GIS 2007 Assignment 4

COMPARISON BETWEEN THE WEB MAP SERVICE SANBI BIODIVERISTY GIS*, PRINTED MAPS AND MAPTRIX (ELECTRONIC MAPS)

Maps are visualizations of knowledge of a certain space. They can either be used for orientation (geographical maps) or for illustrating local information [1].
Most printed maps are geographic maps and used for orientaion. They are widespread and part of everybody’s daily life. Maptrix was designed for schools to teach the general use of maps and the information extraction out of geographical maps. It is available in hard copy and as a computer program [3]. The SANBI Biodiversity GIS is a free online programme that provides access to biodiversity information of South Africa in order to be used for conservation and land use planning [4].

The maps are made for different purposes and presented through a different medium. So, they differ in layout, information provided and application.
Paper is the medium used for most geographic maps. Geographic maps are two-dimensional projections of landscape and infrastructure. They are available in different scales and for nearly every place on earth [2]. Because only a limited area can be shown, several maps are often collected in atlases. The use of scales at a certain ratio (e.g. 1: 25,000) allows the calculation of distances whereas information about longitude and latitude together with a reticule gives information about the position [1]. The advantage of paper maps is their independence of any technical equipment.
The electronic version of Maptrix works with the type of geographic maps described above but presented on a computer. There are 52 5’x 5’ map extractions of 1’x1’ boundary boxes of certain places in South Africa available using a scale of 1:50,000. The extractions were carefully chosen to fit one of the four topics, rural settlement, urban settlement, transport and landscape. The maps are visible in a window smaller than the whole map and a mouse is required to move to the place of interest on the map [3].
Today, seamless electronic maps with a limited zoom function are available. With a printout of these maps the advantages of conventional printed maps can be combined with the choice of the center and zoom.
The Web Map Service SANBI Biodiversity GIS is a freely online available map service for South Africa. Sixty-four maps that show different aspects of biodiversity can be loaded up. Among them are maps that illustrate protected areas, habitat information, ecosystem status and future plans for protection, sometimes specified on certain areas. Additional information can be added in the form of different layers such as the information provided from a conventional geographic map (“base layers”) and the information from all the other provided maps. Beside the different layers, users can also add personal information for example: landmarks, polygons, lines and names. Other advantages are the provided zoom function and the seamless projection. All these different possiblities of adding and removing information makes the SANBI Biodiversity GIS a customizable web map service that can be used to show all relevant information for someone’s purpose. A GIS is not only used to create customized images. Information extraction is another big issue, for example measurement of distances and calculation areas to mention only two of them. Because of the many different available functions, a tutorial for the program is offered on the homepage [4].

GIS programs can provide the most recent information because it can be easily updated in parts (e.g. different layers). Printed maps and electronic maps often do not contain the most recent information. Electronic maps can be updated from time to time whereas printed maps can’t be changed once printed and published.

The information in the form of different features in printed maps and electronic maps is all summarized in a legend. Information beyond the identity of the different features is only seldom available. A GIS like the SANBI Biodiversity GIS offers in addition metadata, downloads, information about the projects shown in the maps, and contact data for more biodiversity information for certain areas. This is necessary to understand and to use the illustrated data.

Maps are a two-dimensional projection of our three-dimensional world and therefore either an equal area, an equal distance or an equal angle illustration [1]. Distortion in one of these geometrical features can’t be avoided. Beside these general map limitations, each of the different types of maps has some specific limitations.
Printed maps and elctronic maps like Maptrix have a fixed zoom level and can contain more or less details than required or show a to big or rather small area. They are not seamless and the area of interest is often not central. Customizable functions such as the use of different layers or addition of data don’t exist. Although the calculation of distances and areas is possible it is often complicated and not more than a rough estimation.
Electronic maps and the GIS require a computer or similar technological equipment, which is not accessible everywhere and to everybody. Some of the electronic programs are in addition very expensive. The GIS programs especially are often difficult to use and the preparation of data is still very complex so they are not yet commonly used. The SANBI Biodiversity GIS is an exception in view of its free accessibility and the tutorial that makes its use easier.

The computer-based technologies will replace the printed maps more and more especially if the prices decrease in the next few years. Navigation is already dominated by electronic technologies such as the navigation systems in cars. Although there is a constant trend towards digitalization, printouts will never become obsolete. The required technology might not always be available and a peace of paper is often still lighter than the navigation systems produced at the moment.
The GIS programs are less important for personal use than for bigger organizations, e.g. industry, universities or politics. These services for data processing and visualizations will grow in the next few years. Today the most GIS are still specified on certain topics like the SANBI Biodiversity GIS. Some topic spanning services will perhaps soon be provided.

