Small dams alter thermal regimes of downstream water
<p>The purpose of this study was to quantify the downstream impacts of different types of small dams on summer water temperature in lowland streams. We examined (1) temperature regimes upstream and downstream of dams with different structural characteristics, (2) relationships between stream t...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-11-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/23/4509/2019/hess-23-4509-2019.pdf |
| _version_ | 1828190260657389568 |
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| author | A. Chandesris K. Van Looy J. S. Diamond J. S. Diamond Y. Souchon |
| author_facet | A. Chandesris K. Van Looy J. S. Diamond J. S. Diamond Y. Souchon |
| author_sort | A. Chandesris |
| collection | DOAJ |
| description | <p>The purpose of this study was to quantify the downstream impacts of different types of small dams on summer water temperature in lowland
streams. We examined (1) temperature regimes upstream and downstream of dams with different structural characteristics, (2) relationships between stream temperature anomalies and climatic variables, watershed area, dam height, impoundment length and surface area, and residence time, (3) the most significant variables explaining the different thermal behaviors, and (4) the dam thermal effect considering a biological threshold of 22 <span class="inline-formula"><sup>∘</sup></span>C, with a calculation of both the number of days with a temperature above this threshold and the average hourly duration above this threshold.</p>
<p>Water temperature loggers were installed upstream and downstream of 11 dams
in the Bresse region (France) and monitored at 30 min intervals during
summer (June to September) over the 2009–2016 period, resulting in 13 paired water temperature time series (two sites were monitored for two
summers, allowing the opportunity to compare cold and hot summers).</p>
<p>At 23 % of the dams, we observed increased downstream maximum daily
temperatures of more than 1 <span class="inline-formula"><sup>∘</sup></span>C; at the remaining dams we observed changes in the maximum daily temperature of <span class="inline-formula">−1</span> to 1 <span class="inline-formula"><sup>∘</sup></span>C. Across
sites, the mean downstream increase of the minimum daily temperature was
1 <span class="inline-formula"><sup>∘</sup></span>C, and for 85 % of the sites this increase was higher than
0.5 <span class="inline-formula"><sup>∘</sup></span>C.</p>
<p>We hierarchically clustered the sites based on three temperature anomaly
variables: upstream–downstream differences in (1) maximum daily temperature (<span class="inline-formula">Δ<i>T</i><sub>max</sub></span>), (2) minimum daily temperature (<span class="inline-formula">Δ<i>T</i><sub>min</sub></span>), and (3) daily temperature amplitude (<span class="inline-formula">Δ<i>T</i><sub>amp</sub></span>). The cluster analysis identified two main types of dam effects on thermal regime: (1) a downstream increase in <span class="inline-formula"><i>T</i><sub>min</sub></span> associated with <span class="inline-formula"><i>T</i><sub>max</sub></span> either unchanged or slightly reduced for impoundments of low volume (i.e., a residence time shorter than 0.7 d and a surface area less than 35 000 m<span class="inline-formula"><sup>2</sup></span>), and (2) a downstream increase of both <span class="inline-formula"><i>T</i><sub>min</sub></span> and <span class="inline-formula"><i>T</i><sub>max</sub></span> of the same order of magnitude for impoundments of larger volume (i.e., a residence time longer than 0.7 d and a surface area greater than 35 000 m<span class="inline-formula"><sup>2</sup></span>). These downstream temperature increases reached 2.4 <span class="inline-formula"><sup>∘</sup></span>C at certain structures with the potential to impair the structure of aquatic communities and the functioning of the aquatic ecosystem.</p>
<p>Overall, we show that small dams can meaningfully alter the thermal regimes
of flowing waters, and that these that these effects can be explained with
sufficient accuracy (<span class="inline-formula"><i>R</i><sup>2</sup>=0.7</span>) using two simple measurements of small
dam physical attributes. This finding may have importance for modelers and
managers who desire to understand and restore the fragmented thermalscapes
of river networks.</p> |
| first_indexed | 2024-04-12T08:19:37Z |
| format | Article |
| id | doaj.art-306f0527c5f54f6586e4685c439105da |
| institution | Directory Open Access Journal |
| issn | 1027-5606 1607-7938 |
| language | English |
| last_indexed | 2024-04-12T08:19:37Z |
| publishDate | 2019-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Hydrology and Earth System Sciences |
