Using remote sensing technology and geographic information systems to assess the risk of floods in the south of the Arab Republic of Egypt

Using remote sensing technology and geographic information systems to assess flood risk in the southern Arab Republic of Egypt

Brief

Remote sensing technology can be used to collect various data and information, which helps build expectations of what might happen in the event of a flood. With the aim of obtaining results that help in making timely decisions, protecting the population as much as possible, or reducing the size of losses in the event of a disaster, satellite visuals may help in obtaining field data during a disaster, but the accuracy of the image is what determines the type of this data and its contribution to estimating the flood risk. However, in this study, Landsat satellite images will be relied upon, not because of its high accuracy or suitability for this type of study, but because Its data is easy to obtain in a way that is almost free and fast, and also for a more advanced goal, which is to highlight the great and effective role of remote sensing technology, and to extrapolate and extract various information from its various sources of remote sensing. To highlight the importance of remote sensing in the field of flood risk assessment.

In this study, the ability of remote sensing to capture images of the southern region of the Arab Republic of Egypt was demonstrated at several different times, before and after the Sudan flood. To reveal the estimated quantities of water from Sudan to us, while the role of geographic information systems programs was highlighted in determining the water body cover of the region. To determine the areas and quantities of water resulting from the flood, and a comparison was made between them. To develop a sound assessment of the possibility of flooding in Egypt, and to assist decision makers.

Keywords:Remote sensing, geographic information systems, floods.

Introduction

The Nile is witnessing, for the first time, a significant rise in water levels that it has not experienced for more than a century, which led to floods in Sudan. The Nile flood also reached Egypt, where the water level rose to a significant degree, and flooded dozens of acres in several villages in the Beheira Governorate in the north of the country. The village of Al-Sawaf, affiliated with the city of Kom Hamada in the Beheira Governorate, was exposed to major floods due to the rise in the Nile level, which led to the drowning of more than 70 acres. As these lands are considered the lands of the Nile River, and are subject to the ownership of the Ministry of Water Resources, which rents them to farmers in the range of 4 thousand pounds per acre annually.

The level continued to rise, which led to the submergence and destruction of dozens of acres plantedwith rice, alfalfa, and some vegetables.

The additional water that comes from the sources of the Nile, passing through Sudan, reaches Lake Nasser behind the High Dam, where it is impounded and its drainage process is monitored, as the purposes vary according to needs in agriculture, irrigation, industry, and drinking water. All of this has led to the necessity of quickly obtaining information regarding the Nile’s periodic changes; To contribute to work on flood forecasts, using satellite and remotely sensed data, and modern technologies to process and analyze that data; Such as geographic information systems programs, in addition to establishing projects that would benefit from rainwater and floods in agriculture.

Study area:

South of the Arab Republic of Egypt,It can be called South Upper Egypt, which is an Egyptian region located in the south of Egypt, overlooking the Red Sea, and bordered by the Red Sea to the east, to the south is the State of Sudan, to the west is the State of Libya, and to the north is the North Upper Egypt region, which includes 7 governorates: the Red Sea, New Valley, Assiut Governorate, Sohag, Qena, Luxor, and Aswan.. Egypt’s southern border with Sudan is its longest border. The length of the border with Sudan is 1,280 km.

The Nile River water is the main source of drinking water:

The Nile depends on the permanent sources in the African Lakes Plateau by 15%, while the rest depends on the rain that supplies the Nile on its way to it, and Egypt uses the artificial Lake Nasser to store the Nile water, and use it in seasons of drought and lack of rain.

In the southern part of the Nile Valley, Lake Nasser was formedafter the construction of the High Dam. The total area of the lake is 5237 km2, at the maximum water level of 180 meters above sea level, taking a longitudinal shape in the same shape as the riverbed before the construction of the High Dam.

