Water temperature characteristics of evaporation ponds with different areas and improvement of Penman model

By analyzing the water temperature characteristics of evaporation ponds, we can deeply understand the energy balance characteristics of evaporation ponds, study the calculation error sources of Penman model, and improve the model, which is of great significance for agricultural planning, water source assessment and hydrological forecast. Based on the water temperature, evaporation capacity and meteorological data of three evaporation ponds with different areas in Taigu water balance experimental station, the vertical distribution of water temperature and the variation characteristics of evaporation capacity of each evaporation pond were analyzed. The model parameters suitable for the three evaporation ponds were explored based on Penman model. The results showed that the water temperature of the 1 m² and 5 m² evaporation ponds decreased significantly with the increase of water depth from April to August, that of the 20 m² evaporation pond was higher, which was uniformly distributed. The monthly evaporation of 1 m² and 5 m² evaporation ponds was similar, whose trend was consistent with the variation of net radiation, and the evaporation peak of 20 m² evaporation pond lagged behind the net radiation peak by 3 months. The addition of comprehensive influence parameters reflecting energy other than net radiation to the Penman model can improve the calculation accuracy of the model, especially in summer. The parameter values of 1 m², 5 m² and 20 m² evaporation ponds in summer are 3.5, 3.3 and 2.1, respectively.