4. Conclusion

Figure 7. Isotherm in the Durian Tunggal Lake during (a) high wind, well-mixed condition and (b) low wind, differential

Figure 8. Temperature and current velocity pattern in Durian Tunggal Lake during (a) high wind, (b) mid-wind speed,

heating condition. Numbers represent profiling locations.

82 Applications in Water Systems Management and Modeling

heavy rain, and (c) low wind.

The hydrodynamic studies of the three lakes in Malaysia here indicate distinct variation of the circulation. The mixing regime is shaped by the bathymetry of the lakes in relation to changes in winds, temperature-solar radiation, and inflows. This study found variation in the major driving force of the hydrodynamic pattern between lakes. Hydrodynamic simulations showed that the Bukit Merah and Durian Tunggal reservoirs are more sensitive to wind-driven motion. Bera Lake is more sensitive to flood inflow by the main river during the monsoon season. Convective motion driven by water temperature gradient was important for Bukit Merah and Bera Lake. The horizontal gradient in the former was driven by variation in depth between shallow and deeper regions, while in the latter it was influenced by variation between sheltered areas and open areas. The hydrodynamic models were capable of evaluating the changes in the stratification pattern and physical process created by the effect of the wind on the lake. This will aid in identifying upwelling and downwelling areas and spatial water quality variation and plankton community structure.

The model provides tool for understanding the hydrodynamic characteristics of lakes. The findings from the hydrodynamic analysis, such as water column and circulation pattern generated by the model, will become useful as the basis for the study of the water quality and environmental variations in water bodies.
