Paper On Analysing The Impact Of Building Activities, In Agriculture Lands, Using Gis Technique- Libya.

Analysing the impact of building activities, in agriculture lands, using GIS technique. Case study: Gharyan, Libya. Ravi Shankar, Urban Planner, WSP International, Tripoli, Libya Abstract Agricultural lands are scarce in Libya. Only 1.2% of the total landi is cultivable. Food security is one of the top issues of Libyan Agricultural policyii, which aims at self-sufficiency for some agricultural products, in order to minimize reliance on foreign sources for food supply. Libyan agriculture encounters a number of difficulties and reduction in agricultural lands due to urbanization is one among them. For the chosen study area, using GIS techniques the trend of urbanization in the fertile agricultural lands is mapped for last four decades. The study gives a clear picture on how the building activities are slowly eating up the agricultural lands. Furthermore, the output from IPM iii model is used as an input to evaluate the possible conversion of agricultural lands into building developments by the year 2025. Keywords: GIS, Libya, Gharyan, Agriculture, Urban Planning, Integrated Planning Model.

Introduction: Gharyan is located at 80kms. southwest of the capital city Tripoli. It is also the main city centre in the Gharyan Sub-region. It lies in the Jabal Nafusah escarpment elevated 700 m above the sea level. Gharyan is in the centre of agriculturally developed area, where the annual rain fall is 250mm.This rainfall is reasonably sufficient for crop cultivation. The major crops grown are olives, almonds, figs, grapes, and rain fed barley.

Map showing location map of Gharyan.

Study Area: Gharyan city tends to cluster with the settlements like Sidi Musa, Taghrinnah, Al Qahasat and Al Magharibah-Bani Wazir and adjacent urban mixed areas. This urban agglomeration has a total population of about 80,000 inhabitants. This may in the future grow to the size of 160,000 inhabitants. Due to the rapid urban growth, the urban sprawl has characterized the development largely during the last three decades. Gharyan had almost exhausted the land within the 2GMP1 area and started growing outside. New settlements like Sidi Musa, Sidi Entatah, Kammoun had emerged because of the agglomeration effect. On this basis the study area is demarcated and and the analysis is carried out within this area.

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2GMP- Second Generation Master Plans prepared in 1980’s.

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Map showing chosen area of study (3GPP ).

Data: The data used for the study are the age of the buildings from the 3GPP building inventory, IPM model projections of population spread in Gharyan from the 3GPP sub regional plans and Agriculture land suitability data from agricultural department. Age of the building: As part of the 3GPP, a database was created for the entire buildings of Tripoli region. This included the housing typology, nature of the building, age of the building and the height of the buildings. From this database the building age is extracted for the study purpose. The buildings are grouped as built before 1975, between 1976-1985, 1986-1995 and 1996-2006. Integrated Planning Model: The IPM is basically designed to spatially distribute the forecasted number of people and workplaces. The Integrated Planning Model (IPM) for Tripoli Region is designed to address planning issues in terms of Scenario based figures for the development of people and workplaces. Agricultural land suitability: There are around 1569 Hac. of moderately fertile agricultural lands which is a sizable amount of land to carry out sustainable agriculture. The type of soil predominantly found in that region are Haploxererpts- (Deep or moderately deep soils). They have a very limited ground water and depend upon rain fed conditions. Most of the cultivable agricultural lands fall under the category of S2rb.

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3GPP- Third Generation Planning Project. Following the 2GMP now, development plans are prepared for all the settlements in Libya to have a planned and guided development.

Examples of image showing the age of the buildings and IPM projection. Analysis: The point data (vector) on the age of building is converted to raster data for raster calculation with agricultural suitability. The trend of urbanization in agricultural and non- agricultural lands for the last 40 years is mapped. This gives a clear picture on reduction in fertile agricultural lands during the last few decades. Cell based modelling of the Agricultural suitability layer and IPM model’s output using Zonal functions are used to map the building developments in agricultural lands by 2025.

Showing the methodology used for mapping decadal growth of buildings in agricultural lands and the usage of IPM model projection .

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Map showing the agriculture land suitability for the study area.

The map clearly illustrates that there were very few developments in agricultural lands during 1975.As the northern part of Gharyan is mountainous, the building activities slightly started shifting towards the agricultural lands during 1980’s.

Map showing the presence of buildings in the agricultural /non-agricultural lands before 1975.

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The maps are from the Libyan agricultural department - land suitability for agriculture was based on the following factors, Soil properties (Crop production) Climate (Temperature, precipitation, Wind, others) Water Status (Quantity, Quality and Suitability) Topography Sustainability to erosion Land use

The period during 1995-2005 showed a sharp increase of building activity in the agricultural lands. The main reason is exhaustion of lands within the main city. The IPM model the follows the trend and by 2025, there will be small patches of agricultural lands less than 10% of total agricultural lands.

Map showing growth of buildings in the agricultural/non-agricultural lands before 1985 &1995.

Map showing growth of buildings in the agricultural/non-agricultural lands before 2006 and possible growth of buildings by 2025.

Conclusion: For the chosen study area, using the GIS techniques the trend in building activities are mapped in the fertile agricultural lands. This gives a clear picture on how the building activities are slowly eating up the agricultural lands. If the same trend of urbanization continues in the agricultural areas without being checked by 2025 there will be very little or no land available within the study area for agriculture production. To conserve the remaining agricultural area the above study was vital along with studies on slope, growth direction, urban sprawl, vacant lands, etc., to identify new areas for urban development. i ii

http://www.nationsencyclopedia.com/Africa/Libya-AGRICULTURE.html Taher Azzabi, Agricultural Research Center, Tripoli (Libya), Food Self-Sufficiency and Agricultural Research in Libya.

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The Integrated Planning Model is a tool created in GIS for the 3GPP, designed to spatially distribute the forecasted number of people in 2025.

References: Polservice. Consulting office, Warsaw, Poland (1980), Tripoli Region Development Plans, Gharyan Master Plan TF-63. National Consulting Bureau (2008), Final Draft Sub- Regional Plans, Gharyan Sub- Region.