Migration and Its Impact on Cities : A Report

Posted on April 29, 2018 by Rashid Faridi

The World Economic Forum has released a report taking a deep dive on migration and cities, exploring the types, causes and patterns of migration, the most affected corridors and cities, the impact on urban infrastructure and services, the solutions that can be employed and how cities can seek to future proof themselves to address this growing challenge.

The report captures the migration stories of 22 of the most affected cities around the world, including from North America (Montreal, Ottawa, Calgary, New York and Boston), Latin America (Sao Paulo and Medellin), Middle East and North Africa (Dubai, Amman, Ramallah), Sub Saharan Africa (Cape Town and Dakar), Asia (Pune, Surat, Guangzhou and Davao City), Europe (Berlin, Athens, Paris, Amsterdam and Rotterdam) and Oceania (Auckland). The report also presents a high level framework to achieve long term migrant integration and in delivering urban infrastructure and services efficiently and effectively to meet the needs of migrants.

 

You can download the the report here (High resolution) or here (Low resolution).

Posted in earth, Migration | 3 Comments

The Gravity Model of Migration

Posted on April 28, 2018 by Rashid Faridi

The gravity model of migration is a model in urban geography derived from Newton’s law of gravity, and used to predict the degree of interaction between two places. Newton’s law states that: “Any two bodies attract one another with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them.”

When used geographically, the words ‘bodies’ and ‘masses’ are replaced by ‘locations’ and ‘importance’ respectively, where importance can be measured in terms of population numbers, gross domestic product, or other appropriate variables. The gravity model of migration is therefore based upon the idea that as the importance of one or both of the location increases, there will also be an increase in movement between them. The farther apart the two locations are, however, the movement between them will be less. This phenomenon is known as distance decay.

The gravity model can be used to estimate:

  • Traffic flow
  • Migration between two areas
  • The number of people likely to use one central place
    It is  a model to predict movement of people, information, and commodities between cities and even continents.

The gravity model takes into account the population size of two places and their distance. Since larger places attract people, ideas, and commodities more than smaller places and places closer together have a greater attraction, the gravity model incorporates these two features.

The relative strength of a bond between two places is determined by multiplying the population of city A by the population of city B and then dividing the product by the distance between the two cities squared.

Population 1 x Population 2
_________________________

        distance²

Thus, if we compare the bond between city A and City B, we first multiply their  populations and then we divide the ressult by the distance squared Therefore, the bond between New York and Los Angeles is greater than that of El Paso and Tucson!

While the gravity model was created to anticipate migration between, it can also be used to anticipate the traffic between two places, the number of telephone calls, the transportation of goods and mail, and other types of movement between places. The gravity model can also be used to compare the gravitational attraction between two continents, two countries, two states, two counties, or even two neighborhoods within the same city.

Some prefer to use the functional distance between cities instead of the actual distance. The functional distance can be the driving distance or can even be flight time between cities.

It was expanded by William J. Reilly in 1931 into Reilly’s law of retail gravitation to calculate the breaking point between two places where customers will be drawn to one or another of two competing commercial centers.

Critiques of the gravity model argue that it can not be confirmed scientifically, that it’s only based on observation. They also state that the gravity model is an unfair method of predicting movement because its biased toward historic ties and toward the largest population centers.

A Helpful Video

Source(s):

Wikipedia

Thought.co

 

Posted in Class Notes, earth, Migration | Leave a comment

Thematic Maps and Thematic Mapping Techniques

Posted on April 24, 2018 by Rashid Faridi

A thematic map is a type of map specifically designed to “show a particular theme connected with a specific geographic area.

Unlike reference maps, which tell us where something is, thematic maps tell us how something is.
There are a number of visualization techniques and thematic map types that have different applications depending on the type of data that you are exploring and the type of spatial analysis that you are looking to do. The methodology and the type of map that you want to create may be different, for example, if you are exploring global shipping data or voter propensity, or environmental disaster impact.

All thematic maps use maps with coastlines, city locations and political boundaries as their base maps. The map’s specific theme is then layered onto this base map via different mapping programs and technologies like a geographic information system (GIS).

