Abstract

The use of satellite remote sensing (RS) has salient progress in water budget calculation and it performs in watershed management. An RS technique can properly enhance hydrogeologic surveys. Moreover, to have an intimate understanding of the changes in water level fluctuations, it is also important to relate them to the surrounding eomorphic, structural, climatic and geologic factors. This research serves twofold. The first one is to operationalize the use of RS and Geographic Information Systems (GIS) techniques to assess the change of water surface area in Duhok dam located in Duhok city, Kurdistan region-Iraq. The second is to present and interpret the available statistical data on water level fluctuations in Duhok dam. The change of water surface in the Duhok dam is examined over a 11 year period using satellite images taken between 2001 and 2012. Three Landsat Enhanced Thematic Mapper Plus (Landsat 7 ETM+) images acquired on 13 June, 2001, 11 June, 2006 and on 11 June, 2012, respectively, were used. The change is tracked from the images using Band 7 with the help of Normalized Difference Water Index (NDWI). The accuracy assessed by using the Normalized Difference Area index (NDAI), and the change in water surface area analysed by comparing it with the related meteorological data of the dam. Results show that the estimated water surface area by RS matches the one on the ground with small relative error (less than 2.15%). A decrease of slightly more than 23% was observed in the water surface area this 11 year period. In addition, over this time period, climate conditions (rainfall, temperature and evaporation) in the study area have been changed significantly. These changes could have affected the reservoir surface area, but so also could external human interference around the dam.

Key words: Geographic information systems (GIS), normalized difference water index (NDWI), normalized difference area index (NDAI), remote sensing (RS), water resource management