Quantitative Hyperspectral Analysis for Characterization of the Coastal Water from Damietta to Port Said, Egypt

ARTICLE IN PRESS The Egyptian Journal of Remote Sensing and Space Sciences (2014) xxx, xxx–xxx

National Authority for Remote Sensing and Space Sciences The Egyptian Journal of Remote Sensing and Space Sciences

www.elsevier.com/locate/ejrs www.sciencedirect.com

RESEARCH PAPER Quantitative hyperspectral analysis for characterization of the coastal water from Damietta to Port Said, Egypt

Islam Abou El-Magd, Ahmed El-Zeiny *

National Authority for Remote Sensing and Space Sciences, Environment Department, 23 Josef Tito St., El-Nozaha El-Gedida, Cairo, Egypt

Received 27 August 2013; revised 15 January 2014; accepted 16 February 2014

KEYWORDS Abstract The coastal zone of the Nile Delta is wealthy of natural resources that currently accom- Hyperspectral remote modate and support not less than one third of the population. However, it is still a promising area sensing; for energy resources and industrial activities that initiated the country to develop new action plans Coastal water quality; for industrial estates and services; it is under extreme environmental pressure. The newly developed Nile Delta; techniques of remote sensing offer effective tool to monitor such environment on a near-real time Egypt basis at minimum in situ sampling. Detection of water quality conditions and parameters is one of the major advantages of hyperspectral remote sensing technologies; which has been widely used to assess water quality conditions of many open water mass and aquatic ecosystems. This research looked at characterization of the water quality using the different functions of in situ measurements of hyperspectral sensors in conjunction with water quality multi-probe sensor. The spectral behaviour of the water at the outlets is quite different from the other sampling sites of the coastal water. Turbidity was recorded at high level of 65 (NTU) and chlorophyll was up to 147 mg/l at the outlets, which were positively correlated with the hyperspectral curve of the spectroradiometer and Hype- rion data. The archived Hyperion data showed some similarities and differences with the in situ data that were mostly due to the timing differences between both datasets; it, however, enabled for understanding of the hyperspectral application in water quality. Ó 2014 Production and hosting by Elsevier B.V. on behalf of National Authority for Remote Sensing and Space Sciences.

1. Introduction

The Nile Delta of Egypt represents about 2.3% of the Egyp- * Corresponding author. Tel.: +20 1007737052. tian territory; however, it supports 63% of the country’s agri- E-mail address: [email protected] (A. El-Zeiny). cultural land (Hereher, 2009) and accommodates about 45% Peer review under responsibility of National Authority for Remote of Egyptian population. Ecologically, it includes about 25% Sensing and Space Sciences. of the total Mediterranean wetlands (Sestini, 1992), which supports the ecological balance and ﬁshing production. The coastal zone of the Nile Delta is wealthy of natural resources that Production and hosting by Elsevier currently accommodate and support not less than one third

1110-9823 Ó 2014 Production and hosting by Elsevier B.V. on behalf of National Authority for Remote Sensing and Space Sciences. http://dx.doi.org/10.1016/j.ejrs.2014.02.001

