Northeast Monsoon Season Research Articles

Seasonal foraging activity of stingless bee Tetragonula travancorica Shanas and Faseeh (Hymenoptera: Apidae: Meliponini)

The foraging hive activity of stingless bee Tetragonula travancorica Shanas and Faseeh was studied from November 2018 to August 2019. The activity varied between the seasons, weather conditions and time hours of study. The outgoing and incoming pollen foragers exhibited two peaks in activity, from 0800-1200 h (first) and during 1500-1600 h (second). The activity of incoming non-pollen foragers displayed only one distinct peak between 1000-1200 h except during the southwest monsoon period. The greatest activity was recorded during the dry season (January-May), followed by the south-west monsoon (June-August) and north-east monsoon (November- December) seasons. Maximum overall activity was recorded during hotter months February, March and April while the lowest was observed in January and December. At any season or time, the number of incoming foragers without pollen was greater than pollen foragers.

The distribution of marine debris along the Pahang coastline, Malaysia during the Southwest and Northeast Monsoons

This study investigated the accumulation of debris at four sites, namely, Gebeng, Batu Hitam, Cherok Paloh, and Air Leleh, along the Pahang coastline, Peninsular Malaysia from March 2019 to February 2020. Plastic was the dominant debris (86.1%) and followed by cloth/fabric-based debris (6.0%), processed lumber debris (3.3%), rubber (2.7%), glass (1.5%), and metal (0.4%). The land-based debris (82.0%) was the major source of the deposition of marine waste. A statistically significant relationship was found between the seasonal variation and marine debris density in tidal and seasonal current along the Pahang coastline. In general, the Northeast Monsoon season had a higher amount of debris than the Southwest Monsoon season.

Soil moisture index estimation from landsat 8 images for prediction and monitoring landslide occurrences in Ulu Kelang, Selangor, Malaysia

Soil moisture is one of the contributing factors that accelerates soil erosion and landslide events due to the increase in pore pressure which eventually reduces the soil strength. For landslide prediction and monitoring purposes, large-scale measurement involves estimating the soil moisture. However, estimation of soil moisture usually involves point-based measurements at a particular site and time, which is difficult to capture the spatial and temporal soil moisture dynamics. This paper presents the estimation of the SMI using Landsat 8 images for prediction and monitoring of landslide events in Ulu Kelang, Selangor. The selected SMI map for dry, moist, and wet seasons are obtained from climatology rainfall analysis over 20-year periods (1998-2017). SMI is assessed based on remote sensing data which are land surface temperature (LST) and normalized difference vegetation index (NDVI) using GIS software. Overall results indicated that rainfall distribution is high during inter-monsoon (IM), followed by northeast monsoon (NEM) and southwest monsoon (SWM) season. High rainfall distribution is a direct contributor towards SMI condition. Results from simulation show that April 2017 is known to have the highest SMI estimation season and selected to be the best SMI mapping parameter to be applied for prediction and monitoring of landslide events.

Rainfalls And Salinity Effects On Fecal Coliform Most Probable Number (MPN) Index Distribution In A Beach Ridge-Shore Ridge System In Mengabang Telipot, Terengganu, Malaysia

A Holocene beach ridge and present day shore ridge system located in a rural area north east of Kuala Terengganu was studied. The relation between fecal coliform (FC) MPN Index (Most Probable Number) distribution with rainfalls and saline intrusions into the unconfined aquifer of the beach ridge–shore ridge system was examined. The probable primary source of the pollutants was also investigated in order to highlight the susceptibility of such aquifers to pollution. Six sampling sessions were made from September 2009 to January 2010. Three represent drier conditions and the other 3, heavier rainfalls corresponding to the northeast monsoon season. This sampling period represent a condition when this area was still not subjected to major coastal erosions and subsequent rock revetment work. Altogether, water samples were taken from 13 wells and 3 river stations. Physical-chemical measurements were made in-situ, while FC was tested at UMT laboratory. Essentially, the results indicated that the groundwater in the unconfined aquifer layer of the beach ridge was moderately to highly polluted with FC (up to 1600 MPN). In contrast, the shore ridge was only slightly polluted, whereas river stations had mixed conditions but generally worse than the beach ridge and shore ridge. These phenomena could be associated with salinity spatial-temporal variations. Samples from heavy rainfall conditions indicated lower pollution levels compared to drier conditions. This phenomenon could be associated with the availability of more infiltrated atmospheric water to dilute pollutants in a high hydraulic conductivity environment as the ridges are made of fine to coarse sands. The results underscore the sensitivity of such environment to pollution transport and distribution and hence implied special attention with regards to water resource management.

