# Math

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Take the greatest care with your significant digits. If you don't this qusestion is not do able. Llyn Gweision ( A welsh lake) has a surface area of 10km2. It is fed by two rivers: the afron Chwefru and the nant aeron. The Chwefru has a catchment area of 1250km2. The aeron has a catchment area of 2.400* 10 to the power of 6 ha. The outflow stream, the afon Rhondda has average annual flow rate of 1367.6ft3s-1 (c.f.s) Rainfall in the region is 40.0 inches y-1 and annual evaporation from the lake surface is 8.10*10 to the power of 6 m3. The equilibrium amount of water stored in the lake is 0.550km3. Of the total amount of rainfall over the Chwefru basin, 32.0% leaves the basin as streamflow. From the aeron basin, the annual streamflow amounts to an equivalent water depth of 33.87mm over the whole basin.Show that for the above inputs and outputs that change in storage=0. If 10% of the flow from the Chwefru is diverted for municipal water supply, how much will lake level fall in one year; is all else staying the same?