3c1bd246-2de9-46b6-8fca-fffd3ffb7338
Rachid Adallal
CEREGE UMR 7330 CNRS
PhD Student
CEREGE Europôle de l'Arbois BP 80
Aix en Provence
Bouches du Rhône
13545
France
adallal@cerege.fr
2020-10-20T15:25:16
ISO 19115:2003/19139
1.0
WGS 1984 UTM Zone 29N
DEM of Agziza lake watershed - PHYMOR project
2015-04-28
High-resolution elevation model of Azigza watershed using the RTK-GPS combined with the assessment of topographic map scanned and a bathymetric map of the lake.
Rachid Adallal
CEREGE UMR 7330 CNRS
PhD Student
CEREGE Europôle de l'Arbois BP 80
Aix en Provence
Bouches du Rhône
13545
France
adallal@cerege.fr
Laurence Vidal
CEREGE UMR 7330 CNRS
Researcher
CEREGE Europôle de l'Arbois BP 80
Aix en Provence
Bouches du Rhône
13545
France
vidal@cerege.fr
http://database.otmed.fr/otmedgeonetwork/srv/eng/resources.get?uuid=3c1bd246-2de9-46b6-8fca-fffd3ffb7338&fname=dem_azigza.png
large_thumbnail
png
Azigza
Elevation
GEMET - INSPIRE themes, version 1.0 INSPIRE themes
2008-06-01
geonetwork.thesaurus.external.theme.inspire-theme
25000
elevation
-5.3
-5.2
32.9
33
GRID
The project PHYMOR aims at studying environmental variability of altitudinal lacustrine systems from the Moroccan Middle Atlas. The main objectives are to:
- To understand hydrological functioning of the hydro-systems and their sensitivity to climate changes;
- To propose a calibration between hydro-climatic parameters and paleo-proxies;
- To reconstruct paleo-hydrological variability based on geochemical studies of lacustrine sediments.
Within the frame of R. ADALLAL PhD-thesis, the first objective was addressed at site Aguelmam Azigza using site monitoring, water isotopic analysis and hydrological modelling.
This water balance requires the knowledge of the lake area–volume-level relationships that were determined by using:
1) A high-resolution elevation model of Azigza watershed using the RTK-GPS combined with the assessment of topographic map scanned
2) A bathymetric map of lake
3) A survey of water level of Azigza lake
DEM is used to mean the digital cartographic representation of the elevation of the earth surface in any form with different accuracies for different application fields. In this study, we used two methods :
1- This first approach aims to extract the altitude of contour line from the topographic map that has no direct access to the individual data of altitude. This method requires a GIS software (in our case, we use ESRI ArcGIS 10,2) and a base topographic map (the topographic map 1:50 000 of Karrouchan, Card Division, Rabat, 1977) . The main necessary steps are : a) Georefencing the topographic map scanned, b) Digitizing the contour line to a point shape, c) Converting vector shape to raster.
2- The second approach is Real-Time Kinematic Global Positioning System (RTK GPS). It is used to collect the field survey data. RTK positioning uses a static GPS receiver as a reference station located at a known point. Another receiver is used as the rover which can move and survey any points of interest. Both receivers make observations of the GPS signals at the same time and a radio data link between the two receivers permits data to be sent from reference to rover, where the calculation of coordinates is carried out. For our field survey, the reference receiver station is set up on the well located near to Azigza lake whose coordinates are determined by precision known (X: 831421.654 m, Y: 3654309.629 m, Z: 1551.413 m). The rover is taken on the back of the rod person to cover a stady area by walking along the watershed. At the end of the field survey the RTK GPS data are imported into Geographic Information System (GIS) software for DEM quality assessment.
The bathymetric survey was carried out using a combination of the Echo Sounder and Global Positioning System (GPS), to generate XYZ data points.
Surfer 12 and ArcGIS 10,2 computer software were used to finalize data evaluation.