Micro Pulse Lidar measurements in coincidence with CALIPSO overpasses: Comparison of tropospheric aerosols over Kattankulathur (12.82oN, 80.04oE)

In this paper, we present validation of the cloud aerosol lidar with orthogonal polarization (CALIOP) level 1 and level 2 tropospheric aerosols products in coincidence to Micro Pulse Lidar (MPL) observations under different sky conditions and different seasons during March 2016–December 2018 over a tropical coastal station Kattankulathur (12.83oN, 80.04oE). In total, 33 simultaneous profiles during clear-sky (18 cases) and cloudy (15 cases; 7 mid-tropospheric (MT) clouds and 8 cirrus clouds cases) conditions are observed, out of which 5, 13, 6, and 9 cases are during winter, pre-monsoon, southwest (SW) monsoon and northeast (NE) monsoon seasons, respectively. CALIOP underestimates MPL within the boundary layer and overestimates in the free troposphere during both the clear-sky and cirrus conditions. In the clear-sky conditions, the mean bias of the level 1 aerosol products is found to be −14 ± 29% (18 ± 19%) below 3.0 km (over 3–10 km) while it is −39 ± 26% (33 ± 24%) below 3.0 km (over 3–8 km) underlying the cirrus clouds. The comparison underlying the thick MT clouds is not reliable. However, a better comparison is observed in the cases of thin MT clouds. A strong seasonal variation in the vertical distribution of the aerosol loadings near the surface with maximum (minimum) loading ~0.01 ± 0.005 km−1sr−1 (~0.004 ± 0.002 km−1sr−1) is observed during the winter (SW monsoon) season. The mean bias of level 2 aerosol profiles over the altitude 0.3–5 km is found to be 14 ± 28%, 15 ± 44%, −14 ± 25%, and 24 ± 34% during the winter, pre-monsoon, SW monsoon, and NE monsoon seasons, respectively.

Vertical distributions and columnar properties of the aerosols during different seasons over Kattankulathur (12.82oN, 80.04oE): A semi-urban tropical coastal station

Seasonal characteristics of the aerosols over Kattankulathur (12.83° N, 80.04° E) is studied using Micro Pulse Lidar observations during 2016–2018 and Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation, Moderate Resolution Imaging Spectroradiometer and Ozone Monitoring Instrument datasets during 2006–2018. The vertical distribution of the aerosols is characterized as the steep decrease with altitude nearly exponentially up to 2–3 km during the northeast (NE) monsoon and winter seasons mainly dominated by clear marine and polluted continental aerosols. While it gradually decreases with altitude up to 4–5 km during pre-monsoon and southwest monsoon (SW) seasons mainly dominated by dust aerosols. The mean aerosol loadings near the surface are ~0.38 km−1 during NE monsoon and winter, ~0.30 km−1 pre-monsoon, and 0.22 km−1 during SW monsoon seasons. Such difference in the seasonal distribution of aerosol loading is mainly attributed to the difference in surface insolation, convection, long-range transport, and the atmospheric boundary layer (ABL) structure and dynamics. The ABL contributes 61%, 46%, 38%, and 63% of the overall aerosol optical depth (AOD) during the winter, pre-monsoon, SW monsoon, and NE monsoon seasons, respectively. The AOD shows a substantial seasonal variation with two local maxima during May and October and minima during January and July. The maximum and minimum AOD is found to be ~0.59 ± 0.16 and 0.4 ± 0.05, respectively. The Angstrom exponent (AE) (fine mode fraction (FMF)) shows a marked seasonal variation with a maximum value of 0.84 (0.60), indicating the dominance of finer particles during winter and minimum value of 0.54 (0.27), indicating dominance coarse particles during SW monsoon. The AE and UV aerosol index values suggest that Kattankulathur is mainly characterized by large-sized absorbing aerosols (30%) such as dust mixture and sea salt particles. Small-sized non-absorbing aerosols such as biogenic aerosols are rarely (<1%) observed.

