Exploring the potential of MODIS visible and thermal channels in monitoring and assessing the impact of desalination plant discharges in the Arabian Gulf
ABSTRACT Sea water desalination has experienced an unprecedented growth in the GCC countries to meet the ever growing demand of water for household consumption as well as for industrial and agricultural purposes. However, the current technologies used in water desalination are also accompanied by negative environmental impacts especially on the surrounding marine ecosystems. Since major seawater desalination plants are located by the shoreline, the main environmental considerations in desalination are water intakes and sea outfall discharges. We intent through this study to evaluate the potential of current polar orbiting satellites in evaluating the impact of desalination plant discharges, usually used to dispose of brine waste stream, on surrounding ecosystems and water quality. The objective of this project is to develop an automated approach for monitoring water quality and temperature (thermal properties) surrounding the discharges of desalination plants in the UAE coastal areas. Visible and thermal measurements provided by MODIS sensors on board of Terra and Aqua satellites are used in this project. The first four bands (visible) and band 31 & 32 (thermal) were selected. Future multi-spectral data from DubaiSat-1 (5-m resolution) will be also used to detect small changes in water color that cannot be detected with the MODIS data (250 m).
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ABSTRACT: Remote sensing from air-borne and space-borne sensors have proved to be a useful methodfor Suspended Sediment Concentration (SSC) estimation as it provides an instantaneous and synopticview of suspended sediments that would otherwise be unavailable. The reason for the success of remotesensing in such surveys is the strong positive relationship that exists between SSC and remotely sensedwater leaving radiance. To find an algorithm relating SSC to spectral radiance over Bahmansheer RiverEstuary at the North-West of Persian Gulf, a three-month field expedition (April to June 2003) wasconducted while the MODIS sensor on board Terra simultaneously flew over the scene. Fifty sevensamples in fifteen trips were collected. The collected samples were analyzed by measuringconcentration, diameters of the sediment particles and by determining the sediment constituents. Totalconcentration ranged between 30 and 500 mg, the range of particle diameter was from less than amicrometer to more than 20 micrometers and finally it was found that the sediment was composed ofQuartz, Kaolinite, Orthoclase, Chlorite, Calcite, Gypsum, Muscovite, Halite, Anhydrite, Apatite, Biotiteand a low amount of Albite. It is found that the spectral characteristics of these compositions are partlyresponsible for the reflected and/or scattered energy in different bands while the correlation betweenlarger suspended particle concentration and spectral radiance was profound.American Journal of Applied Sciences 07/2008;
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ABSTRACT: As on land, plants are the real producers in the sea, and on them depend all marine living resources and the basic sustainability of ecosystems. Primary production is performed by chlorophyll-bearing plants ranging from the tiny phytoplankton to the giant kelps through the process ofphotosynthesis. Zooplankton play an important role as secondary producers, and together with phytoplankton they support the vast assemblages of marine food chain with all their diversity and complexity. Data on chlorophyll pigments, phytoplankton and zooplankton are regarded as a sound basis for environmental appraisal of ecosystems. This paper presents a set of data collected from the Saudi Arabian coastal waters near the desalination plants in AI-Jubail. Materials were collected from six different sites covering the intake and discharge zones during cruises carried out in 1997–1998. Analyses of chlorophyll pigments were made using the spectrophotometric method. Plankton samples were collected using a Nansen plankton net with a mesh size of 75 μ and analyzed following standard procedures. Chlorophyll a, b, c and phaeophytin are the most commonly occurring pigments in seawater. Their concentrations showed wide fluctuation. The phytoplankton community was composed of 35 genera representing the Diatoms, Dinoflagellates and blue- green algae. Zooplankton were composed ofProtozoa, Coelenterata, Ctenophora, Aschelminthes, Annelida, Mollusca, Arthropoda, Echinodermata and Chordata. Arthropoda, represented by Cladocera, Copepoda and Crustacean larvae, formed the largest group followed by