The Nile Valley expands at the Kom Ombo Basin (north of Aswan, about 40 km) until it is about 13 km wide, then it narrows to the north at the Silsila Gorge, until it reaches only 320 metres. Then the valley widens at Luxor until 13 km, and its width between Luxor and Qena ranges between 3 and 18 km. As for the valley between Nag Hammadi after crossing the bend Qena to Cairo, its width ranges between 20 and 30 km.

The course of the Nile contains many islands,the most prominent of which are Mansouriya Island at the bend of Mansouriya, Naqanq Island and Warraq Island, in addition to Aboul Gheit Island between Cairo and Ras El Delta.

Data and software used:

_ Landsat satellite images were used to extract different types of information layers, and were obtained from the Earth Explorer website:https://earthexplorer.usgs.gov

where the datum and ellipsoid are WGS84.

[لاندسات (8OLI جهاز تصوير أرضي تشغيلي) و (TIRSمستشعر حراري بالأشعة تحت الحمراء) من 15 إلى 30 مترًا بيانات متعددة الأطياف من لاندسات 8].

_ The Arc GIS 10.8 program was used to process various data, ArcMap and ArcCatalog, and the ArcGIS Desktop applications to create maps, perform spatial analysis, and manage geographic data. Released version: 10.8.1 (July 2020) Previous version: 0.18 (February 2020). How much was the Erdas Imagine 2014 program used to process Landsat 8 satellite data, And complete various induction operations.

Study Methodology

The study methodology was built on the following steps:

1. Integrated image coverage.
2. Data acquisition and preprocessing.
3. Image processing and interpretation:

The Normalized Difference Water Index (NDWI) of McFeeters (1996) was modified by substituting the mid-infrared band, such as Landsat TM band 5, for the near-infrared band used in NDWI. Modified (MNDWI) can enhance open water features while efficiently suppressing and removing built-up ground noise, as well as vegetation and soil noise.

Augmented Water Information using NDWI is often mixed with ground and area noise, thus overestimating the extracted water. Accordingly, MNDWI is more suitable for enhancing and extracting water information for a water area with a majority built-up land area due to its advantage in reducing – or even eliminating – built-up land noise over NDWI.

4. Data arrangement.
5. Processor validation process.
6. Improve data extracted from remote sensing interpretation, identify detectable or visible features in the image on the ground, and provide a final, completed disaster map.

Results and discussion:

First: Data analysis for the Lake Nasser area and its environs:

At this stage, work was done on three Landsat 8 satellite images in the time periods 8-24-2020, 9-9-2020, and 9-25-2020, based on the researcher’s experience in theoretical extrapolation of the images, and detecting the difference in water quantities between the three images in the different time periods, while the work was based on the remote sensing data analysis program Erdas Imgine in processing and extrapolating the images; To detect the difference in water quantities, whether plus or minus, from 9-25-2020 for the two images Change Detection (Image difference) through applying the approach, and 8-24-2020, by producing two images that illustrate the different differences, their locations and proportions.

 

It is clear from this figure, which results from applying the change detection approach, that the region with high changes is the Lake Nasser region and what is connected to it in the eastern part, which is colored black, indicating the increase and spread of the water area in the region, and we will determine the value of that difference by analyzing the following figure, also resulting from the same image, which is the image of the differences for this region between 9-25-2020 And 24-2020-8

It is clear to us from this figurethat the areas colored in red are the areas of increased water on 9-25-2020, in order to reduce their area, while the slight increase was in some areas colored in black, but it is noted that it is not a serious increase – so far – but it is a strong warning of future increases.

 

Through the MNDWI analysis of the Lake Nasser area and its surroundings in the period 8-8-2020, it was found that the water is concentrated inside the lake, and there is no significant water surplus outside the lake or its surroundings in the southern and western regions of the region.

 

A map that shows only the surplus amount of water and its area, by extracting it from the MNDWI map in the period 8-8-2020, which is concentrated inside Lake Nasser and does not show a large surplus of water quantities outside the lake and around it.