*Geographic Information System

References

[1] Internet source:
http://de.wikipedia.org/wiki/Karte_%28Kartografie%29 Accessed on 18 March 07

[2] Internet source:
http://en.wikipedia.org/wiki/Map Accessed on 18 March 07

[3] Maptrix:
Electronic version

[4] SANBI Biodiversity GIS:
http://bgis.sanbi.org Accessed on 18 March 07

DIFFERENCES, ADVANTAGES AND DISADVANTAGES OF A GIS. DIGITAL MAP AND PRINTED MAPS

Introduction

For the majority of us, maps represent a useful tool which we often use in daily life be it while navigating new hiking trails or when we are looking for a specific landmark, shopping centre or street name in an unfamiliar town or city. The common road atlas is now being replaced with more sophisticated and interactive digital forms which in some vehicles are now being built in as standard features. These systems use computer programmes and GPS (Global Positioning System) satellite technology to assist with voice prompts and are a form of GIS (Global Information System). GIS though still a relatively new technology is becoming more and more useful for a vast range of applications which include every day life, science and agricultural fields, and the military. In this assignment, I will touch on the essence of maps, digital maps, and GIS to provide a basic introduction to their uses, advantages and disadvantages.

Printed maps

Printed maps are used to portray the whole Earth’s surface or a part of it on a flat surface [1]. The term “map” actually refers to the mathematical meaning of transferring information from one form into another [2]. Maps can be presented as different projections which each have their own advantages and disadvantages. Maps generally show true distance, true direction, true area, and true shape, however no maps can represent all four at the same time [1]. A 1:50 000 scale map is restricted to the total area that can be portrayed, but the scale is true between the distance on the map and the distance on the ground [1].

Maps are still the main source of data for GIS systems [2]. The term “map” in mathematics explains the transfer of information from one source to another [2]. To produce a map, the requirements include the selection of various features which are to be included on the map, the characterisation of these features into groups such as “Roads” or “built-up areas,” the simplification of detailed outlines of areas including the coastline, the exaggeration of some features on the map that are often too small in reality to represent, and the use of symbols to classify the different classes of the chosen features for the map. To interpret most symbols and features, a representative key is usually supplied [2]. Without a good knowledge of the many symbols on a map, it is often difficult to find what you are looking for in a short space of time.

Other disadvantages of basic maps is that they are also often stylised, meaning that they are often portrayed in an unnatural way, and require some level of interpretation [2]. Maps are often out of date because they have to be printed and therefore the date of publication is the latest date of accuracy. They also show only a situation that is static and is a reflection of one section in time only. Some maps are very artistic which can make them more difficult to interpret, and area on a map can be rather difficult to determine accurately. It becomes increasingly difficult to use a map of the area if you are positioned on top of a high location within the map location as perspectives change and some objects are blocked from view by other objects. Maps cannot pan or give an oblique angle view on the map location [2]. Due to the cost of producing and making certain maps, the information that they contain is often a compromise with what can be afforded [2].

Printed maps have four general roles to play today. The first role is that of displaying data. Maps display information in a meaningful way, in other words, maps provide information that is directed for a specific use [2]. Maps also useful stores of data in the form of selected information about the map area. In a 1: 50 000 map, about 1000 place names are common. Interestingly the information stored on a common British topographical 1: 50 000 map equates to the requirement of 25 Million bytes of storage when converted to a digital format [2]. Maps show boundaries of areas and land uses that cannot be discerned from merely surveying the landscape [2], and most importantly, maps can be used to analyse. Transparent overlays (invented by Ian McHarg) are often used to test the relationship between two distributions of various objects or situations or resources, and hypotheses can therefore also be formulated and tested with the aid of maps [2].

One of the most useful advantages of having maps, and in this I mean printed maps of the same area over periods of time, i.e., maps that are out-dated, is that these maps can actually be useful in determining and storing information about changes in land use and zonation of properties [2]. Examples of this include the first large scale zonation of land in the United Kingdom in the 1930s by Sir Dudley Stamp, and again in the 1960s by Professor Alice Coleman that used maps to interpret the information [2].

Digital maps

Digital maps are similar in a lot of ways to the printed map in that they are constrained by the same disadvantages, though updating digital maps is generally a lot easier and a much quicker process. Maps that are accessed online are often up to date or updated regularly. One obvious disadvantage here is the need for technology, be it computers that are capable of downloading the map information, or the simple presence of a reliable Internet access point or even electricity. Digital maps are often not practical for this reason for many out door activities unless pre-loaded into portable devices, which can often be unreliable, or isolated rural settlements.

