الفهرس 
General IntroductionOnly 14 pages are availabe for public view
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Abstract
The present study introduces multidisciplinary cost-effective approaches which include the integration of remote sensing and GIS application with a limited field study and lab analyses to estimate and assess the potential productivity of Lake Qaroun as well as the environmental assessment of the lake.
Lake Qaroun is a closed saline basin Located between latitude 30° 24’ and 30° 49’ E and latitudes 29° 24’ and 29° 33’ N. It’s located in the North African Sahara Desert. Qaroun is located below sea level between -43 m and -45 m it is the merely significant natural lake in Middle Egypt. It is situated in a hyperarid region occupying the lowest part of El Fayoum Depression in the Western Desert of Egypt. It was called the ancient Mories Lake which means the great lake. Moreover, the area of the ancient Lake Qaroun was (1270:1700 km2). Acting as a reservoir during the flood season for the River Nile and supports the Nile Delta region with the required water during the drought seasons.
It has a global significance in following the Ramsar convention for the international wetlands. Furthermore, Lake Qaroun is locally considered the main source of livelihood for El Fayoum government in Egypt. Lake Qaroun receives huge amounts of sewage and agricultural drainage water about (400 Mm3/ year). The percentage of discharging into the lake is ordered to firstly Al-Bats (41%), secondly El-Wadi (36%) and finally, the other minor drains (23%).
Different levels of pollution are present in this lake which requires rapid and critical dissections to control the discharge of waste water into the lake which causes further gradual deterioration of the water quality. That requires a continuous monitoring program for this Lake. The main source of pollution in Lake Qaroun is the direct discharge of sewage and agricultural wastes into Lake Qaroun. This is the most serious problem affecting Lake Qaroun’s water quality and its biota. At the end of 2014, Lake Qaroun has been invaded by the Isopoda parasite which mainly causes a decline in productivity to over 70%.
The objectives of the study
The above-mentioned scientific approach of this study will be achieved through the following objectives: -
1- Using statistical analysis to validate the created water parameter algorithm.
2- Using the Morpho-Edaphic model to estimate the potential productivity of Lake Qaroun which is based on the electrical conductivity and the mean depth.
3- Test the Trophometeric model to estimate the potential productivity of Lake Qaroun which is based on several variables one of them being the chlorophyll-a.
4- Long term discussion of Lake Qaroun.
The in situ measurements were (Temperature, pH, depth, EC, ammonia, nitrate, nitrite, total phosphorus, Chlorophyll, and zooplankton).
The multispectral satellite image is represented in Landsat8 (OLI). The reason of selected Landsat-8 images stands on availability as online free downloadable data, in addition, they still have a reasonable spectral and spatial resolution suitable for our aim of study.
The results of satellite images and field data were used to monitor and assess the changes and/or record the development of Lake Qaroun. The interpretation of these outputs and results will be discussed under three main items (Abiotic factors, biotic factors and potential productivity models). In order to give us an overall view of the environmental assessment of Lake Qaroun using the integration between remote sensing data and field data.
The main results of each chapter can be summarized as follow
Chapter 1: Spatial Assessment of Water Quality and Eutrophication in Lake Qaroun
The distribution of water Temperature showed the highest surface temperature in the spring and summer which appeared in the eastern sectors of the lake. Furthermore, during the four seasons, the middle part of the lake is showed the lowest surface temperature.
Hydrogen ion measured to Lake Qaroun dedicated to the alkaline features. The average annual hydrogen ion concentrations in Lake Qaroun range between 8.08 to 8.83 with an average of 8.53 ±0.2.
The investigation of the average annual values of Electrical conductivity in Lake Qaroun showed that the maximum value is 51.42 and the lowest value is 6.02 with an average of 39.39 ±15.47. The distribution of EC in Lake Qaroun in this period indicated the highest value shown in the western part of the Lake where the lowest values showed in front of El Bats drain.
The analysis of ammonia NH4-N showed the average annual maximum value was 4.55, while the lowest value 0.21 with means 1.00 SD±0.74. Eastern sedge is showing the highest Ammonia values in (spring summer and winter while in autumn the highest value is concentrated in the middle of the Lake.
