How to deal with socio economic constraints like unavailability of land, diffuse pollution from farms etc in river restoration projects?

Many restoration projects in rivers are constrained by several factors like unavailability of land in the flood plain due to urban development, farmers in the vicinity of the rivers who use natural fertilizers for their farms, which leach into the rivers and other such factors.

Which are the ways to deal with such challenges ? For example: Financial incentives are given to farmers for creation of buffer strips (where no fertilizers are added) in the vicinity of the river in their farms in some countries (Eg. Scotland), is this feasible in large scale restoration projects ? Can you share some ideas and case studies from your experiences?