Changing trends of rainfall and sediment fluxes in the Kinta River catchment, Malaysia

The Kinta River, draining an area of 2566 km2, originates in the Korbu Mountain in Perak, Malaysia, and flows through heterogeneous, mixed land uses ranging from extensive forests to mining, rubber and oil palm plantations, and urban development. A land use change analysis of the Kinta River catchment was carried out together with assessment of the long-term trend in rainfall and sediment fluxes. The Mann-Kendall test was used to examine and assess the long-term trends in rainfall and its relationship with the sediment discharge trend. The land use analysis shows that forests, water bodies and mining land declined whilst built and agricultural land use increased significantly. This has influenced the sediment flux of the catchment. However, most of the rainfall stations and river gauging stations are experiencing an increasing trends, except at Kinta river at Tg. Rambutan. Sediment flux shows a net erosion for the period from 1961 to 1969. The total annual sediment discharge in the Kinta River catchment was low with an average rate of 1,757 t/km2/year. From 1970 to 1985, the annual sediment yield rose to an average rate of 4062 t/km2/year. Afterwards, from 1986 to 1993, the total annual sediment discharge decreased to an average rate of 1,306 t/km2/year and increased back during the period 1994 to 2000 to 2109 t/km2/year. From 2001 to 2006 the average sediment flux rate declined to 865 t/km2/year. The decline was almost 80% from the 1970s. High sediment flux in the early 1970s is partly associated with reduced tin mining activities in the area. This decreasing trend in sediment delivery leaving the Kinta River catchment is expected to continue dropping in the future

Typhoon activity and some important parameters in the South China Sea

This study aims to statistically describe temporal and spatial variations of sea surface temperature (SST), latent heat flux (LHF), sensible heat flux (SHF), and precipitation rate with typhoon activity over the South China Sea. The correlations of the parameters and their connections with the physical phenomena are clearly presented. This is fundamental to predict a typhoon's intensity and track. The effects were investigated from 1991 to 2011 based on archived data from the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP-NCAR) and the number of typhoons were sourced from the International Best Track Archive for Climate Stewardship (IBTrACS). The results showed that most typhoons occurred in August and September, which was related to high temperature in the summer season and the southwest monsoon in the area. The maximum mean values of SST in May and June were related to the East Asian Monsoon. The average values of LHF were highest in July, and the mean values of SHF were highest in July and August. SHF varied gradually at different months compared with LHF. In addition, the average of precipitation rate was highest in November, which can be related to the northeasterly winter monsoon. The relationships of the aforementioned parameters were obtained using Pearson's correlation analysis. Moreover, the highest and lowest mean values of the parameters in different areas were considered, and their spatial relationships were analyzed

Developmental pressure and nutrient concentrations of Sungai Petani catchment, Kedah

Developmental pressure is encroaching many small towns and cities in Malaysia. The wave of development has caused small towns like Sungai Petani Town and its surrounding catchment area to be affected by the changing land uses due to developmental pressure in the catchment area. This paper examined the temporal patterns of nutrient concentrations longitudinally along the Sungai Petani River from March 2012 to December 2013 due to the unequal distribution of ‘green’ areas with respect to the ‘grey’ areas. Four stations were chosen longitudinally from upper Sungai Petani River downstream towards Sungai Petani Town and were monitored from upstream part of Sungai Petani Town which is the least affected station, through Sungai Petani Town and towards the downstream station below the Sungai Petani Town. Water sampling at all stations were performed through grab sampling technique at depths of about 0.5 m. Water samples were analysed only for dissolved forms of nitrate (NO3), ammoniacal nitrogen (NH4), total nitrogen (TN), phosphate (P04) and total phosphorus (TP).The samples were analysed using standard procedure by Adams (1989) and APHA (1998). Most of the nutrient concentrations increased from upper station to the second station situated in the Sungai Petani Town. Nitrate increases by 6 per cent and 15 per cent in 2012 and 2013 respectively, ammonia increases by 11 per cent and 35 per cent respectively, TN by 16 per cent and 22 per cent respectively, TP by 45 per cent and 44 per cent respectively, and PO4 by 13 per cent and 90 per cent respectively. On the other hand, the concentration decreases from second to the last station at the outlet downstream of the town. Nitrate decreases by 16 per cent and 27 per cent in 2012 and 2013 respectively, ammonia increases by 28 per cent and 44 per cent respectively. TN by 34 per cent and 41 per cent respectively, TP 16 per cent and 28 per cent respectively, and PO4 increases another 2.4 per cent in 2012 but decline by 42 per cent in 2013. The effect of urbanisation and development is clearly the main cause of the deteriorating water environment as shown by the increasing nutrient concentration along the Sungai Petani River where most of the parameters are above the permissible threshold limit

Suspended sediment and phosphorus budget and trophic status of Bukit Merah Reservoir, Perak, Malaysia

Bukit Merah Reservoir (BMR) is one of the 51 impoundments in Malaysia. BMR is the oldest reservoir built in the early 1900s originally to store water for irrigation, but nowadays its functions include also flood control and water supply. Nowadays, it is threatened by land use change in the upper catchments and surrounding activities, which feeding eroded material and chemicals into the reservoir. Suspended sediment, as well as, nutrient fluxes into BMR are becoming an increasing threat to the reservoir, as its sedimentation and eutrophication accelerate. This paper discusses our study on the BMR carried out between March 2008 and April 2009 to assess the water quality status, and to determine the sediment and Total Phosphorus (TP) influx into the south pool lake. An estimated amount of suspended sediment fluxes of about 2,900 t year−1 came from the north pool lake (18%) and 12,900 t year−1 from the main Kurau River inlet (82% of the total input to the BMR). Of these total sediment input (nearly 15,800 t) about 5,600 t (36%) of the total sediment influx was trapped in the BMR. TP influx was about 18.8 t year−1 and about 7 t (37%) was trapped in the reservoir. The amount sediment and TP stored in the BMR affect the water quality of the lake, therefore the mean trophic state of the lake is eutrophic (TSI of 54.4) related to high productivity. Increasing sediment input into the reservoir has affected the reservoir volume and frequent flooding down-stream of the reservoir during rainy seasons, while eutrophication has caused the lake water quality deterioration

