1 Introduction

The term “environment” is critical in geological research, particularly when dealing with rivers, beaches, and estuaries [3, 7]. Many geological settings have been thoroughly researched and interpreted in various locations, with sedimentary environments classed based on particle size distribution [5]. Erosional habitats are distinguished by peculiar erosional processes, diagenetic geomorphology, and distinctive erosional products that are intimately related to depositional conditions due to the distinct depositional processes and products they contain [5]. Sedimentary contexts leave impressions and form sedimentary sequences in the geological record [5]. The literature review includes a diverse range of studies on depositional conditions and sediment properties from throughout the world. Gupta and Rajani [8, 17] investigated the late Holocene morphodynamics of the Thamirabarani delta and Thoothukudi tombolo in South India. Kundu [32] stressed the need of understanding sedimentary facies in petroleum engineering applications. Shi et al. [45] investigated the impact of depositional conditions on the development of tar-rich coal in China's Ordos Basin. Aigbadon et al. [4] researched the facies and sedimentology of Nigeria's southern Bida Basin during the Campanian–Maastrichtian epoch. Kasim, Ismail, and Ahmed [29] studied the grain size and morphometric characteristics of Tertiary sediments in Peninsular Malaysia. Khalil [30] used grain size distribution to locate Middle Cretaceous sandstone reservoirs in Riyadh Province, Saudi Arabia. Al-Taee et al. [6] employed facies analysis and geochemical proxies to study the depositional environment of Iraq’s Sinjar Formation between the late Paleocene and early Eocene periods. Kumar et al. [32] conducted petrographic and geochemical investigations on Paleogene lignite deposits in the Barmer Basin to learn about the depositional environment and paleoclimate. In India's Rajmahal Basin, Sethi et al. [44] investigated the impact of depositional environmental conditions on the mechanical stratigraphy of the Barakar Shales. Ramkumar et al. [40] investigated the tectonic, meteorological, and depositional environmental influences on Neolithic habitation sites in southern India’s Vaigai River basin. Harzhauser et al. [18] explored the Middle Miocene depositional conditions of the Eastern Paratethys Sea in northern Iran. Boukhalfa et al. [11] studied sandstones and red beds from the Lower Cretaceous Sidi Aich Formation in the Chotts basin of southern Tunisia. Afify et al. [2] investigated the depositional conditions, provenance, paleoclimate, and tectonic context of siliciclastic sedimentary rocks from southwestern Sinai, Egypt. Bilal et al. [9] studied the microfacies of the Palaeocene Lockhart limestone from Pakistan’s Upper Indus Basin. Saranaathan, Yamini, and Venkatesh [42] studied the evolution of quaternary landforms between Vedaranniyam and Rameswaram in South India. Ramasamy [39] investigated how morphological characteristics influence the mechanical properties of granular soils from various depositional sites. As geologists, we prioritize understanding the environments in which sediments are deposited and degraded. Depositional sedimentary environments have been defined in a variety of ways [34], including physical, biological, chemical, and geomorphic characteristics. The strength and duration of formative activities on such sediment affect its properties [37]. There is a substantial amount of literature on depositional environments, much of which is aimed for professionals and focuses on the hydrodynamics of sedimentation or sediment transport and deposition mechanisms [43]. Warrier et al. [49] demonstrate how physical weathering, erosive fingerprints, and chemical precipitation alter quartz grains prior to their deposition as lake sediments in glacial settings [35, 36]. Sediments frequently exhibit a mean particle size range of granule to medium sand, moderate to poor sorting, very coarse to very fine skewness, and platykurtic to leptokurtic characteristics [28]. According to Yadav et al. [50], previous studies have looked into numerous areas of sedimentology and geomorphology in different parts of India. These include the Late Quaternary cliff embankment sections of the Sai River in the Central Ganga Plain, the Middle Siwalik Subgroup of Jammu in the NW Himalaya [20], and the Proterozoic sandstone of the Rajgarh Formation in northeastern Rajasthan’s Alwar subbasin [31]. Researchers have also looked into the shapes and types of sediments in rivers like the Khurar River in central India [26], the Bundelkhand Granitic Complex [24], and the Ganga River's floodplain deposits [25, 27]. Furthermore, studies have focused on the spatial variation of textural parameters in small rivers such as the Khurar River [23] and the surface textures of detrital quartz grains from Bundelkhand granite [25, 27]. Abishek and Ravindran [1] added to the literature by evaluating groundwater potential zones for urban development in Srivaikundam, South India. Several studies have investigated how textural properties vary spatially in river systems. Kanhaiya and Singh [21, 22] studied the Khurar River in Khajuraho, Chhaterpur District, Madhya Pradesh, India, to better understand its textural characteristics. This lengthy book sheds light on the historical, current, and prospective states of India's rivers, emphasizing the interdisciplinary approach essential for long-term management [37, 38, 41]. The sediment texture of the estuaries and offshore Tuticorin along Tamil Nadu’s southern coast was studied, revealing bimodal distributions of medium and fine sand [47, 48]. The objective of this research is to assess the depositional impact of grain size analysis using GRADISTAT techniques and soil texture categorization on a ternary plot depicting the clay, silt, and sand ratios in the study area.

