Seasonal variation of oceanographic processes in Indus river estuary

Field investigations were conducted to study spatial and temporal (seasonal) variations in meteorological, hydrodynamic and hydrological variables in Indus River Estuary. The investigations were undertaken during wet, (moderate fluvial discharge), flood (highest fluvial discharge) and dry (zero fluvial discharge) seasons to obtain surface and near bed data during flood and ebb tides. Tides were semidiurnal, showing an asymmetric pattern with longer ebb tides and shorter flood tides. The hydrodynamic data revealed strong seasonal variation, the ebb velocities were significantly higher than flood current velocities during wet season, whereas a slight difference was found in current velocities during dry season, while the ebb phase lasted longer than flood during wet season; however no significant difference was observed during dry season. On the other hand during flood period the water currents were substantially higher and unidirectional related to the strong river flow. Turbidity values were considerably higher during flood season, than wet and dry seasons along the channel. However hydrological parameters such as temperature and dissolved Oxygen also revealed seasonal and spatial fluctuations, though they were within permissible range. The salinity distribution along the channel was related to the incoming river flow and tidal propagation. Higher salinity values were recorded in dry season, suggested that salinity variation at Estuary was due to salt intrusion from the North Arabian Sea, related to the absent of fluvial discharge form Indus River. Present study revealed substantial changes for hydrology and hydrodynamic conditions of the Indus River Estuary, related to the varying Indus River flow, as well as winds are another important atmospheric force in this region which enhanced the tidal forcing during southwest monsoon.

Download Full-text

THE EFFECT OF SEASONAL VARIATION ON PERFORMANCE OF EGG TYPE POULTRY: A Case Study of Mitchell Farms, Mosogar, Delta State, Nigeria

Nigerian Journal of Animal Production ◽

10.51791/njap.v24i2.2306 ◽

2021 ◽

Vol 24 (2) ◽

pp. 101-105

Author(s):

E. E. Guobadia

Keyword(s):

Seasonal Variation ◽

Feed Intake ◽

Egg Production ◽

Management Practices ◽

Secondary Data ◽

Dry Season ◽

Wet Season ◽

Egg Hatchability ◽

Significant Difference

The study was designed to find out the effect of seasonal variation on poultry in Delta State of Nigeria. The variables considered were mortality rate, feed intake, egg production and egg hatchability in the wet and dry seasons of the year. Secondary data were also collected from records kept in the farm. Sites 4AHI-BLK,5AKI-BLK, 9H/BF and 10H/BF were used for the study with each having an average of 2,500-3,500 birds of the same breed and sex aged 1-9 weeks and 21-52weeks. The records were grouped into dry season (October-March) and wet season (April-September) covering three years, 1991-1994. The analysis of the result showed that seasonal variation does not have any significant effect (P < 0.05) on mortality and feed intake in the two seasons. However percentage egg production and egg hatchability revealed a significant difference (P < 0.05) between the two seasons, with a mean % egg production and hatchability of 74±.03 and 80.6 in the wet season and 53.67±0.01 and 55.9 respectively in the dry season. Recommendation is therefore made for proper planning which ensures the utilization of wet and dry season management practices to reduce the effect of high humidity and embient temperature on production.

Download Full-text

Seasonal variation of suspended sediment and its relationship with turbidity in Cam - Nam Trieu estuary, Hai Phong (Vietnam)

Tạp chí Khoa học và Công nghệ Biển ◽

10.15625/1859-3097/16076 ◽

2021 ◽

Vol 21 (3) ◽

pp. 271-282

Author(s):

Minh Hai Nguyen ◽

Sylvain Ouillon ◽

Duy Vinh Vu

Keyword(s):

