I find there are 4 main problems associated with erosion where I work (Portugal):
1) Herbicides overkill leads to the death of useful grasses that help hold soil structure. Some fungicides may kill mycorrhizae which are fundamental in soil maintenance (http://mycorrhizae.com/wp-content/uploads/Effects-of-Fungici...)
2) Tillage avoidance is recommended, and in some cases prohibited. But people do it nevertheless... The consequences are obvious.
3) Dams built with irrigation in mind often accumulate mineral salts at a rate larger than what Nature would drain towards the sea. Since water is used in places with lower rain levels, drainage in those places is low as well, which leads to salination (Sometimes it also leads to lower levels of mineral salts in river mouths, thus a decline in phytoplankton and as as consequence fish populations).
4) Global warming means tougher draughts and heavier rains, which means more erosion.
We're headed to some serious problems if we don't take these issues seriously.