Broad Types

Quantitative 

Choropleth: Color gradient

Chorochromatic: Various Color

Choroschematic: Shown by Symbols

Isopleth:  Lines

Proportional Symbols: Size of symbols

Dot Density Maps: Show Population

Qualitative

Qualitative thematic maps are not dependent on numbers (data). For example, One can map the hospitals in Manhattan without counting them. I may only be interested in their locations to see where the medical gaps are. Then one could layer the map with population data to determine how many people are served, theoretically, by each one—and then compare that ratio with ones for the other boroughs of New York City.Following  are some examples

  • Communication and Transportation Maps
  • Ethnography Maps
  • Linguistic Maps
  • Military History Maps
  • Urban Planning Maps

History of Thematic Maps
Thematic maps did not develop as a map type until the mid-17th Century because accurate base maps were not present prior to this time. Once they became accurate enough to display coastlines, cities and other boundaries correctly, the first thematic maps were created. In 1686 for example, Edmond Halley, an astronomer from England, developed a star chart. In that same year, he published the first meteorological chart using base maps as his reference in an article he published about trade winds. In 1701, Halley also published the first chart to show lines of magnetic variation- a thematic map that later became useful in navigation.Halley’s maps were largely used for navigation and the study of the physical environment.

 In 1854, John Snow, a doctor from London created the first thematic map used for problem analysis when he mapped cholera’s spread throughout the city. He began with a base map of London’s neighborhoods that included all streets and water pump locations. He then mapped the locations where people died from cholera on that base map and was able to find that the deaths clustered around one pump and determined that the water coming from the pump was the cause of cholera.

 In addition to these maps, the first map of Paris showing population density was developed by a French engineer named Louis-Leger Vauthier. It used isolines (a line connecting points of equal value) to show population distribution throughout the city and was believed to be the first use of isolines to display a theme that did not have to do with physical geography.

Lets take a look at some popular thematic maps and mapping techniques.

 Choropleth maps
A choropleth map is a thematic map where geographic regions are colored, shaded, or patterned in relation to a value.This type of map is particularly useful when visualizing a variable and how it changes across defined regions or geopolitical areas.

For example, a choropleth map is extremely useful when looking at vote totals by political party per county in the United States, as below. In a choropleth map, color can be used to represent distinct attributes or, as in the example below, to represent weight of a value (a strong or weak party vote-share shown as light or dark colors).

Isarithmic or Isopleth
Isarithmic maps, also known as contour maps or isopleth maps depict smooth continuous phenomena such as precipitation or elevation. Each line-bounded area on this type of map represents a region with the same value. For example, on an elevation map, each elevation line indicates an area at the listed elevation. An Isarithmic map is a planimetric graphic representation of a 3-D surface. Isarithmic mapping requires 3-D thinking for surfaces that vary spatially.

Heat maps
A heat map represents the intensity of an incident’s occurrence within a dataset. A heatmap uses color to represent intensity, though unlike a choropleth map, a heatmap does not use geographical or geo-political boundaries to group data. This technique requires point geometries, as you are looking to map the frequency of an occurrence at a specific point.

Visualizing the intensity of occurrence using a heat map is a technique commonly used when tracking weather and natural phenomena, in which established borders and boundaries are less useful for understanding impact areas. In the heat map below, drought conditions across the United States are visualized based on intensity, giving us a greater understanding of past and potential impact areas.

Proportional symbol maps
A proportional symbol map can represent data tied to a specific geographical point or data that is aggregated to a point from a wider area.

In these maps, a symbol is used to represent the data at that specific or aggregate point, and then scaled by value, so that a larger symbol represents a greater value. The size of each symbol can be proportional to the value you are visualizing or you can set 3 to 5 ‘classes’ of values allowing for comparison and classification of locations.

Dot density maps
A dot density map uses a dot to represent a feature or attribute in your data.

Some dot density maps are ‘one-to-one’ in which each dot represents a single occurrence or data point, or ‘one to many’ in which each dot represents a set of aggregated data, for example one dot may represent 100 individuals with a certain attribute. Both of these types of dot density map visualize the scatter of your data, which can provide insights into where instances of an occurrence are clustered.

Animated time-series maps
More of a technique than a type, if your data has a temporal component (taking place over time), you can transform any of the above visualizations into an animated time-series map. Looking at your data over time can both improve your ability to gain insights and create a stronger and more compelling visual.

Putting your data on an appropriate time scale will allow you to make important business decisions. Mapping foot traffic over the course of a week, for example, may inform hours of operation for a retail location while mapping and animating a century’s worth of sea level measurements can paint a vivid picture on the impact of global climate change.

With many applications from social listening to resource management to demographic projection, animating your data as a time-series map unlocks a new dimension at which to view your data.