Seasonal Variation ◽

Suspended Sediment ◽

River Flow ◽

Suspended Particle ◽

Strong Dependence ◽

Dry Season ◽

Wet Season ◽

Different Seasons ◽

Spm Concentration ◽

Suspended Particle Matter

We analyzed the seasonal variation of suspended sediment and its relationship with Turbidity in Cam - Nam Trieu estuary based on data measured during three different seasons: Early wet season (May 2015), wet season (September 2015) and dry season (January 2016). The results highlighted the seasonal variation of suspended particle matter (SPM) concentrations with river flow. The average SPM concentration was highest during the dry season, with 62.95 mg/L. They were not significantly different between the early wet and wet seasons, with 59.65 mg/L and 50.94 mg/L, respectively. This study also demonstrated a strong dependence between SPM and Turbidity in the study area. The coefficients of determination varied from 0.867 to 0.971 (linear relationship), and from 0.95 to 0.991 (proportional relationship). Therefore, turbidity can be used to estimate SPM concentration. However, this relationship changed markedly with the seasons, and hence when determining SPM concentration, seasonal factors must be considered.

Download Full-text

Seasonal variation in species richness and abundance of waterbirds in Mole National Park, Ghana: Implication for conservation and ecotourism

Koedoe ◽

10.4102/koedoe.v60i1.1466 ◽

2018 ◽

Vol 60 (1) ◽

Cited By ~ 1

Author(s):

Timothy K. Aikins ◽

Francis Gbogbo ◽

Erasmus H. Owusu

Keyword(s):

Species Richness ◽

Seasonal Variation ◽

National Park ◽

Dry Season ◽

Wet Season ◽

Bird Abundance ◽

Number Of Species ◽

Waterbird Species ◽

Significant Difference ◽

Species Richness And Abundance

Mole National Park is the largest and the oldest national park in Ghana and an important bird area, yet its waterbird fauna is poorly documented because it is situated in the northern ecological zone far away from the coast of Ghana. Information on the seasonal variation in the park’s bird abundance and diversity is generally patchy but necessary for effective birdwatching planning and management of the park’s birds. Therefore, as a guide to potential ecotourists interested in waterbirds, this study described the seasonal variation in waterbird species diversity and abundance at Mole National Park. As waterbirds mostly congregate around open wetlands and their abundance is more appropriately determined by counting all individuals in the congregant, data were collected using the total area count of waterbirds from August 2015 to October 2015 (the wet season) and from December 2015 to February 2016 (the dry season). Secondary data on arrival of tourists in the park were also analysed. The park’s waterbird species richness was 29 in the dry season compared to 18 in the wet season. There was significant difference (p < 0.05) in the abundance of waterbirds in the dry season in which 4014 waterbirds were encountered compared to 646 in the wet season. The yearly tourist arrival data at Mole National Park shows an increasing trend with peak visitation period occurring during the wet season. The chances of tourists encountering more species and numbers of waterbirds in the park are higher in the dry season compared to the wet season.Conservation implications: Species richness and abundance of waterbirds in Mole National Park varied according to the wet and dry seasons with both the number of species and abundance higher in the dry season than the wet season. It is therefore indicative that most birdwatchers who visit the park in the wet season miss out on a number of species and numbers of waterbirds. To achieve effective birdwatching, management should schedule birdwatching activities to coincide with the dry season as the chances of encountering more species and numbers of waterbirds are higher.

Download Full-text

Spatial and temporal variations of hydrodynamics and sediment dynamics in Indus River Estuary,Pakistan

Global NEST Journal ◽

10.30955/gnj.003333 ◽

2021 ◽

Keyword(s):

