Assessment of riparian environments through semi-automated procedures for the computation of eco-morphological indicators: Preliminary results of the WEQUAL project

Abstract

Summary The aim of WEQUAL project (WEb service centre for QUALity multidimensional design and tele-operated monitoring of Green Infrastructures) is the development of a system that is able to support a quick environmental monitoring of riparian areas subjected to the realization of new green infrastructures (GI). The Wequal’s idea is to organize a service center able to manage both the Web Platform and the whole data collection and analysis processes. Through a personal account, the final user (designer, technician, researcher) can get access to the service and requires the evaluation of alternatives GI projects. On the Web Platform, a set of algorithms runs in order to calculate, through automatic procedures, all the ecological criteria required to evaluate a quality environmental index that describes the eco-morphological value of the monitored riparian areas. For this aim, the WEQUI index was developed, which uses 15 indicators that are easy to monitor. In this paper, the approach for environmental data collection and the procedures to perform the automatic assessment of two of the ecological criteria are described. For the computation, the implemented algorithms use data including the vegetation indexes, Digital Terrain Model (DTM), Digital Surface Model (DSM) and a 3D point cloud classification. All the raw data are collected by UAVs (Unmanned Aircraft Vehicle) equipped with a 3D Lidar, multispectral camera and RGB camera. Interpreting all the raw data collected by these sensors, using a multi-attribute approach, the WEQUI index is assessed. The computed ecological index is then used to assess the riparian environmental quality at ex-ante and ex-post river stabilization works. This index, integrated with additional not-technical or not-ecological indicators such as investment required, maintenance costs or social acceptance, can be used in multicriteria analyses in order to evaluate the intervention from a wider point of view. The platform is expected to be attractive for GI designers and policy makers by providing a shared environment, which is able to integrate the method of detection and evaluation of complex indexes and a multidimensional evaluation supported by an expert guide.

A Review of Unoccupied Aerial Vehicle Use in Wetland Applications: Emerging Opportunities in Approach, Technology, and Data

“…Emerging applications of UAVs are extremely promising for informing cost-effective yet spatially comprehensive indicators of wetland health at the landscape scale and support long-term monitoring needs. Our pool of studies in this category included seven mapping, three modeling, three change analysis, and one novel method application that either targeted a particular aspect of wetland ecological health such as water quality (e.g., [105]) and vegetation indicators (e.g., [42,108,111]) or assessed the overall ecological status using different indicators (e.g., [7,34]). These studies employed RGB, Multispectral, Hyperspectral, and SAR sensors, as well as combinations of RGB and Multispectral and RGB and Thermal sensors (Figure 3).…”

“…These studies employed RGB, Multispectral, Hyperspectral, and SAR sensors, as well as combinations of RGB and Multispectral and RGB and Thermal sensors (Figure 3). Multi-sensor combinations especially benefit holistic assessments targeting multiple health indicators by helping to strategically optimize surveying workload between less demanding and easily replicable tasks (such as visual recognition from passive RGB imagery) and more intensive data processing endeavors (such as LiDAR-derived modeling of geomorphology and vegetation structure) [7,34,35].…”

“…Vegetation-based indicators play an especially prominent role in such assessments, including the presence of characteristic [27,35,42,48,106] or special status [64,108] native plant species or signals of vegetation mortality and stress [27,34,42]. Among abiotic indicators, several geomorphological and hydrological characteristics can be informed by UAV data, including shoreline microtopography and slope gradients, water quality, surface roughness, and evidence of anthropogenic impacts [7,34,35,47,107]. Interestingly, only a small fraction of such studies focused on wetland change using UAV data from more than one time frame [108][109][110][111].…”

“…UAVs are beneficial to environmental monitoring because they bridge the constraints in complex, dynamic, limited-access environments that historically have been challenging to survey [3]. Furthermore, they reduce the amount of time and labor expended on surveying and sampling on the ground [4][5][6][7], providing time for targeted managerial activities that may otherwise be overlooked, such as restoration assessments [8][9][10][11]. In recent years, technological advances in UAV instruments such as greater spectral complexity via LiDAR and multispectral sensors and increased volumetric estimations from Structure from Motion (SfM) photogrammetric techniques have transformed applications of UAVs in environmental research [12].…”

“…UAVs are uniquely positioned to cost-effectively overcome these challenges at local observation scales via spatially comprehensive coverage, customizable flight schedules, and diverse sensor instruments for specific applications [18,[30][31][32][33]. The high spatial resolution of UAV-derived imagery makes them an especially valuable surrogate for field assessments by enabling visual recognition of landscape elements and evaluation of multiple indicators of wetland habitat and ecological status (e.g., [7,[34][35][36]). At the same time, some essential aspects of UAV workflows pertaining to in situ infrastructure-e.g., positioning of launching and landing sites, installation of georeferencing markers, among others-may be challenged by wetland landscape properties and accessibility similarly to ground surveys.…”