Digital maps became useful tools through the requirements of scientists who wished to produce quick maps to visualise digital modelling, or censuses. For these uses, the quality of digital maps was often not of major significance, and in 1967 the first ever modelling computer mapping package was released by Harvard University called SYMAP [2].

By creating digital maps, normal map production time and costs, including editorial costs are drastically reduced [2], however, before the development of faster and more efficient computers, the cost of hardware to produce digital maps was also high.

An interesting form of digital mapping includes the creation of Expert systems (which those of you who are doing the Conservation Biology course will be familiar with). In Expert systems, the computer chooses the correct techniques based on the data that has been provided, the map scale, and its purpose [2]. Digital maps are far more common today than printed maps and today [2]. Importantly, digital maps, because they are made up of digital data, can be used for a larger range of purposes than printed maps [2].

The primary advantage of digital maps is their comparative cost. They are cheap to produce and faster to produce. Digital maps can also be tailored to specific requirements of the user, which includes ease of perspective change or scale changes. The digital data within the maps can be used in applications of a GIS [2].

One large disadvantage is the difficulty in producing one complete digital world map or full-scale maps because of the costs involved and the mass of information that would need to be stored and accessed [2]. Another disadvantage is the initial requirement to invest in suitable computers that are not only capable of creating the digital maps, but also saving and storing the mass of data, therefore capital expenses can be high [2]. Through mass production and the loss of the traditional art of cartography that was seen in the creation of printed maps, quality of digital maps is often also inferior, and is often referred to as “cartojunk.” [2] Maps and digital maps are not searchable in the sense that you can type in key words in a search field to access the place or additional stored information on the search as is often the case with a GIS.

The digital maps produced by Lorraine Innes for MAPTRIX, an interactive educational tool, hi-lights the importance that digital maps can have as future components of school curricula, particularly Geography. MAPTRIX educates the user not only about the use of maps as discussed above, but also how they should be interpreted, which is often something most of us are not taught [3]. As part of the Resource mapping module, both the digital and printed MAPRTIX versions were introduced. Although problems were experienced with the speed at which the digital maps’ perspectives could be changed in order to view different locations, some errors were also encountered in the interpretation of particularly the secondary roads, and several spelling and grammatical errors were also encountered within the set question field, eg. “Road of trees” instead of “Row of trees” (Colchester Map, Eastern Cape, South Africa). I can only conclude that the data fed back to students or learners is only as accurate in digital format as what was originally programmed.

GIS

A GIS is a computer-based tool for mapping and analysing events and places on the Earth’s surface. A GIS integrates common data base operations, which include query as well as statistical analysis of the data, and the geographical analysis with better visualisation than is achievable with maps [4]. A GIS has the power to not only to create maps, but also integrate different information and visualise scenarios, present ideas, and provide solutions for complicated problems [4]. A GIS performs six tasks which include data input, data manipulation, data management, query and analysis, and finally visualisation.

GIS can be used for a vast range of tasks for nearly everything. In Industry and particularly in agriculture, GIS is used extensively for mapping of crop yield and crop rotation cycles, as well as projecting future soil loss on farms, be it from erosion, or poor use [5]. Since a GIS can be used to manage information from wherever it is located, GIS are becoming increasingly valuable in business management, allowing information to be obtained about where the customers are, what their preferences are (market research), spending patterns, and how to optimally exploit this information to maximise overall market share to minimise effective competition [5]. Cities and city planners cannot do without GIS to track maintenance, keep inventories and map locations, and model scenarios and distribution of services etc. [5]. GIS is used daily in the conservation of the environment. Species and resources can not only be mapped but can also be modelled, which allows for a preventative view on possibilities or scenarios, allowing greater resolution about a specific problem [5]. Managing forest is also more sustainable with the use of a GIS, and geologists can also use GIS to study geological features and model seismic activity [5].

GIS is primarily made up of hardware and software (the tools for the manipulation of the data and data management system), the data itself, which is the most important component of any GIS because without it, the GIS would not function, the people component who are responsible for running the GIS system since technology has limited intelligence, and the method by which the GIS functions according to a well organised plan which is often referred to in business as the operating practice [6].