Please cite this article in press as: Abou El-Magd, I., El-Zeiny, A., , Quantitative hyperspectral analysis for characterization of the coastal water from Damietta to Port Said, Egypt, Egypt. J. Remote Sensing Space Sci. (2014), http://dx.doi.org/10.1016/j.ejrs.2014.02.001 ARTICLE IN PRESS 2 I. Abou El-Magd, A. El-Zeiny of the population (Abou El-Magd and Hermas, 2010). How- The content of chlorophyll-a is proportional to the amount ever, it is still a promising area for energy resources and indus- of biomass present in the body, while there is a relationship be- trial activities that initiated the country to develop new action tween reflectance and total suspended solids (Li et al., 2010; plans for industrial and services estates. Unfortunately, due to Moses et al., 2012). This includes classifying the trophic status the un-planned development activities the coastal zone and of lakes (Koponen et al., 2002; Thiemann and Kaufmann, coastal water resource are facing unprecedented pollution 2002) and estuaries (Froidefond et al., 2002) characterizing al- from human activities including agriculture discharge, indus- gal blooms and chlorophyll-a (Stumpf, 2001; Gitelson, 1992; trial discharge as well as sewage discharge. Simply, all kinds Polliainen et al., 2001; Gons et al., 2008) and assessment of of pollutants that are carried by rivers and drainage systems ammonia dynamics based on signatures of macrophytes (Tilley ultimately end up into these coastal water resources (El-Zeiny, et al., 2003). This would enable cumulatively to determine the 2010). total suspended matters (Hakvoort et al., 2002; Vos et al., To monitor the quality of such dynamic environment the 2003; Nechad et al., 2010) and total phosphorus (Koponen conventional methodologies are required to regularly obtain et al., 2002). water samples for laboratory analysis. However, these method- The main objective of this research paper is to characterize ologies are accurate and help in proposing mitigation and the water quality of a portion of the coastal zone of the Nile rehabilitation mechanisms, they have some shortcomings. Delta using the different functions of in situ measurements of These include the localized sampling location that could not hyperspectral sensors in conjunction with water quality mul- be generalized, does not consider the other surrounding envi- ti-probe sensor and remotely sensed data. ronment that influences the water quality as well as time con- suming and very costly. Therefore, new techniques of earth 2. Materials and methods observations including the availability of repetitive, synoptic and multi-spectral data from various satellite sensors are pow- 2.1. Area of study erful in monitoring the coastal and marine environment (Nayak, 2002). Such remote sensing tools provide near-real The chosen area of study is an elongated coastal zone area that time monitoring of such dynamic environment. extends from Damietta to Port Said. It represents a vital part Hyperspectral remote and proximal sensing is currently of the Nile Delta region as a resource for fish production, en- extensively and successfully used to study the state of the envi- ergy and some of the industrial activities. It witnessed lots of ronment and to track changes that occur over time. It acquires changes during the last few decades and greatly affected by dif- intensive, very narrow and contiguous spectral bands through- ferent types of man-made activities and changing of the land out the visible, near-infrared and mid-infrared portions of the use and land cover of the surrounding area. This boosts the electromagnetic spectrum (Song et al., 2012). Hyperspectral discharge of pollutants from various types and sources of sensors typically collect 200 or more bands enabling the con- wastes, which negatively affect the region (Fig. 1). struction of an almost continuous reflectance spectrum for The climatic condition of the area is typical Mediterranean every pixel in the scene. Contiguous, narrow bandwidths char- environment with moderate temperature most of the year. The acteristic of hyperspectral data allow for in-depth examination obtained meteorological data are from the nearest climatic sta- of earth surface features which would otherwise be ‘lost’ within tion at El Gamil station in 2011 (Table 1). The predominant the relatively coarse bandwidths acquired with multispectral wind direction in the area of study is almost northwest direc- scanners (Smith, 2001b). tion most of the year, which creates a general eastward-flowing Hyperspectral remote sensing has shown high potential in long shore current (El-Asmar and Hereher, 2010). Statistically, detecting the conditions of the water quality and its parame- it was found that 81% of these waves originate from the north- ters. This is actually based on the interaction between the elec- west direction, 14% from the northeast and just 5% from tromagnetic radiation and the water contents. The shorter the southwest (Frihy et al., 2003). Winter season almost records wavelength the higher is the penetration of the water content, the maximum wave height of 4.2 m which is predominantly which reflects the water column, therefore both wavelength from the west-north-west wave direction; whereas spring sea- and water characteristics are key in this process. In fact, the son records the minimum wave height of 1.16 m which origi- reflectance of the water surface is the result of complex pro- nates from the northwest direction (El-Banna 2007). A tidal cesses of absorption and reflection of sunlight by phytoplank- difference is semi-diurnal and ranges between 25 and 30 cm ton, inorganic particles in suspension, dissolved humus, water along the delta coast. plants and water (Malthus and Dekker, 1994). In this context, the narrow intervals of hyperspectral channels enable a wide 2.2. In situ measurements range of reflectance that is useful in assessing water quality conditions of many open water aquatic ecosystems like our area of study. Unfortunately, this might not be the case in Two systems of in situ measurements were carried out, which all environments where there are surrounding land use and include measuring the physico-chemical parameters of coastal land cover that influence the water characteristics and thereaf- water using the AQUA metre water quality device and the ter the interaction with electromagnetic radiation. In some spectral characteristics of the coastal water using the Ò places where there is complexity of land use and land cover FieldSpec 3 ASD spectroradiometer device. The AQUA categories, such as our area of study, always create problem metre device measures nearly 9 parameters including water in precise identification or characterization of the water temperature, pH, oxidation reduction potentials, specific con- parameters. Therefore, in these cases, there is a need to inte- ductivity, turbidity, chlorophyll, dissolved oxygen, crude oil grate various datasets to precisely characterize the water contamination as well as the depth of the measured parameters quality. (Table 2). However, the spectroradiometer is an optical device

