Kiadokht Ahmadi Soroush
Fax:: +(431) 26060 – 5830
E- mail: [email protected]
There is no doubt that in a country such as Iran, in which Iarge portions of the country fall under the categories of “arid” and “semiarid” lands, the capability of mapping land use land cover is important.
Acknowledge of land use and Landcover is important for many planning and management activities concerned with the surface of the earth.
The primary objective of these investigations are to demonstrate the application of landsat data for supplying governmental organizations with information which will assist in resource planning, development and better utilization through management within Iran.
Methodology In undertaking this study the following steps were performed;
- Data collection- utilization of all available landsat data for this study area, in different bands and dates – Literature review.
- Data interpretation – Land use/land cover classification of the central watershed, based on data analysis and interpretation of available landsat data.
- Mapping Landuse/Land cover-various landuse/land cover recognized and their distribution is shown in the landuse/land cover “map of central watershed which is exhibited at a scale od 1:1,000,000.
General Descripiion of the Centeral Watershed
This study area located in the north west portion of Iranian Central plateau, which is a sub-basin of Iranian internal watershed.
The study area occupies about 92125 sq. Km.
This basin includes 6 sub-basin terminating in the Namak Lake, they are called open or closed svb-basins.
Open sub-bains consist of kashan, Ghomrud, Ghareh chai, shurrud, and jajrud closed svb- basin is called Arak.
The most important cities in this study area are:
Tehran, Hamedan, Gazvin, Kashan, Arak.
The mountainous regions surounding this watershed, in higher elevation is 14929 in north and lower portion is ablut 3117 f near Namak Lake.
Considerable variations in climate can be seen in ceneral watershed. The differences ae primarily a result of topography and can generally be expressed in terms of amount of precipitation and Length of growing season. Three zones, based on these variation, have been designated for this study area utilizing a modified koppen system. These zones are: arid, semiarid, moderate.
They are derives using mean annual and monthly ralves of temperatures and precipitation and their seasonal characteristics. Precipitation in the region is relatively low as the principal storms that originate in the Mediterranean lose a major portion of their moisture on rising over the Alborz or zagros ranges. The average annual precipitation for stations in the central region ranges between 350 and 100 millimeters.
Relative humidity varies widely in the region depending on wind, precipitation and altitude. This climatic parameter was a marked effect on the evaporation in any area and thus on water consumption of all vegetation.
The water resources of the centeral watershed are presented in this project in terms of surface water availability and ground water avalability.
Surface water availability- the main natural drainage of the basin consists of the Jajrud, Karaj – rud, Ghared chai, Khar- rud, Ghom- rud that terminats in the Namak Lake. All of them are fed by several smaller branches. No natural Lakes in this region have potential to contrbute to surface water development, the effect of artificial storage reservoirs will be considered in the supply demand comparisons.
The surface water analysis show that the water of most rivers in this region can be used for agriculture and industrial purposes and also for municipal use.
Ground water availability – this presentation is Largely concerned with the ground water abailability of the plains or valley alluvium of this region.
The ground water of this area consists of the shallow and deep wells, spring and ghanats.
Wells are most important in arid and semiarid area of this watershed, as main souce for water.
By inspection, the tectonic map of Iran indicates that the centeral watershed is composed of the three geological groups: ingneous metamorphic and sedimentary.
Most of the region is covered by sedimentary deposits, conglomrates and evaporits of the centeral Iranian Depression. These deposits are overlain by volcanic rocks and tuffs. The volcanic types are associated with the alborz mountain range and the mountian range running parallel to the zagros mountains between Arak and Qum.
The area where the Zagros mountain range surrounds the inner plateau is generally described as sedimentary, with slight metamorphism.
A small area north-east of Golpayeagan also displays metamorphism. The marked salinity within the region results primarily because the evaporation potential exceeds precipitation. This is evidenced by the runoff that flows into the in land basins. The flows subsequently evaporate, Leaviny a residue of salt concentrates. In addition a number of salt plugs increase the salinity of the natural runoff.
In this area seven physiographic units have been recognized. These are:
Mountains-Hills-Plateau and upper terraces, Pied mont plains, river Plains-Lowland- flood Plain- Alluvial Fans Plains- Colluvial Plains- Sanddune.
Results and Analysis
Landuse/Land cover map of the centeral watershed which is exhibited at a scale of 1:1000,000, based on data analysis and interpretation of available landsat data.
In this area, seven major units have been recognized as follows:
1- Urban or built-up Lands:
This unit consists of residential, industrial, commercial area and major transportation and communications.
This area consists of predominately irrigated croplands, Dry farm croplands,Orchard, Vine yards that occur predominantly in plains, arround the residential area, along the rivers, gentely slop in hills.
3- Range Lands:
This area consist of high, medium,Low,Poor production range lands that mainly occuring on the mountains, hills and plains,
There is low density forests in this watershed because of it low rain fall.
This unit occur only in south of Alborz peidmont.
This unit consists of the main natural drainage and four reserviors.
This area cover by permanent and temporary salt water that consists of shrubs and nonshrus wet Lands.
Mainly ocuring in the lowland areas.
Most of this area located on arid parts of watershes. It consists of salt flats and Playas, sandy area, bare exposed rock.
Conclustions and Recommendations
The following conclusions and recommendations obtained from results and analysis:
- To achieve accurent and desirable results, the interpreters should be well informed about the genetal geography conditios of the area and also be familiar with existing land form.
- There should be a logical relation between level of study and the chosen scale.
- Using of imagery prepared in spring and autumn is more suitable for Landuse/Land cover Mapping, but using imagery prepared at different times of the year could be useful in interpretation of data.
- Its better that the selected images should have uniform colour tons as well as good quality so that folowing and Landuse units from one image to another is smooth.
- The accuracy interpretation for the several categories should be about equal.
- Utilization of all available data and field control is important and for interpretation and accuracy for landuse/land cover mapping.
- Available and standards classification system according to the natural characteristic of the country is
Table : Areal coverage of the various land use/land cover units in the centeral watershed.
|NO||UNIT||AREA OF COVERAGE (SQUARE Kms.)||PERCENTAGE|
|1||Urban for built –up lands||540.6||0.56|