Shallow-water temperature is an essential factor in various ecosystems, particularly in paddy fields, as damage to paddy rice due to high temperatures may severely affect grain yields. Here, a calculation scheme of paddy field water temperature is proposed to calculate water temperature dynamics in paddy fields and comprises three components: (1) the two-layer heat balance model, which is adopted to calculate water temperature, whereby the solution to the heat balance of paddy water considers the effect of the vegetation layer; (2) a novel method of estimating the plant growth status parameter calculated from thermal storage variations of paddy water to quantify the effect of vegetation layers on water temperature; and (3) a series of correction methods for meteorological parameters to ensure that the parameters measured far from the paddy field are suitable for the model. Estimation of the plant growth status parameter obtained from model validation showed that the proposed method has generality under different weather conditions but with the same rice cultivars. Water temperature calculations showed high consistency, yielding root mean square error values between the measured and calculated water temperatures of 1.65 and 0.91 °C in the full observation period and during the nighttime heatwave period, respectively. Hence, the proposed calculation scheme simplifies the simulating conditions using only the common meteorological factors from the existing weather stations and fundamental paddy factors and simulation of the thermal conditions of paddy fields. This effectively reduces the cost of water temperature calculations.

浅水温度是各种生态系统（尤其是稻田）的重要因素，因为高温对水稻的损害可能会严重影响谷物的单产。在此，提出了一种稻田水温计算方案，用于计算稻田水温动态，该方案包括三个部分：（1）采用两层热平衡模型计算水温，从而求解水热。稻田水平衡考虑了植被层的影响；（2）估算从稻田储水量计算得出的植物生长状态参数的新方法，以量化植被层对水温的影响；（3）一系列的气象参数校正方法，以确保远离稻田测得的参数适用于该模型。通过模型验证获得的植物生长状态参数的估计表明，该方法在不同的天气条件下具有相同的水稻品种，具有通用性。水温计算显示出很高的一致性，在整个观测期间和夜间热浪期间，在测得的和计算出的水温分别为1.65和0.91°C时，得出均方根误差值。因此，提出的计算方案仅使用来自现有气象站的常见气象因素和基本稻田因子简化了模拟条件，并模拟了稻田的热力条件。