2 Study area

The study region is located in the Thoothukudi district of Tamil Nadu, between latitudes 8°28′30" N and 77°50′03.1" E and 8°48′00" N and 78°09′30" E (Fig. 1). The locations of the sediment samples collected from various points in the Thamirabarani River basin with the corresponding land use and land cover classifications in the study area. The LULC categories include agricultural, residential, forest, and industrial areas, reflecting the diverse landscape characteristics within the study area.  The Tamirabarani River flows through the taluks of Srivaikundam and Tiruchendur, providing important water source  and finally meet into the Bay of Bengal. The Thamirabarani River, which flows from the Western Ghats into the Tamil Nadu uplands, governs the district's drainage system. It consists of various streams that flow from hillocks and eventually reach the sea after covering lengths ranging from 10 to 20 km. The Vaippar, Nambiyar, Thamirabarani, and Karamanaiyar rivers are among the most notable that drain the district. August has an average temperature of 31.6 °C, while moderate weather prevails from January to February. The hottest months are April through August, which make up the summer season. Rainfall, influenced by the southwest and northeast monsoons, is the principal water supply, causing surface runoff and flooding in low-lying areas. Runoff occurs when the rain falls too heavily for the soil to absorb. It consists of Quaternary alluvium, Teri sands (dunes), Tertiary sediment/sand, weathered gneisses, and charnockite. The examined area lithological composition is dominated by coastal regions with fluvial marine deposits, including Archean rocks such as gneisses, granites, and charnockite that comprise the Thamirabarani delta [33]. The study region contains a mixture of porous and fissured rock layers. The primary aquifer systems consist of worn and cracked Archean hard rock formations, as well as Tertiary and more recent porous sedimentary strata. Alluvial deposits dominate the surface strata (see Fig. 2).

Fig. 1
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Location and sediments collection map of the study area

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Fig. 2
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 The flow chart of sediments analysis  in  the study area [1]

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3 Methods and materials

This technique evaluates consolidated sediments by passing them through a series of nested wire mesh stages. Larger particles remain in place, whereas tiny particles pass through. At April 2021, 18 samples were collected from the Thamirabarani River at Srivaikundam (Table 1). This study aimed to explain the depositional distribution of sediments in river environments (Fig. 3). The sieved materials were collected and weighed individually. A granulometric research was conducted to determine the weights of the various fractions. GRADISTAT version 4.0 by Blott and Pye [10] was used in this investigation (Figs. 4 and 5). It comes in Microsoft Excel format, which allows for both spreadsheet and graphical output. The software is best suited for interpreting data from sieve or laser granulometer analyses (see Table 2). Granulometric analysis was carried out utilizing visual [14] and moment approaches to better understand sediment transport and depositional environments [15]. The sediment samples were thoroughly examined in the mechanical laboratory of the Department of Geology at V. O. Chidambaram College in Thoothukudi. GRADISTAT tools, such as grain size analysis and statistical methodologies, offer a methodical approach to comprehending these differences. Researchers can learn about sedimentary processes, environmental changes, and depositional histories by evaluating sediment features at various spatial and temporal scales. This contributes in paleo-environmental reconstruction, sedimentary basin research, and resource exploration. The soil was classed based on the results of both analyses. The soil was classified using the water limit value, the particle distribution curve, and the clay, silt, and sand ternary plot [12]. The data collected was compared to the soil classification chart from the Unified Soil Classification. The percentages of sand, silt, and clay should be computed and compared to the highlighted areas in the ternary or triangular picture above [19]. , The collected percentages of sand, silt, and clay were shown in a ternary diagram for soil classification.

