Vol.:(0123456789) 1 3 Environmental Earth Sciences (2019) 78:224 https://doi.org/10.1007/s12665-019-8229-9 ORIGINAL ARTICLE Estimating RESCON model parameters for efcient sediment fushing in a dam reservoir Muhammad Bilal Idrees 1  · Jin‑Young Lee 1  · Tae‑Woong Kim 2 Received: 18 July 2018 / Accepted: 6 March 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract In this study, we developed a parameter estimation method of a reservoir conservation model that was developed by the World Bank for efcient sediment fushing operation in dam reservoirs. The parameters for sediment fushing operation are fushing discharge, duration, frequency, and necessary reservoir drawdown. The parameter estimation method was applied to Shahpur Dam in Pakistan, in which sediment balance ratio and long-term capacity ratio were used as indicators of fushing efciency. For efcient fushing of Shahpur Dam, we recommended that bottom outlets at the dam be retroftted to achieve a fushing discharge of 7.5 m 3 /s. The reservoir water elevation should be drawn to a minimum level of 430 m, and the fushing operation should be performed annually over a 15-day span. Flushing using these parameters would result in 100% sediment balance, with 69% of original dam capacity recovered in the long term. We also assessed constraints on dam site for successful fushing. The drawdown ratio was 0.72, sediment balance ratio at full drawdown was 1.58, fushing width ratio was 0.88, and top width ratio was 1.23. For every increment of 0.5 m 3 /s in fushing discharge, the amount of sediment fushed increased by 0.020–0.025 million tonnes. This method can provide guidelines for implementation of sediment fushing operations for reservoir sediment management. Keywords RESCON model · Sediment fushing · Sediment balance ratio · Long-term capacity ratio Introduction Natural streams, particularly rivers, carry high sediment loads. Rivers that empty into a reservoir exhibit reduced fow velocities resulting in sedimentary load deposits in the reservoir. Global annual reservoir storage loss due to sedi- mentation ranges 0.1–2.3%, with an average value of approx- imately 1%; China leads the world in lost reservoir storage volume at 2.3% (Wisser et al. 2013). Consequently, it would be necessary to construct 300–400 reservoirs annually just to maintain current worldwide storage volume (Chaudhry and Rehman 2007; Wisser et al. 2013). On average, 33.5 km 3 of reservoir storage volume is lost every year due to sedi- mentation (White 2010). Furthermore, sedimentation causes various problems such as reduced dam safety and abrasion of sluice outlets and power generation equipment, which, in severe cases, can lead to reservoir retirement. Building a new reservoir is not feasible for many reasons: ideal reservoir sites have already been utilized (Schmutz and Moog 2018), and the building of a new reservoir may be politically unfeasible (Kirchherr 2018; Thorkildsen 2018) or environmentally impractical (Moridi and Yazdi 2017; Huang and Wu 2018; van Oorschot et al. 2018). Only way to minimize the need to build a new reservoir is to maintain existing storage capacity by adopting sediment management and reservoir conservation approaches (Schleiss et al. 2016); therefore, the science of sediment management has gained importance in recent years. Water resources engineers must convert the global inventory of non-sustainable reservoirs into sustainable assets for future generations by applying sediment management measures (Palmieri et al. 2003). Previous studies have described various reservoir sedi- ment management measures including sediment routing, drawdown fushing, reservoir emptying and fushing, vent- ing density currents, and dredging (Morris and Jiahua 1998; Wang and Hu 2009; Schleiss et al. 2016). Sediment fushing is an approach whereby fow velocities in a reservoir are * Tae-Woong Kim twkim72@hanyang.ac.kr 1 Department of Civil and Environmental Engineering, Hanyang University, Seoul 04763, Republic of Korea 2 Department of Civil and Environmental Engineering, Hanyang University, Ansan 15588, Republic of Korea