GIS is made up usually of vector and raster structures for data input. Raster is also referred to as grid information, while vector provides a basic visual representation from which no mathematical or statistical analysis can be easily deduced. There are advantages and disadvantages to both methods, and GIS that integrate both structures of data input generally have a better range of data manipulation [7].

Advantages of vector data include the representation of data at its original resolution and form without losing its uniqueness, otherwise referred to a generalisation of objects (as explained in printed maps above) [7]. The graphic representation of the data is more detailed and often more pleasing to the eye, and data obtained from printed maps required no additional conversion since printed maps are in vector form anyway [7].

Disadvantages of vector data include analysis of data, which can only be done if the data is converted into a topological structure [7]. Topology is the study of geometric properties and spatial relationships, which remain unaffected by smooth changes in shape or the size of objects. It is also difficult to process large maps using vector data because of the sheer size of the information that needs to be stores, and elevation data is not well represented in vector form [7].

Advantages of raster data include the implication of geographic location by its position in the cell matrix, in other words, an objects location at the top right hand corner no longer requires the storing of its actual geographic co-ordinates [7]. The analysis of data is also relatively quick and is also therefore suitable for mathematical modelling as well as quantitative analysis [7].

Disadvantages of raster data include the relative loss of resolution where the resolution is actually determined by the cell size selected [7]. Linear features are rather difficult to represent, and associated large amounts of attribute data can be slow to process [7]. Some data integrity or data corruption can also occur as a result of data conversion from vector to raster forms, which will be expressed in the end product, and unfortunately raster structures often produce lower quality imagery that does not conform to many of the needs of cartography [7].

General advantages of a GIS over a map or digital map include the ability to pan to observe different perspectives on objects at oblique angles, with the ability to access additional information about a location or site, take measurements at any relative scale without the restriction of the printed map scale, and the searchability of the entire GIS. GIS are also relatively easy to integrate into various aspects of our modern lives in many forms to assist with a variety of functions, where maps generally have a limited use. The ability of GIS to be integrated and connected to other computer operated system such as GPS and credit card transaction and cell-phone operations, not only has a huge potential for expansion, but may also provide future problems regarding the accessability of daily information about our personal lives. This may lead to problems relating to the violation of privacy.

In conclusion, although it is easy to compare maps to a GIS and source information about their advantages and disadvantages, GIS is certainly the fastest growing form with the most applications, without which many of our daily functions that we take for granted would not be possible.

David Vaughan
Senior aquarist, Quarantine
Two Oceans Aquarium
Cape Town, South Africa
+27 21 418 38 23
dvaughan@aquarium.co.za

References

[1] Kansas GIS: http://www.kansasgis.org/catalog/projections.html Accessed on 20 March 07, 16:58.

[2] Internet source: http://www.geog.ubc.ca/courses/klink/gis.notes/ncgia/u02.html#SEC2.2.2 Accessed on 19 March 07, 13:15.

[3] Innes L. (date not given). Evaluating learning material for map reading. Pdf Internet source: Accessed 19 March 07, 13:19.

[4] Internet source: http://centrin.net.id/~agul/gis_what.html Accessed on 19 March 07, 13:52.

[5] Internet source: http://centrin.net.id/~agul/gis_apl.html Accessed on 19 March 07, 14:00.

[6] Internet source: http://centrin.net.id/~agul/gis_comp.html Accessed on 19 March 07, 14:15.

[7] SANBI: http://bgis.sanbi.org/GIS-primer/page_19.htm Accessed on 19 March 07, 15:16.

Assignment 2

1. Image

Projection: Azimuthal Equal Area
Centre: Random
0°E
-30°N
Direction: 0

Distance: shows distances in spherical projection
Area: shows areas in spherical projection
Shape: spherical
Direction: north view, the center is Greenwich mean time(0°E) and -30°N

2. Image

Projection: Longitude Latitude
Centre: North pole
0°E
90°N
Direction: 90

Distance: shown distorted, only in reference to longitudes and latitudes
Area: shown distorted, only in reference to longitudes and latitudes
Shape: flat, longitudes and latitudes in a flat projection
Direction: centre is the north pole, with Asia above, North America below and Africa on the right side

3. Image

Projection: Azimuthal Distance
Centre: South pole
0°E
-90°N
Direction: 0

Distance: shown distorted
Area: shown distorted
Shape: spherical, areas get bigger from the centre to the periphery
Direction: South pole in the centre


4. Image

Projection: Heart Equal Area
Centre: Standard
0°E
0°N
Direction: 0

Distance: in spherical projection
Area: in spherical projection
Shape: like a heart
Direction: Africa in the centre with the North pole above and the South pole below


