Using a dataset for water table fluctuations in wetlands and a basic equation for the evapotranspiration rates, evapotranspiration rates are estimated with MATLAB by approximating and averaging the nightly rise in water levels and daily net change in water levels. The data for these fluctuations depicts a sharp decrease in water table levels during the daylight hours, when phreatophytic vegetation transpiration rates and evaporation rates are high. The water level increase during nighttime hours is due to low evapotranspiration levels and a somewhat constant flow of groundwater into the water table. The specific yield refers to the sensitivity of water table levels to changes in water volume in the area. After eliminating data affected by recent rainfall, a set of slopes for nightly recovery rates and for net daily water level changes is estimated for each day and averaged together for monthly approximations. Assuming the area’s specific yield is one and using the previously discussed averaged values, monthly approximations for evapotranspiration rates are calculated.
