Hydrograph-Based Hydrologic Alteration Assessment and Its Application to the Yellow River

Abstract

With the evolution of society and increasing population, increasing amounts of water resources are being developed to support the needs for such commodities as water and energy, but this development has significantly changed the hydrologic processes in many rivers from their natural state. In this paper, a hydrograph-based hydrologic alteration assessment (HHA) is proposed to describe the hydrologic regime with the attributes of biodiversity and river health, and to assess the hydrologic regime alteration impacted by four main reservoirs in seven sections in the trunk of the Yellow River, and also a comparison to IHA-RVA. The results indicate the following: (1) the hydrologic regimes in the Yellow River have experienced significant changes, from upstream to downstream, corresponding to the construction and operation of the reservoirs; (2) the Sanmenxia reservoir in middle reach has a relatively smaller influence on the hydrologic regime than the largest reservoir of Longyangxia in upper reach; and the hydrologic alteration in the midstream reach is less than in the upstream and downstream reaches; and (3) HHA and IHA are both suitable for assessing hydrologic regime alteration, but HHA is benefit to diagnose the regulation of reservoirs, and IHA places more significance than HHA on the extreme mean flow, which is an advantage in small-discharge regimes and a disadvantage in large-discharge regimes in terms of biodiversity and river health.