Ashraf M. S. Mahrous
Assistant Lecturer, Department of Architecture, Faculty of Engineer
AL – Minia University, Egypt
Email: [email protected]
Prof. Mojmir Kyselka
Faculty of Architecture, VUT Brno, Czech republic
Assoc. Prof. Peter Spicka (Ph.D.)
Arch. Dept. faculty of civil
Slovak technical University.
This paper presents a GIS powerful tool for seawater management project in inland of western desert of Egypt. The main objective of this paper is to soft the estimated hard weather to be fit for tourism industry and compensate the depreciated water from the underground storehouse. To achieve its objectives the paper proposed to desalting and transforming the seawater from Mediterranean Sea to the five cities and creates new lakes. This water will be absorbed through the sand layers to supply the underground storehouse, also it will be evaporated to soft the hared weather. The planning task of this project is “site selection”. This paper seeks for answer one query: How to define the optimal site of the proposed lakes and the optimal path of the channel the water will flow in. To find a decision-maker helpful answer for this query, we have used ArcView GIS and ArcView spatial analyst software to modeling process of the problem solution. Then the paper presents a suitability map of the optimal sites for the new lakes and channel. At the end we have finished this paper on some Conclusions and recommendations.
Last 30 years of the elapsed century testified a hard weather, high temperature, and rare rain over whole the global that caused melting the ice in the Antarctica continent and oceans. This cause increasing of the sea level 1mm annually and extension of the sea boundaries. But melting of all ice in Antarctica and oceans need 20 C° more than the current temperature, if that were fact the sea water level will be 60-70 meters higher than the current level. (Josef Matyas, 2001). Western desert of Egypt is one of many areas must be beneficiary from this situation. It contains five oasis Kharga, Dakhla, Farafa, AL-Baharia, and Siwa. It also contains under sea-level depression: El-Qattara depression situated in east of Siwa oasis and Sitra, Nuweinmisa, Bahren, and Areg depression south of Siwa oasis. Kharga City, Mute City, Farafra City, Bawity City, and Siwa City are the main cites in the five oases respectively. Most of people -in this cities- work in agriculture and tourism field.
Agriculture is depended on the underground water for irrigation and drinking. There are three different theories concerns on this quantity of underground water, the first: concludes that the underground water is not renewed but the water collected at the old rainy ages and stored underground. (Abdo Shata, Mohamed Draz, and Asmaa Shata, 1996) The second: concludes that the water is renewed and comes from the rainfall on Tpsty, Aerdy, and Inedy mountains in Chad and west of Sudan. This water flows through the sandstone and the sand layers in the EWD, however decrease of the water level in wells is interpreted by the quantity of obtained water more than the flowed water. (Ibrahem H. Hameda, 1964) The third: integrates the previous two theories and considered this water is renewed and non-renewed. (Sabry M. Hamad, 1996). Generally, the water is decreased in the wells where it was flow from springs but now it must be dragged by machines. Properly, the underground water maybe extinct, thus the agriculture is menaced too.
The tourism is depended on many types of tourist potential facilities such as monuments, very famous hot and cold water wells and springs, therapeutic tourism and safari, and adventure-good deserts. Tourists there prefer the dry weather of desert however it will not be suitable weather for tourism in next 50 years. Therefore we try to find a dream-solution to soft this expected hard weather and preserving the underground water’s level in inland western desert of Egypt. We suggest desalting and transforming the seawater from Mediterranean Sea to the five cities and create new lakes. Some of this transformed water will be absorbed through the sand layers; this water will be a great solution to compensate the depreciated water from the underground storehouse. The another some of water will be evaporated by the high temperature; this will increate the air humidity and soft the weather.
The problem is how to define the optimal sites for the new lakes beside the Egyptian western desert cities (EWDC), define the optimal path of water channel from Mediterranean Sea to these lakes, and define the position of desalting station and pumping stations. This type of problems named “site selection problem” Traditional technology is unsuccessful to solve this problem. High advanced technology must be used to infest the desert. GIS technology is the best way to perform this task easily. The selection will be based on the optimal sites, which is located in smooth and plane topography.
- -import the Digital Terrain Elevation Data (DTED) it is one grid theme for each square Decimal Degree (24 00 00 East : 36 00 00 East longitude / 22 00 00 North : 32 North latitude) these grids show the elevation of the Egypt land.
- -Mergence all the grid themes into one Grid theme using Map Calculator tool.
- -adjustment the elevation grid theme to the real world coordinate using warp extension.
- -Analyzing the grid theme related to the value of elevation.
