Pond heat and temperature regulation (PHATR): Modeling temperature and energy balances in earthen outdoor aquaculture ponds

A pond heat and temperature regulation (PHATR) model was designed to: (1) predict the temperature for earthen outdoor aquaculture ponds and (2) determine the size of energy transfer mechanisms affecting energy gains or losses for these ponds. The model solves a first order, no-linear differential equation using a 4th order Runge-Kutta numerical method and various input data (weather data, pond characteristics and flow rate data). Output data (predicted pond temperature) was compared to measured pond temperature collected from the warmwater ponds at the Louisiana State University Agricultural Center Aquaculture Research Station, Baton Rouge, Louisiana. The model over-predicted the temperature for unheated ponds by 0.7 °C and for heated ponds by 2.6 °C. Fluctuations in flowrates of warm water used to heat the pond are believed to be responsible for the greater error in predicting heated pond temperatures. On average, the two most important energy vectors for unheated ponds were longwave pond radiation (39%) and longwave sky radiation (31%). At certain times, solar radiation accounted for as much as 49% of all energy transferred to unheated ponds. For heated ponds, on average, important energy transfer mechanisms were longwave pond radiation (25%), longwave sky radiation (19%), warm geothermal-well water (19%) and discharged water (15%). At certain times, solar radiation accounted for as much as 50% and warm well water 60% of all energy transferred to heated ponds.