Assiut university researches
Using Multispectral Satellite Images to
Estimate the Environmental State of Coral
Reefs at Hurghada Region, Red Sea Coast,
Egypt
‫ا س تخدام صور اآلق مار ال ص ناع ية م ت عددة االط ياف ف ى‬
‫ت قدي ر ال حال ة ال ب ي ئ ية ل ل ش عاب ال مرجان ية ف ى‬
.‫ م صر‬،‫م نط قة ال غردق ة ب ساحل ال بحر االح مر‬
Mostafa Atef Soliman Khaled
‫م صط فى عاطف س ل يمان خال د‬
Ahmed Hamed Obuid-Allah, Mahmoud Hussein Ahmed, Turkya Abo
El-Magd Mohamed, Sameh Bakr El-Kafrawy.
‫ سامح ب كر‬،‫ ت رك ية أب وال مجد محمد‬،‫ محمود ح س ين أحمد‬،‫أحمد حامد ع ب يدهللا‬
‫ال ك فراوى‬
Abstract:
Coral reefs provide an excellent case study of the application
of marine remote sensing to a shallow coastal ecosystem that
is spatially limited. Coral reefs exhibit high diversity, high
productivity, and faces severe anthropogenic and climatic
threats. Coral reefs, lagoons and their associated
environments exhibit a high degree of natural variability in
terms of water quality, benthic patchiness, and water depth.
This variability presents a significant challenge for many
analytical optical algorithms. So the remote sensing is a good
tool to monitor the past, the present and the future status of
coral reefs and its habitat. The ‘Coral Reef GIS’ can be used
for understanding the spatial characteristics of the coral reefs,
for modeling different spatial and temporal processes, to
evaluate various proposed management scenarios or to
determine potential risk zones that mark the localization of
the reefs under potential stress due to changing conditions.
Coral reefs are an essential part of the earth’s ecosystem.
They are sensitive indicators of the health of marine
environments and are important economically, providing
people around the globe with food, jobs, coastal storm
protection, and recreational opportunities. Many of the world’s
reefs have been severely damaged over the past few
decades due to a combination of factors including habitat
destruction, land-based pollution, sedimentation, overfishing,
vessel groundings, coastal development, disease, and
climate change. A few previous researches based on
multispectral satellite images with moderately high resolution
studied the coral reef habitat mapping, land use/land cover,
bathymetric mapping and change detection at Hurghada, Red
sea, Egypt. Hurghada was chosen as an appropriate site for
this study for these reasons: 1. Degradation of offshore reefs
due to increased diving pressure and associated activities in
the region is increasing at an alarming rate. 2. The proposed
tourist developments are huge and will pose a threat to the
marine natural resources in the region. 3. Lack of
management plans to regulate diving operations, hence,
decrease pressure on existing dive sites. The present work
was designed to carry out the following points:  Assess coral
reef habitat changes at Hurghada region from 1972 to 2011
using multispectral satellite images.  Build up a complete
geographic database of coral reef, land use changes and
water quality conditions in the region.  Record some
ecological factors that may affect corals including, water
temperature, pH, dissolved oxygen, total dissolved solids,
conductivity, salinity and some heavy metals (Cu, Cd, Pb and
Zn). These mentioned goals were achieved by using
multispectral satellite images to estimate the changes by
using moderately resolution as Landsat (MSS, TM and
ETM+) and SPOT XS from 1972 – 2011. Based on these
images six studied sites were chosen to make the survey and
habitat ground truthing. The image processing analysis was
performed using the following software’s, ENVI 5.0, ERDAS
10, and Arc GIS. The SPSS software used to perform the
statistical analysis. Field survey was planned to represent the
range of physical environments within a study area. The
locations of approximately 150 points were recorded for each
water body habitat type (for guiding multispectral
classification and for accuracy assessment) and 200 points
were recorded for each land body classes. Groundtruth field
work at the study area was conducted over a period of 12
days during 2011. Habitat transect data were collected using
SCUBA diving and snorkeling to obtain more details of the
coral reef condition, such as live coral, dead coral, bleached
coral percentage and the dominant species. About 135
transects were surveyed using the line intersect transect
technique at the study area. The length of each transect was
100 m. Pictures were also taken by underwater camera along
transects at each site, for cross reference and species
identification. Also different pictures were taken to record the
effects of degradation of coral reefs. Reef habitat
classification scheme was used to record the observations at
each dive site. A Portable Echo-Sounder was used to
measure the water depth. About 240 depth points were
collected and each coordinate point was recorded with the
JunoTrimble GPS, including the time of acquisition. Sea
surface temperature, salinity, dissolved oxygen (mg/L), pH,
conductivity and total dissolved salts were measured directly
in the field using Hydrolap instrument. Four heavy metals
were seasonally determined; Lead (Pb), Cadmium (Cd),
Copper (Cu) and Zinc (Zn). The important results of the study:
1. The total changes during the 39 years of the shore line is
6.29 km2, (5.65 km2 accretion and 0.64 km2 erosion) and
urban development is 16.47 km2 the road network is
8.738km2. The total changes of coral reefs area during 39
years (1972-2011) decreased about 5.34 km2. 3. The total
changes of mangrove during the period of study 39 years
decreased about 26 m2. 4- The total changes of sea weeds
during 39 years decreased about 9.85 km2. 5- The total
change of sea grass during 39 years decreased about 7.63
km2. 6- The mean value of live corals for all studied sites
ranged between (54.67±8.12% and 28.33±10.47%). The
mean value of dead corals ranged between (67.67±6.04%
and 44.33±6.51%). The mean value of bleached ranged
between (11.00 ± 7.12% and 1.000 ±2.070%).