Figure 1 The area of study – coastal zone from Damietta to Port Said (source SPOT5, 2011).

Table 1 Average climatic data in the area of study in 2011. Variable Units Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Maximum temperature (mean daily value) °C 17.4 17.9 19.4 22.5 25.1 28.2 30.0 30.3 28.8 26.7 23.0 19.4 24.06 Minimum temperature (mean daily value) °C 11.1 11.7 13.4 16.3 18.8 22.1 23.7 24.2 23.3 21.3 17.5 12.8 18.02 Precipitation (mean monthly value) mm 18.0 12.0 10.0 5.0 4.0 0.0 0.0 0.0 3.0 8.0 7.0 16.0 6.92 Relative humidity (mean value) % 68.0 66.0 65.0 64.0 66.0 67.0 68.0 68.0 68.0 65.0 67.0 69.0 66.75

that uses detectors other than photographic film to measure spectral profile of both data sets was overlaid to compare the the distribution of radiation in a particular wavelength region; spectral interactions between the water and hyperspectral. which measures the radiant energy (radiance and irradiance). It measures the spectral behaviour in the visible, near-infrared 2.3.2. Geographical information systems (GIS) (VNIR) and short-wave infrared (SWIR) spectra between 350 For spatial analysis and spatial correlation all the obtained and 2500 nm in a precision of 1 nm. Two field trips were con- geographic and satellite data are transformed into a GIS Sys- ducted by both devices at specific locations of the coastal water tem to map the environmental status, conditions and forecast and other fresh water of Lake Manzala. Fig. 2 shows the loca- the environmental degradation of the study area. This system tion of the in situ measurements using both devices. was developed to be a dynamic interface for mapping and gen- erating environmental scenarios. This was based on the Arc- 2.3. Remotely sensed data GIS package.

2.3.1. Satellite sensors 3. Results SPOT 5 satellite imagery dated 2011 was used to map the existing land use and land cover of the study area as well as to 3.1. Land use and land covers determine the water quality of the area of study. The image was geometrically corroded to the UTM grid system Zone 36 Recent high resolution satellite image of SPOT 5 dated 2011 North and radiometrically corrected to remove all the haze was used to characterize the coastal water and mapping the and aerosol effects. Then digital image processing of enhance- surrounding land use and land cover. The important categories ment was used to differentiate the different tone of water in re- of land use and land cover of the study area that influences the sponse to the water quality or/and characteristics. It was also water characteristics and quality were determined and mapped classified to determine and map the existing land use and land from the supervised classification of the SPOT 5 image and cover categories of the study area that has a direct or indirect digitization of the key features (Fig. 3). The accuracy level of impact on the water quality. this classification was 84% based on the maximum likelihood Archived Hyperion hyperspectral images dated 2002 and classifier, which was based on the accuracy of the training sam- 2003 were used for hyperspectral analysis and compared with ples together with the actual reflectance of the image. the in situ hyperspectral data. However, they are at two differ- Key class is the international coastal road, which intersects ent dates with nearly 10 year time gap but it helps to under- the wetland of Lake Manzala and divides the area of study. stand the hyperspectral behaviour of the water quality. The Such infrastructures of roads had accelerated the development

