Re-route rivers? Have we done feasibility or 'fisibility' studies?

Governor Ferdinand Waititu. Photo/CITIZEN TV Kenya

I have seen mixed reactions on matters re-routing of rivers in the city and its environs as opposed to demolishing buildings built on riparian lands.
This is after Kiambu Governor Ferdinand Waititu alias Baba Yao made the remarks which have been received with a pinch of salt.
The re-routing or as Google calls it River engineering, is the process of planned human intervention in the course, characteristics, or flow of a river with the intention of producing some defined benefit.
This kind of environmental change is essential as it helps protect against flooding, or to make passage along or across rivers easier.
However there are also drastic effects on the same rivers once re-routing is done.
A wise man says the day the bottom of the bucket falls there is no stoppage
When Governor Baba Yao calls on the government to stop demolishing illegally built structures i ask myself this; Why would a government spare some illegal structure built on riparian land, or even reserve? Did the owners of these properties do due diligence on the land before the commenced on building? A lawyer friend tells me that most people just buy land, get title deeds and start on development without visiting the survey's office which can easily asnwr such questions most Kenyans now have.
I am pushed to ask why would the government have to spend more millions buying a piece of land to just re-route a river on whose path you as a developer has set up some structure?

In the USA, one Kissimmee River was once re-routed and it helped prevent flooding in certain areas which allowed citizens to expand into previously uninhabitable territories.
However the consequence led to massive destruction of the ecosystem surrounding it. Endangered, threatened, migratory, and many other kind of species which called the floodplains and rivers of the Kissimmee their home found themselves living in a now uninhabitable area.
Fishermen and locals, who had relied on the river as a source of income and sustenance, now had to turn to other methods to make a living.
 With the reconstruction in 2014, wildlife begun to return along with the native, untouched land that Florida was once famous for.
Before we all subscribe to a populist move by Governor Waititu it is wise we way options, even if it is in our verbal engagements.