Seasonal and diurnal variations of observed convective rain events in Metro Manila, Philippines

The seasonal and diurnal characteristics of localized convective rain events in Metro Manila, Philippines were examined using observations from 16 automated weather stations in the city during the years 2013–2014. After partitioning total rainfall to determine the proportion that is mainly due to localized convection, the diurnal patterns of frequency and intensity of convective rain were then investigated during the northeast monsoon (from November to March), summer (from April to May), and southwest monsoon (from June to October) seasons. Maximum changes in meteorological variables were used to further verify and characterize localized convective rain events over the city. Results show higher rainfall (by ~500 mm) over northern Metro Manila compared to the southern area throughout the period of study. Although total rainfall was highest during the southwest monsoon season, it was during the summer season, when the total rainfall was least, that the largest proportion of rainfall, i.e. 55%, was attributed to convective rain. Almost 45% of the total convective rain events were identified as localized rain events. During the summer season, localized convective rain events in Metro Manila were prominent and vigorous (i.e. greater change in meteorological variables) in the afternoon, and were noted to move along the direction of the prevailing wind, i.e. from the northeastern side of the city towards the west. Increased understanding of the meteorological characteristics of these localized rain events can help improve rainfall forecasting over Metro Manila, leading to better disaster risk reduction and resilience in the city.

Patterns in Rhizosolenia- and Guinardia-associated Richelia abundances in the tropical marginal seas of the western North Pacific

Abstract Richelia is a widespread, heterocystous, N2-fixing cyanobacterium that occurs in oligotrophic seas. It can be symbiotic within rhizosolenoid hosts, including Rhizosolenia (R-R) and Guinardia (G-R), and occasionally occurs as free-living (FL-R) filaments. We investigated the Richelia abundances in the South China (SCS) and Philippine Seas (PS) during the northeast (NEM) and southwest monsoon (SWM) seasons between 2001 and 2016. Field results showed that G-R was most abundant in the SCS during the SWM. Both R-R and FL-R were more abundant in the PS than the SCS and during the SWM versus the NEM. In general, R-R were more abundant than G-R, except at the SCS-SWM stations where abundances were comparable. Multivariate statistical models indicate that as R-R and G-R were abundant in warmer seawaters, nitrate plus nitrite was a key factor negatively controlling R-R abundance while silicate was more positively related to G-R. Positive correlation between G-R and FL-R abundances and microscopic observations imply that like Rhizosolenia-associated Richelia, filaments released from Guinardia hosts can remain viable outside their diatom hosts for time periods on the order of days. Overall, results reveal different distribution patterns between the two rhizosolenoid-Richelia symbioses and both G-R and R-R likely contribute to FL-R in the field.

Tracing local sources and long-range transport of PM10 in central Taiwan by using chemical characteristics and Pb isotope ratios

Central Taiwan is among the most heavily polluted regions in Taiwan because of a complex mixing of local emissions from intense anthropogenic activities with natural dust. Long-range transport (LRT) of pollutants from outside Taiwan also contributes critically to the deterioration of air quality, especially during the northeast monsoon season. To identify the sources of particulate matter < 10 μm (PM10) in central Taiwan, this study performed several sampling campaigns, including three local events, one LRT event, and one dust storm event, during the northeast monsoon season of 2018/2019. The PM10 samples were analyzed for water-soluble ion and trace metal concentrations as well as Pb isotope ratios. Local sediments were also collected and analyzed to constrain chemical/isotopic signatures of natural sources. The Pb isotope data were interpreted together with the enrichment factors and elemental ratios of trace metals in PM10, and reanalysis data sets were used to delineate the sources of PM10 in central Taiwan. Our results suggested that Pb in PM10 was predominantly contributed by oil combustion and oil refineries during the local events (48–88%), whereas the lowest contributions were from coal combustion (< 21%). During periods of high wind speed, the contribution from natural sources increased significantly from 13 to 31%. Despite Pb represented only a small portion of PM10, a strong correlation (r = 0.89, p < 0.001, multiple regression analysis) between PM10 mass and the concentrations of Pb, V, and Al was observed in the study area, suggesting that the sources of PM10 in central Taiwan can be possibly tracked by using chemical characteristics and Pb isotopes in PM10. Moreover, the Pb isotopic signals of PM10 collected during the LRT event confirmed the impact of LRT from Mainland China, and the chemical characteristics of the PM10 significantly differed from those of the PM10 collected during local events. This study demonstrates the robustness of using a combination of Pb isotopic compositions and chemical characteristics in PM10 for source tracing in complex and heavily polluted areas.

