Da Italiano a Inglese Scienze Agricoltura

Sistemi di pagamento dell’acqua per l’irrigazione e costi della distribuzione idrica.

I don't want to translate with 'payment systems', because this is the title of a research paper analising all the different ways to calculate water charges for the use of water in agriculture. I am convinced that 'payment systems' would be wrong, because it only refers to the act of paying, and I would like to use (water) RATE ASSESSMENT SCHEMES instead. The problem is: I tried it on Google and got very few instances of it being used. Any suggestions? HEEEEELP!!!!! (paper due tomorrow 9 am)