drainage drainage reclamation channel is an outdated way to lower groundwater levels. dikes of gray stones. supplies water to irri

agriculture blue bridge channel concrete dam dikes distribution ditch drainage dry elbe farm farmer farming field fields flood grass gray green groundwater gutter irri irrigate irrigation land landscape landscaping lawn level levels lower lowland lowlands natural nature outdated park polder protection rainwater reclamation recultivation renovation rock solution source stones stream supplies supply swamp system technical water way wetland