Sediment Transport ◽

River Discharge ◽

Saltwater Intrusion ◽

River Estuary ◽

Dry Season ◽

Water Levels ◽

Spatial And Temporal Variation ◽

Indus River ◽

Wet Season ◽

Dry Seasons

<p>Field investigations were conducted to study the seasonal variation of hydrodynamics and sediment transport in Indus River Estuary (IRE), Pakistan. The data of water levels, currents, salinity, and suspended sediment concentration (SSC) were collected hourly covering both wet and dry seasons. Tidal amplitudes were higher near the mouth than those at the middle and upper estuary. The ebb phase lasted longer than that of the flood during the wet season. The asymmetric tidal pattern with higher ebb velocity was observed during the wet season. A slight difference in current velocity was found during the dry season. The flood currents were higher at middle estuary than those in wet season. During the wet season, salinity variation within a tidal cycle slightly increased from the upper estuary to the mouth. Salinity was substantially higher during the dry season than the wet season at all three stations, with the absence of the flood-ebb variation, showing a strong saltwater intrusion. The SSC data revealed that the sediments were mainly brought into the estuary by freshwater discharge during the wet season. Sediment re-suspension process persists during the dry season, due to the tidal currents. A stronger saltwater intrusion occurred in the dry season due to weak river discharge. An estuarine turbidity maximum zone was formed near station-2 due to the combined effects of tides, river discharge and saltwater intrusion. Overall, field observations have shown a significant spatial and temporal variation in flood/ebb and wet/dry seasons for hydrodynamics and sediment transport in IRE.</p>

Download Full-text

Seasonality of Mansonia titillans during dam construction, Biritiba-Mirim, São Paulo State, Brazil

Biota Neotropica ◽

10.1590/s1676-06032013000100007 ◽

2013 ◽

Vol 13 (1) ◽

pp. 70-73 ◽

Cited By ~ 2

Author(s):

Frederico Alves D'Avila ◽

Almério de Castro Gomes

Keyword(s):

Early Spring ◽

Dry Season ◽

Southeastern Brazil ◽

Rank Test ◽

Late Winter ◽

Dam Construction ◽

Wet Season ◽

Paulo State ◽

Significant Difference ◽

Wilcoxon Rank Test

A two and a half year survey was conducted at a dam in southeastern Brazil. Shannon Traps were used for sampling. Kruskal-Wallis test showed little relation between rainfall and abundance. The data clearly show three abundance peaks, all of them in the end of the dry season, in consonance with the scarce literature existent. Although Kruskal-Wallis Test did not find a clear preference for the dry season, Pairwise Wilcoxon Rank Test revealed a significant difference between Fall and Spring samples. Ma. titillans population had a peak on late winter/early spring, close to the begin of wet season.

Download Full-text

Study on the Transport of Terrestrial Dissolved Substances in the Pearl River Estuary Using Passive Tracers

Water ◽

10.3390/w12051235 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1235

Author(s):

Bo Hong ◽

Guangyu Wang ◽

Hongzhou Xu ◽

Dongxiao Wang

Keyword(s):

Water Resource Management ◽

River Flow ◽

River Estuary ◽

Pearl River Estuary ◽

Dry Season ◽

Pearl River ◽

Transport Time ◽

The Pearl River Estuary ◽

Passive Tracers ◽

The Pearl River

Highly populated river deltas are experiencing marine environment degradation resulting from the tremendous input of terrestrial dissolved substances (TeDS). The Pearl River Delta is one of the deltas with degradation of the water quality and ecological condition. The Pearl River Estuary (PRE) was investigated to reveal the fate and transport timescales of TeDS in order to provide guidance on water resource management and pollutant transport prediction. By using passive tracers in a calibrated 3D numerical model, the TeDS transports from five different outlet groups were investigated systematically. The TeDS transport time was computed by using the concept of water age, which is a measure of the time that has elapsed since the tracer was transported from the upstream boundary to the downstream concerned area. The tracer impacted area was defined by the area with tracer concentrations > 0.2 (arbitrary unit). The domains that were impacted by the tracer coming from each outlet group were identified separately. In the wet season, the impacted area was larger than in other seasons. The most prominent variations appeared in the Jiaomen–Hengmen–Hongqili (JHH) and Modaomen (MD) outlets. The hydrodynamic conditions controlled the offshore spreading of the TeDS. Assuming the TeDS were conservative, it took approximately 10–20 days for the TeDS to be transported from the head water to the entrance of the outlet. For the TeDS coming from the head water of the Humen outlet, it took approximately 40 (80) days for the TeDS to be transported out of the mouth of the Lingding Bay during the wet (dry) season. For the case of the TeDS coming from the head water of the JHH outlets, it took approximately 20 (40) days for the TeDS to be transported out of the Lingding Bay during the wet (dry) season. For the MD, Jiti and Yamen–Hutiao outlets, it usually took approximately 10 days for the TeDS to be transported from the head water to the inner shelf. The correlation coefficient between the river flow and tracer concentrations was 0.78, and between the river flow and transport time it was −0.70 at a station in the lower Lingding Bay. At the estuary mouth, the impacts of other forcing fields got stronger.

