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International Institute for Geo-Information Science and Earth Observation (ITC) 2003

The aspects of water balance in the irrigated area : southwest part of Urumieh lake

Behmanesh, O. (Orang)

Titre : The aspects of water balance in the irrigated area : southwest part of Urumieh lake.

Auteur : Behmanesh, O. (Orang)

Etablissement de soutenance : University of Twente International Institute for Geo-Information Science and Earth Observation (ITC)

Grade : Master of Science in Geo-Information Science and Earth Observation 2003

Résumé
The future availability of water for human use depends on how water resources are managed. Espe-cially in the arid and Semi arid regions, e g. study area where management of water resources is important and vital. Therefore for management of available water resources and its preservation in terms of quantity and quality, it is necessary to study the source of water and appropriate method of utilisation. This research has applied remote sensing and GIS technique to determined the aspects of water balance in irrigated area in the Southwest part of Urumieh Lake. In order to undertake the study the dynamics of irrigated area determined and the volume of crop water requirement and consumed groundwater for irrigation have calculated from 1991 to 2001using GIS and CROPWAT model. Then the environmental impacts of water use on the discharge to the lake, dynamics of shore zone and impacts of groundwater use on saline area extension and changes of groundwater salinity have been investigated. The hydrograph of groundwater fluctuations in last ten years illustrate decrease of the water table. The drought of recent years has resulted a sharp rise in demand for water in these regions and more and more groundwater is used. It increased from 20-30% to 70-80 during last 10 years. This has caused a lowering of water table about 1.5 m in this period. There is a correlation between dynamics of shore zone and precipitation, discharge of rivers in to the lake and consumed water for irrigation. Depends on these factors the shore zone is very dynamic. The most transgression of the lake has occurred in 1994 and the most retrogression is related to 2002. Frequently fluctuation of Lake Boundary has caused the salinization of surrounding area. Extent of this area has been increased about 4650 hectare during last 35 years, which about 60% of this is related to last 9 years. Soil salinization through lake water incursion has occurred in the areas where are close to the coast of the lake. Excessive pumping has allowed the landward penetration of brine. It has accelerated in recent years that drought and extraction of water for irrigation have reduced flow of the rivers to the lake. It is more critical in the areas where the only resource for irrigation is groundwater and there is no sufficient fresh water to leach salt away. It can be observed especially in the eastern south part of the study area.

Version intégrale (ITC)

Page publiée le 5 février 2018