A opção -nd
no seu comando significa no-directories .
Você deve remover a opção -nd
do seu comando e obterá a mesma estrutura como no site:
wget -r -l 10 -e robots=off http://biomet.ucdavis.edu/Evapotranspiration/
2.6 Directory Options
‘-nd’ ‘--no-directories’
Do not create a hierarchy of directories when retrieving recursively. With this option turned on, all files will get saved to the current directory, without clobbering (if a name shows up more than once, the filenames will get extensions ‘.n’).