Kidron Valley in Smiths Bible Dictionary
            (turbid), The brook, a torrent or valley, not a "brook," or, 
as in the margin of Revised Version, "ravine;" Gr. winter 
torrent. It was close to Jerusalem, between the city and the 
Mount of Olives. it is now commonly known as the "valley of 
Jehoshaphat." The channel of the valley of Jehoshaphat is 
nothing more than the dry bed of a wintry torrent, bearing 
marks of being occasionally swept over by a large volume of 
water. It was crossed by David in his flight, 2Sa 15:23 comp. 
2Sam 15:30
 and by our Lord on his way to Gethsemane. Joh 18:1 
comp. Mark 14:26; Luke 22:39
 The distinguishing peculiarity of the Kidron valley --
mentioned in the Old Testament-- is the impurity which appears 
to have been ascribed to it. In the time of Josiah it was the 
common cemetery of the city. 2Ki 23:6 comp. Jere 26:23
                          
 Read More about Kidron Valley in Smiths Bible Dictionary