wet were uncommon and positively associated with lianas. Pug marks occurred mainly in the lower-elevation, treeless areas dominated by forbs. Whereas the nature and strength of the relationships of pug marks to plant lifeform or vegetation structure remained constant from season to season, those involving dung pats changed seasonally. In the dry season, dung pats were associated with the higher-elevation areas where trees, lianas, dense mid-level foliage (1.5-2.5 m) and leaf-litter were common. In the wet, they were associated with low vegetation (<1 m) dominated by forbs, and were negatively correlated with the factors important in the dry.

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Dry season and soil texture affect the chemical control of monocotyledonous in sugarcane

Comunicata Scientiae ◽

10.14295/cs.v8i3.1594 ◽

2018 ◽

Vol 8 (3) ◽

pp. 477-485

Author(s):

Hudson Kagueyama Takano ◽

Denis Fernando Biffe ◽

Jamil Constantin ◽

Rubem Silvério de Oliveira Junior ◽

Guilherme Braga Pereira Braz ◽

...

Keyword(s):

Soil Texture ◽

Rainy Season ◽

Clayey Soil ◽

Dry Season ◽

Weed Species ◽

Wet Season ◽

Sugarcane Crop ◽

Dry Conditions ◽

Loam Soil ◽

Great Complexity

The chemical weed control in sugarcane during the wet season is more effective than the control carried out during the dry season. The objective of this study was to evaluate the efficacy of herbicides in the rainy season and in the dry season in sugarcane crop, and in different soil textural classes. The experiments simulated dry season and rainy season basing on periods of days in which experiment was submitted to irrigation restriction. In each experiment, it was tested 50 and 100% of the dose of the main herbicides commonly used in sugarcane to control B. decumbens, B. plantaginea, P. maximum and D. horizontalis. In general, in dry conditions, as well as varying the soil texture, there are restrictions in the choice of herbicide to be used due to the reduced effectiveness of some treatments in certain situations. In the very-clayey soil, especially in the dry season, the efficacy of herbicides is better, whereas, for the sandy-clay-loam soil in dry conditions, the effectiveness of herbicides is restricted. Thus, this study, despite the great complexity of the variables to be analyzed, permitted to establish guidelines for decision making on the most appropriate herbicide to be applied in each studied condition, in order to control these weed species.

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Profile of Geohelminth Eggs, Cysts, and Oocysts of Protozoans Contaminating the Soils of Ten Primary Schools in Dschang, West Cameroon

Journal of Parasitology Research ◽

10.1155/2017/1534675 ◽

2017 ◽

Vol 2017 ◽

pp. 1-6

Author(s):

Vanessa Rosine Nkouayep ◽

Blandine Ngatou Tchakounté ◽

Josué Wabo Poné

Keyword(s):

Rainy Season ◽

Primary Schools ◽

Public Health Problem ◽

Dry Season ◽

Soil Samples ◽

Contamination Rate ◽

Wet Season ◽

Important Public Health Problem ◽

Helminth Infections ◽

The City

Helminthiasis and protozoans infections have been recognized as an important public health problem. The aim of the present study was to screen soil samples collected from 10 primary schools in the city of Dschang for the presence of soil-transmitted helminth eggs, cysts, and oocysts of protozoans. A total of 400 soil samples were collected around latrines, at playgrounds, and behind classrooms in each school. These samples were examined using the sucrose flotation method. From the result obtained, an overall contamination rate of 7.75% was observed. Five genera of nematodes (Ascaris, Trichuris, Capillaria, Cooperia, and hookworms) were identified, while neither cysts nor oocysts of protozoans were detected. The contamination rate and the number of species found were significantly different in wet season as compared to the dry season. During the rainy season, this rate was 12.5% with all the parasitic stages identified, while, in the dry season, the soil contamination rate was 3% with the presence of only two genera (Ascaris and Trichuris). This suggests that parasite infection may occur mainly in rainy season rather than in the dry season. The most common eggs were those of Ascaris with 2% and 5% contamination rates in the dry and rainy seasons, respectively. Also, the soils around latrines were more contaminated (11.9%) as compared to those collected behind classrooms (7.5%) and those at playground (2.5%). It was concluded that the pupils of these schools may have played a major role in the contamination of their environment. Thus, sanitary education, enforcement of basic rules of hygiene, and deworming remain a necessity in the entire population of the study area in general and in the schools in particular in order to prevent helminth infections and to ensure effective environmental health.