 

Through the MNDWI analysis of the Lake Nasser area and its surroundings in the period 9-16-2020, it was found that water is concentrated inside the lake, and there is a large water surplus outside the lake or its surroundings in the southern and western regions of the region, and the concentration is greater inside the lake, which indicates its high level.

 

A map that only shows the excess amount of water and its area,This was extracted from the MNDWI map in the period 9-16-2020, which shows that there is a large difference and surplus in water, greater than what was evident in the period 8-8-2020; Which raises the risk of a significant increase in water quantities, which could lead to flooding of the Nile River itself coming from the southern and western borders.

Second: Data analysis for the Nile River region and its environs between Egypt and Sudan:

 

It is clear from this figure, which results from applying the change detection approach, that the region with high changes is the region of the Nile River between Egypt and Sudan and the water branches connected to it on both sides of it, and the color in black indicates the increase and spread of the water area in the region. We will determine the values of that difference by analyzing the following figure, which is also the result of the same image, which is an image The differences for this region are between 9-16-2020 and 8-31-2020.

It is clear to us from this figurethat the areas colored in red are the areas of increased water on 9-16-2020 due to reducing their area, while the slight increase was in some areas colored in black.

 

It is clear from the previous figurethat the water is concentrated in the lower areas around the Nile in the south and southwest region.

It is clear from the previous figure that the water was concentrated and appeared in the lower areas around the Nile in the south and southwest region, which had not been previously apparent in previous periods; Which heralds a significant increase in water quantities in the southern and southwestern sides of the Arab Republic of Egypt.

 

Water body separation map shows the size and location of the condensation and expansion of surplus amounts of water, which were not previously apparent in previous periods, and which also indicate its coming from the southern and southwestern side across the Egyptian-Sudanese border.

Conclusion

Flood maps can be produced and the resulting losses assessed by analyzing data from satellite images, determining the locations of floods and affected areas, and ways to reach them. These maps help housing institutions and local and international relief and rescue bodies to identify places of danger, activate monitoring work and address the conditions of those affected. One of the most important elements for determining quantities, areas and direction of water is the application of techniques for separating volumes and bodies of water, making the necessary comparisons between satellite images at different times, and monitoring and analysis. The results, leading to the production of a data-analyzed water body map; To support and assist decision makers.

The results of the study showed that the initial indicators of the flood indicate that it is likely to continue to be at higher than average limits, and that what is expected during the month of September and beyond is that there will be a continuous increase of water in Lake Nasser and the Nile River at the Sudanese border, especially in the water season, and the occurrence of flooding in Sudan, with the expectation of an increase in torrents on the Red Sea coast, and that it may The Arab Republic of Egypt is experiencing an unprecedented flood for many years, especially in the south and southwest regions of the country.

 Recommendations

1. The necessity of preparing and emptying part of the waters of Lake Nasser into the Toshka spillway, and purifying the septic tanks located at the end of the Rasheed branch and the Damietta branch before reaching the Mediterranean Sea.
2. Agricultural drainage plants must be in very good condition; Because it can sink because the water drainage process can take place in the Nile River, and from there to the Mediterranean Sea.
3. The crisis management units in the governorates must be ready from now, and we should not assume that the matter is in Sudan and not in Egypt.
4. We must think of a way to benefit from this excess water instead of wasting it in the desert or the Mediterranean Sea.
5. The readiness of Lake Nasser, the High Dam, and the Aswan Reservoir must be emphasized, with heavy rainfall rates expected to continue. Which increases the levels of the Blue Nile.
6. Local units must call on citizens to evacuate all buildings, homes, livestock pens, warehouses, fish cages, etc.; In order to ensure the safety of lives and to preserve property.

References

•  MCFEETERS, S.K., 1996, The use of normalized difference water index (NDWI) in the delineation of open water features.
• International Journal of Remote Sensing, 17, pp. 1425–.2341.