Table 1 Geographical location of sediment samples for Thamirabarani River and estuary in the study area
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Fig. 3
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Geomorphology of the study area [1]

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Fig. 4
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Grain Size Analysis Using Sieve Shaker

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Fig. 5
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Particle size distribution curve from the study area

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Table 2 Grains weight % for different Sieve size in the study area
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3.1 Grain size statistical analysis

Grain size statistics are frequently calculated by transferring the weight percentages of samples retained in each sieve unit to other statistical measures, as described by [13]. These statistical measures, such as mean, median, and mode, are used to examine certain aspects of the data shown in Table 3. A measure of central tendency describes a dataset by determining its center position and displaying it as a single value.

Table 3 Mean, Median, Mode, Skewness, and Kurtosis values of sediment samples in the study area (R.L. Folk and W. Ward in [14])
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3.2 Central tendency

The average, or mean, is calculated by summing all of the values in a data set and dividing by the total number of values. The median is the value that divides the highest and lowest values in a data set evenly. It is calculated by sorting the data set from lowest to highest and determining the value in the exact center. The mode is the most usually occurring value in a set of data.

$${\text{M}}\phi \, = \, \left[ {\phi_{{{16}}} + \, \phi_{{{5}0}} + \, \phi_{{{84}}} } \right] \, /{3}$$
(1)

3.3 Sorting

Folk and Ward developed a sorting system based on computed phi values, which assesses the variation in size groups around the mean. In the example provided of a beach-foredune, the wind power is sufficiently strong to transport sand but not the coarser shell material, which has been selectively removed.

$$\sigma \phi \, = \, \left( {\phi_{{{84}}} {-} \, \phi_{{{16}}} /{4}} \right) \, + \, \left( {\phi_{{{95}}} {-} \, \phi_{{5}} /{ 6}.{6}} \right)$$
(2)

3.4 Skewness

Skewness, a measure of the degree of symmetry in a grain size distribution, reflects sorting into the tails and accounts for the majority of graphic asymmetry in grain size. Deviations from zero in estimated asymmetry values suggest greater dissimilarity, whilst larger values indicate increased similarity. The formula for skewness is given below:

$${\text{Sk}}_{{1}} = \, \left( {\phi_{{{16}}} + \, \phi_{{{5}0}} - { 2}\phi_{{{5}0}} } \right) \, /{ 2}\left( {\phi_{{{84}}} {-} \, \phi_{{{16}}} } \right) \, + \, \left( {\phi_{{5}} + \, \phi_{{{95}}} {-}{ 2}\phi_{{{5}0}} } \right) \, /{ 2}\left( {\phi_{{5}} - \, \phi_{{{95}}} } \right)$$
(3)

3.5 Kurtosis

Kurtosis determines the sharpness or peak of the grain size frequency curve by comparing the spread, or sorting, of the tails in the middle section of the distribution to the spread in the tails.

$${\text{K}}_{{\text{G}}} = \, \left( {\phi_{{{95}}} {-} \, \phi_{{5}} } \right) \, /{ 2}.{44 }\left( {\phi_{{{75}}} {-} \, \phi_{{{25}}} } \right)$$
(4)

4 Result and discussion

This is an investigation of sediment samples gathered from the Thamirabarani River and estuaries. Mechanical filtration and microscopic grain analysis were carried out on 18 samples. The soil texture is classified based on particle size and percentage distribution. These are drawn or plotted on the three sides of an equilateral triangle. The United States Bureau of Soils developed the first figure depicting soil textural categorization, which is now widely used to classify coarse-grained soils. Sediment samples from Maruthur, Vadavallanadu, Agaram, Pakkapatti, Alikkudi, Muthulangkurichi, Naduvakurichi, and Arampannai were analyzed using a mechanical sieve shaker with sieve openings of 18φ, 25φ, 30φ, 35φ, 40φ, 50φ, 60φ, 70φ, 80φ, 140φ, and 170φ, representing very coarse sand, coarse sand, medium sand, fine sand, very fine sand, coarse silt, fine silt, and clay.

