## 1 Introduction
LIDAR systems can collect data from a canopy's top layer to the ground [17], creating a more accurate digital elevation model (DEM) by removing vegetation. From a global point of view, certain studies [18; 19; 20] are noteworthy as they establish the basis for understanding salt marsh erosion due to climate change. Recently, several researchers have focused on the dynamics of salt marshes in the Iberian Peninsula [21; 22; 23; 24]. In the Donana marshlands (Huelva, Seville, and Cadiz Provinces, Spain), sediment residence times are prolonged, with a significant intermediate storage of eroded material, a common trait among major marsh systems worldwide, such as those in Chesapeake Bay (USA) [25]. Additionally, increased sediment storage can lead to major changes in marshland systems' physical structure and ecological health, crucial for understanding the flora and fauna in these areas. Another study used geomatic techniques to assess the dynamics and evolution of an Asturian coastal sandy system in northern Spain [26]. Another effect of long sediment residence times in river systems is that significant historical changes can impact a system's behavior for decades [14; 25; 27]. Understanding and assessment of a system's response to historical global changes are essential, as the temporal scale of analysis is vital for forecasting how the net sediment response will relate to flood distribution over time. Hitherto, most marshland studies have concentrated on understanding soil loss and erosion through mapping vegetation cover and general land use changes (LUCs). Some researchers have investigated various methods for determining variable states using soil reflectance or vegetation cover characteristics [12]. Additionally, LUCs have been used to analyze watershed dynamics [28] and assess fluvial sediment transport degradation [29]. The number of published articles on the innovative use of LIDAR images in this research area is relatively low, despite its significant potential, possibly due to the fact that it is more difficult to obtain at various scales compared to satellite images, consequently favoring remote sensing for marshland studies. Moreover, utilizing LIDAR techniques alongside iterative scientific methods and fieldwork to quantify erosion processes can offer new insights for predicting the total volume of eroded soil in wetlands and other regions globally. Notwithstanding, high-resolution LIDAR data are essential for areas with complex networks of basins or aquifers. A promising approach is the use of emerging image processing techniques [30] this being increasingly recognized by researchers worldwide. Nevertheless, it is worth noting that the acquisition of DEMs at a global scale using radar has a much longer historical trajectory, as evidenced by the use of DEMs generated from the NASA Shuttle Radar Topography Mission (SRTM), whose first version dates back to the year 2000 [31]. In this regard, this research aims to forecast the average soil deposition in the full area of the Donana salt marshes, using a novel approach involving DEM data and geographic information systems (GISs). To accomplish this primary goal, predicting volumetric change processes is an essential secondary objective of this research, alongside the development of a new remote sensing index and algorithm. Although DEMs obtained from either LIDAR or drone data (with scarce temporal coverage or limited spatial and temporal coverage, respectively) are currently used, this study was conducted using DEMs from the SRTM, with a resolution of 1 arc-sec (approximately 30 m) and a major temporal extent [31]. Additionally, it is important to highlight that this study's novelty lies in the use of a patented procedure that allows us, using climatic data from the study period, to infer changes in the Donana marshlands through big data analysis. It is also crucial to consider various works conducted by other researchers [21; 24; 32; 33], focusing on coastal gulf areas in Texas (USA) and Cadiz (Spain).