1. Introduction
Land use and land cover (LULC) change has a significant impact on rivers, affecting the amount and quality of water that flows through them. Changes in land use patterns such as deforestation, urbanization, and agricultural intensification can alter the natural balance of water flow in river systems, leading to increased sedimentation, erosion, and runoff, which can degrade water quality and reduce the amount of water available for river flow. LULC changes can also have harmful impacts on aquatic life and human health by altering the temperature, pH, and nutrient levels of the water. Additionally, these changes can increase the risk of flooding and droughts. Therefore, it is crucial to consider the impacts of LULC changes on rivers when planning and managing land use to ensure sustainable and healthy river ecosystems [
1,
2,
3].
The Hooghly River provides a constant water supply to the nearby regions for domestic, agricultural, industrial, and transportation purposes [
4]. However, the river water gets severely polluted during monsoon and post-monsoon periods, which is a significant concern [
5]. The cause of this problem can be attributed to changes in LULC due to urbanization, agricultural intensification, and demographic shifts. These changes have a direct impact on the water quality of the Hooghly River, especially in the vicinity of Kolkata. The alteration in water quality and the increase in sediment load can disturb the water supply for various uses, including domestic. Therefore, a study is required to understand the relationship between LULC changes, demographic shifts, and water quality in the Hooghly River. Such a study would help in devising strategies to mitigate the adverse effects of LULC changes and demographic shifts on the water quality of the Hooghly River.
The significance of this study goes beyond the local region of the Hooghly River and has implications for an international standard. Water pollution caused by changes in LULC and demographic shifts is a global problem that affects water bodies worldwide. By understanding the relationship between LULC changes, demographic shifts, and water quality in the Hooghly River, the findings can be extrapolated to other regions facing similar challenges. This study can provide insights and solutions to other parts of the world that are dealing with similar issues related to water quality, making it a valuable contribution to the global scientific community. Moreover, the study can also help in formulating policies and guidelines to prevent and mitigate water pollution, which can have a far-reaching impact on improving the quality of life for people globally. Thus, this study has significant international significance as it can help in addressing the problem of water pollution caused by LULC changes and demographic shifts in various parts of the world.
An extensive literature survey from available sources indicates several past contributions in relevant study areas. Over-exploitation of natural resources due to rapid industrialization and other man-made activities, including improper waste disposal, has led to significant and progressive degradation of water quality throughout the river Hooghly [
6]. The assessment of LULC and water quality in the study area has been conducted by numerous researchers through field-based analysis [
7,
8,
9], theoretical and/or statistical modeling [
10,
11], and design and future prediction recommendations [
12,
13]. Similar studies for other Indian rivers are also evidenced [
14,
15]. Since the southern deltaic portion of the river Hooghly is located close to the Bay of Bengal, intrusion of saltwater is common and its occurrence alters the characteristics of sediment and riverbed materials [
16,
17,
18,
19,
20,
21,
22]. Several studies have investigated the impact of land use and land cover (LULC) changes on hydrological responses and urban floods in Iraq. Mustafa et al. [
23] analyzed extreme rainfall events and their effects on flash floods in the Erbil-Kurdistan region. Furthermore, Mustafa and Szydłowski [
24] found that an increase in built-up areas and a decrease in agricultural land resulted in a significant increase in peak discharge and runoff volume in the same basin. Noori et al. [
25] estimated rainfall distribution in the Duhok sub-basin using the IDW method and identified optimal parameters for spatial interpolation. Quraishi and Negm [
26] reported that urban growth in the same basin led to larger surface runoff volumes in urban areas. These studies offer valuable insights into hydrological events in the region and can assist in the development of effective flood management strategies.
Despite the fact that extensive work has been undertaken in recent years on the water characteristics of the river Hooghly, as indicated by the literature review above, there is still plenty of scope for in-depth and precise systematic investigation. The current research aims to address the need for further investigation into the water characteristics of the Hooghly River by utilizing GIS and remote sensing techniques to observe changes in LULC, followed by a field-based assessment. Specifically, the research seeks to examine modifications in LULC along the river, analyze demographic alterations in the river’s vicinity, and evaluate water quality at designated sites. By achieving these objectives, the study aims to provide valuable insights into the impact of LULC and demography on water quality in the Hooghly River.
4. Conclusions
The river Hooghly is a significant water resource for West Bengal, India, providing water for consumption and navigation. As Kolkata city continues to expand, there are concerns about the impact on the quality of water in the river and surrounding areas. To address these concerns, the water quality has been assessed at various specific locations in the vicinity of Kolkata. The quality of water in the river is primarily influenced by LULC and population. In particular, the LULC within 15 km of the river’s left and right banks has been evaluated. The findings indicate that there is a notable change in LULC across all buffer zones, with the degree of change increasing gradually towards the outer buffer zones.
The water quality parameters have been assessed and compared with historical values, revealing an upward trend. Although the current values are not yet alarming, the continued deterioration could result in hazardous conditions, especially in densely populated areas with increasing built-up areas and high freshwater demands. Analysis showed that all parameters were present at high levels in all sampling locations, with the trend being more pronounced in and around Kolkata city. Localities in the vicinity of Dakshineshwar, Shibpur, and Garden Reach are particularly vulnerable to water quality deterioration due to LULC changes and increasing population density [
52,
53]. Urgent measures are necessary to prevent further deterioration.
Analysis of land use and land cover change has shown a growing trend in the built-up area surrounding the Hooghly River, which is attributed to an increase in population and demand for food production. Additionally, there has been an expansion of agricultural areas at the expense of water bodies, leading to concerns about the impact of chemical fertilizers on the water quality of the river Hooghly.
This study has demonstrated the impact of changes in land use and land cover (LULC) and population growth on water quality. The results reveal that areas experiencing significant LULC changes and population growth exhibit poorer water quality [
54]. To mitigate this issue, it is recommended that strict measures be implemented to manage population density through the development of sustainable management plans. Furthermore, effective LULC management is essential for maintaining the health and quality of surface water resources and their dependent ecosystems.