4.1 Grain size analysis

In the study area, sediment samples are classified as clay percentage, coarse silt, fine silt, medium silt, very fine silt, coarse sand, and very coarse sand. Gravel is defined as having more than 50% of the coarse particles retained by a 4.75 mm screen. The percentages of gravel in the research region may be seen in samples RS 11-Keelur and RS 12-Sriparankusanallur, which represent 20% gravel deposited in the area, and low levels of gravel sediments in RS 2-Vadavallanadu, RS 8-Arampannai, and RS 17-Palayakayal, which represent 4% gravel deposited. Rivers and waves tend to gather significant amounts of gravel. Sand is what remains after more than half of the coarse particles pass through the 4.75-mm sieve. Sand particle sizes are classified as extremely coarse, coarse, medium, fine, and very fine in the study region. The extremely coarse and coarse sand samples are RS 1-Maruthur, RS 2-Naduvakurichi, RS 9-Kongaranyankurchi, and RS 14-Kurangani, and they account for 24% and 20–30% of the very coarse and coarse sand deposits in the research area, respectively. Samples of RS 3, 4, 11, 12, 14, and 18 from the localities of Agaram, Pakkapatti, Keelur, Sriparankusanallur, Kurangani, and Palayakayal encompass the medium particle size of sand, accounting for 20–32% of the sand in the research area. Fine and very fine sand material is observed in samples of RS 2, 18, and R 1, 7, accounting for 25–30% and 24% of the regions of Vadavallanadu, Palayakayal, Maruthur, and Naduvakurichi, respectively. Sand is generated by the erosion and weathering of minerals over hundreds or millions of years as rocks, mainly quartz (silica) and feldspar, slowly degrade along rivers and streams. Silt is made up of rock and mineral particles that are larger than clay and smaller than sand. Because of their small size, silt particles are difficult to separate. A particle must be smaller than 0.005 cm (0.002 inches) wide to be categorized as sediment. The study area's silt particle size (17–20% coarse grain and 30% fine grain) is most likely associated with Vadavallanadu, Agaram, Alikkudi, Muthulangkurichi, Athichanallur, and Eral. Clay is so fine-grained that it is difficult to see individual mineral particles with the naked eye. Clays are rocks with particle sizes smaller than 4 µm in diameter. Most sedimentary rocks are described in terms of mineral composition and particle size. While this also applies to clays, the particle size description is the most reliable and most utilized. Figure 6 show that the samples likely covered by RS 3, 4, 8, and 18 accounts for 18–20% of Agaram, Pakkapatti, Arampannai, and Palayakayal respectively. Clays typically contain mica, chlorite minerals, feldspars, and a tiny proportion of tectosilicates (including quartz).

Fig. 6
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Particle grain size percentage of the Thamirabarani River in the study area

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4.2 Soil texture classification

