Uplift Force on Gravity Dam

Q. A gravity dam profile is as shown in figure

If the water on the downstream is completely removed, the uplift force will_______
(Assume unit weight of water = $10kN/m^3$)

1. increase by 120 kN/m
2. decrease by 40 kN/m
3. decrease by 600 kN/m
4. increase by 400 kN/m

Q. Uplift force acting on a gravity dam having height $H_1$ and water level on upstream side and downstream side as $h_1$ and $h_2$ metres is $U_1$. Another gravity dam of same slope and construction material is having a height of 1.2 times $H_1$; but has the same water levels $h_1$ and $h_2$ as that of first gravity dam. If the uplift force acting on the second gravity dam is $U_2$, which of the following relationships will be correct?
(assume base width is same for both dams)

1. $U_2=1.2U_1$
2. $U_2=1.44U_1$
3. $U_2=0.8U_1$
4. $U_2=U_1$