Classification of US Hydropower Dams by their Modes of Operation

Abstract

A key challenge to understanding ecohydrologic responses to dam regulation is the absence of a universally transferable classification framework for how dams operate. In the present paper, we develop a classification system to organize the modes of operation (MOPs) for US hydropower dams and powerplants. To determine the full diversity of MOPs, we mined federal documents, open‐access data repositories, and internet sources. We then used CART classification trees to predict MOPs based on physical characteristics, regulation, and project generation. Finally, we evaluated how much variation MOPs explained in sub‐daily discharge patterns for stream gages downstream of hydropower dams. After reviewing information for 721 dams and 597 power plants, we developed a two‐tier hierarchical classification based on (i) the storage and control of flows to powerplants, and (ii) the presence of a diversion around the natural stream bed. This resulted in nine tier‐1 MOPs representing a continuum of operations from strictly peaking, to reregulating, to run‐of‐river, and two tier‐2 MOPs, representing diversion and integral dam‐powerhouse configurations. Although MOPs differed in physical characteristics and energy production, classification trees had low accuracies (≤62%), which suggested that accurate evaluations of MOPs may require individual attention. MOPs and dam storage explained 20% of the variation in downstream subdaily flow characteristics and showed consistent alterations in subdaily flow patterns from reference streams. This standardized classification scheme is important for future research including estimating reservoir operations for large‐scale hydrologic models and evaluating project economics, environmental impacts, and mitigation. Copyright © 2016 John Wiley & Sons, Ltd.

Global proliferation of small hydropower plants – science and policy

“…The general principle of hydropower generation is the conversion of water pressure into mechanical shaft power by hydroturbines (Paish 2002). Despite the diversity of operation modes, hydropower can be classified according to the level of flow control (ie proportion of water stored) and the presence of diversion structures (McManamay et al 2016).…”

“…The degree of flow control ranges from installations that store water in reservoirs to schemes that do not retain much water (ie run-of-river) and are subjected to natural fluctuations of river discharge (Figure 1). Some facilities are intermediate to these classes, in the sense that they control the flow only during specific periods of the year or times of day (McManamay et al 2016). Reservoirs are created to minimize variability in water supply, storing water for periods of low flow or high electricity demand (Egré and Milewski 2002).…”

“…SHPs can be operated as complexes of multiple installations both in close proximity and distributed broadly within a watershed. For example, some run-of-river SHPs are located downstream of large reservoirs that are used to store water and control flow (McManamay et al 2016). Others can use water transported from remote basins via interbasin transfer, causing major alterations to the ecosystem (Cada and Zadroga 1982; Anderson et al 2006).…”

Managing rivers under changing environmental and societal boundary conditions, Part 1: National trends and U.S. Army Corps of Engineers reservoirs

“…Not only were environmental changes evident but important societal changes have also occurred, which have critical implications for reservoir operations (McManamay, Oigbokie, Kao, & Bevelhimer, ). Population growth has historically been linked to greater per capita demand for energy and water.…”

Flow alteration signatures of diversion hydropower: An analysis of 32 rivers in southwestern China

“…Diversion hydropower systems, such as the ones studied herein, are often described as run‐of‐river systems. Although the operational definitions of run‐of‐river and diversion may overlap (one system could be both run‐of‐river and diversion), the two terms refer to different design aspects and are not necessarily synonymous (McManamay, Oigbokie, Kao, & Bevelhimer, ). Clarification as to the relationship between operational designations diversion and run‐of‐river and the implications to river flows may assist managers assessing the environmental effects of dams.…”