of fish farms that play a key role of point discharge of chem- icals and contamination to the coastal water of the Mediterra- nean Sea. The urban settlements were mapped at Port Saeid, Damietta, new Damietta city and Ras El-Bar cities along with 10,030 24,760 14,101 15,147 28,244 28,910 5098 5374 Crude oil (rfu) À À À À À À À À other small urbanized areas and rural urban. These urban and human communities are very close to the coastal water and influence the water quality by continuous discharge of human wastes to the water. Irrigation canals and drainage were also mapped where most of the irrigation pesticides and agricul- Dissolved oxygen (%Sat) tural wastes end with the coastal water or to the wetland of Lake Maznala that also go to the sea via the outlets. Finally, the natural vegetation class is found to be flourished and in- creased in size that has negatively converted the water mass g/l)

l of Lake Manzala into semi-closed basins. Chlorophyll ( The land use and land cover categories played a role as point source of pollution and contamination of the coastal water as well as the wetland of Lake Manzala. The spectral channels of SPOT 5 (visible and near infrared) were digitally processed to categorize the marine water mass into three different categories (Fig. 4-Left): Turbidity (NTU)

(1) deep water, which is shown in green colour, (2) continental or transitional water, which is shown in orange reddish colour, and (3) coastal water, which is shown in yellow colour. S/cm) l Speciﬁc conductivity ( The deep water is merely shown in one category due to the high absorption of the infrared radiation. This might be due to probably of being far from the human activities and low affected by the turbulence that induce exchanging process be-

Depth (meter) tween bottom sediment and its waters. While, continental waters, are more dynamic than deep water and more affected by actions of waves and human activities. However, the lateral coastal water is highly inﬂuenced by the currents and the turbidity as well as shallow depth that enabled for radiation reﬂection from the bottom sediment

reduction potential (mV) and suspended matters. It is clearly shown that natural and anthropogenic factors are inﬂuencing this zone. Furthermore, action of waves causes moving of sediment particles from bot- pH Oxidation tom to up in the process of turbulence, raising the value of turbidity in these waters. Thus, there are continuous ex- changes of different constituents between sediment and water. Fig. 3-Right shows the two plume fans at the mouth of the outlet connection between Lake Manzala and the Mediterra- C) °

temperature ( nean Sea. This is probably a function of the water characteristics and quality moving from the Lake into the sea. This might be attributed to the difference in water temperature, concentration of nutrient or/and phosphorus load or other algal occurrence. The transitional category of water between both deep water and lateral coastal water is a mixture of water properties and quality that are mostly inﬂuenced by the lateral coastal water in some areas (Fig. 4-Left).

3.2. In situ measurements measurements of Aqua metre water quality device. M = Marine; B = Bogaz; G = El-Gamile Outlet; Al Lessan = Al Lessan (i.e. mouth of the Nile River with the Sea). 3.2.1. Aqua metre water quality measurements In situ To examine the potential characterization of water properties from optical remote sensing (e.g. SPOT 5 data); in situ measurements of water quality parameters were obtained. Table 2 Table 2 Actual Water Marine-El-Gamile Outlet-1 17.17 8.94 160 0.41 30,410 65.4 57.07 151 Bogaz El-Gamile Outlet-1 15.28 8.72 174 0.4 6619 27.65 147.1 176.75 Marine-El-Gamile Outlet-2 16.51 8.91 182 0.45 21,960 41.7 68.21 137.4 Bogaz El-Gamile Outlet-2 15.42 9.22 130 0.48 6071 18.3 121.6 209.5 Bogaz El-Gamile Outlet-3 16.42 9.01 150 0.49 8607 17.9 9.37 133.5 Marine-El-Gamile Outlet-3 15.78 9.02 194 0.51 23,420 27 136.8 145.6 Deiba Triangle 16.48 8.65 147 0.49 30,260 7.5 0.08 169.3 Al Lessan (mouth ofBogaz the EzbetBorg Nile River withMarine the water Sea) (Damietta Harbour) 16.725 8.505 174 17.6 16.92 0.195 8.42 139 31,343 8.5 160 0.18 57.35 29,200 0.31 1.145 12.6 57,780 109.6 5368 27.2 7.61 109.4 1.65 109.9 4098 Abbreviations: shows example of the measured parameters by the Manta2

