## 1 Introduction  
Turbidity is unimportant parameter for water quality and a surrogate for the transparency of water [1; 2; 3; 4; 5]. Turbidity can damage many aquatic organisms and fishes by degrading spawning grounds, reducing feed supplies, and affecting gill function [6]. A decrease or increase in water transparency can adversely affect the organic components of systems that adjustto light-dispersing environments [7; 8; 9; 10; 11; 12; 13; 14; 15]. In estuarine waters with high turbidity, dissolved oxygen concentrations can significantly decrease due to irregularities in heterotrophic and autotrophic processes, which may contribute to the depletion ofmarine organisms [16; 17]. Typically, turbidity is assessed visually using aSecchi disk, or presumably through nephelometry [1; 5]. However, these methods only represent the locations from which the sample was collected. Recently, remote sensing of sea color has become a valuable method to retrieve and monitor suspended sediment concentration (SSC) and turbidity in coastal turbid waters on the surface [18; 19; 20; 21]. Traditional water quality sampling is cost-effective and time-consuming, as it involves the collection and analysis of the water. Also, the traditional method of water monitoring does not provide the spatial or temporal view of the entire body of water that is necessary for proper management [22]. The use of remote sensing technology to analyze water quality is concise; it alsocaptures the entire field of study to create consistent surface data and periodically demonstrate the point-by-point spatial variability of water quality [23]. Although research on various remote sensing technologies is devoted to total SSC retrieval, research on retrieving turbidity is limited [21]. Even thoughstatellite remote sensing cannot identify near-bed absorption, it is used to identify spatial and temporal variations in turbidity at the surface.\"Near-bed absorption\" refers to the bottom of a stream or other body of water. The turbidity of the surface water can influence the reflection of the water body, but not from the bottom of the stream/lake/ocean, because the reflection data are obtained from the top 2 m of surface water [24]. The Ramganga River is an important tributary of the Ganges River. It originates from the lower Himalayas in Uttarakhand, covering the vast Ganga Flood Plains (GFP) of Uttar Pradesh, and then converges with the Ganges River. It is the primary source of water for the Jim Corbett National Park (Tiger Reserve) situated in the Uttarakhand, and is one of the critical water sources for domestic, industrial, and agricultural use in the western Uttar Pradesh [25; 26]. The upper reaches of the study area consist of hillocks and streams, while agricultural fields mainly dominate the middle and lower reaches; therefore, when sufficient rainfall increases the contribution of suspended substances, due to weathering and erosion processes in the upper regions and agricultural runoff in the middle and lower regions, the turbidity and total SSC increase considerably [27]. The aquatic life of the Ramganga River is negatively affected by the large amount of turbidity in the water, and harmful bacteria and pollutants may also be associated with the particles that cause turbidity. Estimating turbidity distribution in the Ramganga River with diverse geomorphology and a complex environment requires anunconventional approach. Remote sensing technology provides reliable information for monitoring and understanding the variation of turbidity in time and space, particularly in the substantial zone with limited access, such as Jim Corbett National Park area of the Ramganga River Basin. Mapping turbidity and other indicators of water quality is routinely performed using information acquired with wide-swath imagingspectro-radiometers designed to measure sea color--for example, Orbview-2/SeaWiFS, ENVISAT/MERIS, and Aqua/MODIS [28].