| spelling | doaj.art-306f0527c5f54f6586e4685c439105da2022-12-22T03:40:38ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382019-11-01234509452510.5194/hess-23-4509-2019Small dams alter thermal regimes of downstream waterA. Chandesris0K. Van Looy1J. S. Diamond2J. S. Diamond3Y. Souchon4River Hydro-Ecology Lab, National Research Institute of Science and Technology for Environment and Agriculture, UR Riverly, Lyon, FranceOVAM, Stationsstraat 110, 2800 Mechelen, BelgiumRiver Hydro-Ecology Lab, National Research Institute of Science and Technology for Environment and Agriculture, UR Riverly, Lyon, FranceUniversité de Tours, E.A 6293 GéoHydrosytèmes COntinentaux, Parc de Grandmont, 37200 Tours, FranceRiver Hydro-Ecology Lab, National Research Institute of Science and Technology for Environment and Agriculture, UR Riverly, Lyon, France<p>The purpose of this study was to quantify the downstream impacts of different types of small dams on summer water temperature in lowland streams. We examined (1) temperature regimes upstream and downstream of dams with different structural characteristics, (2) relationships between stream temperature anomalies and climatic variables, watershed area, dam height, impoundment length and surface area, and residence time, (3) the most significant variables explaining the different thermal behaviors, and (4) the dam thermal effect considering a biological threshold of 22 <span class="inline-formula"><sup>∘</sup></span>C, with a calculation of both the number of days with a temperature above this threshold and the average hourly duration above this threshold.</p> <p>Water temperature loggers were installed upstream and downstream of 11 dams in the Bresse region (France) and monitored at 30 min intervals during summer (June to September) over the 2009–2016 period, resulting in 13 paired water temperature time series (two sites were monitored for two summers, allowing the opportunity to compare cold and hot summers).</p> <p>At 23 % of the dams, we observed increased downstream maximum daily temperatures of more than 1 <span class="inline-formula"><sup>∘</sup></span>C; at the remaining dams we observed changes in the maximum daily temperature of <span class="inline-formula">−1</span> to 1 <span class="inline-formula"><sup>∘</sup></span>C. Across sites, the mean downstream increase of the minimum daily temperature was 1 <span class="inline-formula"><sup>∘</sup></span>C, and for 85 % of the sites this increase was higher than 0.5 <span class="inline-formula"><sup>∘</sup></span>C.</p> <p>We hierarchically clustered the sites based on three temperature anomaly variables: upstream–downstream differences in (1) maximum daily temperature (<span class="inline-formula">Δ<i>T</i><sub>max</sub></span>), (2) minimum daily temperature (<span class="inline-formula">Δ<i>T</i><sub>min</sub></span>), and (3) daily temperature amplitude (<span class="inline-formula">Δ<i>T</i><sub>amp</sub></span>). The cluster analysis identified two main types of dam effects on thermal regime: (1) a downstream increase in <span class="inline-formula"><i>T</i><sub>min</sub></span> associated with <span class="inline-formula"><i>T</i><sub>max</sub></span> either unchanged or slightly reduced for impoundments of low volume (i.e., a residence time shorter than 0.7 d and a surface area less than 35 000 m<span class="inline-formula"><sup>2</sup></span>), and (2) a downstream increase of both <span class="inline-formula"><i>T</i><sub>min</sub></span> and <span class="inline-formula"><i>T</i><sub>max</sub></span> of the same order of magnitude for impoundments of larger volume (i.e., a residence time longer than 0.7 d and a surface area greater than 35 000 m<span class="inline-formula"><sup>2</sup></span>). These downstream temperature increases reached 2.4 <span class="inline-formula"><sup>∘</sup></span>C at certain structures with the potential to impair the structure of aquatic communities and the functioning of the aquatic ecosystem.</p> <p>Overall, we show that small dams can meaningfully alter the thermal regimes of flowing waters, and that these that these effects can be explained with sufficient accuracy (<span class="inline-formula"><i>R</i><sup>2</sup>=0.7</span>) using two simple measurements of small dam physical attributes. This finding may have importance for modelers and managers who desire to understand and restore the fragmented thermalscapes of river networks.</p>https://www.hydrol-earth-syst-sci.net/23/4509/2019/hess-23-4509-2019.pdf |
| spellingShingle | A. Chandesris K. Van Looy J. S. Diamond J. S. Diamond Y. Souchon Small dams alter thermal regimes of downstream water Hydrology and Earth System Sciences |
| title | Small dams alter thermal regimes of downstream water |
| title_full | Small dams alter thermal regimes of downstream water |
| title_fullStr | Small dams alter thermal regimes of downstream water |
| title_full_unstemmed | Small dams alter thermal regimes of downstream water |
| title_short | Small dams alter thermal regimes of downstream water |
| title_sort | small dams alter thermal regimes of downstream water |
| url | https://www.hydrol-earth-syst-sci.net/23/4509/2019/hess-23-4509-2019.pdf |
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