Chapter 28, Problem 1TS

To determine

The percentage of freshwater supplied by polar ice caps, groundwater, and streams, lakes and rivers.

Answer to Problem 1TS

The percentage of freshwater supplied by polar ice caps is $77.6\%$, groundwater is $22.1\%$, and streams, lakes and rivers is $0.33\%$.

Explanation of Solution

Given info: The fresh water supply on Earth is $2.76\%$.

The amount of water locked in icecaps and glaciers is $2.14\%$, underground water is nearly $0.61\%$, and surface water is $0.009\%$. Moreover, water in the form of soil moisture is $0.005\%$.

Write the expression for the scale up factor.

$S\text{=}\frac{100\%}{f}$

Here,

$f$ is the fresh water supplied

Substitute $2.76\%$ for $f$ in the above expression to get $S$.

$\begin{array}{c}S=\frac{100\%}{f}\\ =\frac{100\%}{2.76\%}\\ =36.2318841\end{array}$

Write the expression for the percentage of fresh water in icecaps and glaciers.

$P_i=S\times 2.14\%$

Substitute, $36.2318841$ for $S$ in the above expression to get $P_i$.

$\begin{array}{c}{P}_i=36.2318841\times 2.14\%\\ P_i\approx 77.6\%\end{array}$

Write the expression for the percentage of fresh water in ground.

$P_g=S\times 0.61\%$

Substitute, $36.2318841$ for $S$ in the above expression to get the value of $P_g$

$\begin{array}{c}{P}_g=36.2318841\times 0.61\%\\ P_g\approx 22.1\%\end{array}$

Write the expression for the percentage of fresh water in surface water bodies.

$P_s=S\times 0.009\%$

Substitute, $36.2318841$ for $S$ in the above expression to get the value of $P_g$.

$\begin{array}{c}{P}_g=36.2318841\times 0.009\%\\ P_g\approx 0.33\%\end{array}$

Conclusion:

Therefore, the percentage of freshwater supplied by polar ice caps is $77.6\%$, groundwater is $22.1\%$, and streams, lakes and rivers is $0.33\%$.