**7. Imprints of active tectonics**

The rivers in WH containing the knickpoints over the Mesozoic formations; are related to active geological structures. The maps of local relief, swath, stream length gradient index, and channel steepness (**Figures 1D** and **2**) represents two major topographic zones. The high elevated zones are located between 28 and 228 m. The high relief locations represent remnants of a relict landscape that was preserved at high elevations caused by erosionally balanced rapid Late Quaternary uplift [23]. The low relief zones are marked by Banni and Rann surfaces (**Figure 1C**). The DEM generated swath profiles shows incision into the alluvial surfaces. This incision is associated with multiple phases of tectonic events and intensified climate forcing during early to mid-Holocene [23]. The sedimentation in lower reaches of river valleys is predominantly controlled by processes that act in response to tectonically triggered and climatically enhanced events [23]. The uplift involve the Bela and WH that shows abrupt and anomalous variation in elevation as noticed in the swath profiles (**Figure 1D**). The swath profiles shows maximum elevation correspond to uplifted region and low elevation correspond to valley floor. The swath analysis of each profile shows asymmetrical nature of valley shape. The results of the SL index are shown in **Figure 2A**. Integrated longitudinal river profiles with SL and Ks longitudinal profiles of all rivers are illustrated in **Figure 3**. The SL values range from 5 to 2300 which are grouped into five classes: class-1 (low activity: 5 **≤** SL **≤** 100), class-2 (intermediate activity: 101 **≤** SL **≤**500), class-3 (moderate activity: 501 **≤** SL **≤** 1000), class-4 (active: 1001 **≤** SL **≤** 1500), class-5 (very active: SL **≥** 1501) (**Figure 2A**). The high and moderate classes of the SL values correspond to significant faults except for the Bela zone, may be caused by the high rock resistance prevailed in that area. The *Ks* and *Ɵ* were estimated from the log–log plot of *S* vs. *A*. The Ks values range from 5 to 125. To evaluate segmental tectonic activity; these values were also grouped into five classes: class-1 (low activity: 5 **≤** Ks **≤** 25), class-2 (intermediate activity: 26 **≤** KS **≤** 50), class-3 (moderate activity: 51 **≤** KS **≤** 75), class-4 (active: 76 **≤** Ks **≤** 100), and class-5 (very active: Ks >101) (**Table 1**; **Figure 2B**). It is observed that the Ks values are high close to the E-W faults.

**Equation**

M = A +

M = A +

M = A + M = A +

B\*log (RLD)

B \* log (MD)

B \* log (RA)

B \* log (SRL)

[55]

F1 F2 F3 F4 F5 F6 F7 F8

> Mw =

4.67

1.36\*log SRL+

Johnston

F9

21.17

19

7.2

1.36 4.67

0.8 0.3

2.2

0.31

5.6-6.5-7.0

3.1

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143

0.9

0.14

5.6-6.2-6.7

1.4

[56]

Surface rupture length (SRL).

Sub-surface rupture length (RLD).

Standard deviation (s).

Maximum displacement (MD).

Average displacement (AD).

Moment magnitude (M).

**Table 2.**

Regression analysis of surface rupture, subsurface rupture length, and displacement.

