The situation where your yard is very flat and foundation wall is not high enough, an underground slope is a good idea. The underground slope is really beneficial in terms of creating a relatively dry area of soil and allows one to dig the deep French drains at a distance from the foundation where it is secure for the structure and easy to dig.
CORRECTING DOWNSPOUT DRAINAGE ISSUES
The next step is to check how to correct any downspout drainage issues. Downspout drainage issue is a matter of concern and it is important to get the water out of the home and spread out over an area of the yard that can absorb it. Change your gutter and downspout arrangement if you have too much roof area draining.
The alternative option is the usage of a rain barrel to collect the surge of water when it rains and then slowly drain the barrel the following day. Attach it to a hose leading to a garden or flower bed. The important thing not to ignore is installing an overflow pipe on a rain barrel for the rainy days.
Connect with the drain system professional team to have full assistance.