Fixing these kinds of issues are massive undertakings. First you need to check the whole path and start in specific places, because if you start in the wrong place you move the issue to another point where the potential for disaster might be even bigger.

For example, the water level before a dyked area is raised allowing water to pass over a natural barrier and flood an entire valley. Or you move the issue downstream and flood larger areas. When dealing with nature, you are dealing with massive forces.

The Dutch Duke system is a product of hundreds of years of development, and in some cases costly trial and error.