Li Bing's biggest problem while building the irrigation ditches was the massive amount of silt and debris carried by the Min River, which continuously filled up the ditches. He solved this by constructing a special dividing weir known as the "Fish Mouth" to help divert the silt-laden water away from the irrigation system.
They used gated ditches and leaves.
salination of rivers
Grinding a lens to the required precision aw well as the mass of the lens distorting its shape.
i am not sure.
salination of rivers
Your face was biggest problem .
irrigation
The cultivable land is fixed but the, pollution is increasing variability of rainfall is the biggest problem faced by the Indian Farmer's is therefore very,important to develop modern irrigation system and increase the production in the areas of cultivable land.
The Sumerians couldn't take the heat so they made a irrigation system. The built canals that connect to the river but the problem was that there crops would get ruined from the floods the irrigation system.
Verrazano's biggest problem was that his ship sinked and drowned
They build a kind of irrigation system
I think the biggest problem was the small buisnesses got ran out of buisness