Chordata. The distribution of phyto- and zooplankton was examined and discussed on a seasonal, annual and inter-annual basis. In terms of species, overall species composition was not affected by plant discharge. The study brings out a greater understanding of the changes experienced by biotic communities as a result of impingement, entrainment and entrapment consequent to water passage through the plant structures. The study reflects the ecological relationships that the phytoplankton and the zooplankton of the region possess with respect to intake and discharge. Further, the study has brought to light a very redeeming feature of the ecosystem to sustain its productivity and planktonic abundance. It was observed that seawater temperature, conductivity and total suspended solids did not act as limiting factors. Besides throwing much light on the little known biological aspects of desalination sites, the data provided constitute a significant addition to the knowledge base of marine living resources in an industrial zone of Gulf coastal waters.Desalination 05/2003; 154(3):291-302. · 3.96 Impact Factor
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ABSTRACT: High concentrations of suspended particulate matter in coastal waters directly affect or govern numerous water column and benthic processes. The concentration of suspended sediments derived from bottom sediment resuspension or discharge of sediment-laden rivers is highly variable over a wide range of time and space scales. Although there has been considerable effort to use remotely sensed images to provide synoptic maps of suspended particulate matter, there are limited routine applications of this technology due in part to the low spatial resolution, long revisit period, or cost of most remotely sensed data. In contrast, near daily coverage of medium-resolution data is available from the Moderate-resolution Imaging Spectroradiometer (MODIS) Terra instrument without charge from several data distribution gateways. Equally important, several display and processing programs are available that operate on low cost computers.The utility of MODIS 250 m data for analyzing complex coastal waters was examined in the Northern Gulf of Mexico. Using simple processing procedures, MODIS images were used to map the concentration of Total Suspended Matter (TSM). A robust linear relationship was established between band 1 (620–670 nm) MODIS Terra 250 m data and in situ measurements of TSM (r2=0.89; n=52; MSE=4.74) acquired during six field campaigns. This study demonstrates that the moderately high resolution of MODIS 250 m data and the operating characteristics of the instrument provide data useful for examining the transport and fate of materials in coastal environments, particularly smaller bodies of water such as bays and estuaries.Remote Sensing of Environment 10/2004; · 4.77 Impact Factor
EXPLORING THE POTENTIAL OF MODIS VISIBLE AND THERMAL
CHANNELS IN MONITORING AND ASSESSING THE IMPACT OF
DESALINATION PLANT DISCHARGES IN THE ARABIAN GULF
Ammar Al Muhairi1, Hosni Ghedira2, Hussain Al-Ahmad3, Ali Dawood3, and Mohammed Al-Mualla3
1Associate Research Engineer, DubaiSat-1 Program
Emirates Institution for Advanced Science & Technology (EIAST), Dubai, UAE.
2American University in Dubai, Dubai UAE
3Khalifa University of Science, Technology and Research (KUSTAR), Sharjah, UAE
Sea water desalination has experienced an unprecedented
growth in the GCC countries to meet the ever growing
demand of water for household consumption as well as for
industrial and agricultural purposes. However, the current
technologies used in water desalination are also
accompanied by negative environmental impacts especially
on the surrounding marine ecosystems. Since major seawater
desalination plants are located by the shoreline, the main
environmental considerations in desalination are water
intakes and sea outfall discharges. We intent through this
study to evaluate the potential of current polar orbiting
satellites in evaluating the impact of desalination plant
discharges, usually used to dispose of brine waste stream, on
surrounding ecosystems and water quality. The objective of
this project is to develop an automated approach for
monitoring water quality and temperature (thermal
properties) surrounding the discharges of desalination plants
in the UAE coastal areas. Visible and thermal measurements
provided by MODIS sensors on board of Terra and Aqua
satellites are used in this project. The first four bands
(visible) and band 31 & 32 (thermal) were selected. Future
multi-spectral data from DubaiSat-1 (5-m resolution) will be
also used to detect small changes in water color that cannot
be detected with the MODIS data (250 m).
