**4.2 Bedform length (Lb)**

Ref. [20] have presented a model relating bedform length (*L*b) to bedform height (*H*m) as:

$$H\_{\rm m} = \partial\_0 L\_{\rm b}{}^{\partial}{}\_1$$

Where ∂<sup>0</sup> and ∂<sup>1</sup> are empirical parameters with associated uncertainties and values are ∂<sup>0</sup> = 0.0513; ∂<sup>1</sup> = 0.7744 [21] (**Table 1**) and *L*<sup>b</sup> is bedform length. Substituting the values of empirical parameter in Eq. (5) we get

$$H\_{\rm m} = 0.0513 \, L\_{\rm b}^{0.7744} \tag{5}$$

An empirical relationship between bedform length and bed forms height has been presented by ref. [22] as:

$$H\_{\rm m} = 0.0677 \, L\_{\rm b}^{0.8090} \,\tag{6}$$

On the other hand, ref. [23] who used the data from the Rio Parana (Argentina) and those from the Lower Rhine (The Netherland) and Negro (Brazil) obtained relationship between bed form height and length which affords another assessment of the bed form length.

$$H\_{\rm m} = 0.21 \, L\_{\rm b}^{0.560} \tag{7}$$

When previously estimated value of *H*<sup>m</sup> is substituted, Eq. (5) indicates that the bedform length of dunes was about 34.21 m in Brahmini sub-basin and decreased down the paleoslope to about 23.33 m in Hurra sub-basin; Eq. (6) indicates bedform height in between 25.52 m and 17.65 m, and from Eq. (7) it is 28.18 m and 14.16 m in up dip basins (Brahmini, Pachwara) and decreased down dip to 18.36 m and 14.16 m in down dip basins (Chuperbhita, Hurra). The overlap in these three approximations suggests that the bedform length of the Barakar River was about 34.21 to 14.16 m. These dunes are classified as large dunes and such dunes become progressively smaller and their lengths become shorter as the flow strength decreases. For equilibrium dunes, the maximum steepness, *H* m/Lb. is approximately 0.055 (*L*<sup>b</sup> = dune wavelength), *L*b/Dc is approximately 6, and the minimum Dc/*H* <sup>m</sup> is approximately 3. It appears that for all types of river dunes irrespective of those not in equilibrium with the flow in the Barakar sandstone have Dc/*H* <sup>m</sup> average between 6 and 10. Recently ref. [24] suggests that steeper slopes tend to develop elongate, narrow braid bars than rivers with shallower slopes supports above contention that during deposition of Lower Barakar sediments, the River had long braid bars (≈35 m) than during deposition of Upper Barakar (≈15 m).


*Analyzing Sedimentary Rocks to Evaluate Paleo Dimensions and Flow Dynamics of Permian… DOI: http://dx.doi.org/10.5772/intechopen.106994*


**Table 1.**

*Paleo- dimensions, flow dynamics and paleochannel parameters of early Permian Barakar River.*
