Question about temperature simulation

I have a question about temperature simulate.

the data i have about temperature contain air temperature and inflow temperature, not including solar radiation, if i want to get the temperature simulation in a pond or river, which mode should i choose and will the result be reliable?

Hi, there is no substitute to the real measured data while doing any kind of simulation. For your situation, you can either use CEQUAL-W2 option or Full heat balance for the temperature simulation. Do you have all other data such as precipitation, humidity, cloud cover ? If you have those data, then you could choose to compute the solar radiation internally in the model. It all depends on how close you get to your measured data without including solar radiation data. Which time of the year and which place are you doing simulation ? Solar radiation and cloud cover definitely has a big impact in temperature simulation. If you are doing simulation in US water bodies, you could find the regional airport near to your study area and then download / request solar radiation data along with other heat exchange input parameters.