The fast growing population in the world and the rapid growth in cities
have intensified the need to collect data regarding planted areas, preservation
of the existing land sources, other issues on protection of nature and
information about the population. In various issues, the need for geographical
information including information on land has emerged (Fistikoglu, 1996).
Accordingly, the organization and processing of high amount of positional
data as per needs constantly evolving according to purpose and time have
required the use of computer aid and paved the way for the Geographical
Information System (GIS). The Geographical Information Systems (GIS) have
become an important tool utilized in management of so many and different
data that the classic archiving methods could not manage in recent years.
Thanks to these systems, it has become pretty easier to process map based
data and other data base. In addition, one of the most important benefits
of Geographical information system is that they help to make right decisions
on events related to geographical assets. Furthermore, through these systems,
it has become possible to create thematic maps and make queries related
to the position on these maps (Burrough, 1998).
In today`s world, GIS is employed for many agricultural purposes such
as estimation on plant pattern in agriculture, harvest estimation, determination
of lawn and meadow areas, determination of fallowing lands, follow up
of plant evolution, soil classification, irrigation and drainage analysis,
conservation planning of water resources, estimation on resources regarding
agriculture and animal husbandry and determination of rural settlement
areas (Yomralioglu, 2000; Turoglu, 2000).
Increases having resulted from employment of new technologies and methods
in animal and plant production have contributed to a rise in fertility.
However, various chemicals and fertilizers applied to soil and plants
as a result of evolving agricultural techniques and practices have negative
impacts on the productivity of the soil, underground and surface water
resources (Topbas et al., 1998). One of the environmental problems
posing threat to the agricultural sector is use of fertile agricultural
lands for non-agricultural purposes (settlement, military, tourism, industry
etc.). Therefore, literature information on the land cover included in
the Ergene Basin Environmental Arrangement Plan has been used in this
study and maps have been drawn for use of land, soil classes, utilization
of fertilizer and pesticides and forestry areas as per cities within the
borders of the basin (T.U., 2007). The objective of the study is to make
the maps prepared serve as the basis for basin planning studies to be
carried out in the future.
MATERIALS AND METHODS
Ergene Basin is located in the middle of the Thrace region and surrounded
by the borders of the Northern Marmara Basin, Meriç Basin and Bulgaria.
Ergene Basin is one of the existing 13 sedimentation basins in Turkey.
In terms of its geographical structure, it is in the form a basin closed
to the sea. The survey of the basin equals to 10.730 km2 and
cultivable lands account for about 73% of the basin. Forests, heathlands,
rock cliffs, settling areas, industrial places and lake surfaces form
the remaining 27% of the basin (Hazar, 1997).
The mountain chain extending from the North of Edirne to Lalapasa, Kirklareli
Merkez, Kofçaz, Demirköy, Vize, Saray towns and remaining
between Black Sea coasts is called Istranca (Yildiz) Mountains. To the
South of the region extend Ganos Mountains from the region covering Enez,
Kesan, Malkara ve Sarköy towns to Tekirdag. Areas which fall out
of the scope of the defined mountainous region of the basin are plateaus
of medium height or low ones. These plateaus are very similar to one another
in terms of terrestrial forms and natural structure characteristics. The
situation of the river basin is given in Fig. 1.
|| The situation of the river basin
In general, terrestrial climate reigns over Ergene Basin. December and
January are the rainiest and July and August are the driest months of
the year. The average annual precipitation is 622 mm. Since Ergene basin
is surrounded by very high mountains to the North and South, it receives
less precipitation compared with the neighboring lands. There is a wide
forestry cover in particular oak and beech throughout the high sections
of Istranca Mountains. A great part of Ergene Basin, on the other hand,
lacks trees (Kantarci, 1997; Çengel et al., 2001).
The most important surface water resource of the basin is Ergene River
and its ramifications. Ergene River stems from resources in about Saray
town of Tekirdag, joins with Çorlu Stream and afterwards flows
to the west and flows into Meriç River in Uzunköprü town
of Edirne. The total length of the river is 285 km and its average annual
flow rate is 27,270 m3 h-1. The most important ramifications
of Ergene River are Sulucak Stream, Burgaz Stream, Teke Stream, Seytan
Stream and Hayrabolu Stream (Hazar, 1997).
According to the new soil classification (soil taxonomy), with regards
to types of soil, there are Vertisol, Inceptisol, Alfisol, Entisol and
Mollisol in the basin. In regards to soil classes, Mollisol is considerably
fertile and significant, Alfisol and Inceptisol are cultivable; however
Vertisol creates problems when used for agricultural purposes and it accounts
for about 30% of the region. Dry and wet farming are performed in the
basin and the main crops are wheat, paddy and sunflower. 21.881 ha of
the soil in Ergene Basin is exposed to the risk of very severe erosion
and 126.324 ha severe erosion (Tok, 1997).
Land use for agricultural purpose in Ergene Basin constitutes approximately
73% of the total land. Agricultural chemicals and pesticide use are as
important as that of fertilizer in the basin. Producers of the region
prefer use of pesticide instead of manual hoeing or using agricultural
machines in fight against weeds as pesticide is cheaper and more efficient.
Contaminant nitrogen and phosphor resulting from use of fertilizer in
agricultural and forestry areas are amongst important pollutant sources.
Chemical fertilizers applied heavily in the basin include more nitrogen.