The United States Department of Agriculture classifies soil texture into twelve categories. These include sand, loamy sand, sandy loam, loam, clay loam, silty clay loam, sandy clay, and clay. According to García-Gaines and Frankenstein [16], soil textures are classified based on the proportions of sand, silt, and clay present. For example, “sandy clay” and “silty clay” are classifications based on the primary ingredient particle size or a combination of the most prevalent constituent particle sizes. In this section, loam is characterized as having properties similar to sand, silt, and clay. The trilinear diagram is based on a classification of soil texture associated with Thamirabarani river deposits. The graphic depicts the percentages of sand, silt, and clay used to determine the composition of sediment samples. The samples are classified as clay, clay loam, sandy clay loam, loam, and silty loam, according to the figure that depicts the different types of soil found in the study area (Fig. 7). The bulk of tests indicate that the Vadavallanadu, Alikkudi, Muthulangkurichi, Kongarayankurichi, Athichanallur, Alwarthirunagari, Eral, and Mukkani regions are likely made up of clay-type soil, with percentages ranging from 40 to 55%. Numerous samples revealed clay loam soil, including Sriparankusanallur and Alwarthirunagari. Sandy clay loam (< 20–40%) is the second most common soil type, found in Maruthur, Naduvakurichi, Keelur, and Palayakayal. In the research region, loam (20%) and silty loam (> 80%) are two additional soil textures. Silty loam and loam locations include Agaram, Pakkapatti, Arampannai, Palayakayal, and Kurangani. Silt loam is typically found on river slopes or in river habitats. The lower river terrace with agricultural land contains silt loam, whereas the upper river terrace with maize fields has primarily loamy soil.

Fig. 7
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Soil texture classifications of the river sediments in the study area

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4.3 Microscopy studies for sediments

According to the microscopic examination, the majority of the grains are round, well rounded, flattened, sub-angular, and angular in both size and shape [46]. The grain size analysis has been used for the river, estuarine environment of sediment samples as cementing media of rock in the study area. In Fig. 8A, microscope images of the Maruthur sediments show quartz grains, magnetite, and worn quartz. Figure 8B depicts sediments from the Vadavallanadu area, which are distinguished by intact quartz fragments with rounded grain forms. Figure 8C shows microscope views of the Agaram sediments, which include quartz sediments, rounded fragments, and pyroxene. Figure 8D shows microscope views of the Pakkapatti deposits, which contain worn quartz and calcite fragments. Figure 8E shows microscope views of the Alikkudi deposits, including gneissic pieces and quartz grains. Figure 8F illustrates microscope views of the Muthulangkurichi sample, which show intact granitic sediments in river segments. In Fig. 8G, microscope views of the Naduvakurichi sediments reveal magnetite and quartz grains in crystal form. Figure 8H shows microscope views of the Arampannai sample, emphasizing worn gneissic fragments that have bedded with river sediments. Figure 8I shows microscope views of the Kongarayankurichi strata, which reveal magnetite and quartz particles. Figure 8J depicts microscope images of the Athichanallur sediments, which are derived from red soil and contain quartz sediments visible in magnetite and quartz grains. Figure 8K shows microscope views of the Keelur deposits, including magnetite, quartz in crystal form, and quartz in garnet. Figure 8L depicts microscope views of the Sriparankusanallur sample, which contains worn gneissic fragments that have sunk into river sediments. Figure 8M depicts microscope views of the Alvarthirunagari sample, which contains worn gneissic pieces bedded in river sediments as ilmenite and quartz grains. Figure 8N shows microscope views of the Kurangani sample, which indicate sediments mixed with clay fragments that deposited in the river habitat. Figure 8O depicts microscope views of the Eral sample, which reveal sediments settling from the riverfront in ilmenite and quartz crystal form. Finally, Fig. 8P shows microscopic views of the Mukkani sediments, which include worn quartz, magnetite, and quartz grains. Figure 8Q, R show microscope views of the Palayakayal sample and the Palayakayal river basin sample, respectively, revealing clay-preserved sediments mixed with the river environment.

