I would like to understand the basics of dynamic programming and use it to optimize reservoir operation for flood risk reduction, hydropower production.
You can consult the work by Liu et al (2012): Optimal Reservoir Operation Using Stochastic Dynamic Programming. Journal of Water Resource and Protection · January 2012. DOI: 10.4236/jwarp.2012.46038. Where they deal with the problem of optimal operation of an existing system.
If you want to deal with the problem of optimal expansion of a reservoir system I suggest the work by Wathne et al (1975): Optimal Capacities of Water Supply . Water Resources Bulletin. Vol 11, No. 3.