JZS (2017) 19 – 3-4 (Part-A) 25 Water Quality Assessment Models for Dokan Lake Using Landsat 8 OLI Satellite Images Hasti Shwan Abdullah 1 , Mahmoud S. Mahdi 2 & Hekmat M. Ibrahim 1 1Faculty of Engineering-Sulaimani University, Bakrajo Street, Sulaimaniyah-lraq 2Building & Construction Engineering Department-University of Technology, 52 Street, Baghdad- Iraq. Email: hekmat.ibrahim@univsul.edu.iq Article info Abstract Original: 15 November 2016 Revised: 15 April 2017 Accepted: 16 May 2016 Published online: 20 September 2017 It is impractical to monitor water quality more than a small fraction of lakes by conventional field methods because of expense and time requirements. Satellite image is more convenient to be applied to collect the required data for monitoring and assessing water quality in the lakes. Therefore, this study aims to estimate the concentration of some water quality parameters (Temperature, DO, BOD, pH, Turbidity, TSS, TDS, EC, NO 3 , PO 4 and E. coli) by applying developed models based on the remote sensing and GIS techniques on the Landsat 8 OLI satellite image using twenty points in Dokan lake, Kurdistan Region, Iraq at two different seasons. Multiple linear regression is used to obtain mathematical models for estimating the concentration of some water quality parameters depending on spectral reflectance of Landsat 8 OLI. In this study, new band (coastal blue) of Landsat 8 OLI has been undertaken in developing of models. Moreover, new Independent Component Analysis (ICA) and new 7 band ratios with 16 band combinations have been used. The best models are obtained for TSS, Turbidity and DO with coefficient of determination (R 2 ) of 0.98, 0.98, and 0.83 respectively. Generally, for spring season, the performance of all models is reduced due to seasonal change, variance of parameters and other factors. However, high R 2 of 0.86 has been shown for Temperature. The results of the developed WQPs models have been mapped to show the water quality parameters concentration distribution within Dokan lake. The conclusions present that correlation of all bands of Landsat 8 OLI is appropriate to water quality parameters. Key Words: Dokan Lake WQPs Image Processing Landsat 8 GIS Introduction Water quality monitoring is the systematic collection and evaluation of data about the chemical, physical, and biological quality of the water bodies, and assesses how external changes, both natural and anthropogenic, affect that quality. To get a true picture about the nature of the river and lake water, it is required to measure the quantity and quality of water through water quality monitoring, which implemented in many methods and techniques. The traditional method of water quality monitoring consists of collecting and analysing water samples after testing them in laboratory which requires more times and costs. Recently, with advance and increasing role of technology, new techniques and methods are developed for assessing water quality such as remote sensing (RS) and geographical information system (GIS) that achieved through using satellite data to monitor water quality to reduce time and cost for the process, and to increase accuracy of results. Ming, et al. [1] established an integrated water quality monitoring system data which obtained from SPOT data with GIS techniques in central Taiwan. Also, Hedger, et al. [2] highlighted the role that remote sensing may play in helping to optimize sampling that are more commonly implemented. Journal homepage www.jzs.univsul.edu.iq Journal of Zankoy Sulaimani Part-A- (Pure and Applied Sciences)