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Ruminal volatile fatty acids and ammonia in cattle grazing dry tropical pastures

The Journal of Agricultural Science ◽

10.1017/s0021859600054836 ◽

1976 ◽

Vol 86 (2) ◽

pp. 367-372 ◽

Cited By ~ 10

Author(s):

M. J. Playne ◽

P. M. Kennedy

Keyword(s):

Fatty Acids ◽

Butyric Acid ◽

Rainy Season ◽

Volatile Fatty Acids ◽

Live Weight ◽

Cattle Grazing ◽

Dry Season ◽

Wet Season ◽

Tropical Pastures ◽

Grazing Cattle

SummaryTotal VFA concentrations, individual VFA proportions and ammonia concentrations in the rumen of cattle grazing tropical pastures for 7 months during the dry season were compared with concentrations of these metabolites in cattle grazing in the wet season and in cattle given two pasture hays in pens.Neither total VFA nor ammonia concentrations were altered by periods of new pasture growth within the dry season although responses in live weight occurred. Further evidence that concentrations of total VFA were insensitive to differences in feed quality was shown in the pen experiment.VFA concentrations were 53% higher in the rainy season than in the dry season and ammonia concentrations doubled from 62 mg/1 in the dry to 128 mg/1 in the wet season. Ruminal ammonia was related to ingested bolus N concentration (r= 0·58,P< 0.001) during the dry season.Individual VFA proportions did not vary greatly. The highest acetic (79·1%) and lowest butyric acid (5.10%) proportions occurred in the same sample. Iso-valeric and valeric acid proportions were related positively to ruminal ammonia (P< 0·001).In grazing cattle, concentrations of VFA and ammonia in their rumen taken at hourly intervals between 07.00 and 18.00 h did not vary greatly with time. Samples taken before 10.00 h had higher VFA and ammonia levels.

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Seasonal variation in egg production and mortality of Muscovy ducks (Cairina Moschata)

Biotechnology in Animal Husbandry ◽

10.2298/bah1502181o ◽

2015 ◽

Vol 31 (2) ◽

pp. 181-192

Author(s):

A.O. Oguntunji ◽

O.A. Oladejo ◽

K.L. Ayorinde

Keyword(s):

Seasonal Variation ◽

Rainy Season ◽

Egg Production ◽

Dry Season ◽

Seasonal Effect ◽

Muscovy Duck ◽

Wet Season ◽

Randomized Design ◽

Muscovy Ducks ◽

Completely Randomized Design

Seasonal variation is one of the principal non-genetic factors influencing performance of poultry in tropical environment. This study was conducted to investigate influence of seasonal variation on egg production and incidence of mortality in intensively-reared non-descript Muscovy ducks in Nigeria. Egg production and incidence of mortality in sixty two (62) female Muscovy ducks was studied in a 12-month trial divided into two major seasons: wet (April - September) and dry (October - March) and four sub-seasons: early rainy season (April - June), late rainy season (July - September), early dry season (October - December) and late dry season (January - March). Student?s t-test and Completely Randomized Design was used to analyse seasonal and sub-seasonal effect on performance, respectively. Season and sub-season significantly (P < 0.05) affected egg production; higher egg production was recorded in wet season compared with dry season (16.18% vs. 1.32%). Among sub-seasons, highest egg production was recorded in late rainy season (20.92%) while the least (0.00%) was obtained in late dry season. Conversely, there was no significant (P > 0.05) effect of season and sub-season on mortality. It is evident that seasonal variation had no effect on incidence of mortality but significantly affected egg production of Muscovy duck and the adverse effect is more pronounced in dry season most especially in late dry season.

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Effects of genotype and season on the productive performance of commercial egg-type chickens in the derived savanna zone in Nigeria

Nigerian Journal of Animal Production ◽

10.51791/njap.v39i2.815 ◽

2021 ◽

Vol 39 (2) ◽

pp. 4-13

Author(s):

A. O. Oguntunji ◽

A. E. Salako

Keyword(s):

Rainy Season ◽

Egg Production ◽

Genetic Basis ◽

Dry Season ◽

Productive Performance ◽

Performance Indices ◽

Wet Season ◽

Derived Savanna ◽

And Performance ◽

Season Interaction

Twelve (12) month production records of two commercial egg-type chickens, Nera Black (NB) and Isa Brown (IB) reared on a commercial farm in Ilora, Oyo State, Nigeria were analysed to assess effects of season and genotype on their performance. The production record was sorted according to the two recognized major seasons: wet (April-September) and dry (October-March) in the study area. Besides, the each major season was further partitioned into two sub-seasons namely: early rainy season (ERS: April-June), late rainy season (LRS: July-September), early dry season (EDS: October-December) and late dry season (LDS: January-March). Results of data analysis showed that genotype had no significant effect (P>0.05) on all the performance indices. Conversely, season significantly (P<0.05) affected all the performance parameters evaluated and hens performed better in wet seasons compared with dry months. There was significant (P<0.05) genotype by season interaction effect on egg production but not (P>0.05) for other productive parameters. IB strain performed better in wet season most especially in LRS while NB hens had better performance in dry season. Results from this study indicated that regardless of the season, the two egg strains should be employed for commercial egg production but adequate measure should be taken to combat the adverse effect of thermal stress on the welfare and performance of layers in the study area most especially in LDS months. Discrepancies in genotype by season interaction suggest genetic basis to differences in performances and physiological abilities of the investigated egg-strains to cope with stresses emanating from change in season.

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