Lakes are a fundamental component of the environment and the territory and represent a precious source of fresh water for various uses. The area of the Prealps north of the Po valley in Italy is characterized by the presence of lakes which represent almost 80% of the total volume of fresh water in Italy (Rogora et al., 2018). The Insubric lakes (Lugano, Maggiore and Como) have their shared basins between Italy and Switzerland, and they are the objective of the SIMILE project, a cross-border Italian-Swiss Interreg project that aims to improve their coordinated management and strengthen stakeholder participation in the processes of knowledge and monitoring of water resources by analyzing data acquired from in-situ to satellite sensors. The present work refers to data collected by remote sensing methods which offer the possibility to obtain synoptic views of water bodies to monitor water quality parameters (WQPs) such as the chlorophyll-a (Chl-a), the total suspended matter (TSM) and the lake surface water temperature (LSWT). This work presents an extensive evaluation of the space-time trends of the parameters based on the SIMILE remote sensing database. Authors: Alessandro Austoni, Juan Francisco Amieva, Mariano Bresciani and Maria Antonia Brovelli

1. SIMILE
SIMILE - Information System for the integral monitoring of the
Insubric Lakes and their ecosystems
Strengthening of cross-border governance
ANALYSIS OF THE REMOTELY SENSED WATER QUALITY PARAMETERS OF
THE INSUBRIC LAKES: METHODS AND RESULTS OF THE INTERREG SIMILE
PROJECT
39th International Remote Environmental
Sensing Symposium 24th-28th April 2023
Alessandro Austoni, Juan Francisco Amieva, Mariano
Bresciani, Maria Antonia Brovelli

2. SIMILE
SIMILE Informative System for the Integrated Monitoring of
Insubric Lakes and their Ecosystems

3. SIMILE
GOALS PROTECTION OF WATER QUALITY OF
THE INSUBRIC LAKES
IMPROVEMENT OF LAKE
HYDRIC RESOURCE
EVALUATION AND
MANAGEMENT CAPACITY
STRATEGIES COORDINATION OF EXISTING MONITORING
SYSTEMS WITH NEW DATA COLLECTION
METHODS (HF SENSORS, SATELLITE
IMAGES, CITIZEN SCIENCE)
INCREASING ENVIRONMENTAL
AWARENESS AND PROMOTE LEGAL AND
ADMINISTRATIVE COOPERATION
BETWEEN CITIZENS AND
INSTITUTIONS
CROSS-BORDER
OPERATIVE AGREEMENT
AND POLICY-BRIEF

4. SIMILE
In situ sensors(HFM)
Hydrodynamic
and ecological
modelling
Business Intelligence
platform
Satellite based maps
OGC
Services and
open source
software
THE SIMILE PROJECT ECOSYSTEM

5. SIMILE
Satellite data Citizen Science
High frequency
monitoring (HFM)
Water issues RS HFM CS
Acidification - pH pH
Algal bloom chl-a
chl-a, phycocyanin,
phycoerythrin
Presence of algae
Aquatic life - Dissolved oxygen
Dissolved oxygen, presence of
fauna (e.g. dead fish)
Pollution - -
Presence of waste, discharges,
foams, oils and smells
Turbidity
Total suspended matter
(TSM)
Turbidity Transparency (Secchi disk)
Warming Temperature Temperature Temperature
MONITORING METHODOLOGIES

6. SIMILE
TUTORIAL
https://www.fondazionepolitecnico.it/w
p-content/uploads/2020/03/simile-app-
tutorial-eng.mp4
Schiume

7. SIMILE

8. SIMILE
WEBGIS

9. SIMILE
Data considered for the study
Total number of maps
389
Initial acquisition date:
15/1/2019
Final acquisition date:
5/11/2022
3 Lake Water Surface
Temperature
Chlorophyll -a
1 Total Suspended
Matter
2
Total number of maps
392
Initial acquisition date:
15/1/2019
Final acquisition date:
5/11/2022
Total number of maps
69
Initial acquisition date:
1/1/2019
Final acquisition date:
11/9/2022
Period
Initial date
End date
Winter 1/1/2022 20/3/2022
Spring 1/4/2022 15/5/2022
Summer 1/7/2022 31/8/2022
Autumn 1/10/2022 30/11/2022
Transition Spring-
Spring-summer
15/5/2022 15/6/2022
Transition Summer-
Summer-autumn
1/9/2022 1/10/2022
The analysis considered the
periods established by the Water
Framework Directive
Landsat 8 - TIRS
Sentinel 3
Sentinel 3