Figure 2 Sampling locations (top = second field samples, bottom = first field samples).

Aqua metre sensor. Indeed, there is a clear spatial variability in creates depletion of the dissolved oxygen and creates eutrophic the water quality at the sampling locations, which is mainly environment. Chlorophyll-a concentration is varied based on subjected to changes in water constituents and the water dis- the sampling location, which showed high values of chloro- charge from the Nile Delta. This is also attributed to the influ- phyll-a in the fresh water of Lake Manzala and at the Bogaz ence of man-made activities including changes of the land use Outlets. The highest recorded value was 147 lgl/l at Bogaz and land cover within the study area as well as the drainage El-Gamile Outlet-2. Conversely, the marine sea water showed system. very low chlorophyll concentrations (Fig. 5). The sampling locations of the in situ measurements were Turbidity mainly indicates the amount of suspended parti- chosen to be at three different environments: cles in water; these particles may be algae, plant remains and sediments. The turbulence of the suspended particles in the 1. Point at the outlets that connect the fresh water from Lake coastal marine water was the main factor of getting turbidity Manzala with the marine water (sometimes called Bogaz), in the study area reaching up to 65%. El Gamil Outlet-1 and 2. Points on the coast representing the coastal marine water Al lessan (mouth of the Nile River with the Sea) sampling sites 3. Points at the fresh water of Lake Manzala. showed the highest recorded turbidity, however the fresh water of Lake Manzala showed calm water with low level of turbid- This enabled for drawing picture of comparison between ity (Fig. 6). Electric conductivity is function of the total dis- the water characteristics at both environments. Bogaz El-Ga- solved solids (TDS); the highest EC values were recorded in mile Outlet-1 recorded the lowest value of temperature, while the coastal marine water (Saline water). However, the lowest the coastal marine water near Damietta harbour recorded values were in the fresh water of the Nile River and the mod- the highest value of temperature (17.6 °C) that was probably erate values were in the Lake Manzala water (partially brack- due to the time of measurements during the day, since the low- ish). Unfortunately, pH exhibited no significant spatial est value was taken in the morning, while the highest one was variations in the area of study, which showed weak alkaline. recorded at mid-day; or probably due to the mixing of fresh The highest pH value was recorded at Bogaz El Gamile Out- water and marine water at the Bogaz Outlet. DO (dissolved let-2 that is mainly attributed to the man-made activities of fish oxygen) creates good environment for algal growth via the farming at this area, which likely use ammonia loaded Chicken process of photosynthesis; therefore, it is highly recorded in Manure for fish feed that increases the pH in this region. the fresh water of Lake Manzala and the Bogaz Outlets than Although ORP (the process of oxidation and reduction marine water. However, in some cases the over growth of algae potential) showed nearly no significant difference between

Figure 3 Important units of land use/cover from on screen digitizing.