The role of motorized boats in fishers’ productivity in marine protected versus non-protected areas in Davao Gulf, Philippines

The Philippine fisheries sector continues to play a critical role in the livelihood of coastal households; however, the country’s fisheries production level has been declining at the municipal level. To reverse this trend, marine protected areas are established in critical geographic areas to ensure that management and conservation follow sustainable fishing practices. Mabini, Davao de Oro, and San Isidro, Davao Oriental are coastal municipalities located in the southern Philippines. Mabini is a declared National Integrated Protected Area System (NIPAS) while San Isidro is a non-NIPAS fishing area. This paper aimed to identify the determinants of coastal fish catches among 406 fisherfolks in both Mabini and San Isidro during the Northeast Monsoon season during 2018–2019. The study utilized power analysis to calculate the sample size for two independent groups. Stratified random sampling was used to determine the respondents in each village. Further, quantile regression was used to estimate the Cobb–Douglas production function model in determining the impact of the drivers across varying fish catch levels. Effort time, boat length, input costs, other costs, distance, and boat type are significant drivers of catch output in Mabini, while for San Isidro, effort time, input costs, other costs, and distance variables are positively associated with fish output. Compared with San Isidro, fishers in Mabini using motorized boats have relatively higher fish catch levels, which is more pronounced in upper catch quantiles. Thus, access to motorized boats is crucial in addressing the impact of regulatory restrictions on fishers’ livelihood in marine protected areas.

A socio-ecological system perspective on trade interactions within artisanal fisheries in coastal Kenya

Assessments of coastal artisanal fisheries are progressively adopting a social-ecological system (SES) approach as an effective means to accumulate knowledge and integrate findings on different aspects of the fisheries. Ostrom’s SES framework was used to guide assessment of interactions between and within the harvesting and supply-chain processes and the effect of external drivers, seasonal monsoons and tourism, on both processes in a coastal artisanal fishery system in Gazi Bay, Kenya. Specific analyses focused on seasonal catch composition, key resource user groups involved in the fish trade and the resource units traded by each user group. The snowball method was used to identify key resource user groups within the fishery sector, who were then interviewed using semi-structured questionnaires (n = 60). Additionally, existing annual shore-based catch assessment and monthly fish landings data for the years 2014 and 2015 were incorporated for analysis of artisanal catch properties (species composition and weight). Comparison of seasonal catch composition was carried out using sample-based rarefaction curves. Higher fish landings and higher species diversity were recorded during the North-East Monsoon season. Further, a simple fish harvesting-supply network comprising of six key resource user groups (i.e. hotels, fish processing companies, dealers, small-scale fish processors (mama karanga), fish mongers and fishers) was outlined. The tourism industry, through hotels, creates a high demand for fish coinciding with a higher catchability and supply during the calm North-East Monsoon season and consequently, dealers hire migrant fishermen to target pelagic fish. Evidence of interactions within and between different fishery sub-systems, as well as the effect of monsoon seasons and tourism on the exploitation and market dynamics of the multispecies fishery, highlight the need for comprehensive management plans to strengthen self-organization among resource users and to increase adaptive capacity within the fishery system.

