Negative Impact on Narmada river due to excessive sand mining

The Narmada river flows through Madhya Pradesh, Maharashtra, and Gujarat between Vindhya and Satapura hill ranges before falling into the Gulf of Cambay in the Arabian. It is one of only two major rivers in peninsular India that runs from east to west (longest west flowing river), along with the Tapti River. It is one of the rivers in India that flows in a rift valley, bordered by the Satpura and Vindhya ranges. As a rift valley river, the Narmada does not form a delta, Rift valley rivers form estuaries. Other rivers which flow through the rift valley include the Damodar River in Chota Nagpur Plateau and Tapti. The Tapti River and Mahi River also flow through rift valleys, but between different ranges. It flows through the states of Madhya Pradesh (1,077 km (669.2 mi)), and Maharashtra, (74 km (46.0 mi)), (39 km (24.2 mi)) (actually along the border between Madhya Pradesh and Maharashtra (39 km (24.2 mi)) and then the border between Maharashtra and Gujarat (74 km (46.0 mi)) and in Gujarat (161 km (100.0 mi)). Narmada is a meandering river: The local socio-economy, as well as the main drinking water supply for many cities located at the banks of the river. So, the river is a lifeline of many districts as well as cities like Bhopal, Narmada Puram, Jabalpur. The river originates from amarkantak near Jabalpur and ends in Bharuch city of Gujarat. The total length of the river is about 1,312 km (815.2 mi). The study was carried out at a location of raisin district shown in the study area falls between 23°1’28.10” N latitude and 78°38’28.53” E longitude. The research area has level topography, with a strip of river that is primarily composed of medium-grained sand, some coarse-graded sand, silt, and clay. Loosely compacted black soils with a high moisture content and low cohesion are found along the Narmada riverside.

Erosion due to illegal mining of sand

Thorough reviews of the literature were conducted at every phase of the investigation. Secondary data was gathered from a variety of sources, including textbooks, websites, newspapers, scientific journals, essays, and satellite photos.. The images of Landsat 4-5 TM C1 Level-1 of 1993,2003 and Landsat 8 OLI/TIRS C1 Level-1 of 2013 and 2019 were taken from USGS Earth Explorer. Time series data of 10 years of the study area were collected from Google Earth Pro. Arc GIS 10.4 Software was used for identifying amount of bank consumption as well as river shifting.

 

 Landsat satellite images used for this study purposes.

Satellite/Sensor	Spatial Resolution (m)/Row/Path	Date of Acquisition	Spectral bands (um)	Data source
Landsat-8 (OLI/TIRS)	30/45/136	23/06/2023	Band 2 Blue (0.450 - 0.51 µm) 30 m. Band 3 Green (0.53 - 0.59 µm) 30 m. Band 4 Red (0.64 - 0.67 µm) 30 m. Band 5 Near-Infrared (0.85 - 0.88 µm) 30 m. Band 6 SWIR 1(1.57 - 1.65 µm) 30 m. Band 7 SWIR 2 (2.11 - 2.29 µm) 30 m.	https:// earthexplorer. usgs.gov/ .com

Evaluation of Erosion and Accertion

For the designated bank, the measurement of newly built land and lost land between 2009 and 2019 was completed independently . After drawing the riverbank lines for two chosen years, movement was found in kml file format.

Erosion occurs where the recent bank line entered through the previous line, and accretion occurs as it exits. The specific amount of erosion and accretion was ascertained. A map was created and a kml file was transformed into a layer with the use of GIS conversion tools. Lastly, a graphic showing erosion and accretion was drawn.

Channel Migration, River Flow Pattern and Cross-section

Through the study of satellite imagery, river channel migration was identified. Landsat satellite images 4-5 TM C1 Level-1 and Landsat 8 OLI/TIRS C1 Level-1 were used in the study. An unsupervised categorization of the target area, which showed the river flow pattern, was done using Arc GIS 10.4. There are multiple processes in this drawing process. First, each point's geographic coordinates were gathered using Google Earth Pro program and saved as a kml file. Six sets of data in all were collected from the study region. There are four data sets for each point: 1993, 2003, 2013, and 2023. Second, GPS Visualizer was used to update and convert the altitude values of these sites into GPX format. Moreover, TCX and Microsoft Excel Office 2016 analyzed and transformed these GPX files into CSV format. software. Finally, these data were plotted into Surfer 13 software to delineate contour maps as well as elevation profiles of each site.

 Map of erosion and assertion generated through GIS (Pink represent erosion and Green represent assertion)

 Net erosion and accretion statistics of the Narmada River, Raisen 

Time duration	Location (Narmada river)	Erosion (ha)		Erosion Rate (ha/year)	Accertion (ha)	Accertion Rate (ha/year)
1993-2023	Right bank	47.73	14.774	22.22	11.72	19.6
	Left bank	71.05	71.05	19.8	9.54	11.2
	Total reach	118.78	85.78	42.02	21.26	30.8

 

 

 

 

 

 

 

 

 study area from 1993 to 2023.

 

Normalize Difference Water Index (NDWI)

The processing of satellite pictures taken on October 26, 2009, and November 23, 2019 allowed for the visualization of riverbank erosion. A map known as the Normalized Difference Water Index (NDWI) was developed in order to compare the riverbank lines of two distinct photographs. To distinguish between the open ground, vegetation, and water body in the study area, NDWI is utilized in this investigation.

This following formula has been used to make the NDWI map:

NDWI = 𝐺𝑅𝐸𝐸𝑁−𝑁𝐼𝑅/𝐺𝑅𝐸𝐸𝑁+𝑁𝐼𝑅

NDWI values in between -1 to 1 indicate water body because of higher reflectance of NIR band than G band whereas, negative NDWI values indicate vegetation.

 

 

                                              Land Use Land Cover of study area 1993-2003

       Land Use Land Cover map of 2013-2023

Conclusion

Both GIS-based geographical analysis and erosion-assertion data, which combined confirm the extent of ecological degradation, make the environmental effects of sand mining in the Narmada River more and more obvious. Significant channel shifting, bank erosion, and riparian vegetation loss in high-extraction zones are among the notable changes in river morphology that GIS indexing has shown. Field data showing increased rates of erosion, sediment imbalance, and decreasing groundwater levels further corroborate these geographical findings. The statement data supports the disturbance of biodiversity and the loss of aquatic ecosystems. Uncontrolled sand mining is endangering the sustainability of nearby ecosystems in addition to the river's structural integrity. To protect the ecological balance of the Narmada, this study emphasizes the critical necessity for real-time GIS monitoring, eco-restorative measures, and scientifically informed sand mining regulations.