Developing Rating Curves for Nubia Lake, Sudan, Using RS/GIS

Abstract

Estimating the water capacity of any lake required an extensive measurements and complicated approximation manual methods, which consuming time, effort and money. Rating curves are considered a useful tool to estimate the capacity in a cost-effective way. In addition, generation of these rating curves using Remote Sensing (RS) data and GIS technique has led to save time, effort and money. In this paper, the measured available data of the Aswan High Dam Lake (AHDL) (particularly Nubia Lake) and the extracted data from processed satellite images for different years are used to develop rating curves for the lake by utilizing the created 3D profile of the lake. This profile is then used to estimate the relationship between the lake capacity and the level. Also, the relationship between the lake surface area and the level are developed for the active sedimentation zone of the lake for the years 2000, 2004, 2006, 2008, 2010, and 2012. Equations are presented for individual years and collectively. The accuracy of the developed relationships is assessed by comparing its results with the observed data for the lake. The root mean square error is found to range between 5-10 and 2-4% for (volume/level) relationship and (area/level) relationship respectively. Moreover, results indicated that the present approach overestimate the water capacity by less than 1% compared to the results of the method used by AHDA at year 2012 at the same water level (175 m amsl).