Long-term trends in gamma radiation monitoring at the multi-facility nuclear site, Kalpakkam, South-India

In this work, the analysis of the long-term environmental radiation monitoring data collected within the Department of Atomic Energy site, Kalpakkam using gamma monitors such as GammaTRACERS (GTs) from 2013 to 2018 and Autonomous Gamma Dose Loggers (AGDLs) located in the site boundary at distances from 1.25 to 2.5 km from 2016 to 2018 are presented with respect to dose variation in different locations/wind sectors/seasons. The average background dose rates are in the range of 140–220 nGy/h except at a location (GT2) where a dose rate of 400 ± 20 nGy/h is found. It is observed that the detectors generally measure the normal background doses and at times slightly higher doses (above background) due to exposure to 41Ar plume during normal operations from Madras Atomic Power Stations. The monitors were categorized into four groups: Group 1 to Group 4. Dose rates higher than normal were observed in Group 1 detectors during winter and North-east monsoon seasons and in Group 3 and Group 4 detectors during summer and South-west monsoon seasons and during January to March months in Group 2 detectors. The gamma dose rates during 41Ar plume transit vary in the range of 600–900 nGy/h. The cumulative annual effective doses at the site boundary, analyzed from 2016 to 2018, due to normal operational releases varied from 11 μSv to 114 μSv in different sectors which is significantly lower compared to annual dose limit (1000 μSv) for public.

High‐resolution climate change projection of northeast monsoon rainfall over peninsular India

AbstractIn this study, projected changes in mean northeast monsoon (NEM) rainfall and associated extreme rainfall and temperature events, over peninsular India (PI) and its six subdivisions, are quantified. High‐resolution dynamically downscaled simulations of the Weather Research and Forecasting (WRF) regional climate model driven by the boundary conditions from the Community Climate System Model version 4 (CCSM4) model (WRF‐CCSM4) are compared with statistically downscaled simulations of NASA Earth Exchange Global Daily Downscaled Projections (NEX‐GDDP). Over PI, these downscaled simulations show low bias in mean NEM rainfall (≤ − 0.44 mm·day−1) and high pattern correlation coefficient (≥0.75), giving confidence in their future projections. Under future warming over PI, both downscaled simulations project future significant enhancement in NEM rainfall with WRF‐CCSM4 projecting 1.98 mm·day−1 (83.78% change with respect to the present‐day mean) whereas the multimodel ensemble (MME) of eight NEX‐GDDP models project 0.67 ± 0.58 mm·day−1 (19.78%) by the midddle of the century and 1.42 ± 0.97 mm·day−1 (42.76%) by the end of the century. Analysis of extreme rainfall events shows that WRF‐CCSM4 projects future enhancement (reduction) in extreme rainfall (R95p) days over 91.4% (8.6%) of grid‐points over PI. In future, coastal areas of Karnataka and Andhra Pradesh will likely experience increased extreme rainfall occurrence by more than 25 days and 15–20 days respectively. Projected future enhancement in the mean and extreme NEM rainfall is attributed to the increased precipitable water under a warming climate. Future projection of extreme temperature indices shows an increase in minimum and maximum temperatures over PI during the NEM season. Over PI, future winter nights and days are found to be warmer than those in the present day and the temperature change in future winter nights is found to be larger than that in winter days. This climate change information would help decision‐makers in evaluating existing policies and devising revised policies to reduce risk due to climate change.

Hydrological Response of the Pampanga River Basin in the Philippines to Intense Tropical Cyclone Rainfall

AbstractThe Philippines is frequently affected by tropical cyclones (TCs), and understanding the flood response of the Pampanga River basin (PRB) from TC-induced rain is needed in effective disaster risk management. As large uncertainties remain in TC rain forecasting, we propose a simple checklist method for flood forecasting of the PRB that depends on the general TC track, season, and accumulated rainfall. To this end, flood events were selected based on the alert, alarm, and critical river height levels established by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA). Results show that all flood events in the PRB were induced by TCs. All intense TCs that directly traversed the PRB resulted in critical-level floods. These TCs also had the shortest flood onset of 7–27 h from alert to critical level. Flooding from distant landfalling TCs, on the other hand, are dependent on season. TCs traversing north (south) of the PRB induced flooding only during the southwest (northeast) monsoon season. These TCs can raise water levels from alert to critical in 11–48 h. Remote precipitation from non-landfalling TCs can also induce critical-level flooding but with a longer onset time of 59 h. These results indicate that a simple checklist method can serve as a useful tool for flood forecasting in regions with limited data and forecasting resources.