Cartograms
A dasymetric map is an alternative to a choropleth map. As with a choropleth map, data are collected by enumeration units. But instead of mapping the data so that the region appears uniform, ancillary information is used to model internal distribution of the phenomenon. For example, population density will be much lower in forested area than urbanized area, so in a common operation, land cover data (forest, water, grassland, urbanization) may be used to model the distribution of population reported by census enumeration unit such as a tract or county.

Source(s):

Carto

Wikipedia

ThoughtCo

 

Posted in Class Notes, earth, Geography Practicals/Lab and Statistical Techniques | Leave a comment

Migration :Why and How people Migrate or they Dont

Posted on April 23, 2018 by Rashid Faridi

Migration is defined as a permanent or semi-permanent change of residence with an opening intention of settling at destination region permanently or temporarily of an individual or group of people over a significant distance.

The roving instinct, it is said, is intrinsic to human nature: the need to search for food, pasture, and resources; the desire to travel and explore; but also to conquer and possess. Population movements have been the carriers of innovation from one region to another.in In this quest, he becomes a tourist and a migrant. there is a strong inter-linkage between these two.

Cause of migration can be a natural calamity, climatic change, epidem­ics, over population, better employment opportunities, desire to get rich quickly need for political freedom.

Migration can be voluntary and involuntary. People migrate for economic benefits under voluntary migration and involuntary includes social, religious and political. It can be short-term where people move for short periods and long-term where they move for good. The long-term migration is called emigration.

 The latest figures from the United Nations Population Division inform us that, as of 2010, there are 214 million international migrants in the world. If all these migrants were put in a country of their own, it would be the fifth-largest in the world.

There are some pressing questions. Why has such a large proportion of the world’s population not migrated? Is it because they do not want to, or do not have the need to? Is it because their ‘moorings’ are holding them firmly in place – their family ties, jobs, culture, familiarity and simply feeling ‘at home’? Or could it be that many millions would want to migrate, but are prevented from doing so, either by their own poverty which isolates them (they do not have a passport, and/or cannot pay for the ticket to travel) or because of the political and institutional barriers to their movement? These can be called intervening obstacles to migrate. It is one of the ironies of globalization that whilst goods, capital, knowledge, entrepreneurship, and the media are free to flow across borders, labour, that other crucial factor of production, is not. In fact, on the whole, people are less free to migrate now than they were a hundred years ago.

Hence, the otherwise attractive notion of the ‘age of migration’ needs to be qualified: migration for some, but not for others. Fine if you are white, from a wealthy country in Europe, North America or elsewhere in the developed world, or if you have money to invest or valuable skills to deploy. But if you are from a poor country in Africa, Latin America or parts of Asia: forget it. Basing his analysis on the empirical example of Cape Verde, an island country with a long tradition of emigration to various parts of the world, Jørgen Carling draws attention to the separation between Cape Verdeans’ widespread aspiration to migrate, and their current inability to do so. For them, the ‘age of migration’ has become the ‘age of involuntary immobility’ (Carling 2002).

 The UNPD’s figure of 214 million can be regarded as a ‘best estimate’ but it obscures two major statistical problems. First, the criteria for defining who is a migrant vary from country to country, the chief difference being between citizenship and birthplace or prior residence. Naturalisation converts foreign-born immigrants into citizens and thus removes them from the migration count if citizenship is the criterion of measurement. People born in the host country to immigrant parents – the  ‘second generation’ – can remain classified as non-citizens on the ius sanguinis or ‘blood’ rule and thus be counted as part of the ‘foreign’ or ‘immigrant’ population, even though they themselves have not immigrated. The second problem is the – by definition unknown – quantity of ‘undocumented’ or ‘irregular’ immigrants, often branded ‘illegal immigrants’.Migration is important because of the way it shapes and re-shapes societies, making them more diverse and complex. But it also creates sharp divisions between those who accept the need for migrants and welcome the economic and cultural contributions they make, and those who oppose them. The latter group, politically motivated, often exaggerate the numbers of migrants, employ repeated use of prejudicial terms such as ‘illegal immigrants’ and ‘bogus asylum-seekers’ and tend to scapegoat migrants for the ills of the society they seek to join – like crime, drugs and unemployment. These anti-migration discourses need to be confronted by a more objective analysis of the process of migration, starting with a recognition of the diversity of the phenomenon.

Links(s) and Source(s):

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