- -creating the suitability maps of optimal sites for the leaks and channel
Braking down the problem
The problem must be braked into smaller and smaller pieces, until the required data and steps to solve the problem are known. These steps are objectives that will be solved to measure the suitability of each location. A consideration in defining these objectives is that they must be something measurable. How is it possible to measure what is the optimal site for the lakes and path for the channel? Suitable areas must be at the low levels to be economic in digging, the successful lakes is that near to the cities to archive its aims, and good path of channel is that the shortest. So, the three objectives are answering for “where are the low-level areas? Are these areas near enough to the cities? Where is the short path of the channel? These objectives become data layers or themes.
Where are the low-level areas?
To create a map of suitable elevation areas, some characteristics of low-level areas must be defined using analysis of grid theme of the whole area. From a data set of the area the low-level areas can be selected, ranked map of these area can be created, and compare this with real-estate data to evaluate the result of ranked map. From this evaluation result the suitable elevation areas can be defined.
Data set of area: – DTED is downloaded data represents the elevation value in meters unit for each square cell. This cell is the smaller measurable unite. The cell’s size depends on the resolution of the raster image and the available detailed data. The used data contain cells have square size 29.808 second. Single value is store for each cell. This value indicates to the average elevation level of the cell.
Low-level areas: – using query builder tool the low-level cells can be selected with a logical expression such as ([Value] < 0) will select every cell have value less than 0. This is understood that the selected area is the under Sea-level areas.
Ranked map: – The legend type, classification type, numbers of classes, classification field, classes label, and color ramps can be specified using legend editor tool. Specifying these parameters will define the raked map from low to high level of land.
Real-state data: – it can be optioned from field survey or some stored data such as paper maps for landmarks such as depression, hill, or geodetic point. In this study the paper maps of partial area which contain some of these landmarks are available.
Evaluate of ranked map: – the map must be evaluated to insure the accuracy of data. The evaluation can be done by comparison of some samples from the real state with the same position in the ranked map. The successful sample must be leave as the same state and the unsuccessful sample can be corrected using the Editing toll or it can be removed and ignored.
Suitable Elevations areas: – from the legend of ranked map the elevations are shown from the most low-level areas to the most high-level areas. The cell value of the sea is equal 0, the cell of elevations over the sea level is ranged between 1 – 2447 meter, and the cell of the under sea level is ranged between -32766 to -32382. So the suitable area for lakes must be negative elevation and less than 85 meter. The negative values has been reclassified to one range called “under sea level”
Are these areas near enough to the cities?
The design of separate urban elements to support urban tourism and recreation activities has long a long tradition in the urban environment (Bendict Dellaert, 1995). In many cases cultural and monumental urban setting have been preserved to be enjoyed by both residents and tourist. (Wylson A. and P. Wylson, 1994) The urban environment in its totality in many cities supplements the perception and use of the separate urban elements (Ashworth G. J., 1991). So, that is the proposed tourist facilities must do duplicate function in both of urban and tourist society. (Jansen-Verbeke M., 1988) This directs the decision of site-selection to necessarily to be near enough to the city. Therefor, the fit site of proposed lakes must be far maximum 10 km form the centers cities. So a map showing the areas within 10 km of each city in EWDA must be created using the Find Distance function of ArcView GIS.
Where is the suitable path of the channel?
The best path of channel is that located in the short path and has small number of dropped slopes from low-level to high-level in the water flowing direction. In another words, the path, which located in middle elevation between maximum and minimum level, in this case the suitable elevation is that has value 180 m. The middle level map is created using the logical expression ([Elevation] < 180).
The diagram of the model shows the start of process is to statement of the problem, then breaking down the problem to find the objectives, and assigning value to the objective to ranking the value from the best to the worst of each theme. The last step is to create the composite suitability map of the locations for the proposed lakes by combine the suitability maps of each objective: map of area level, map of far area, and map of length path.
Fig. (1) shows the diagram of modeling process.
Assigning value to the objective
After creating the suitability maps of the three objectives, the numeric values must be assigned to classes within each map.
Ranking the values of elevation surface
Using legend editor of the Elevation theme, the classification type has been specified as Natural Breaks to looking for groupings and patterns inherent in the data with minimizing the variation within each class. The number of classes has been specified as 66 class the lowest class describes the under Sea level, the zero value class describes the Sea Level, and the another 64 classes are divided into 64 ranges of elevations.
