Spatial database and web-GIS for managing and validating river embankment monitoring data

Thanks to the increasing development of ICT, river embankments would become safer by using Early Warning Systems (EWS). Accordingly, the real-time assessment of the stability of river embankments should analyze a large number of geospatial and temporal data, such as ground surface, geology, hydraulic and mechanical soil characteristics, water level in the river, groundwater pressure, surface and soil displacements, meteorology. This study focuses on the development of a system (Fig. 1) made of a spatial database (DBMS) and a webGIS able to storage, validate, mapping and display the data to assist the decision makers in managing an EWS. By developing a Sensor Observation Service (SOS) the database could be linked to the sensors (including geospatial data and manual measures), and the webGIS could interact with users for displaying the data and collecting more additional information. The database was set up by using PostgreSQL and Post GIS; the webGIS displays the time series of data through graphs made with Open Flash Charts. Special attention was paid in the development of procedures to assess the reliability of the measurements. For this purpose the database includes all the information needed to describe the instrument conformance, such as the sand pack size and casing diameter of open-standpipe piezometers for evaluating their time lag, and the calibration curves of transducers with the possibility of their updating. The non-functioning instruments are identified through the analysis of the electrical signal and their positions are displayed by maps. The analysis of the redundancy and coherence of measurements is used for detecting doubtful data. The system, combining a spatial DBMS and a webGIS, was applied to the monitoring data of an embankment of the Adige River in Northern Italy (Fig. 2). Measurements of groundwater pressure, soil vertical displacements, soil and instrument temperature, meteorology and water level of the river were processed.