Remote Sensing for the Quantification of Land Surface Dynamics in Large River Delta Regions—A Review

Abstract

River deltas and estuaries belong to the most significant coastal landforms on our planet and are usually very densely populated. Nearly 600 million people live in river deltas, benefiting from the large variety of locational advantages and rich resources. Deltas are highly dynamic and vulnerable environments that are exposed to a wide range of natural and manmade threats. Sustainable management of river deltas therefore requires a holistic assessment of historic and recent ongoing changes and the dynamics in settlement sprawl, land cover and land use change, ecosystem development, as well as river and coastline geomorphology, all of which is difficult to achieve solely with traditional land-based surveying techniques. This review paper presents the potential of Earth Observation for analyses and quantification of land surface dynamics in the large river deltas globally, emphasizing the different geo-information products that can be derived from medium resolution, high resolution and highest resolution optical, multispectral, thermal and SAR data. Over 200 journal papers on remote sensing related studies for large river deltas and estuaries have been analyzed and categorized into thematic fields such as river course morphology, coastline changes, erosion and accretion processes, flood and inundation dynamics, regional land cover and land use dynamics, as well as the monitoring of compliance with respect to anthropogenic activity such as industry expansion-related habitat destruction. Additionally, our own exemplary analyses are interwoven into the review to visualize related delta work.

Applications of Google Earth Engine in fluvial geomorphology for detecting river channel change

“…Here we suggest a critical evaluation of available discharge record data (including spatial and temporal resolutions) relative to the functional timescales of the geomorphic processes and the specific purposes of the application. Moreover, we note overlap between the identified applications and suggest this could facilitate cross-disciplinary collaboration, particularly at the interface of process systems (e.g., fluvial-coastal interactions; Kuenzer, Heimhuber, Huth, & Dech, 2019). GEE analysis will broaden the range of river morphological types for which we have significant data sets enabling improved identification of morphological style from the sedimentary record, of interest to source-to-sink sedimentologists, and potentially extending inferred river analogues to other planets (Santos et al, 2019).…”

Assessing Po River Deltaic Vulnerability Using Earth Observation and a Bayesian Belief Network Model

“…The use of EO from satellites and Copernicus information along with modeling plays a key role in the provision of spatial products representing land surface attributes in a continuous way determining an advantage for a valuable data-driven approach and in coastal processes understanding. First, the combination of satellite data coupled with spatially referenced ancillary measures, including vegetation, topography and bathymetries, climate, and geology, [4,23,24,40,53,54,81,82,95], has proved to be a cost-effective approach to classify and quantify coastal parameters [23,53,54,82,83] influencing the delta's vulnerability (Tables 1 and 3). Second, the use of EO data contributes to a better understanding and regular monitoring of landforms and coastal dynamics.…”

“…The complexity and diversity of the problems that affect the deltas clearly require reliable and comprehensive datasets in a spatial, temporal, and variable typology sense. Many recent advances in this research field hinge on the idea that the spatial and temporal variability of vulnerability can likely be accessed by integrating field observations with quantitative tools, like Earth observation (EO) data, since they allow objective study and accurate and repeatable data acquisition [20][21][22][23].…”

“…The use of EO definitely plays a major role in the provision of spatial products representing the land surface (including both morphological and ecological parameters), describing their dynamics and evolutions, and enabling to map and monitor highly vulnerable areas for ecosystem services [23,24] conservation. Currently, many remotely sensed EO data are globally available in satellite data archives and are freely accessible, as are their derived products (e.g., Copernicus core services and Copernicus Downstream services); thus, they are becoming largely used in a wide number of applications [25].…”

Using RGISTools to Estimate Water Levels in Reservoirs and Lakes

“…Remote sensing is an effective and efficient source of information to constantly survey water bodies at multiple scales and for different purposes [27]. For example, it has been used to study the ecological impact of human activities on a lagoon in the Mediterranean [28], study the dynamics of large delta rivers [29], quantify flooded areas [30], or survey newly dammed water reservoirs [31].…”