5 research outputs found
Foraging behavior of stingless bee Heterotrigona itama (Cockerell, 1918) (Hymenoptera : Apidae : Meliponini)
No full textRainfall, evapotranspiration and rainfall deficit trend in Alor Setar, Malaysia
No full textRainfall and potential evapotranspiration are important variables in water balance study. Rainfall data were obtained from Malaysian Meteorological Department while estimates of potential evapotranspiration were calculated using Penman-Monteith method. Trend analysis of monthly and annual rainfall, potential evapotranspiration and rainfall deficit are essential to manage irrigation system in agricultural systems. This is because changes in trend of these parameters may affect the water cycle and ecosystem. Annual and monthly values of these variables were analysed from 1980-2009. Results indicated increasing trends of 16.2 mm yr-1 and 3.01 mm yr-1 for both annual rainfall and potential evapotranspiration, respectively. Consequently, these trends resulted in annual rainfall deficit of 1.69 mm per year. </jats:p
Sensitivity Analysis in Watershed Model Using SUFI-2 Algorithm
No full textAbstractThe idea of watershed modeling is embedded in the interrelationships of geospatial and hydro-meteorological data and represented by mathematical abstractions. The behavior of each process is controlled by its attributes as well as by its interaction with other processes active in the catchment. Sensitivity analysis is an integral part of model development and involves analytical examination of input parameters to aid in model validation and provide guidance for future research. The Soil Water Assessment Tool (SWAT) model is utilized in the study for the simulation of the daily streamflow. Sensitivities of 21 input parameters have been analyzed using the SUFI-2 algorithm in SWAT Calibration Uncertainties Program (SWAT_CUP). For Langat River Basin, five SWAT input parameters show the most sensitive for both of the local and global sensitivity procedures, including of CN2.mgt, GW_Delay.gw, SLOPE.hru, SOL_AWC.sol and SOL_K.sol
Nutrients dynamics and trophic status of lake Kenyir
No full textInformation about nutrients dynamics is very important for the lake’s productivity and ecosystem. Such information is lacking in the case of lake Kenyir, which is the largest man-made lake in Malaysia. A 12-month study (Jan-Dec 2017) was conducted to understand spatio-temporal nutrients dynamics and trophic status of the lake Kenyir. The study was conducted in three sampling zones (downstream, middle and upstream) in the Tekak river located northeast of lake Kenyir. Each sampling zone was subdivided into three sampling sites, which were considered as replications. The distance between any two sampling sites was approximately 500 m. A series of water quality parameters (temperature, dissolved oxygen, pH, conductivity, nitrate-nitrogen, nitrite-nitrogen and ammonia-nitrogen, phosphate-phosphorous and chlorophyll-a) and trophic status were determined monthly in each sampling site. Results indicate that all water quality parameters remained within expected ranges for aquatic animal particularly for fish. According to Malaysian National Water Quality Standards, most of the water quality parameters are in class I. All water quality parameters significantly (p0.05). Both total suspended solid and turbidity decreased from upstream to downstream. Chlorophyll-a showed two low value loops: one from March to May and another from August to December. The highest chlorophyll-a was observed in June compared to other months. A significant negative correlation (r=-0.29, p<0.01) was observed between chlorophyll-a and temperature. TRIX index significantly changed over time. It indicates that water of lake Kenyir was oligotrophic (low productive) with low nutrients concentrations. The results of this study are very important for regular ecological monitoring and conservation of the lake. A proper management can improve the productivity of this lake
Durian yield trends and distribution patterns in peninsular Malaysia
No full textThis study mainly aimed at gathering information on durian production trends and distribution in Peninsular Malaysia. Time series data from 2000 to 2017 involving planted areas and their respective production of durian were used for the analysis. The production trends and the magnitude of the slopes for all planted areas were then analyzed using Mann-Kendall and Sen's slope estimator. The results indicated that the hectarage of planted areas showed a downward trend in most parts except for Raub and Rembau districts. Despite the decrease in areas planted with durian, some areas exhibited an upward trend in annual production, particularly in the northern and central regions. This study also revealed that there was a shift in the distribution of durian production throughout the study period. These findings will be useful for policymakers and practitioners to improve durian orchard planning and management. However, future research should be conducted to determine the impact of climate variability on the shifting of durian production in Peninsular Malaysia