5. Image

Projection: Azimuthal Stereographic
Centre: Standard
-165°E
1°N
Direction: -47

Distance: shoes distances through lines
Area: shows areas not distrorted or in a projection but just flat
Shape: flat, shows equator and the central longitude as a straight line, shows not the whole globe
Direction: Pacific in the centre, with North America on the right side, Australia to the left side and Asia above


6. Image

Projection: Cylindrical Equal Area
Centre: Random
-126°E
1°N
Direction: 114

Distance: shown through lines
Area: shown in cylindrical projection
Shape: cylindrical
Direction: Pacific in the centre with North America on the left side, South America above and the South pole on the left side


7. Image

Projection: Azimuthal Orthographic
Centre: Standard
0°E
0°N
Direction: 90

Distance: distances shown through lines
Area: areas shown in spherical projection
Shape: spherical projection of both sides of the “sphere”, connected in the centre
Direction: South pole in the centre, Africa on the left side


8. Image

Projection: Bonne
Centre: North pole
0°E
90°N
Direction: 0

Distance: shown through lines
Area: distorted through the projection
Shape: shows the whole globe in a spherical projection with the normally covered parts to the side and above
Direction: North pole in the centre with Asisa on the right side and North America to the left side

9. Image

Projection: Mollweide
Centre: South pole
0°E
-90°N
Direction: 0

Distance: shown through lines
Area: in projection
Shape: spherical with the normally covered parts to the side
Direction: South pole in the centre, Asia on the right side and South America on the right side a little bit above

10. Image

Projection: Sinusodial
Centre: North pole
0°E
90°N
Direction: 0

Distance: shown through lines
Area: shown in projection
Shape: shows the central lines that connect North and South pole as straight line and an edge between the halfs of the globe that are shaped like vaulted parables
Direction North pole in the centre, with Asia on the right side and North America to the left side

OASES OF THE WORLD

A. INTRODUCTION

B. DAKHLA OASIS, EGYPT

DAKHLA OASIS: IMAGE 1
DAKHLA OASIS: IMAGE 2
DAKHLA OASIS: IMAGE 3
DAKHLA OASIS: IMAGE 4

C. SIWA OASIS, EGYPT

SIWA OASIS: IMAGE 1
SIWA OASIS: IMAGE 2
SIWA OASIS: IMAGE 3
SIWA OASIS: IMAGE 4

D. GHARDAIA OASIS, ALGERIA

GHARDAIA OASIS: IMAGE 1
GHARDAIA OASIS: IMAGE 2
GHARDAIA OASIS: IMAGE 3
GHARDAIA OASIS: IMAGE 4

E. GUERRARA OASIS, ALGERIA

GUERRARA OASIS: IMAGE 1
GUERRARA OASIS: IMAGE 2
GUERRARA OASIS: IMAGE 3
GUERRARA OASIS: IMAGE 4

F. KUFRA OASIS, LYBIA

KUFRA OASIS: IMAGE 1
KUFRA OASIS: IMAGE 2
KUFRA OASIS: IMAGE 3
KUFRA OASIS: IMAGE 4

G. SAN PEDRO DE ATACAMA, CHILE

SAN PEDRO DE ATACAMA: IMAGE 1
SAN PEDRO DE ATACAMA: IMAGE 2
SAN PEDRO DE ATACAMA: IMAGE 3
SAN PEDRO DE ATACAMA: IMAGE 4

H. EN GEDI OASIS, ISRAEL

EN GEDI OASIS: IMAGE 1
EN GEDI OASIS: IMAGE 2
EN GEDI OASIS: IMAGE 3
EN GEDI OASIS: IMAGE 4

I. TURPAN OASIS, CHINA

TURPAN OASIS: IMAGE 1
TURPAN OASIS: IMAGE 2
TURPAN OASIS: IMAGE 3
TURPAN OASIS: IMAGE 4

J. YZAD OASIS, IRAN

YZAD OASIS: IMAGE 1
YZAD OASIS: IMAGE 2
YZAD OASIS: IMAGE 3
YZAD OASIS: IMAGE 4

K. TAYMA OASIS, SAUDI ARABIA

TAYMA OASIS: IMAGE 1
TAYMA OASIS: IMAGE 2
TAYMA OASIS: IMAGE 3
TAYMA OASIS: IMAGE 4



A. INTRODUCTION

Oasis is a Greek word and means “inhabited place”.