F10

34

33

6.6

54.13

48

17.2

50

38.6

38.6

56.7

43.8

37.6

15.2

38.6

38.6

55.6

40.6

40.6

55.8

42.8

16.6

55.6

26

5.2

56

21

21

5.16

1.22

3.98

1.02

3.9

1.1

0.34

5.4-6.4-7.3

3.4

6.81

0.78

0.49

1.3

0.11

6.1-6.7-7.3

1.1

4.33

1.49

0.63

0.8 0.79

0.3 0.4

1

0.06

6.2-6.8-7.2

0.67

0.9

0.08

6.7-6.7-7.2

0.84

3.1

0.07

6.7-6.7-7.3

0.71

1.8

0.09

6.7-6.6-6.6

0.9

4.3

0.14

6.7-6.7-7.3

1.4

**References**

**Fault (SRL** 

**(RLD** 

**Average** 

**Coefficient**

**MD** 

**AD** 

**Offset ratio** 

**Magnitude** 

**Slip rate** 

**(mm/y)**

**(km)**

**(km)**

**(m)**

**(M)**

6.3-6.3-7.3

—

**km)**

**km)**

**RLD**

**A**

**B**


SeisNetG [13, 15, 51]. Theses integrated approaches provide a clue to understand what instigate to generating a negative flower structure of drainage patterns and its role in the seismicity in the regions. The snapshot of the seismic images play important role to understand brittle-ductile dynamics. It also shed light about hidden causative faults and the drainage patterns that can dictate the degree of damage through shaking (**Figure 1B**). Several faults in the Kachchh areas are mapped on the surface but still there are many among the existing factory of faults which still remains undiagnosed and not mapped on the surface [15, 51]. That is why we have determined almost all geological evidences and crustal heterogeneities parameters in the present study to understand the nature and extent of underlain structures controlling drainage network. The available 16 fault-plane solutions of the inferred fault planes of the events (Mw ≥ 3.5) recorded during 2007–2014 [13, 15, 51] (**Figure 1B**). The results obtained from morphotectonic analysis of fluvial networks and seismological approaches are jointly

The rivers in WH containing the knickpoints over the Mesozoic formations; are related to active geological structures. The maps of local relief, swath, stream length gradient index, and channel steepness (**Figures 1D** and **2**) represents two major topographic zones. The high elevated zones are located between 28 and 228 m. The high relief locations represent remnants of a relict landscape that was preserved at high elevations caused by erosionally balanced rapid Late Quaternary uplift [23]. The low relief zones are marked by Banni and Rann surfaces (**Figure 1C**). The DEM generated swath profiles shows incision into the alluvial surfaces. This incision is associated with multiple phases of tectonic events and intensified climate forcing during early to mid-Holocene [23]. The sedimentation in lower reaches of river valleys is predominantly controlled by processes that act in response to tectonically triggered and climatically enhanced events [23]. The uplift involve the Bela and WH that shows abrupt and anomalous variation in elevation as noticed in the swath profiles (**Figure 1D**). The swath profiles shows maximum elevation correspond to uplifted region and low elevation correspond to valley floor. The swath analysis of each profile shows asymmetrical nature of valley shape. The results of the SL index are shown in **Figure 2A**. Integrated longitudinal river profiles with SL and Ks longitudinal profiles of all rivers are illustrated in **Figure 3**. The SL values range from 5 to 2300 which are grouped into five classes: class-1 (low activity: 5 **≤** SL **≤** 100), class-2 (intermediate activity: 101 **≤** SL **≤**500), class-3 (moderate activity: 501 **≤** SL **≤** 1000), class-4 (active: 1001 **≤** SL **≤** 1500), class-5 (very active: SL **≥** 1501) (**Figure 2A**). The high and moderate classes of the SL values correspond to significant faults except for the Bela zone, may be caused by the high rock resistance prevailed in that area. The *Ks* and *Ɵ* were estimated from the log–log plot of *S* vs. *A*. The Ks values range from 5 to 125. To evaluate segmental tectonic activity; these values were also grouped into five classes: class-1 (low activity: 5 **≤** Ks **≤** 25), class-2 (intermediate activity: 26 **≤** KS **≤** 50), class-3 (moderate activity: 51 **≤** KS **≤** 75), class-4 (active: 76 **≤** Ks **≤** 100), and class-5 (very active: Ks >101) (**Table 1**; **Figure 2B**). It is observed that the Ks values are high

analyzed in the next section.

142 Tectonics - Problems of Regional Settings

close to the E-W faults.

