Evaluating the effect of land use / land cover changes trend on groundwater resources status, using sattelite images (Case study: Gilan-e gharb plain)

One of the direct methods of land use impacts on the hydrological conditions of each region is relation between land use changes and the groundwater table fluctuations that can assist managers in optimized management of natural resources. In this study، to evaluating the impacts of land use changes on groundwater level drop in Gilan-E gharb plain، satellite images from MSS، TM and ETM sensors in 1985، 2000، 2010 were used. After processing and analysis of images، the region were classified into six classes in terms of land use including forest، pastoral، gardening، dry and water farming، farming and residential areas. Quantitative data of piezometric wells that exist in the plain during 1999- 2010 was used to examining aquifer changes and the resulting layers were also classified. The results showed that pasture land has devoted the largest area (more than 50% of the total area)، as it formed 61. 8% (9927 ha) and 67. 15% (10782 ha) of the area in 1985 and 2000 respectively، its extent has decreased during the period from 1379-1389 and formed 50. 23% (8066 ha) of the region. Evaluation of dry and water farming was also showed that it has been faced with decreasing in the amount of the area 0. 84% (130 ha) during 1985-2000، but the changes in the period 2000 to 2010 has been increased 1429 ha which formed 8. 9% of the region. Assessment of groundwater drop showed that it has been increased through replacing pasture lands class with farming classes. This changes has caused to 83. 93% of the area in 2010 had a groundwater drop more than 50 cm per year، so that the area of this region was 43. 85% in 2000. Human intervention is undoubtedly the most important factor of the region degradation.