thermodynamics - Energy Analysis of Niagara Falls in Linus Pauling's "General Chemistry"

I just started reading Linus Pauling's "General Chemistry" and the first example confuses me. He writes:

Example 1-1. Niagara Falls (Horseshoe) is 160 feet high. How much warmer is the water at the bottom than at the top, as the result of the conversion of potential energy into thermal energy? The standard acceleration of gravity is 9.80665 m s$^{-2}$.

Solution. The gravitational force on a mass of 1 kg at the earth's surface is 9.80665 N. The change is [sic] potential energy of 1 kg over a vertical distance $h$ (in meters) is 9.80665 $\times$ $h$ J. In this problem $h$ has the value 0.3048 $\times$ 160 = 48.77 m (conversion factor from Appendix I); hence the change in potential energy produces 9.80665 $\times$ 48.77 = 478 J to thermal energy. The energy required to raise the temperature of 1 kg of water by 1$^{\circ}$C is given above as 1 kcal = 4.184 kJ = 4184 J. Hence the increase in temperature of the water is 478/4184 = 0.114$^{\circ}$C.

Now what I don't understand is why he doesn't account for change in kinetic energy and heat flow between the water and the environment.

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