An oasis is an area covered with vegetation in the desert. Because of different water sources oases can be classified into the following groups:
- Groundwater oasis:
The water is brought to the surface with a pump or a well
- River water oasis:
A river supplies the oasis with water from rain-laden areas.
- Spring water oasis:
A spring water oasis is located at places where groundwater table reaches the earth’s surface. It is the most common type of oasis.
- Oasis with an artesian well:
The groundwater rises to the surface because of overpressure.
Oases were once very important for the caravan trade and agriculture but they lost their importance in times of modern transportation techniques. One of the most important products was once the date. But some of the North African oases had a structural change and could intensify their agriculture because of the use of deeper laying water resources.
One of the biggest problems of oases is still the salinisation. It occurs whenever water evaporates because the soluble salts remain in the soil. The salinisation in some oases is extended so far that agriculture is not possible anymore.


B. DAKHLA OASIS, EGYPT

Dakhla is one of the five western oases in the Libyan Desert in Egypt. The 14 villages are situated in a swale surrounded by rocks and are home to 70.000 people. The oasis has 30.000 ha cultivable land where basically date palms, citrus fruits and mulberrys are grown.


DAKHLA OASIS: IMAGE 1

NORTH EAST VIEW
















This image shows an overview of the Dhakla Oasis facing north east.
Co-ordinates: 28°59'18.21"E, 25°30'45.48"N, width of image: 79,81km

DAKHLA OASIS: IMAGE 2

NORTH WEST VIEW
















This image shows the water sources of the Dakhla Oasis facing north west.
Co-ordinates: 28°59'18.21"E, 25°30'45.48"N, width of image: 2,35km

DAKHLA OASIS: IMAGE 3

NORTH WEST
















This image shows fields and irrigation system in the Dakhla Oasis facing north west.
Co-ordinates: 28°59'18.21"E, 25°30'45.48"N, width of image: 250m.

DAKHLA OASIS: IMAGE 4

NORTH VIEW
















This image shows huge salinsation of fields in the Dakhla Oasis facing north.
Co-ordinates: 28°59'18.21"E, 25°30'45.48"N, width of image: 720m.


C. SIWA OASIS, EGYPT

Siwa is also one of the five western oases in the Libyan Desert in Egypt. This oasis is 80km long, 2- 20km wide and located 18m under the sea level. In several villages live about 23.000 people. Most of them are farmers that cultivate date palms and olive trees.


SIWA OASIS: IMAGE 1

NORTH VIEW
















This image shows an overview of the Siwa Oasis facing north.
Co-ordinates: 25°32'3.60"E, 29°13'21.74"N, width of image:39,89km.

SIWA OASIS: IMAGE 2

NORTH VIEW
















This image shows a village in the Siwa Oasis facing north.
Co-ordinates: 25°32'3.60"E, 29°13'21.74"N, width of image: 3,97km.


SIWA OASIS: IMAGE 3

NORTH VIEW
















This image shows fields and the irrigation facing the north.
Co-ordinates: 25°32'3.60"E, 29°13'21.74"N, width of image: 270m.

SIWA OASIS: IMAGE 4

EAST VIEW
















This image shows salinisation and huge water channels facing east.
Co-ordinates: 25°32'3.60"E, 29°13'21.74"N, width of image: 2,15km.



D. GHARDAIA OASIS, ALGERIA

Ghardaia (Algeria) is located in a valley called M`zab in the nothern part of the Sahara. The wadi Mzab supplies all oases in the valley with water after heavy rainfalls. In several smaller towns and villages live 82500 people. Most of them are farmers and cultivate date palms. Ghardaia has its own airport and exports not only dats but also petroleum and natural gas.


GHARDAIA OASIS: IMAGE 1

EAST VIEW
















Overview of the Ghardaia Oasis in Algeria facing west.
Co-ordinates: 3°40'47.07"E, 32°29'19.07"N, width of image: 11,56km.

GHARDAIA OASIS: IMAGE 2

NORTH WEST VIEW
















Village in the Ghardaia Oasis. View: north west.
Co-ordinates: 3°40'47.07"E, 32°29'19.07"N, width of image: 760m.

GHARDAIA OASIS: IMAGE 3

SOUTH EAST VIEW
















This Image shows some fields in the Ghardaia Oasis facing east.
Co-ordinates: 3°40'47.07"E, 32°29'19.07"N, width of image: 500m

GHARDAIA OASIS: IMAGE 4

WEST VIEW















This image shows a riverbed in the Ghardaia Oasis facing west.
Co-ordinates: 3°40'47.07"E, 32°29'19.07"N, width of image: 2,65km


E. GUERRARA OASIS, ALGERIA

Guerrara is also an Oasis in the M`zab valley. (no more information available)

GUERRARA OASIS: IMAGE 1

NORTH VIEW
















Overview of the Guerrara Oasis in Algeria facing north.
Co-ordinates: 4°40'7.51"E, 32°46'41.86"N, width of image:12,11km.