Download Full-text

Quantification of Temporal Variations in Base Flow Index Using Sporadic River Data: Application to the Bua Catchment, Malawi

Water ◽

10.3390/w11050901 ◽

2019 ◽

Vol 11 (5) ◽

pp. 901 ◽

Cited By ~ 10

Author(s):

Laura Kelly ◽

Robert M. Kalin ◽

Douglas Bertram ◽

Modesta Kanjaye ◽

Macpherson Nkhata ◽

...

Keyword(s):

Water Resources ◽

River Flow ◽

Temporal Variations ◽

Dry Season ◽

Base Flow ◽

Flow Index ◽

Wet Season ◽

Data Application ◽

Base Flow Index ◽

Long Term Trends

This study investigated how sporadic river datasets could be used to quantify temporal variations in the base flow index (BFI). The BFI represents the baseflow component of river flow which is often used as a proxy indicator for groundwater discharge to a river. The Bua catchment in Malawi was used as a case study, whereby the smoothed minima method was applied to river flow data from six gauges (ranging from 1953 to 2009) and the Mann-Kendall (MK) statistical test was used to identify trends in BFI. The results showed that baseflow plays an important role within the catchment. Average annual BFIs > 0.74 were found for gauges in the lower reaches of the catchment, in contrast to lower BFIs < 0.54 which were found for gauges in the higher reaches. Minimal difference between annual and wet season BFI was observed, however dry season BFI was >0.94 across all gauges indicating the importance of baseflow in maintaining any dry season flows. Long term trends were identified in the annual and wet season BFI, but no evidence of a trend was found in the dry season BFI. Sustainable management of the investigated catchment should, therefore, account for the temporal variations in baseflow, with special regard to water resources allocation within the region and consideration in future scheme appraisals aimed at developing water resources. Further, this demonstration of how to work with sporadic river data to investigate baseflow serves as an important example for other catchments faced with similar challenges.

Download Full-text

Spatial clustering and longitudinal variation of Anopheles darlingi (Diptera: Culicidae) larvae in a river of the Amazon: the importance of the forest fringe and of obstructions to flow in frontier malaria

Bulletin of Entomological Research ◽

10.1017/s0007485311000265 ◽

2011 ◽

Vol 101 (6) ◽

pp. 643-658 ◽

Cited By ~ 38

Author(s):

F.S.M. Barros ◽

M.E. Arruda ◽

H.C. Gurgel ◽

N.A. Honório

Keyword(s):

