1.  

A 226-ha lake receives 854mm of precipitation over a year. The average evaporation rate is 3.5mm d' over exactly half the year, and 0.5mm d for the other half. A stream drains the lake at an annual average discharge of 44 L sd. If there are no detectable surface water inputs to the lake what must the net groundwater flux density be to maintain the lake's storage over the year? (Assume the lake area receiving groundwater is equivalent to the lake storage area.) Does this value represent an input or an output to the lake? The final answer should be in mm per year.