GIS is based on the integration of three main components of the computer
technology. These are methods and techniques for database management,
processing, imaging and drawing of data graphical display and positional
analysis. In a GIS database, data (processed or raw satellite data, climate,
soil, surface measurements, height, precipitation, temperature, population,
roads etc.) derived from very different resources regarding the issue
to be analyzed and questioned are kept on the computer as layers and new
information is produced by questioning the criteria of a certain branch
of expertise. For example, the most suitable areas for the production
of a new type of plant are designated according to the type of soil, precipitation,
temperature, land use and inclination. This information can be realized
as an image, map, graphic, statistical analysis etc. (Ordu and Demir,
In this study, after the selection of GIS package software (MapInfo)
to be employed in the application, data have been collected, they have
been associated to one another and the system was questioned. In the application
study, first of all, necessary details and type of these details (point,
line and area), attributes of these details and layers of details have
been detected. Separate layers (such as soil and forest etc.) have been
established for classes of details. In accordance with the type of detail
to be stored in the layer, layers have been created in the form of point,
line or area. Afterwards, data have been placed in their places in the
most suitable layers. Details in the form of point, line and area are
represented by different symbols according to their attributes.
Maps with a scale of 1:250.000 pertaining to Ergene Basin have been digitized
and these digital maps have been converted into the format of MapInfo.
Since layers are kept as separate files in MapInfo, layers to be associated
with the database have been combined as separate files and converted.
During the process of conversion, every point, line, area or writing object
if there is have been assigned an ID no. While entering data of attribute,
either new attributes are added to tables of the existing layers or a
table which does not include a layer is constituted, new registers are
added via the existing program and as many attributes as possible can
be entered. However, if data tables are Microsoft Excel etc., based, it
is not possible to make any operation (geographical analysis) without
converting these tables into MapInfo format. This conversion process is
ready in the relevant program. Combination process of non-graphical data
prepared in a different software program (Microsoft Excel) and graphical
data has been realized through Table>Update Column>Join. These data
are combined via common areas in tables.
|| Thematic display of classes of soil
In GIS, it is possible to mark information of attribute pertaining to
data in a layer on the region upon the info instruction and display it
in tables. If there is more than one object in the same geographical location,
the Info Tool window display how many objects there are and to which tables
they belong to.
The most important steps of GIS are making queries, necessary analysis
and receiving results. Thematic maps have been drawn up by storing all
the existing digital data in a database. A thematic map can be defined
as the change of the map to the different forms depending on the underlying
information. In this way, we can display the same data in very different
forms via thematic maps.
The thematic maps prepared are as follows: The thematic map of the basin
has been drawn up in the soil layer according to classes of soil. Every
class of soil (Alfisol, Inceptisol, Mollisol and Vertisol) has been colored
differently according to their ID numbers. The distribution of class of
soil, use of land and utilization of pesticide and fertilizer have been
located on in the form of bar graphics on every city in the basin. In
this way, it becomes possible to make comparison of different data on
a visual basis. Thematic display of classes of soil is presented in Fig.
2, land use in the basin in Fig. 3 and types of
soil in the basin in Fig. 4. Use of pesticide and fertilizer
is displayed in Fig. 5.
|| Land use in the basin
||Types of soil in the basin
|| Use of pesticide and fertilizer
||The thematic display of the forestry areas
Thematic maps have been drawn up as Ranges and Individual according to
characteristics of data. Data displayed in parenthesis in the legend window
of the thematic map are the number registers within this range.
In the layer of forest, the distribution of forestry areas in the basin
has been displayed. Forestry areas have been ranked from the dark color
to light ones. Dark colors indicate more intense forestry areas while
light colors less dense ones. Names of the layers are listed as very dense,
medium dense, coppice and lowly dense and they have been colored accordingly.
Forestry areas exist only in the northern part of the basin and the surface
of forestry areas becomes less day by day. The thematic display of the
forestry areas is presented in Fig. 6.
RESULTS AND DISCUSSION
In today`s world, there is a need for comprehensive information on field
in studies conducted on natural environment. In this case, Geographical
information systems are the most efficient technological tool in order
to collect environmental data, store in the digital environment and realize
There are various features of a river basin such as its topography, geology,
land use, basin borders, population intensity and these features include
very different parameters related to the basin. It is very difficult to
evaluate such type of comprehensive information. Thus, it has become inevitable
to employ geographical information systems in management and planning
of a basin in recent years.
Ergene basin on which this study has been conducted covers a significant
part of Thrace. This basin includes the most important agricultural lands
of the region and has a considerable industrial power. The mainstay of
the basin is mainly based on agricultural activities. Nitrogen and phosphor
components emanating from over fertilization of agricultural lands become
a part of water resources through the surface flow. In particular, wastewater
including fertilizers and pesticides from lands of paddy which requires
much water play an important role in pollution. There should be efforts
in the basin to prevent water pollution resulting from agricultural activities.
Natural methods should be developed in the fight against insects instead
of use of pesticide. In addition, new Technologies in agriculture should
be followed. The feasibility of use of methods such as ecological agriculture,
pesticide rotation and resistant seed should be studied in the region.
In this study, the attention has been attracted to the increasing non-agricultural
use lands in Ergene basin the main economy of which is based on agriculture.
Though the size of non-agricultural land use varies according to cities,
it is mainly settlement areas of low and high density, industrial area,
military area and tourist area. In thematic maps drawn up, the use of
land and soil types of the basin have been defined and it has been exemplified
that agricultural soil of I. and II. class is utilized for non agricultural
This study has defined the existing situation in the basin and aimed
to form the basis for planning, development and management of basin resources
in the future. The presentation of visual digital data to the decision
making authority is very important in accelerating the decision making
process. Furthermore, techniques of distance perception can be employed
in future planning studies. On the other hand, the presented study has
also delineated the fact that the use of GIS at the most efficient level
requires sufficient and suitable databases and an understanding of GIS