In a world where socioeconomic development and population growth are driving up human demand for freshwater, reservoirs provide an integral part of the solution to many water challenges such as water stresses, flood and drought disasters, and so forth. Reservoirs are engineered to effectively allocate water resources both spatially and temporally, and therefore can be harnessed for multiple purposes like flood control, power generation, water supply, irrigation, and navigation. The long-term and full display of reservoir's benefits is based on the sustainable operation of reservoirs, which is largely affected by its effective storage capacity, and this capacity is more than often hampered by sedimentation problem which is a headache of many reservoirs around the world, especially those on sediment-laden rivers. Statistics show that reservoirs around the world are losing 0.5%–1.0% of their total storage capacity to sedimentation every year. In the meantime, with the continuous trend of global warming, the frequency and intensity of extreme weather events are both increasing, which brings about significant impact on the hydrological and sedimentation processes. Many rivers are experiencing more intense and longer floods, more severe and prolonged droughts, as well as more complex riverbed changes. In 2022, Pakistan, Indonesia, Brazil, Australia, and South Africa were all afflicted by floods, and Pakistan, which was hit the most seriously, had one-third of its land inundated by massive floods. Meanwhile, most part of Europe, the Yangtze River basin of China, the Midwest of the United States, and the East and North Africa are still suffering from droughts, with water levels in Lake Mead in the United States and Poyang Lake of China dropping to record lows. As a result, there is a growing need of reservoir capacity to ensure water supply and withstand floods in response to the increasingly acute drought and flood problems caused by extreme weather events. On the other hand, new dam sites for reservoirs are nearly exhausted and new generations of dams are significantly more costly to build. Thus, we must protect the economic lives of existing reservoirs by all means we can, and that include maintaining the storage capacity of reservoirs and restoring the part that is lost to sedimentation. In fact, the long-term maintenance and sustainable utilization of the reservoir capacity and the effective restoration of the silted storage capacity have become an important way to cope with the shortage of water resources and to neutralize the risk of floods, winning this hot topic wide attention. Tremendous efforts have been made by the Chinese scientists and engineers to address this issue because many rivers in China carry relatively high sediment load, resulting in higher-than-average annual capacity loss rate for its reservoirs compared globally. Lessons and experiences accrued over the years were both abundant. Back in the 1950s–60s, when systemic construction of reservoirs began in China, the understanding of sedimentation and its problems was limited. The reservoir operation was mainly focused on “water storage and sediment interception.” There were no structures designed or scheduling for discharging sediment. The Sanmenxia Reservoir, the first large water conservancy complex built on the main-stem Yellow River, was completed in 1960 but was functioning ill only one and a half years later. Severe sedimentation drastically raised the riverbed at the back-water area, jeopardizing flood control safety in the Guanzhong Plain. To solve this sedimentation problem, the Sanmenxia Reservoir had to go through major structural changes: the spillway tunnels were added, the electricity generation water pipes were reconstructed and the diversion bottom holes used originally during construction were dug open. The reservoir operation approach has also been changed twice: from “water storage and sediment interception” to “flood detention and sediment discharge” and then to “storing clean water and discharging muddy flow.” Over a decade later, an inter-year equilibrium sediment exchange process has largely taken hold in the reservoir area. The practices adopted at the Sanmenxia Reservoir make a template for addressing long-term storage capacity issues for reservoirs on sediment-laden rivers. The operation principle of “storing clean water and discharging muddy flow” has since then been practiced and improved in many reservoirs in China, gradually shaping the theory and techniques of water-sediment regulation. In this issue of River, Prof. Chunhong Hu reviews the application of such principle for sediment regulation in China's Three Gorges Reservoir and puts forward an optimized approach of “regulating sediment for greater benefits.” Under the premise of controllable flood risk and allowing for reasonable sediment deposition in the reservoir area, this new approach is to reflect the significantly changed water-sediment conditions and satisfy the needs of socioeconomic development. Reservoir regulation is made in accordance with the water and sediment inflows to control the volume and the form of sedimentation. Methods include peak sediment regulation, silting reduction and dispatching at the end reach of reservoir, and cascade reservoir sediment operation, and so forth. Real-time scheduling of small and medium floods, dynamic control of reservoir level in flood season, and early impoundment nearing the end of flood season are used to maximize the multiple benefits of reservoirs. Of course, measures to discharge or get rid of sediment after it enters the reservoirs are the last technical means that we resort to. If sediment loads coming to the reservoirs are to be prevented, we need to have a strong focus on good land use practices, soil and water conservation, and ecological restoration to minimize the sediment that comes into the river. To prevent reservoir sedimentation, we must have a comprehensive view and adopt an integrated manner to ensure its root causes are taken care of. We need to treat the mountains, rivers, forests, farmlands, lakes, grass, and sediment as an integral life community. Any problem happened to any factors in the community is to be addressed in a systematic and coordinated way from the root or upstream causes by leveraging or improving all the other factors. This is what the Chinese saying goes Treating the disease rather than one of the symptoms of the disease. River highly welcomes more in-depth discussions on this issue in the future!