Figure 4 Classified SPOT 5 image of the coastal water in the area of study. the sampling sites (i.e. both fresh and marine water environ- oil pollution in these sites due to the oil leakages from ships ments); the coastal marine water showed the highest values that found all time for trade purposes, or/and human activities above 150 mV. The fresh water from Boghazes shows also high for recreational purposes (Fig. 7). value above 100 mV but less than the marine water. Finally, crude oil contamination was not significantly recorded in all 3.2.2. Spectroradiometer sampling locations except at Al lessan (mouth of the Nile River The second in situ measurement was hyperspectral behaviour with the Sea) and BoGaz Ezbet El-Borg sites that recorded of the water using the spectroradiometer for the first time in noticeable concentrations. It is probably subjected to crude this area of study. This kind of measurements enabled to

Figure 5 Spatial variations of water temperature, chlorophyll and dissolved oxygen.

Figure 6 Spatial variations of turbidity, pH and specific conductivity. understand and investigated the characterization of the water penetration of this short wavelength to the water column column within the region. The wide range of the spectral re- and reflecting the properties of the water contents. sponse with narrow interval is possibly a function of the prop- The area of study is subjected to different types of pollu- erties of the water column. The sampling sites were nearly at tants, resulted from different industries, including fertilizers, the same geographic location of the sampling sites using the pesticides, plastics and heavy industries of the New Damietta Aqua metre for water quality. For simplicity in the analysis industrial zone. The discharged wastewater into the marine the spectral response of some geographically closed sampling environment increases the spectral reflectance of the water in sites was averaged. These merged locations were categorized visible and near IR portions of the light (Farooq, 2011). The into Coastal marine water and fresh water at Bogaz outlets interaction of these pollutants with the spectrum is different or/and Lake Manzala. based on the concentration and the width of the wavelength. Fig. 8 represents the spectral reflectance of the coastal mar- This is why the short wave length of the visible light and the ine sampling locations from Damietta to Port Said. The re- red edge of visible and near infrared spectrum interact with corded reflectance was categorized into three spectral regions the pollutants in the water column (Farooq, 2011). For exam- according to the width of the wavelengths; which includes ple the sampling site of the New Damietta city showed high the visible spectra, near infrared spectra and middle infrared spectral reflectance in visible and Near IR regions. This area spectrum. The most significant spectral response was from is an industrial estate that discharges loads of wastewater into the visible and red edge spectral region. This is due to the the Mediterranean Sea close to the sampling site.

Figure 7 Spatial variations of crude oil and oxidation reduction potential.

Figure 8 Spectral reﬂectance signature of coastal samples.

Indeed, waves, currents and man-made activities are notice- with windows of absorption and reflection that is correlated ably playing a key role in the level of turbidity in the area of with the algae. Fresh water of Lake Manzala and the Outlets study, which is described as dynamic environment. This is to- showed this high level of chlorophyll, which is probably due gether with the land use and land cover that showed various to the high level of wastewater that is rich with nutrients (i.e. human activities of fish farming that always impact negatively nitrogen and phosphorus) that are important for growing up on the water quality. The high level of agricultural wastes from of algae. El Gamile Outlet-1 at the outlet and even at the coast- the drains also plays a main role in the water quality of the al marine water of the Mediterranean Sea contains high levels area of study. Therefore, the outflow of fresh water that is of total suspended solids and algae content, which might be highly concentrated with pesticides and fertilizers is almost sourced from the fresh water coming from Lake Manzala. changing the characteristics of the coastal marine water. This However, this was not the case at El Gamile Outlet-2 facing is almost reflect in the spectral behaviour of the sampling sites. the Sea, which might reflect that the loads of discharge at this Fig. 9 shows the spatial variations of reflectance in the area of outlet is less than the observed one at the Outlet-1. study especially in visible and in near IR regions. El Gamile Outlet-1 showed higher level of total suspended solids than 3.2.3. Integration between in situ spectroradiometer and Aqua El Gamile Outlet-2, which is reflected in the high spectral Meter results reflectance observed in the outlet-1 than the outlet-2 particularly in the visible region. Integration of the in situ measurements from the spectroradi- Some sampling sites showed high level of chlorophyll that is ometer and the Aqua metre devices enabled to correlate the re- almost from algae. This is clearly shown in the spectral curve sults from both systems. However, there was little time gap

Figure 9 Spectral reﬂectance signature of Bogaz samples.