GUERRARA OASIS: IMAGE 2

WEST VIEW
















This image shows the water sources of the Guerrara Oasis facing west.
Co-ordinates: 4°40'7.51"E, 32°46'41.86"N, width of image: 4,14km.

GUERRARA OASIS: IMAGE 3

NORTH VIEW
















Big fields in the Guerrara Oasis facing north.
Co-ordinates: 4°40'7.51"E, 32°46'41.86"N, width of image: 3,59km

GUERRARA OASIS: IMAGE 4

EAST VIEW















in the Guerrara Oasis facing east.
Co-ordinates: 4°40'7.51"E, 32°46'41.86"N, width of image: 4,23km



F. KUFRA OASIS, LIBYA

The Kufra Oasis is located in the south east of Libya. In the 1970ies several big irrigation projects made intensive agriculrure possible. For the last 30 years the oasis was irrigated with fossile ground water. Today the ground water level is about 60m lowered. There are no data about how long the Kufra will be supplied with water. But scientist expect that this Oasis will dry out in only a few years

KUFRA OASIS: IMAGE 1

NORTH VIEW
















Overview of the Kufra Oasis in Libya facing north.
Co-ordinates: 23°19'10.79"E, 24°8'49.35"N, width of image: 49,29km

KUFRA OASIS: IMAGE 2

SOUTH VIEW
















This image shows the big round fields and a part of the irrigation system facing south.
Co-ordinates: 23°19'10.79"E, 24°8'49.35"N, width of image: 4,15km.


KUFRA OASIS: IMAGE 3

NORTH VIEW
















This image shows big fields in the Kufra Oasis with irrigation system facing north.
Co-ordinates: 23°19'10.79"E, 24°8'49.35"N, width of image: 4,71km.

KUFRA OASIS: IMAGE 4

NORTH VIEW
















Square fields in the Kufra Oasis facing north.
Co-ordinates: 23°19'10.79"E, 24°8'49.35"N, width of image: 4,63km.

GREAT WATERFALLS OF THE WORLD

Introduction

Waterfall can be defined as vertical movements of water that occurs where a band of hard rocks crosses the path of the river. The movement of the water from the river is less able to erode the hard rocks, thus leave the hard rocks as steep in the river’s long profile. The steepness of the hard rocks plays an important role in the water movements, such that the steeper the hard rock , the faster the water movement and thus more energy associated with water.

The energy due to the running water leads to abrasion and erosion. This erosive factor causes the waterfall to become less steep until it eventually out with the natural flow of the river (http://www.geographyhigh.connectfree.co.uk/). It takes many years for a waterfall to become extinct.

Most waterfalls are valuable sources of hydropower, as moving water turns the turbines that produces electricity.
Source: www.geographyhigh.connectfree.co.uk/s3rivergeohighlandforms.html

The diagram illustrates the vertical movements of water as it falls from the hard rock, and making a pool at the base (plunge pool).

1. VICTORIA FALLS

Zimbabwe

The Victoria Falls are located on the Zambezi River, on the border between Zambia and Zimbabwe. They are roughly 1.7 km (1.7 mile) wide and 128 m (420 ft) high. Victoria Falls are considered a remarkable spectacle because of the peculiar narrow slot-like chasm into which the water falls. The falls are part of two national parks, Mosi-oa-Tunya NP in Zambia and Victoria falls national park in Zimbabwe; these are one of southern Africa main tourist attraction (http://en.wikipedia.org/).

The coordinates are –17°55'20.73"S 25°51'13.64"E[-17.9201217°25.852273°E]
Source: http://en.wikipedia.org/wiki/victoria_falls

2. RUACANA FALLS

Namibia

Ruacana Falls are located on the border of Namibia and Angola; the falls are more or less controlled by a dam upstream. The Ruacana falls provide fresh water to the northern part of Namibia and the southern part of Angola. Also they are a valuable source of hydroelectric power and main attraction of tourist in Namibia.

