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Table 2 Formula for computation of morphometric parameters

From: Flood risk analysis: causes and landscape based mitigation strategies in Dire Dawa city, Ethiopia

No Morphometric Parameters Formula/ definitions/methods References
Linear aspect
1 Stream order Hierarchical order Strahler 1964a, b
2 Stream Length (Lu) Length of the Stream (km) Horton 1945
3 Mean Stream Length (Lsm) Lsm = Lu / Nu, Where, Lu = Total Stream length of order ‘U’, Nu = Stream length of next higher stream order. Horton 1945
4 Stream length Ratio(Rl) Rl = Lu/Lu-1; where, Lu = Total number of stream segment of order ‘U’, Lu-1 = Stream length of next lower order Horton 1945
5 Bifurcation Ratio (Rb) Rb = Nu / Nu+ 1 Where, Nu = Total Number of stream segments of order ‘U’ Nu+ 1 = Number of segments of the next higher order. Schumm 1956
Areal aspect
6 Drainage Density (Dd) Dd = L/A Where, L = Total length of Stream, A = Area of the Watershed Horton 1945
7 Stream Frequency (Fs) Fs = N /A. Where, N = Total number of Stream, A = Area of the Watershed. Horton 1945
8 Texture ratio (T) T = N1/P. Where N1 = Total number of first order stream, p = perimeter of watershed Horton 1945
9 Form Factor (Rf) Rf = A / (Lb) 2. Where, A = Area of the Watershed, Lb = Maximum Basin length. Horton 1932
10 Circularity Ratio (Rc) Rc = 4ðA/ P2. Where, A = Area of the Watershed, P = Perimeter of the basin, Ð = 3.14 Strahler 1964a, b
11 Elongation Ratio (Re) Re = 2√ (A/ð) / Lb. Where, A = Area of the Watershed, Lb = Maximum Basin length, Ð = 3.14. Schumm 1956