Morphometric Analysis of Drainage Basin.pptx

morhpmetric analysis of a fluvial orginated drainage basin

1. Morphometric Analysis of Drainage Basin

2. MEANING MORPHOMETRY :- is the science that deals with quantitative measurements of shape or geometry of any natural form. Morphometric analysis is the analysis of different  characteristics of basin (fluvially originated ), based on quantitative evaluation of different parameters . Drainage basin:- OR Catchment area Area of land drained by a river and its tributaries ,bounded by a watershed.

3. Basin Attributes

4. These Parameters are clubbed under the 3 aspects as:- Linear aspects (length ; related to channel patterns) Areal aspects (area) Relief aspects . (relief i.e. Absolute & Relative) The concept was 1 st initiated by Horton in 1932 and later diff. Geologist , hydrologist and geomorphologist had contributed to it .

5. Why do we Study? T o understand geological structure of underlying rock geomorphological formations and hydrological chr acterstics Of a drainage basin 2. To find out the Geomorphological basin control of flow and runoff ..

6. Applications and uses of Morphometric analysis:-   In watershed management In identifying and planning the GW potential zones. In prediction of floods , their extent and intensity.

7. Linear Aspects :- Stream order Bifurcation ratio ( Rb ) Stream number (Nu) Length Ratio (RL) Length of overland flow ( Lg ) Sinuosity index (SI) Areal Aspects :- Stream frequency ( Sf ) Drainage density (Dd ) Texture ratio ( Rf ) Form factor (Ff) Elongation Ratio (Re ) Circulatory Ratio ( Rc ) Constant of Channel Management Relief Aspects:- Basin relief (R, H) Relief Ratio ( Rh ) Dissection Index (Di) Ruggedness Index ( Ri ) Channel Gradient ratio. Slope (  )

8. Linear Aspect 1) Stream ordering and stream order Stream ordering Its a method Of determining of the hierarchical position of a stream with in a drainage basin Stream order It’s the position/ order of a Stream in the hierarchy of tributaries, in a drainage basin

9. From trunk stream to fingertip stream From fingertip stream to Trunk stream “ Stream Segment method ” The hierarchical order increases only when two stream segments of equal order meet and form a junction . No change in order if a lower order stream joins a higher order stream . No reclassification and renumbering of streams required

10. Addition of two streams (Irrespective of the their order) When Two similar segments are combined, they will be multiplied by 2 to form the next higher order . When the segments are not similar, then simple addition is carried out Lowest order is 2

11. 2) Bifurcation Ratio ( Rb ) Ratio b/w no of streams of higher order to lower order where Nu=number of streams of given order, and Nu+l =number of streams of next higher order. varies from 2 to 3or4 (2 in flat & rolling ; 3/4 in Mt. areas) Useful measure of flood proneness high bifurcation ratio indicates a high drainage density. 3) Stream Number(Nu):- total no. of streams in each order with in a basin Nu = Rb (k-u) Where Nu= number of stream segments of a given order Rb = constant bifurcation ratio u= basin order k= highest order of the basin

12. If the Rb is constant , the no of streams of successively lower order tend to form a Geometric series . “Horton’s law of stream number” For ex:- IF, Rb =4; Highest order stream =6 stream order (H-L)= 6,5,4,3,2,1 Stream number(Nu)= 1,4,16,64,256,1024 4) Length Ratio (RL) The proportion of increase of mean lengths of stream segments of two successive orders of the basin RL= Lµ (mean length of all strreams of a given order) Lµ-1 Lµ = Σ Lµ ( total stream length of a given order) Nµ ( total no of streams in that given order)

13. 5) Sinuosity Index:- Sinuosity is the degree of deviation of a river from its expected straight path to its observed actual path Channel sinuosity= OL (Observed path of stream) EL (expected straight path of a stream )

14. Areal aspects 1) stream frequency Stream Frequency ( Sf ) total no of streams per unit area , irrespective of order Sf = Nu (total no of streams of all orders A (area of the basin) Stream Number (Nu) Linear aspect total no of streams of a particular order

15. 2) Drainage Density (Dd) expression of closeness or spacing of channels within a basin Dd= Lu (total stream length of all orders) A (Area of the basin) Low in Pt regions; High in Mt. regions Ranges from 0.55 to 2.09 km/km2

16. 3) Texture ratio ( Rt ): product of Sf and Dd Rt =Nu( total no of streams of all orders) P ( parameter of the basin) Rt values <2indicate very coarse, 2–4 coarse, 4–6 moderate, 6–8 fine, >8 very fine drainage texture. 4) Form factor (Ff):- Ff= A ( area of basin LxB ) Lb 2 (square of basin length) Values 0 (Elongated); 0.7854(perfect circular) ; 1 (near circular) Hence high value indicated More circular: low value indicated more elongated

17. 5 ) Elongation Ratio (Re);- Re= diameter of circle with same area as basin basin length Value 0( max elongated) to 1 ( max circular) 6) Circulatory Ratio ( Rc ):- Re= 4 A (Area of the basin) P 2 ( square of perimeter ). Values 0 to1 High , medium and low values indicate old, mature and young stage of drainage basin

18. 7 ) Constant of channel maintenance (CCM ):- Reciprocal of Drainage density ( Dd ) Expressed as required minimum area for the maintenance and devt . of a channel ↓ CCM indicates high flood potentiality Low in Mt. ; High in Pt. regions

19. Relief Aspects Basin relief:- Absolute relief (R) – Max altitude of a Basin Relative Relief (H) – Diff. b/w Min. and Max. altitude An indicator of erosional stage of a basin High in Mt-plain front Low in pt-plain front 2)Relief ratio ( Rh ):- Rh = H (Relative Relief in Km) Lb (Basin length) circular Basin → Rh ↑ Elongated Basin → Rh ↓ Indicates overall steepness High in mt . than Pt. regions

20. 3) Dissection Index (Di) :- Di= Relative relief (H) Absolute Relief (R) It indicates the vertical erosion and dissected chr . of a basin Range → ( no vertical dissection; ex- pt.,plains ) 1 ( max vertical dissection ; ex- mt .) 4) Ruggedness Index ( Ri ) :- Ri = Dd × H Indicated the stage of geomorphic development of a basin If, high→ young stage Low Ri → old stage 5) Channel gradient ratio

21. 6) Slope:- Determine infiltration V/S Runoff relation High→ Low infiltration and High runoff Gentle slope → high infiltration and low runoff.

22. Shortcomings:- over Quantification of a concept (As quantitative and statistical methods offer no substitute for original thoughts.) precise and accurate measurement of complex landforms is highly difficult and tedious task. too much application of mathematical equations

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