The average annual values of Nitrate Concentration (NO3) are ranged from values 0.06 µg/l to 0.69 µg/l. With mean values of 0.18 ±0.21 µg/l. Although the results are still in the permitted value, they should control this range. In autumn, spring and winter the lowest values were distributed in the western sector of the lake and the highest values were distributed toward El Bats drain.
Total Nitrogen TN average annual variation was ranged between 0.86 mg/L to 7.73 mg/L with an average 2.28 mg/L ±2.06 mg/L. The spatial distribution of total nitrogen is similar to Nitrate distribution.
The average annual values of Total Phosphorus ranged between 120.70 µg/l to 372.48µg/l with a mean 170.95 ± 80.30 µg/l. The spatial-temporal distribution of the TP in spring, summer, and winter are the same where the highest values appeared in the eastern part of the Lake near El Bats drain.
The average annual values of chlorophyll-a are ranged between 45.51 µg/l to 395.55µg/l with a mean of 156.49±128.86 µg/l. Distribution of the seasonal chlorophyll values gives one of the interesting results that the chlorophyll concentration is low in the western sector in all seasons.
Trophic and productivity indices
Evaluating the trophic state of the lake
Carlson trophic State index was conducted on Lake Qaroun to classify its water trophic state. The final CTSI is the average from the values derived from each module TSI (CHL-a), TSI (TP), and TSI (SDD) CTSI map that showed the overall eutrophic state that represented 38% eutrophic and 62%hypereutrophic state.
Evaluating the potential productivity using trophometric index
The Trophometric index is combination between the trophic and morphometric variables. The variables are Morphometric variables, VOAP, Morph edaphic variables and chlorophyll of the Lake. The result was 662 Tonnes.
Chapter 2: Zooplankton Community characterization of Lake Qaroun
Zooplankton four groups are represented in the lake during the investigation period Protozoa, Rotifera, Copepoda, and Meroplankton.
The average population density for the winter season was 159,600 Org. / m3. It sharply increased in the next summer season to reach an average population density of 977,800 Org. /m3.
The Changings in water quality are the main factors controlling zooplankton abundance.
Chapter 3: Applying Geospatial Technology in assessing the Potential Productivity of Lake Qaroun
Electrical conductivity algorithm
The estimated selected water quality Red and infra-red bands give the best relation with the EC during the autumn season. The developed algorithm showed a cubic equation expressed as follows:
EC =– 476.800 + 879.266 (B3/B4)2 – 436.411 (B3/B4)3 With R=0.93 and R2 =0.87. selected as it showed significant regression coefficients (P<0.001), the highest R2, ENS, d, and the least error metrics (RMSE, MAE, PBIAS, and MAPE).
The results which had been driven to the EC model derived in the current study using Landsat-8 OLI for Lake Qaroun can be used very efficiently as a decision support tool to assist managers not only in monitoring the lake’s electrical conductivity regularly, during the month of November, but also in making preliminary estimates of the lake’s potential yield. Landsat-8 band ratio B3/B4 was found to be the most prominent independent variable for EC retrieval in Lake Qaroun. The model showed a very good performance in estimating 95% of EC values significantly with high acceptable accuracy. It is worth mentioning that the model developed in the current study is site-specific and can be relevant only to other lakes that resemble the environment in Lake Qaroun.
Application of Morph edaphic index (MEI)
The potential fish yield is a way to use mathematics relations to measure or calculate the Lake’s productive capacity and detect the gap between the predicted yield and actual yield. Consequently, give the stockholders a fast overview of the productivity state of the water body. Morph edaphic index (MEI), and Trophometric index were applied.
Morph edaphic index (MEI): the variables in this model are EC value or total dissolved solids (TDS) and depth this model was applied two times one from measured values and the second from extracted values from satellite images for 2015 and 2018 based on MEI values, the potential fish yield average values estimated during Nov. 2015 (1017.01 and 987.64 tonnes from Landsat and field, respectively) were lower than those obtained during Nov. 2018 (1166.74 and 1163.32 tonnes from Landsat and field, respectively). The increase was in the mean values of electrical conductivity from 39.16 mS/cm (in Nov 2015) to 48.98 mS/cm (in Nov 2018).