Effect of reservoirs on streamflow and river regimes in a heavily regulated river basin of Northeast Spain

Abstract

Dams modify downstream hydrology because they alter natural river regimes and divert river flows. The Segre Basin is one of the main tributaries of the Ebro River in Northeastern Spain, and has a drainage area of 13,000 km 2. In this study, we used data on long-term (1951-2013) river flows and climatic series to analyze the downstream cumulative effect of dams on natural river regimes and the disassociation between changes in climate and runoff in the Segre Basin. The headwaters of this basin are in the Pyrenees Mountains, and water flow has been highly regulated since the second half of the twentieth century due to the construction of numerous dams. We compared long-term monthly averages of upstream and downstream sectors, and assessed the relationship between the climatic and hydrological time series. Our results show that the progressive increase of the impounded ratio index (reservoir capacity) increased the disassociation between climate and runoff. This markedly exacerbated the negative trend in downstream runoff, so this decline that cannot be solely explained by climatic changes. Our results provide evidence that reservoirs can cause a significant decline in downstream runoff and significant alterations of natural river regimes.

Unraveling the influence of atmospheric evaporative demand on drought and its response to climate change

“…In these water bodies, the water evaporated is enhanced as a response to an increased AED (Friedrich et al, ; Martínez‐Granados, Maestre‐Valero, Calatrava, & Martínez‐Alvarez, ). If regulated water in reservoirs is used for irrigation, there is an important indirect hydrological effect of the AED as a consequence of enhanced ET in cultivations (Porter & Semenov, ), and subsequent decrease of the water returns to the river courses (Vicente‐Serrano, et al, ), increasing hydrological droughts downstream (Vicente‐Serrano et al, ).…”

Occurrence, Distribution, and Risk Assessment of Antibiotics in a Subtropical River-Reservoir System

“…The number of reservoirs have increased dramatically over the past several decades, reaching about 16.7 million dams and over 50,000 large dams in the current world [16]. Undoubtedly, these dams have the potential to disrupt the original geochemical processes and ecological connectivity of rivers [16,17]. Based on the geographical distribution from the river to reservoir, river-reservoir systems are commonly used to describe its hybrid environmental properties.…”

Assessing the Impact of Reservoir Parameters on Runoff in the Yalong River Basin using the SWAT Model

“…The results show that: (1) the reservoir has a delay and reduction effect on the flood during the flood season, and has a replenishment effect on the runoff during the dry season; (2) the impact of the reservoir on runoff processes and changes in runoff distribution during the year increases with the reservoir capacity; (3) the mitigation of flooding is more obvious at the river basin outlet control station when the reservoir is further downstream; (4) an arrangement with the smaller reservoir located upstream and the larger reservoir located downstream can maximize the benefits of the reservoirs in flood control.The long-term trend of interannual variation in runoff downstream of the reservoir does not appear to be related to long-term climate change, as there was no correlation (or very weak correlation) between the flow downstream of the reservoir and the climate variables (precipitation and temperature) [6]. The results of Vicente-Serrano et al [7] showed that the gradual increase of reservoir capacity in the basin complicated the non-linear correlation between precipitation and runoff, and that the reservoir could lead to a significant decline in runoff downstream and also to significant changes to the natural river conditions. One of the main hydrological effects of the reservoirs on runoff was a reduction of runoff variation, and uniformity of flow, which was due to the decrease in peak flow and the enhancement of minimum flow [8].…”

“…The long-term trend of interannual variation in runoff downstream of the reservoir does not appear to be related to long-term climate change, as there was no correlation (or very weak correlation) between the flow downstream of the reservoir and the climate variables (precipitation and temperature) [6]. The results of Vicente-Serrano et al [7] showed that the gradual increase of reservoir capacity in the basin complicated the non-linear correlation between precipitation and runoff, and that the reservoir could lead to a significant decline in runoff downstream and also to significant changes to the natural river conditions. One of the main hydrological effects of the reservoirs on runoff was a reduction of runoff variation, and uniformity of flow, which was due to the decrease in peak flow and the enhancement of minimum flow [8].…”