Fig. 8
figure 8figure 8figure 8figure 8figure 8figure 8

A Microscope views of the Maruthur sediments, a. b. c. quartz grain, d. magnetite and e. f. weathered quartz. B Microscope views of the Vadavallanadu area, the sediments preserve from quartz fragments. e. rounded grain shape. C Microscope views of the Agaram sediments, a. d. c. d. quartz sediments, e. rounded fragments and f. pyroxene. D Microscope views of the Pakkapatti sediments, the weathered fragments of quartz and calcite was preserve in this area. E Microscope views of the Alikkudi sediments, a. b gneissic fragments and c. d. e. f. quartz grain. F Microscope views of the Muthulangkurichi sample, the granitic sediments are preserved in the river segments. G Microscope views of the Naduvakurichi sediments, a. magnetite and b. c. d. e. f. quartz grain in crystal form. H Microscope views of the Arampannai sample, the weathered gneissic fragments settled with the river sediments. I Microscope views of the Kongarayankurichi sediments, the identified the grains are magnetite and quartz fragments in the area. J Microscope views of the Athichanallur sediments, the sample derived from the red soil with quartz sediments in the river deposit grains are visible in magnetite and quartz. K Microscope views of the Keelur sediments, a. magnetite, b. quartz in crystal form, c. quartz in garnet and d. e. f: quartz grain. L Microscope views of the Sriparankusanallur sample, the weathered gneissic fragments settled with the river sediments. M Microscope views of the Alvarthirunagari sample, the weathered gneissic fragments settled with the river sediments in ilmenite and quartz grains. N Microscope views of the Kurangani sample, the sediments are mix with clay fragments settled with the river environment (well sorted grain). O Microscope views of the Eral sample, the sediments settle from the river side in ilmenite and quartz crystal form. P Microscope views of the Mukkani sediments, a. b: weathered quartz, c. magnetite, d. e. f: quartz. Q Microscope views of the Palayakayal sample, the sediments are preserved from clay mix the river environment. R Microscope views of the Palayakayal river basin sample, the sediments are preserved from clay mix the river environment

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4.4 GRADISTAT statistical analysis

The sediment classification mean value suggests that the bulk of the samples are medium sand, with some other samples in the area being fine sand (Table 4). River sediment sorting was described for all weakly sorted samples, implying weak currents or transfer via water movement. The river ecosystem has symmetrical and finely to extremely finely skewed properties, as evidenced by the skewness quantity. The skewness signal gives information about the state and nature of the depositional agent energy. The kurtosis value in sediment classification is particularly platykurtic, with some other samples being mesokurtic in the river. The skewness sign is identified as the most sensitive indication of environmental deposition environments.

Table 4 GRADISTAT sediment classification of the study area
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5 Conclusions

The analysis of grain size in sediment samples from the Thamirabarani River basin, notably in the Srivaikundam area, provides important insights into the depositional conditions that shape this region. The research area sediments have a wide range of properties and are divided into several categories, including clay percentage, coarse silt, fine silt, medium silt, very fine silt, coarse sand, and very coarse sand. These sediments, which are typical of river depositional environments, are important for understanding the basin of geological history and dynamics. Meta-sedimentary formations make up the majority of this study area. These formations contribute to the sediment cover, which is primarily composed of medium- to fine-sand deposits. The sand contains medium-sized particles, demonstrating major geological processes and sediment movement across the earth. These particles are especially prevalent at specific sampling sites such as Agaram, Pakkapatti, Keelur, Sriparankusanallur, Kurangani, and Palayakayal. These areas, which account for 25–30% and 24% of Vadavallanadu, Palayakayal, Maruthur, and Naduvakurichi, respectively, provide critical insights into the basin’s sedimentary history and depositional patterns. Sand formation is a complex process that involves the erosion and weathering of minerals over long periods of time, often millions of years. Sand composition is heavily influenced by rock disintegration, specifically quartz (silica) and the feldspar mineral group. The progressive dissolution of rocks as they travel via rivers and streams emphasizes the dynamic nature of sedimentary processes within the basin. Gradient and discharge play an important role on the morphology, flow, and sediment deposition of the Thamirabarani River basin. Rivers with variable slopes and discharge rates have distinct morphological and sedimentary properties. Meandering rivers, for example, feature a wide range of materials, from pebbles and stones within the channel to sandy point bars at the outside margins of meanders, when water velocity drops. Grain size analyses provide a thorough understanding of depositional conditions found in a variety of habitats, including beaches, rivers, aeolian landscapes, and estuaries. By detecting and defining sedimentary patterns and grain size distributions, researchers obtain significant insights into the geological processes that shape the Thamirabarani River basin and its surroundings. Learning about grain size and the environment in which sediments were deposited provides a comprehensive picture of how the Thamirabarani River basin in Srivaikundam developed and evolved over time. These findings not only improve our understanding of historical geological processes, but also help to make educated decisions about land use planning and environmental management programs in the basin.