Alternative Water Resources Quality Assessment during Flood Disaster in Kuala Krai, Kelantan, Malaysia

Quality assessment of water resources is important to ensure the well-being of residents, especially the victims who are affected by floods and having difficulties in obtaining clean water supply when the floods hit. This paper seeks to discuss the quality assessment of water resources in the district of Kuala Krai, Kelantan. Field methods were used to collect water samples during the northeast monsoon season in the month of December 2016/January 2017 involving six well stations, four flood water stations and four rainfall stations. The quality assessment of water resources involved six key parameters, namely DO, pH, BOD, COD, NH3N and SS using the Water Quality Index (WQI) analysis. The results of the analysis showed that the WQI percentage of well and flood water stations accounted for 61.31 to 75.95% which is Class III of moderately contaminated status, except the T6 station that recorded 80.99% of WQI value which is Class II of good status. The findings also showed that all WQI values from the rainwater stations were at 87.85 to 89.10%, which is Class II of good status. This condition explains that the rainwater resources have better quality than the well and flood water resources. With the help of this research, the flood manager’s party can take systematic management measures in ensuring that flood victims receive water supplies during flood events. In this regard, infectious diseases resulted from the consumption of contaminated water among flood victims can be reduced.

EVALUATING THE EFFICIENCY OF HOUSEHOLD STORMWATER DETENTION SYSTEM

This paper describes the evaluation of water storing capacity of a household stormwater detention system based on field data. Collection of field data is often sidelined due to the cost and human capital incurred. However, the true value of field data is demonstrated here by comparing the observed and design data. A field test is completed in a real-life terrace house, utilizing the house’s 95m2 side canopy as roof catchment and 4.40m x 4.70m car porch area to station a detention tank. Precast concrete modular units with 3.9m3 effective storage volume are assembled within the tank. Downpipe with 0.1m diameter is installed to connect the roof gutter to the detention tank; while pipeline with 0.05m diameter is installed as the outlet from tank to the house perimeter drain. The mentioned setup is subjected to actual rainfalls from December 2019 till February 2020 that corresponded with the peak of Northeast Monsoon season. Ten observed storm events with peak hourly total rainfall readings ranging from 22 to 48mm are selected for analysis. Rainfall and water level readings from the field test allow the derivation of roof runoff volume and detained water volume in the tank. It is found that the household stormwater detention system is able to capture about 50% of the roof runoff. However, the current setup is found to cause flooding for rainfall over 40mm. The flooding issue, however, is undetected by the design data that underestimated the water storing capacity. This is due to the use of uncommon precast concrete modular units that may not have its flow characteristics represented by existing formula and model. No matter how uncommon the modular units be, various types and forms of stormwater detention system are becoming the new normal in the industry and field test is the best tool to validate their performances.

Seasonality of macrobenthic assemblages and the biotic environmental quality of the largest monsoonal estuary along the west coast of India.

This study deals with the macrobenthic assemblages and the biotic environmental quality of Kochi backwaters (KBW), India. Due to the heavy river discharge, extensive limnetic and turbid conditions prevailed in the KBW during the southwest monsoon (June to September). This exerted a profound adverse effect on the abundance, richness, and diversity of macrobenthic assemblages. Overall, mesohaline conditions with a clayey sand bottom substratum favored the high macrofaunal abundance during the southwest and northeast monsoon seasons. But mesohaline condition and sandy silt bottom were found to support high macrofaunal abundance in the KBW during the pre-monsoon season. Polychaete dominated the macrobenthic community, regardless of seasons. Capitella capitata, Heteromastus similis, Paraheteromastus sp., Prionospio cirrobranchiata, Minuspio cirrifera, Pagurapseudopsis kochindica, P. gymnophobia, Ctenapseudes indiana, C.chilkensis, Tanais sp., Villorita cyprinoides, Grandidierella sp., Ampelisca sp., and Littorina sp. were the dominant ones observed during the study. The sediment organic carbon, in general, showed a positive correlation with polychaete abundance during all three seasons. The ecological status of KBW during all three seasons was assessed as per BO2A index, which ranged from 0.05 to 0.18, suggesting a healthy to a moderately polluted bottom environmental condition.