Ranking the values of distant map
The map unit of the elevation’s theme is Decimal Degree, so the distant-map unit is created in Decimal Degree. Using the Find distance function the continuous map of distance from EWDC (Kharga, Mute, Farafra, Bawity, and Siwa) and the coastal cities Alexandria and Matrouh is created. This map is called Distance to cities and automatically ranked into 13 classes with value according to the distance between cities. The decimal degree equal 103 Km, therefor, the 1 km must be considered as 1/ 103 or 0.0097 of map unit.
Ranking the path map
The map of middle elevation level is created by the theme of suitability Path that created as line features according the levels under 180 meter, each feature has value of path length in the length field of attribute table. By using legend editor of this theme and specifying the legend type as Unique Value, the path map will be ranked into unique class for each feature. Then the distance maps to each path are created using the find distance function for each path. These maps called Distance to estimated Path # 1, Distance to estimated path # 2, and Distance to estimated path # 3.
Creating the composite suitability map
1-suitability map for the lakes
Map calculation function is used to create the composite suitability map of the optimal sites for the proposed lakes using the logical expressions: –
(( [Elevation] < 85) and ([Distance to cities] < 0.097)) or ([Elevation] < 0) This expression performs a theme named “suitable site for new lakes” contains selected area which located in elevation level less than 85 meter and not far 10 km from each city in addition to the under sea level areas
Fig. (2) shows the suitability map of proposed lakes and channel path
As shown in the figure (2), the suitable location of the proposed lakes is the all around of Kharga, north of Mute, the all around of Farafra, northeast of Bawity, and the all extensions of Siwa. In addition to the under sea level area such as Depressions of Qattara, Sitra, Nuweinmisa, Bahren, and Areg.
2-suitability map for the channel
By using the Map query function, the composite suitability map of channel path can be created. Three alternatives for the path according to the path features in the vector map such as length.
The three alternatives theme (#1, #2, #3) are created using the logical ( [Elevation] < 180) and ([Distance to estimated Path # 1] < 0.0097), ( [Elevation] < 180) and ([Distance to estimated Path # 2] < 0.0097), and ( [Elevation] < 180) and ([Distance to estimated Path # 3] < 0.0097) respectively. These logical expressions create the path in middle level and not far the estimated paths 1km from each side.
As shown in the figure (2), the part of path that marked in doted-line is on high elevation level and the part that is marked in solid-line is on low elevation level. On another words, the doted-line represent the part of estimated path which is higher than the middle level (180 meter) and need to digging process, the sold-line represent the part of estimated path which is lower than the middle level and doesn’t need digging. Thus, the best path is that contains high present of solid-line and short length totally.
There are tow ways to carrying out the channel: The first is digging the proposed path at the high elevation level to be at the level 180 meter and pumping the water on this level by just one pumping station on the coast. The second is using pumping station at the beginning of each high elevation distance of the proposed path and make the channel on the natural elevations. To decide whish way and which path is the optimal solution, a compare must be between the total length of each path, the length of the high elevation, and the number of sites need pumping station. The table of sum of attributes of estimated path shows that the short path is the second alternative. The short length need digging is also in the second alternative. Therefore, in case of using the first way the optimal path will be the second alternative. In case of using the second way the optimal path will be the third alternative where the number of pumping station is less than as in the first alternative moreover its total length is shorter the second alternative. Thus, the optimal solution can be selected according the cost of digging distance 107 km to level 180 meter or cost of eight pumping stations.
Table of sum of attributes of estimated path
ID; Count; SUM LENGTH (Km);Length of high elevation (over 180m );Length of low elevation (under 180 m);Number of pumping station
1; 2; 1302;250;1052;8
2; 4; 1116;107;1009;9
3; 1; 1130;215;915;8
Therefor, we recommend the second and third alternative and leave the decision to the result of economical study, which must be performed at near of execution’s time because the economic factors are variable with time. We estimate this project will be fact in next 50 years for the next reasons: –
1-the sea level will be higher 1 m over the existing.
2-the solar energy and wind power will be available and economic to convert to electricity power, this power will be used in pumping and desalting stations.
The desalting water station proposed site be at the Mediterranean Sea coast, the proposed sites of pumping of the water is located at the end of each low level parts (Solid-line) of the path to pump the water to the high level parts (Doted-line) of the path.
Conclusions and recommendations
This paper concludes that in the Egypt might be the most beneficiary county from the melting the ice at Antarctica continent and oceans if this proposed had been carrying out. The powerful technology for planning and execution of this project is the GIS technology. Performing this project will develop tourism and agriculture field in the Egyptian western desert areas. Large areas will be new inhabited areas. The suitable area of the new lakes and path of water channel is that in the suitability map.
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