10. SIMILE
100%
0%
Chlorophyll – a
[% available data]
Lake Water Surface Temperature
[% available data]
Total Suspended Matter
[% available data]
Low availability
in Lake Lugano
and in coastal
zones
Better spatial resolution
of Landsat-8 ->
Higher availability in
coastal zones with respect
to the other two datasets
Data Availability analysis

11. SIMILE
Statistical analysis - histograms
Chlorophyll – a
Total Suspended
Matter
Lake Water Surface
Temperature
The transition periods Spring – Summer and Summer autumn correspond to
the same statistical distribution
Relative
frequency

12. SIMILE
Statistical analysis – box plots
Chlorophyll – a
Total Suspended
Matter
Lake Water Surface
Temperature

13. SIMILE
Spatial analysis – periods (90th percentile)
Total Suspended
Matter
• Greater values in Spring,
transition periods and
summer
• Greater values in northern
regions
• North rivers contribution to
tsm concentration increase
(Mera and Adda for Como
lake and Ticino for Maggiore
lake)

14. SIMILE
Spatial analysis – periods (90th percentile)
• Direct consequence of tsm
increase, more orgnic
material for
phytoplancton growth
• Greater values in spring,
summer and transition
periods
• Superficial algal blooms
Chlorophyll – a

15. SIMILE
Spatial analysis – periods (90th percentile)
Chlorophyll – a
• These zones have natural
"barriers" as mountains,
that block wind circulation
• The lugano lake is also the
smallest and shallowest
• Greater values in summer
and summer-autumn
transition (as expected)
(Lugano lake)

16. SIMILE
REFERENCES
• Biraghi, Carlo Andrea, Daniela Carrion, and Maria Antonia Brovelli. 2022. "Citizen Science Impact on Environmental Monitoring towards
SDGs Indicators: The CASE of SIMILE Project" Sustainability 14, no. 13: 8107. https://doi.org/10.3390/su14138107
• Bratic, G.; Carrion, D.; Cannata, M.; Rogora, M.; Strigaro, D. & Brovelli, M.A. (2022) Lake water quality monitoring tools. The International
Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLIII-B4-2022, 599–606, doi.org/10.5194/isprs-
XLIII-B4-2022-599-2022, 2022. [pdf]
• Toro Herrera, J. F., Carrion, D., Bresciani, M., and Bratić, G.: SEMI-AUTOMATED PRODUCTION AND FILTERING OF SATELLITE DERIVED WATER
QUALITY PARAMETERS, International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLIII-B3-2022,
1019–1026, doi.org/10.5194/isprs-archives-XLIII-B3-2022-1019-2022, 2022. [pdf]
• Vavassori, A., Oxoli, D., and Brovelli, M. A. (2022). Population Space–Time Patterns Analysis and Anthropic Pressure Assessment of the
Insubric Lakes Using User-Generated Geodata. ISPRS International Journal of Geo-Information. 2022; 11(3):206.
https://doi.org/10.3390/ijgi11030206 [pdf]
• Biraghi, C. A., Lotfian, M., Carrion, D., and Brovelli, M. A. (2021). AI IN SUPPORT TO WATER QUALITY MONITORING. International Archives of
the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLIII-B4-2021, 167–174, doi.org/10.5194/isprs-archives-XLIII-B4-
2021-167-2021 [pdf]
• Gerosa, C., Bresciani, M., Luciani, G., Biraghi, C. A., Carrion, D., Rogora, M., and Brovelli, M. A. (2021). ZONATION OF SUBALPINE LAKES
BASED ON REMOTELY SENSED WATER QUALITY PARAMETERS, International Archives of the Photogrammetry, Remote Sensing and Spatial
Information Sciences, 551–558, doi.org/10.5194/isprs-archives-XLIII-B3-2021-551-2021 [pdf]
• Toro Herrera, J. F., Carrion, D., and Brovelli, M. A. (2021). A COLLABORATIVE PLATFORM FOR WATER QUALITY MONITORING: SIMILE
WEBGIS. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLIII-B4-2021, 201–207,
doi.org/10.5194/isprs-archives-XLIII-B4-2021-201-2021 [pdf]

17. SIMILE
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