Do I need to provide any measures around the open ditches described below:

I have uncovered 2 x 150yr old underground water culverts each about 200m long in one of my fields.

This uncovering has created access ditches for both culverts about 0.5m deep to 1m deep from culvert top to ground level.
I have left the culvert sandstone tops in place.

I need to monitor the culverts over a number of months to determine how much ground water they deal with before I design a new field drain system.
To carry out the monitoring I will lift selected culvert tops, identify water flow and return the tops immediately.

The culverts are about 0.75m (30") wide & 0.5m (20") high and consist of flat sandstone slab bottom with loose laid sandstone walls covered with flat sandstone top.

The culverts can be traced through lower land eventually discharging into a river.

No one except me has permission to go into the field.
The field does not have any public footpath through it or on its perimeter.
The field is fully enclosed with stock proof 1m high fencing including 2 top runs of barb wire with 60% of the perimeter having hedges, it has one gate from another of my fields.
I have removed all stock from the field.

Any help and advice would be welcome.