الفهرس 
INTRODUCTION
Geo- environmental AspectsOnly 14 pages are availabe for public view
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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%).