Property border wall and drain done by pwd

I have a plot of land adjacent to a normal road (not SH or NH). The Public Works department modified the road few years ago and built a kind of drain where the rainwater that flows along the public road gets diverted into our property. They built the drain on Govt. property but the water is directed right into our property. We were not at the place when they built such a drain, we were outside the state and therefore could not object to the construction, we came to know about such an issue couple of months ago only. Now we were reconstructing a border wall (increasing the height of a pre-existing wall) and at the same time building a small wall (around 2 bricks height) against the drain that was created. All constructions are done on our side of the land, nothing is placed or extending on Govt. property. Unfortunately, we completed the construction when some one told us that we needed the permission from the Panchayat to do so. Kindly advise on how can we proceed further and also about consequences. During rainfall, all public water flows into our property because of this drain.