well as a temp fix find as much rubble and stuff as you can and lay it in swales across the stream of water coming down to slow down the water, that is what they do along expressways in Michigan. you can use stones, bricks, logs, branches, or piles of anything..even old fencing with some stuf stuck into it..probably even pallents..just anything to slow the flow of water..
then as you are able to build up swales to hold the water in different levels..by throwing other stuff on top..like
compost, soil, logs,
hay, anything to build up something to hold that water..
make them in a crescent shape to hold more water than a flat shape..like a bunch of small dams..
good luck to you on this..
another thing you can do is what we did here..dig a trench, bury perforated pipe with a sock liner over it..and then cover with gravel and then grow sod over that..it will drain BELOW grade to your pond