Reservoir sedimentation is a momentous problem and has severe consequences on water management, flood control and production of energy. As the river flows into the reservoir, the sediments that travel along with it get deposited and thereby reduces the capacity of the reservoir. From this, it is obvious that study of sediment deposition has to be done periodically as it may affect the safety of dams and, without proper management, negatively impact the environment. This study has attempted to find out the amount of sediment deposition in Idukki reservoir, over the years. As the conventional method such as hydrographic survey is non-economical and time-consuming, the satellite remote sensing method is recommended for this analysis. LANDSAT 8 OLI/TIRS satellite images for the period 2017–2019 were used to assess the water spread area using Normalized Difference Water Index (NDWI), determine the sediment deposition and evaluate the revised capacity of the reservoir. After intensive analysis, a decline of 11.6% was observed between the cumulative capacities of the original base year (1974) and the latest (2019). The loss in live storage capacity between the years 1974 and 2019 was 0.10 km³ which is equivalent to 100 hm³. The study also evaluates the impact of the Kerala Floods 2018 in the Reservoir and also assess the need for desilting.

水库淤积是一个重大问题，对水资源管理、防洪和能源生产产生严重影响。当河流流入水库时，随之而来的沉积物会沉积，从而降低水库的容量。由此可见，沉积物沉积的研究必须定期进行，因为它可能会影响大坝的安全，如果没有适当的管理，会对环境产生负面影响。多年来，这项研究试图找出 Idukki 水库中沉积物的沉积量。由于水文调查等传统方法既不经济又费时，因此建议采用卫星遥感方法进行分析。2017-2019 年期间的 LANDSAT 8 OLI/TIRS 卫星图像用于使用归一化差值水指数 (NDWI) 评估水扩散区域，确定沉积物沉积并评估修改后的水库容量。经过深入分析，原始基准年（1974 年）和最新基准年（2019 年）的累计产能下降了 11.6%。1974 年至 2019 年间的实时存储容量损失为 0.10 公里³相当于 100 hm ³。该研究还评估了 2018 年喀拉拉邦洪水对水库的影响，并评估了清淤的必要性。