In water-resources engineering, the sizing or reservoirs depends on accurate estimates of water flow in the river that is being impounded. For some rivers, long-term historical records of such flow data are difficult to obtain. In contrast, meteorological data on precipitation is often available for many years past. Therefore, it is often useful to determine a relationship between flow and precipitation. This relationship can then be used to estimate flows for years when only precipitation measurements were made. The following data is available for a river that is to be dammed:

(a) Plot the data.
(b) Fit a straight line to the data with linear regression. Superimpose this line on your plot.
(c) Use the best-fit line to predict the annual water flow if the precipitation is 120 cm.
(d) If the drainage area is 1100 km2, estimate what fraction of the precipitation is lost via processes such as evaporation, deep groundwater infiltration, and consumptiveuse.

Precipitation, cm 88 9 108.5 104.1 139.7 127 146 16.7 116.8 99.1 94 19.5 16.1 Flow. m's 23.2 15.3 16.6 18.1