Variation of suspended sediment transport in the Timah Tasoh Reservoir catchment, Perlis, Malaysia : human impacts and the role of tropical storms

In recent years, soil erosion, sediment transport and deterioration of water quality in many river systems in Malaysia have become major concerns. Headwater streams emanating from forested and agricultural lands supply much of the potable water in this country. The quality, quantity and timing of water from these headwater catchments are strongly influenced by human activities such as deforestation associated with land conversion for agricultural purposes. This study investigates the impact of human acitivities and the role of tropical storms on the variation of sediment transported into the Timah tasoh Reservoir, Perlis, Malaysia

Accelerated development and changes in rainfall trends and variations in Malaysia: a case study of the Kinta River basin 1960-2006

Environmental impact induced by rapid urbanization and development may be traced from changes in local rainfall trends and variations. This study examined the trends and variations of rainfall in the Kinta River basin, Perak, a region in Malaysia that is rapidly urbanizing and developing. Long-term rainfall data from the year 1960 to 2006 were obtained from the Department of Irrigation and Drainage (DID) involving 15 rainfall stations in the Kinta River basin were employed to analyse long-term variations and precipitation trends. Results of the Mann-Kendall tests show that the Kinta River basin received high rainfall during the Northeast monsoon (950 mm) as compared to that received during the Southwest monsoon (309 mm). The tests also showed that the annual rainfall in the Kinta River basin had an increasing trend from the year 1960-2006 with the value of S=217 as did the monthly rainfall (except in the months of June and July 8) and seasonal rainfall during Northeast monsoon (S = 216) and Southwest monsoon (S = 97). These trends of increasing rainfall appeared to give the early impression that the basin should not have any problems with regard to water supply, in particular, for the purpose of agricultural irrigation and domestic use. However, careful planning should still be undertaken in view of the rapid development of the basin due to rapid urbanisation of the areas surrounding the Ipoh City as there will certainly be growing demand for water in this area in the near future

Residual concentration of PAHs in seafood from Hormozgan province, Iran : human health risk assessment for urban population.

This study is to determine the concentrations of sixteen poly aromatic hydrocarbons in eighteen pooled samples of fish, shrimp, crab and bivalve from markets of Hormozgan province, Iran. The poly aromatic hydrocarbon levels varied from 16 ± 8.4 to 28.18 ± 3.74 ng/g wet weight. The investigated samples were classified as minimally contaminated. Distribution patterns showed that PAHs with 4, 5 and 6 rings dominated, confirming the pyroge nic source of detected PAHs. Fish contributed more than other biota groups in transforming of PAHs to Hormozgan Province people. The average of B (a)P eq)values for the studied biota was 2.71 ± 2.28 ng/g that was greater than calculated local screen value. This finding was implemented in poor quality of studied biota and necessity for risk management

Suspended sediment, phosphorus budget and trophic status of Bukit Merah Reservoir, Perak, Malaysia

Bukit Merah Reservoir (BMR) is one of the 51 impoundments in Malaysia. BMR is the oldest reservoir built in the early 1900s originally to store water for irrigation, but nowadays its functions include also flood control and water supply. Nowadays, it is threatened by land use change in the upper catchments and surrounding activities, which feeding eroded material and chemicals into the reservoir. Suspended sediment, as well as, nutrient fluxes into BMR are becoming an increasing threat to the reservoir, as its sedimentation and eutrophication accelerate. This paper discusses our study on the BMR carried out between March 2008 and April 2009 to assess the water quality status, and to determine the sediment and Total Phosphorus (TP) influx into the south pool lake. An estimated amount of suspended sediment fluxes of about 2,900 t year-1 came from the north pool lake (18%) and 12,900 t year-1 from the main Kurau River inlet (82% of the total input to the BMR). Of these total sediment input (nearly 15,800 t) about 5,600 t (36%) of the total sediment influx was trapped in the BMR. TP influx was about 18.8 t year-1 and about 7 t (37%) was trapped in the reservoir. The amount sediment and TP stored in the BMR affect the water quality of the lake, therefore the mean trophic state of the lake is eutrophic (TSI of 54.4) related to high productivity. Increasing sediment input into the reservoir has affected the reservoir volume and frequent flooding downstream of the reservoir during rainy seasons, while eutrophication has caused the lake water quality deterioration

PCBs and DDTs in surface mangrove sediments from the south of Iran (ID NO. 048)

Mangrove sediments were collected during wet and dry seasons from nine stations in Khamir, Laft and natural reservoir mangrove-dense areas of Hormozgan province in the south of Iran. Σ PCBs ranged from 5.33 to 15.5 ng/g dry weight and the dominant congener was no.153. Average Σ DDTs for Khamir and Laft mangroves were 16.58 ± 1.51 and 18.8 ± 9.98 ng/g dry weight. DDT was more abundant than DDE and DDD isomers, which indicated the input of DDT. The sediment quality guideline shows that the concentration of Σ PCBs were below the ER-M guideline, whereas levels of Σ DDTs were between ER-L and ER-M. The mangrove ecosystem in Hormozgan province is suffering from urban and industrial development