Index Terms— environmental impact, remote sensing,
desalination plants, MODIS, water quality.
The four major desalinations plants in the UAE have
been selected in this study with total capacity of around 750
million gallon per day (MGD): Jebel Ali, Al Marfa, Umm
Al-Nar, and Shuwayhat (figure 1).
Umm Al Nar
Shuwayhat Al Marfa
Fig. 1: Monitored desalination stations
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The geographic coordinates and current production
capacities of these stations are presented in table 1. This
paper will cover the first stage of this project that focus on
the evaluation of the impact of Jebel Ali station in Dubai
which has the highest production capacity in the UAE.
Table 1: location and capacity of monitored stations
*As of March 2008
The arid climate of the Arabian Gulf contributes to
sedimentation through increased wind action and the
infrequent but heavy rainfalls which cause flash floods.
Additionally, high water temperatures with high evaporation
rate and low water inflow through rivers and precipitation
cause a circulation pattern that favor inorganic carbonate
development of sediments, as shown in MODIS image
presented in figure 1.
2. LITERATURE REVIEW
Several studies related to environmental impacts of
desalinated plants in the Arabian Gulf have been carried out
in the past 10 years. In 2002, Abdul Azis et al.  presented
a set of environmental data collected in the Saudi coastal
waters near Al-Jubail desalination plant. Water samples
from six different sites covering the intake and discharge
zones were collected between 1997 and 1998. Twenty-eight
species of phytoplankton were identified and analyzed. This
study found that the desalination plant discharge has no
significant effect on phytoplankton and chlorophyll pigments
. Another study was also performed in 2005 by Abu
Dhabi Water & Elec. Authority  to evaluate the
environmental impact of Umm Al-Nar desalination station in
the UAE. This station is surrounded by a sensitive
ecosystem with extensive areas of mangroves and seagrass
meadows. The spatial distribution of high temperature and
salinity as well as water flow properties surrounding the
desalination plant has been observed and studied. Their
observation had shown no significant deterioration of water
quality surrounding the plant.
Other type of environmental study was also performed
to evaluate and mitigate the potential damage of an eventual
oil spill accidents. Elshorbagy and Elhakeem (2007) have
produced a set of 10 hazard contour maps for the prediction
of oil spill travel time and critical wind direction in
association with five selected mega-desalination plants along
the UAE coast: Al-Shuwayhat, Al-Marfa, Umm AlNar,
Taweelah, Jebel Ali and Al-Layah. The author produced
to frequent and visible
hazard maps using a three-dimensional coupled set-up of a
hydrodynamic model (Mike3-HD) and oil spill model
Satellite measurements have been widely used for water
quality monitoring in the last three decades. CZCS and
SeaWiFS, which were launched in 1978 and 1997
respectively, were the first two earth observation satellites
devoted to water quality monitoring and measurement. The
long gap between launching the two instruments proofs that
the lack of suitable sensors has limited the use of remote
sensing in the past . Water quality monitoring from space
has been extended by the launch of MODIS sensors on
board of Terra and Aqua satellites. Satellite data has been
used to measure different water quality parameters including
color, phytoplankton (chlorophyll a), total suspended matter
(TSM), colored dissolved organic matter (CDOM), turbidity
Hu et al. (2004) have successfully used MODIS data to
map chl a, aCDOM(400) and TSM values in Tampa Bay
(Florida, USA). For TSM estimation, they used a channel
difference algorithm: R(645)−R(859).
algorithm R(469)/R(555) was used to retrieve aCDOM(400)
and chl a. For the combined data set, the authors used a
multi-band ratio which is based on complex ratio of channel
differences. A high correlation coefficients (up to 0.96)
between satellite data and water parameters were obtained
250-m resolution data of MODIS has been also used by
Miller and McKee (2004) to map the concentration of TSM
in the Northern Gulf of Mexico. The authors found more
than 90% correlation between the first band of MODIS (645
μm) and in situ measurements of TSM .