Simulation of the Hydrodynamic Field in Nhat Le Estuary, Quang Binh Province

Hydrodynamic field is the primary research problem of all studies on coastal estuarine areas. Over the years, there have been many studies on Nhat Le estuary's region (Quang Binh). Still, these studies have not focused on simulating the characteristics of the hydrodynamics of this area. This study will present the ability to apply a mathematical model to simulate hydrodynamic fields for the region of Nhat Le estuary and Quang Binh sea by constructing the MIKE 21 model set based on the actual measurement database by the Center for Environmental Fluid Dynamics implemented in 2018. Through the calculation scenarios under different conditions, the longshore current mainly consists of Southeast - Northwest (especially with NE waves, the current direction is Northwest - Southeast) with current speed mostly in the range of 0.1 - 0.4 m/s. In estuarine areas, river flows have complicated developments, including many component flows. In the dry season, the river flow is not strong and is dominated by changes in the tide phase, withdrawal in a day. There are days of high flood flow in the flood season, overwhelming the tidal currents; the maximum flow velocity at the door can reach more than 6 m/s. Waves in the southwest monsoon season are relatively small, about 0.25 - 0.6 m; while the waves in the Northeast monsoon season are quite large and very strong during the storm, but when the depth is about -3 to -4 m, the wave height decreases sharply, spreading to the door. In particular, when there are floods in the river, the waves that propagate through this depth will almost calm.

Is flood water safe for consumption at evacuation centre in kuala krai district, kelantan, malaysia?

Clean water supply has an important role among flood victims at evacuation centers during the flood. However, the water supply from various unknown and unverified sources such as hygiene status can affect the flood victims health. Therefore, the purpose of this study is to evaluate the flood water quality in the Kuala Krai flooding areas. The methodology of data collection in this study are fieldwork methods. It has been used to collect flood water samples during the northeast monsoon season in December 2016 and January 2017. A total of four flood water stations have been select based on the four flood evacuation centers based on the number of flood victims. A total of 13 water quality parameters were analyzed: pH, DO, BOD, COD, SS, NH3N, turbidity, NO3, Fe, Mg, Ca, Cu and E. coli bacteria. Flood water quality assessment in this study is based on the Malaysian National Water Quality Standards by the Malaysia Department of Environment (DOE). The results showed that flood water quality was in class III which was considered as moderate pollution. This situation explains that flood water needs to be fully treated for drinking water. To ensure the safe water supply for flood victims, a water supply risk management during floods has to be developed to ensure flood victims will have a good clean water supply and reduce the spread of flood-related diseases.

Diagnostic analysis of two dos-à-dos extreme northeast monsoon seasons with dipolar rainfall performance

Northeast monsoon season over the southern peninsular India during October–December 2015 and 2016 saw two back-to-back extreme seasonal rainfall performances with excess rainfall leading to floods in 2015 and largely deficient rainfall leading to drought conditions in 2016. Contrasting climate settings and Asian winter monsoon circulation features and the modulations in the seasonal flow pattern over the peninsular India and the dynamical and thermo-dynamical features associated with such contrasting seasons are discussed. During 2015, strong El Nino and positive IOD led to strengthening of easterlies over the peninsular India which resisted the eastward propagation of MJO and confined it mostly in phase 2–4. Associated with positive IOD, enhanced warming prevailed over western Indian Ocean, which led to anomalous ascending motion over the Arabian Sea and adjoining southern peninsula in the winter monsoon Walker circulation feature with anomalous upper tropospheric divergent outflow over these regions. During 2016, weak La Nina, negative to neutral IOD, MJO in the other half of the hemisphere, anomalous low-level cyclonic circulation over the central parts of southern Bay of Bengal and anomalous subsidence over the peninsular India in the Walker circulation with the upper tropospheric divergent outflow shifted to east of 100° E were associated with weakening of easterlies and penetration of continental northerlies into the southern peninsula. Associated with good rainfall activity, there was mid-tropospheric warming of about 1–3 K/day during November 2015, but, in 2016, only a heat sink is observed over most parts of the peninsular India in the mid-troposphere.