2007 Volume 30 Issue 1 Pages 67-81
A sustainable water resources management has become a major concern all over the world. In agricultural areas, water quality degradation occurs due to excessive application of fertilizer especially where high yielding crops are cultivated. To make the balance between food production and environmental conservation, it is essential to evaluate the effects of agricultural activity on water environments and ecosystems. As is widely known, water temperature plays a major role in water quality dynamics through biogeochemical processes. The present study, therefore, aims to develop a mathematical model for simulating daily water temperature in paddy fields. In the model, only three meteorological data of air temperature, sunshine duration and relative humidity, and crop information of leaf area index (LAI) are required. Sensitivity analyses were conducted on each input variable for identifying the contribution of these variables to the water temperature estimation. As a result, the present model showed high applicability in estimating water temperature in paddy fields. Air temperature was found to have the strongest effects on water temperature, which was followed by relative humidity, sunshine duration and LAI. Despite the low contribution to the water temperature, LAI affected all of the heat fluxes, which would suggest the importance of the crop growth model. An integration with hydrological and water quality models are recommended for further application of the present model.