The coordinates are–17°23'32.82"S 14°12'44.03"E[-17.388803°S14.2073383°E]

Source: http://www.onime.com/Africa/landscapes/waterfalls/ruacanafalls.html

3. NIAGARA FALLS

United State of America/Canada

Niagara Falls is a set of massive waterfalls located on the Niagara River in eastern America, on the border of the United State and Canada. The falls were formed after the receding of the glaciers of the most recent ice age, as water from the newly formed Great lakes carved a path through the Niagara escarpment enroute to the Atlantic Ocean, (http://en.wikipedia.org/). These falls are very wide and they are very valuable source of hydroelectric power for both Ontario and New York.

The coordinates are 43°04'39.86"N -79°04'32.52"W [43.07331°N
-79.0720867°W]

4. IGUAZU FALLS
Brazil/Argentina

These are water falls of the Iguazu River located on the border of Brazilian state of Parana (in the southern region) and the Argentine province of misiones. These waterfalls consist of about 270 falls along 2.7 kilometres (1.67 miles) of the Iguazu River. Some of the individual falls are up to 82 m (269 feet) in height, though the majority are about 64 metres (210 feet). The falls are shared by the Iguazu National Park (Argentina) and Iguazu National Park (Brazil) (http://en.wikipedia.org/).

The coordinates are –17°55'33.78"S 25°51'22.14"E [-17.922297°25.85369°E]

Source: http://en.wikipedia.org/wiki/Iguazu_falls

5. ANGEL FALLS
Venezuela

The Angel Falls (indigenous name Kerepakupay Vena) is the world’s highest free-falling water falls at 979 m (3212 ft) with an uninterrupted drop of 807 m (2648 ft) lying in the Canaima National Park, Venezuela, and they are located in the river Churun, an affluent of the Carrao (http://en.wikipedia.org/). These falls were not known to the western world until an American aviator; James Crawford Angel visited the falls in 1935 on a flight while searching for a valuable ore bed (http://en.wikipedia.org).

The coordinates are 5°28'59.07"N -61°56'17.64"W [5.4765117°N
-61.9362733°W]

Source: http://en.wikipedia.org/wiki/Angel_falls

6. AUGRABIES FALLS

Republic of South Africa

Augrabies are water falls located about 120 km west of Upington in the Northern Cape Province, South Africa. The falls covers an area of 820 km and stretches along the Orange River. These falls are in a dry area, and they are about 60 metres high. When the river in which they are found is flooded, these falls produces tremendous waterfalls.

The coordinates are –28°35'21.82"S 20°20'00.42"E [-28.58697°S 20.333403°E]
Source: http://en.wikipedia.org/wiki/Augrabies_falls

7. TUGELA FALLS

South Africa

Tugela Falls are the world's second highest waterfall. The total drop in five free-leaping falls is 3,110 feet (947 meters). They are located in the Drakensberg (Dragon's Mountains) in the Royal Natal National Park in KwaZulu-Natal Province, Republic of South Africa (http://en.wikipedia.org/). These falls provide pure and safe drinking water to the people living in this provinnce.

The coordinates are–28°44'13.14"S 28°54'51.18"E[-28.7355233°S28.90853°E]

8. YOSEMITE FALLS

North America

Yosemite Falls is the highest measured waterfalls in North Amaerica. Located in Yosemite National Park in the Sierra Nevada mountains of California. Yosemite Falls is one of the major attraction in the park, especially in late spring when the water flow is at its peak (http://en.wikipedia.org/).Yosemite falls are regarded as one of the 6th highest falls in the world with a total of 2425 feet (739 m)distance from the top of the upper falls to the baseof the lower falls (http://en.wikipedia.org).

The coordinates are 37°45'23.03"N -119°35'52.38"W [37.7538383°N -119.5920633°W] Source: http://en.wikipedia.org/wiki/victoria_falls

9. WALLAMAN FALLS

Quensland Australia

Wallaman Falls is a waterfall located in the northeast tropics region of Queensland, Australia, approximately 50 km West of the township of Ingham, and Northwest of Townsville and Thuringowa (http://en.wikipedia.org/). The falls have two main drops, the second of which is commonly cited to be Australia's largest single drop, between 268 and 305 m in height

The coordinates are -18°34'47.16"S 145°48'00.71"E [-18.5745267°S 145.8001183°E]

Source: http://en.wikipedia.org/wiki/victoria_falls

10. MTARAZI FALLS

Eastern Zimbabwe

Mtarazi is a free leaping waterfall that leaps in the delicate tiers in the Eastern highlands of Zimbabwe. Mtarazi is the second tallest waterfall in the world.

The coordinates are –18°13'08.32"S 32°44'29.98"E [-18.2180533°S

32.73833°E]