As you know, these parameters need for flood routing based on Muskingum method in rivers and therefore you need two observed hydrographs. one is for upstream (or input) and the other is for downstream (or output of a reach). By solving Muskingum Method for desired reach and compare the output of this method and Observed hydrograph at the end of the reach you can find X and K values. Also, there are some formulas that estimate these values, but for accurate results you should have observed hydrograph, especially at the outlet of the reach.
Calculating the Parameters of Muskingum Methods for a Rectangular Channel 1Asif Mazhar Ansari, 2 S.K.Ukarande 1M. H. Saboo Siddik College of Engineering, University of Mumbai 2Y.T. College of Engineering & Management, University of Mumbai