Figure 10 Spectroradiometer reflectance of coastal locations. between both measurements, it provided high correlation. For water via the outlets always generate the plume fans at the example, the high reflectance of the coastal water was corre- mouths of the two main outlets. The high level of turbidity lated directly with the high level of total suspended solids and concentration of algae provide an indication for the excess (i.e. Turbidity) particularly at marine coastal water at El Ga- of nutrients and fertilizers or/and contamination of the water. mil outlet-2, and Al-Lessan. The turbidity was also highly cor- For example, El Gamile Outlet-1, Al lessan and Ezbet El-Borg related at the Bogaz outlet locations of BoGaz Gamile 1 and recorded high values of total dissolved solids, while Bogaz BoGaz Ezbet El-Borg between both measurements. Gamile 1 & 2 recorded the high levels of chlorophyll. Secondly there was a high correlation with the spectral re- The contamination from crude oil is limited to two sites at sponse of chlorophyll in the green radiation and NIR which Al lessan and Ezbet El-Borg, which are considered as is correlated with the high level of chlorophyll recorded by industrial and shipping areas. Such contamination has an ad- the Aqua metre. This was clearly shown at sampling sites of verse impact on the marine organisms as well as harming the the marine coastal water, El Gamile Outlet-1 and Al Lessan local community that might use the coast for recreational (mouth of the Nile River with the Sea) (Figs. 10 and 11). activities. It is found that Ras El-Bar, Ezbet El-Borg and The fresh water of Lake Manzala also recorded high level of Gamile 1 represent the most contaminated regions in the study algae at both BoGaz El Gamile Outlet-1 and BoGaz El Gamile area that is mainly attributed to the existing trade ships in Ras Outlet-2 (Figs. 12 and 13). el-Bar and Ezbet El-Borg for commercial and recreational From the above results, it could be discussed that the load activities. However, main source of contaminating Gamile 1 of nutrients and other contaminants discharged to the fresh is the usage of dead chicken residuals for feeding fishes in water in Lake Manzala and then transferred to the marine Manzala Lake.

Figure 11 Aqua metre measurements at the coastal sampling locations.

Figure 12 Spectroradiometer reﬂectance of Bogaz outlet sampling locations.

Figure 13 Aqua metre measurements at Bogaz outlet sampling locations.

Figure 14 Spectral signature of the four regions (EO-1, Aug. 2003).

Figure 15 Spectral signature of the four regions (EO-1, Nov. 2002).

Figure 16 Spectral signature of the four regions (EO-1, Sep. 2002).

3.3. Hyperion hyperspectral An initial step was establishing a spectral library from the in situ spectroradiometer to be correlated with the Hyperion It was anticipated for this research to capture up-to-date data. However, the timing between both data sources was hyperspectral images using the airborne hyperspectral camera different but it was good exercise for building the human tech- owned by the national authority for remote sensing, which, nical and scientific capacity in this field. It also used to provide unfortunately for out of control reasons, was out of function. some correlation and assuming that the environmental condi- Therefore, the archived Hyperion (EO-1) hyperspectral data tion of the area study has not extremely changed. The spectral were used to proof the concept and develop our capacity. profiles of both datasets were generated for the sampling sites, The only available datasets that cover portion of the area were which indeed showed some similarities and differences that dated August 2003, September 2002 and November 2002. might be due to the changes in the physical, chemical and/or

Figure 17 Comparison of different sites between EO-1 (Aug. 2003) and spectroradiometer.

biological characteristics because of the difference in the tim- however September shows difference between both. This might ing of both datasets. be due to the difference in the season and flow of agricultural Figs. 14–16 show the spectral profile of four sampling sites wastes or/and fertilizers. It is also shown that the red edge and from the Hyperion data, which represent three different near infrared spectrum is the more significant reflectance that dates August 2003, November 2002, and September 2002, provides indication of the water quality. It is also clearly respectively. The correlation between these three profiles shown that the reflectance from the fresh water in Lake shows little similarities between August and November, Manzala has the highest response in all dates, which might

