Abstract: In recent years, the upper Yellow sees a situation that the relationship of water and sediment is deteriorating and increasingly more reaches of desert strath are shrinking due to sediment deposition, which has affected the safety of ice prevention and the comprehensive development and utilization of water resources. Joint regulation of the cascade reservoirs in this basin is one of the effective technical countermeasures for slowing down sediment accumulation, achieving more water-sediment regulation benefit, and improving the flow capacity of river channel in the dangerous reaches. This paper presents a preliminary analysis on the concept of regulatable sediment transport-required (STR) water volume in the upper Yellow, and a discussion on the relationship of this STR volume versus regulatable water volume. Using these two concepts, we calculated the regulatable water volume of the Longyangxia reservoir during 1987~2010, and analyzed the STR volume and the benefits of reservoir water-sediment regulation for the historical years, for two scenarios of satisfying comprehensive water utilization demand and satisfying power generation water demand. Results show that in the first scenario the Longyangxia's surplus water volume can completely meet the water demand by sediment transport and in the second scenario the regulation benefit is not significant owing to the scattered water discharges by power generation. This reveals that for this reach, a suitable reduction in its power generation demand is favorable in terms of satisfying its water-sediment regulation demand. This work would supply a basis for decision-making on how to improve water-sediment relationship and how to implement water-sediment regulation in the upper Yellow.