River Flow ◽

Spatial Clustering ◽

Malaria Incidence ◽

Malaria Prevalence ◽

Larval Habitat ◽

Dry Season ◽

Adult Mosquito ◽

Anopheles Darlingi ◽

Wet Season ◽

Larval Distribution

AbstractDeforestation has been linked to a rise in malaria prevalence. In this paper, we studied longitudinally 20 spots, including forested and deforested portions of a temporary river in a malarigenous frontier zone. Larval habitat parameters influencing distribution of Anopheles darlingi (Diptera: Culicidae) larvae were studied. We observed that larvae were clustered in forested-deforested transitions. For the first time in the literature, it was verified that parameters determining larval distribution varied from deforested to forested areas. The proximity to human dwellings was also a significant factor determining distribution, but larvae was most importantly associated with a previously undescribed parameter, the presence of small obstructions to river flow, such as tree trunks within the river channel, which caused pooling of water during the dry season (‘microdams’). In deforested areas, the most important factor determining distribution of larvae was shade (reduced luminance). Larvae were absent in the entire studied area during the wet season and present in most sites during the dry season. During the wet-dry transition, larvae were found sooner in areas with microdams, than in other areas, suggesting that flow obstruction prolongs the breeding season of An. darlingi. Adult mosquito densities and malaria incidence were higher during the dry season. Our data correlate well with the published literature, including the distribution of malaria cases near the forest fringes, and has permitted the creation of a model of An. darlingi breeding, where preference for sites with reduced luminance, human presence and microdams would interact to determine larval distribution.

Download Full-text

Seasonal variation in quality of Louhajong river water, Tangail

Bangladesh Journal of Scientific Research ◽

10.3329/bjsr.v28i1.26239 ◽

2016 ◽

Vol 28 (1) ◽

pp. 9-16

Author(s):

Md Rakib Hasan Sarker ◽

Asadul Islam ◽

Ariful Islam ◽

Md Mahbubul Hoque ◽

Shimul Roy

Keyword(s):

Seasonal Variation ◽

River Water ◽

Water Samples ◽

Dry Season ◽

Fish Culture ◽

Chemical Parameters ◽

Wet Season ◽

Physico Chemical ◽

Standard Level

Water samples were collected from three points of Louhajong river (Dighulia, Kagmari Bridge and Oloa) to see the seasonal variation in physico-chemical parameters. The results revealed that some of the parameters such as TDS, alkalinity and acidity have exceeded the standard level in dry season in all of the points, which are unsuitable for different purposes including fish culture. During dry and wet seasons the highest concentrations of BOD was recorded as 2.0 and 0.8 ppm at Kagmari Bridge (point-2) respectively. DO ranged from 1.4 to 3.1 and 2.4 to 3.8 ppm during dry and wet seasons. Maximum and minimum EC was recorded as 890 and 130 ?s/cm at Dighulia (point-1) during dry and wet seasons. The results suggest that at wet season Louhajong river may be suitable for fish culture and other purposes.Bangladesh J. Sci. Res. 28(1): 9-16, June-2015

Download Full-text

Distribution and Size of Barnacle Chelonibia patula Fouling Blue Crab Callinectes amnicola in Southeast Nigeria

Croatian Journal of Fisheries ◽

10.1515/cjf-2016-0017 ◽

2016 ◽

Vol 74 (3) ◽

pp. 93-102

Author(s):

James Philip Udoh ◽

Aniekan Johnny Otoh

Keyword(s):

Public Health ◽

Spatial Distribution ◽

Health Risk ◽

Blue Crab ◽

Carapace Width ◽

River Estuary ◽

Wet Season ◽

Low Salinity ◽

Host Interaction ◽

Significant Difference

Abstract The distribution and occurrence of epibionts on the dorsal carapace, ventral carapace and chela of 325 specimens of Callinectes amnicola (De Rocheburne, 1883) (103.4 - 138.7 mm carapace width) from the Qua Iboe (QIRE) and Imo River (IRE) estuaries in southeast Nigeria was determined. The only ectosymbiont observed was cirriped barnacle, Chelonibia patula, mostly of smaller sizes (2.25 mm), infesting only 25-29% of intermoult crabs, more on females and in the Imo River estuary, with an average of four barnacles per crab, presupposing low level of epibiont-host interaction. There was no significant difference (P>0.05) in spatial distribution but epibionts were highest in the dry season in low salinity IRE (0.53‰) and in wet season in the medium-salinity QIRE (17.4‰). No public health risk has been reported among crab consumers in the study area. This study highlights epibiont-host interaction in the study area largely unknown for proper management of the fishery.

Download Full-text