I'm very interested in understanding the sate of the art on hydrogeological modelling with special concern to semi-arid environments in order to implement a system within FEFLOW software.
That may be a bit too specific, but here is a paper I found in my literature database, that may be of interest. It reviews the capabilities of several (software) codes for numerical modeling of groundwater recharge (through the unsaturated zone) in semi-arid settings. You may find useful findings and remarks especially in the discussion. (see the attached RGate page link)
Also, I did a quick web search on google and found this book which may be insightful as well. You may borrow it for free from a library to check if it's effectively useful to you. (see the attached web link)