$($a$)$ You$$ve been charged with estimating the average annual evaporation rate for $2018-2020$ of Lake Elsinore, a $1200$ ha natural lake in San Jacinto Basin. The Elsinore Valley Municipal Water District has an evaporation pan that was calibrated against an evaporation estimate based the Penman equation $($and an intensive monitoring campaign$)$ in $2017.$ The pan evaporation in $2017($E p$2017)$ was $270$ cm and the Penman estimate of evaporation for Lake Elsinore was $135$ cm$.$ Subsequent pan evaporation rates by year are as follows:

Ep$2018=330$ cm

Ep$2019=130$ cm

Ep$2020=240$ cm

$($b$)$ What was the average annual volumetric flux rate of evaporation over this time period in m$3/$yr$?$