title: Adding water flow arrows to Matplotlib Contour Plot
body: <p>I am generating a groundwater elevation contour with Matplotlib. See below</p>
  
  <p>Here is what I have now; how can I add water flow arrows like the image below?
  <img src="https://i.stack.imgur.com/nVYBf.png" alt="enter image description here"></p>
  
  <p>I want to add arrows to make it look like this:
  <img src="https://i.stack.imgur.com/eFkLy.jpg" alt="Groundwater Contour with Arrows"></p>
  
  <p>If anyone has some ideas and/or code samples that would be greatly appreciated.</p>