Research ArticleAPPLIED ECOLOGY

Fragmentation of Andes-to-Amazon connectivity by hydropower dams

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Science Advances  31 Jan 2018:
Vol. 4, no. 1, eaao1642
DOI: 10.1126/sciadv.aao1642
  • Fig. 1 Dams existing or under construction (red) and proposed (yellow) in Andean Amazon river basins.

    Estimated fish species richness for each basin is depicted by the fish symbol; fish data were provided by the Amazon Fish Project (4).

  • Fig. 2 Fragmentation of Andes-to-Amazon connectivity by hydropower dams.

    (A) Freshwater ecoregions of the Andean Amazon (20), where most existing and proposed dams are concentrated in the Amazonas High Andes ecoregion. (B and C) Fragmentation for individual sub-basins under two scenarios: (B) dams existing and under construction and (C) all dams existing, under construction, and proposed. Color gradation from blue to red denotes increasing fragmentation, represented by decreasing total length of the individual river network. That is, fragmentation is increasing as rivers go from blue (big, connected river networks) to red (small, isolated river networks).

  • Table 1 Existing and proposed dams on Andean-origin rivers in the Amazon basin, classified according to major basin, country, size (installed generation capacity, based on available data), and freshwater ecoregion (20).
    Existing/
    in construction
    Proposed
    NumberTotal MW
    (≥)
    NumberTotal
    MW
    Basin
      Caquetá001687
      Putumayo0000
      Napo91669222949
      Marañón3627238225,785
      Ucayali6718733711,852
      Madre de Dios*25965118595
      Beni2062535000
      Mamoré527963871
      Madeira3276931815,466
    Country
      Colombia001687
      Ecuador3137666410,710
      Peru8628388432,482
      Bolivia259031112,861
      Brazil26450
    Size (MW)
      No data510
      1–103720721111
      11–100351268572608
      101–10001734576725,801
      1001–4500490251528,219
    Ecoregion
      Amazonas High Andes141750212323,325
      Western Amazon Piedmont161612,487
      Ucayali-Urubamba Piedmont00107271
      Mamoré-Madre de Dios
    Piedmont
    0098507
      Others2645023150

    *The Madre de Dios estimates include the Beni River basin.

    †The Madeira estimates include the Madre de Dios, Beni, and Mamoré river basins.

    ‡The Brazil estimate includes only the Santo Antônio and Jirau dams.

    • Table 2 Fragmentation of the Andean tributaries of the Amazon by existing and proposed hydropower dams.

      River network length and longest continuous river reach (km) are based on river lengths in HydroSHEDS (48). For fragmentation metrics, the Mainstem and Tributary Connectivity scores follow the approach of Dynesius and Nilsson (54). The DCI follows Cote et al. (16) and Grill et al. (17), where 100 equals full connectivity.

      BasinRiver
      network
      length (km)
      Longest continuous
      mainstem river
      reach (km)
      Longest reach
      (km)—existing
      dams
      Longest reach (km)
      —existing and
      proposed dams
      Mainstem
      connectivity—
      existing dams
      Mainstem
      connectivity
      —existing and
      proposed dams
      DCI—
      existing
      dams
      DCI—existing
      and proposed
      dams
      Caquetá46,871221622162216100.0%100.0%10099.60
      Putumayo21,165195219521952100.0%100.0%100100
      Napo17,99911081108981100.0%88.5%92.6382.01
      Marañón61,61916561551113593.7%68.5%82.4028.17
      Ucayali59,74724632376187996.5%76.3%79.6832.65
      Madre de
      Dios
      48,324141714171346100.0%95.0%97.0953.49
      Beni20,10312601260767100.0%60.9%97.1839.13
      Mamoré42,010204820481427100.0%69.7%99.5661.16
    • Table 3 Breakdown of hydropower development and estimated fish species richness by elevation range.

      Data on fish species are provided by the Amazon Fish Project (4).

      Elevation range (masl)Existing dams/under constructionProposed damsEstimated number of fish species
      >400052165
      3000–4000231035
      2000–3000292469
      1000–20003057257
      500–1000741602
      <5003271549

    Supplementary Materials

    • Supplementary Materials

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      • table S1. Hydropower dams existing, under construction, or proposed in Andean Amazon river basins.

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