MODIS data were also compared with SeaWiFS data by
Dall’Olmo et al. (2005) in estimating chl a in turbid water
using Red and NIR bands. MODIS (667,748) appeared to
provide the most accurate prediction of chl a .
MODIS data has also been used in monitoring water
quality in the Middle East region (Red Sea and Arabian
Gulf). Nasr et al. (2007) estimated chl a, TSM and Sea
Surface Temperature (SST) in the Red Sea. OC4 algorithm
was used to estimate chl a and other two empirical
algorithms were used for estimating TSM and SST. The
derived and the measured chl a and SST were very well
correlated (RMSE= 0.13 and 0.37) respectively. While the
concentration of TSM needed an offset for satisfactory
correspondence (RMSE= 4.86) .
Reza (2008) used MODIS data to develop an algorithm
for retrieving Suspended Sediment Concentration (SSC)
from MODIS spectral radiance over Bahmansheer River
Estuary at the North-West of Arabian Gulf. Algorithm 1 was
obtained from the relationship between the measured
concentrations and MODIS channel 1 reflectance difference
(Δρch1). The resulting r2 was poor (0.59). As for algorithm 1,
Algorithm 2 was obtained but with channel 4 reflectance
difference (Δρch4). A better r2 of 0.77 was found. Algorithm
III - 358
2 has shown more sensitivity to SSC variation and was
recommended for turbid estuaries and coastal waters
In this project, different existing tools such as the Ocean
Color Chlorophyll (OC4) algorithm will be also tested. This
algorithm, based on a four-band maximum band ratio
formulation, has been successfully used to estimate chl-a
concentration. Similar MODIS-based algorithms have also
been developed to map the Total Suspended Matter (TSM)
distribution and Sea Surface Temperature (SST).
3. DATA ANALYSIS
Visible reflectances and sea surface temperatures have
been derived from MODIS data. An average of six scenes
has been used each month. The images presented in figure 2
show the sensitivity of the three visible channels of MODIS
to the variation of water properties. High sensitivity was
observed with the blue channel where the reflectance has the
better response to the variation in water turbidity.
10 2030 4050
10 203040 50
Green (545-565 nm)
Fig. 2. Three visible channels and one temperature channel derived from MODIS on January 10th 2009
In addition to its sensitivity to water properties, the
measured reflectances can be also affected by the satellite
acquisition angles which vary from day to day. Figure 3
shows how reflectance changes with the acquisition angle
within a specific area. The green channel shown mor
sensitivity to satellite acquisition angle. An angle of 45º
results in highest reflectance and reflectance decreases with
a higher or lower angle. In the NIR band, the reflectances
are much less sensitive to the acquisition geometry.
The in situ measurements were provided by Jebel Ali
desalination plant in a monthly basis. The difference in
temperature of intake and brine discharge was about 10˚C in
average. Moreover, there was a difference of about 1.1˚C in
average between the temperature of the intake seawater and
the one measured by MODIS. Figure 4 illustrate the
difference between field-measured and satellite-measured
Fig. 3. Reflectance vs. Acquisition angle
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Fig. 4. Comparison between field-measured and satellite-
The preliminary results show that satellite-based
temperature is closer to the intake temperature rather than
brine temperature. This observation shows that the high
temperature of the brine has a local impact on surrounding
water. However, it is important to mention that the low
spatial resolution of MODIS thermal channel (~1 km) make
it less sensitive to local variations of the temperature.
Additionally, the short distance between the intake and the
outfall to the shoreline adds more noise to the measured
temperature by increasing the contribution of the land
radiation to the temperature measured by the satellite.
For the next stage, the spatial and temporal variation of
water reflectance will be analyzed in two other stations in
the UAE. The correlation level between satellite reflectances
and concentrations of some water quality parameters will be
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waters,” Remote Sens. Environ., vol. 93, pp. 259-266, 2004.
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