Diarrhea is a common complication of colon resection surgery, since the water from the stool in intestines is absorbed mainly in colon, so the result is watery diarrhea.
The short tract or the short transit time of passing food is another cause for diarrhea.
To avoid over stimulation of the tract, intestinal movements, you should eat soft food in small amounts more frequently, like having 5 or 6 meals a day.
Try not to take liquids along with the meal, but between them, with the same purpose to avoid stimulating intestinal peristaltic.
Don't consume warm or too cold drinks.
Diet low in fat, low in fiber and low in sugar is recommended.

You may ask your surgeon for some medications, too!

I was curious, I have had 1/3 of my colon removed and a resection yrs ago, I was told to eat a very high fiber diet. At 1st my colon had to learn to pick up the duties for what had been removed my body did not absorb enough water and I felt like I had alligator skin...inside and outside I was dry, so I def could not have reduced fluid intake, I think you should contact your Drs office regarding your diet, different parts of the colon have different jobs, and having different areas removed cause different needs and symptoms. You may need a individualized plan for diet and fluid intake, your Dr or maybe even the nurse can help you with the proper diet that you need for your particular situation, it will probably be as simple as making a phone call to the office....hopefully anyway.