To cite cde in publications use:

  Robert A Briers (2019). cde - R package to retrieve data from the
  Environment Agency Catchment Data Explorer site. Journal of Open
  Source Software, 4(39), 1473. URL
  https://doi.org/10.21105/joss.01473/.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {cde - R package to retrieve data from the Environment Agency Catchment Data Explorer site},
    author = {{Briers Robert A}},
    journal = {Journal of Open Source Software},
    year = {2019},
    volume = {4},
    number = {39},
    pages = {1473},
    url = {https://doi.org/10.21105/joss.01473},
  }