**7. Imprints of active tectonics**

**Table 2.** Regression analysis of surface rupture, subsurface rupture length, and displacement.

Conventionally the hypsometric integrals reveal complex interactions between erosion and tectonics [39, 52, 53]. Hypsometric integrals are thought to be affected by basin parameters such as geometry, area and rapid lowering of basin elevations [53, 54]. The hypsometric integral of each basin has been computed based on drainage area and basin geometry. Hypsometric integrals are thought to be affected by basin parameters such as geometry, area and rapid lowering of basin elevations [53, 54]. The HI of each basin has been computed based on drainage area and basin geometry. However, we deployed conventional statistical technique for the entire basin as well as the computation is implemented to individual squire where high and low values can be obtained together. The contour map shows spatial distribution of high and low values, imply that the WH experiencing rapid changes in elevation and incision; owing to tectonic and climatic variations [23]. The higher values of HI clustered around the uplifted regions however the lower values representing low lying areas (**Figure 2C**). In the analysis of HI, it is considered whether the curve is convex in its upper portion, convex to concave, or convex in the lower portion. The HI curves of all basins are given in **Figure 4**. It is assumed that if part of the hypsometric integral is convex in the lower portion, it could be associated with uplift along a fault or associated with recent folding.

along the structures (**Figure 6F**). The tectonic movement in this region resulted changes in surface elevation by forming approximately 9 m high fault scarp (**Figure 6G**). A significant gradient change in the valley floor causes development of 3 m high knickpoint (**Figure 6H**). The litho-units are tightly folded within the fault zone. The southern limb of the fold is steeply (~75°) dipping towards south. These steeply dipping beds are characterized by presence of slickensides parallel to the strike direction (E-W) of the F5 (**Figure 6I**). Kothyari et al. [23] believe that these features are results of middle to late Holocene tectonic reactivation of GF. Furthermore, the significant amount of changes have been observed within the hydrological network between 8 to 4 ka [23]. The north flowing Karaswali River takes 90<sup>o</sup>

Evolution of Drainage in Response to Brittle - Ductile Dynamics and Surface Processes…

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and flows in west direction, parallel to GF (F4). East–west offsetting of the two rivers is also

**Figure 6.** (A) Detailed map showing major tectonic features observed in the F2 zone (inset; DEM of growing ridge showing ground uplift (~1.5 m) near the fault zone (modified after [57]); (B and C) fault scarp; (D and E) development of E-W oriented tensional cracks within the fault zone. These tensional cracks are displaced by small scale strike slip faults. (F) Map shows locations of ground deformation observed along the trace of F4. Inset shows development of tensional fractures within the tertiary sandstone bed (modified after [23]); (G) development of ~9 m high fault scarp near Deshalpar, (H) lateral spreading of ground east of Deshalpar, and 3 m waterfall was developed along the F3, (I) well developed slickensides are visible parallel to strike of F4. *The drainage map of* **A** and **F** *are generated using georeference SOI topographic map in Global mapper 18 software and for final editing we used Surfer 14 software. The inset DEM of the area has been generated with the help of reconnaissance Real Time Kinematic (RTK) survey. The DEM has been generated in Surfer Software.*

observed south of the Gedi village (**Figure 6F**).

turn

145

In present study 10 north flowing and 17 south flowing rivers of WH were analyzed in order to estimate river offset and tectonic control by the faults that cut across the area (**Figure 2A, B**). The estimated values of offset along F2 ranges between 1.1 and 3.9 km, along F3, 0.49–1.3 km, along F4 0.63–4.3 km, along F5 0.8–1.8 km, along F6 0.79–3.1 km, along F7 0.3–0.9 km, along F8 0.4–1 km, along F9 0.8–0.9 km, and along 10 the offset ranges between 0.3 and 2.2 km respectively (**Figure 2D**). The stream offset along the F2–10 is comparatively less westward. However, the computed values of offset ratio of about 0.34 km for F2, 0.11 km for F3, 0.14 km for F4, 0.09 km for F5, 0.07 km for F6, 0.08 km for F7, 0.06 km for F8, 0.14 km for F9 and 0.31 km for F10 respectively (**Table 2**).