Figure 18 Comparison of different sites between EO-1 (Nov. 2002) and spectroradiometer. be attributed to the high level of algae, nutrients and phospho- November 2002 and September 2002 respectively at the same rous. The second highest level of reflectance is the sampling site four sampling sites of Lake Manzala, Al Lessan, Bogaz Ezbet of Ras El Bar which has high level of turbidity. Elborg, and Ras El Bar. The in situ spectroradiometer reflec- Figs. 17–19 show the comparison between the in situ spect- tance shows higher reflectance in all sites rather than the Hype- roradiometer library and the Hyperion data of August 2003, rion data and differences in the pattern in some wavelength

Figure 19 Comparison of different sites between EO-1 (Sep. 2002) and spectroradiometer. range. The visible spectrum shows a higher difference in the with differences in the magnitude. This proves the efficiency magnitude of reflectance between the in situ spectroradiometer of conducting the in situ measurements at the same time of and the Hyperion data, where the in situ spectroradiometer re- the sensor imaging; which allow for calibration and correla- sponse is much higher than the Hyperion. Even the pattern of tion. Such differences in the magnitude and pattern are mainly response is not highly correlated. The red edge and near infra- attributed to the time of taking the samples and as well as the red spectrum shows differences in the magnitude between both characteristics of the water. The pattern of the Hyperion re- profiles, however there is some correlation in the pattern. In sponse is maintained with differences in the season; however the middle infrared there is a high correlation in the pattern it is also the same with the in situ spectroradiometer.

4. Discussion To monitor this area earth observation of remote sensing is showing potential for regular monitoring and assessment. Hyperspectral remote sensing is currently showing high poten- Hyperspectral images are showing high potential in such re- tial in studying water quality. This has challenged us for using search with limited calibration from in situ measurements. such technology to characterize the coastal water between However, the hyperspectral data were not up-to-date, the Damietta and Port Saeid in the Mediterranean Sea. It was knowledge and capacity of using such dataset were developed anticipated to use an airborne hyperspectral data for this re- for future research and implementation. For further consolida- search using the local HySpx camera, however, the lack of tion, there is a need for an accurate plan to capture airborne obtaining this dataset limited the complete synergy between hyperspectral data at the same time of in situ measurements the in situ measurements and the airborne hyperspectral. This to precisely validate the data and establish the model for water leads to rely on using the archived hyperspectral data of Hype- quality monitoring. rion. Both in situ measurements using spectroradiometer and water quality multi-probe sensor (Manta2) were integrated to map and characterize the water quality of the study area. Acknowledgments The dynamic interaction between the fresh water flow from Lake Manzala to the marine Coastal water of the Mediterra- The authors acknowledge the national authority for remote nean Sea via the outlets was clearly recognized via plumes at sensing and space sciences (NARSS) for sponsoring this re- the mouths of these outlets. These plumes are reflecting and search under the umbrella of research and development frame- subjected to the changes in the water characteristics or/and work of the fiscal year 2011–2012. quality including turbidity, total nitrogen, total phosphorus as well as phytoplankton content. The spectral response of References the water at the outlets is quite different from other sampling sites showing high level of turbidity reaching up to 65 (NTU) Abou El-Magd, I., Hermas, E., 2010. Human impact on the coastal and high level of phytoplankton reaching up to 147 lg/l. For landforms in the area between Gamasa and Kitchner Drains, example, the turbidity level and the conductivity were higher Northern Nile Delta, Egypt. J. Coastal Res. 26, 3. in the marine coastal water particularly at Ras El Bar site El Banna, M., 2007. Erosion and accretion rates and their associated rather than the fresh water of Lake Manzala. 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