Adaptations of increased water demand: hydropower projects in the framework of climate change

Decreasing water supply: accelerated glacier retreat

PRESENT AND FUTURE WATER RESOURCES SUPPLY AND DEMAND IN THE CENTRAL ANDESA COMPREHENSIVE REVIEW WITH FOCUS ON THE CORDILLERA VILCANOTA, SOUTHERN PERU

Glaciers have always been an important element of Andean societies and livelihoods as direct freshwater supply for agriculture irrigation,hydropower generation and mining activities. Peru’s mainly remotely living population in the Central Andes has to cope with a strongseasonal variation of precipitation and river runoff interannually superimposed by ENSO impacts. Direct glacier and lake water dischargethus constitute a vital continuous water supply and represent a regulating buffer as far as hydrological variability is concerned. Thiscrucial buffer effect is gradually altered by accelerated glacier retreat which leads most likely to an increase of annual river runoffvariability. Furthermore, a near-future crossing of the ‘peak water’ is expected, from where on prior enhanced streamflow decreases andlevels out towards a new still unknown minimum discharge. Consequently, a sustainable future water supply especially during low-levelrunoff dry season might not be guaranteed whereas Peru’s water demand increases significantly.

Here we present a comprehensive review, the current conditions and perspectives for water resources in the Cusco area with focus onthe Vilcanota river, Cordillera Vilcanota, Southern Peru (for location details see Figure 1).

Introduction

These findings have strong implications for the still at 0.9% (2.2%)annually growing population of the Cusco department (Cuscocity). People mostly depend on these water resources but indicatea strong water vulnerability due to a remaining high degree ofabsolute poverty, 30% and an improved but still inadequate accessto drinking water accounting for 84% of the population in 2012(INEI, 2008; 2013).

The Vilcanota area has been traditionally the breadbasket for thewhole Cusco area. While agriculture is the most important socio-economy sector, a growing export-oriented crop productiondepends highly on a minimum river streamflow ensuring sufficientwater quantity and quality. Hydropower, with 53% of the totalelectricity nationwide the energy pillar of Peru’s economy, mightalso be heavily affected by diminishing water resources.Nevertheless, improved power plants have to balance out Peru’s by7.5%/year increasing energy demand (MINEM, 2013). For instance,the Santa Teresa I hydropower plant will start operations this yearbut requires a year-round minimum river discharge of 61 m³/s at fullcapacity of 98 MW. Furthermore, plans exist to expand theupstream Machu Picchu hydropower plant to a total of 190 MWand to construct Santa Teresa II until 2020 with a river runoff of 105m³/s at full capacity of 268 MW (see Figures 1-3). These efforts donot consider future water availability of the Vilcanota river and theneed for new reservoirs as well as local impacts for theagriculturally dependent communities.

Figure 1: Overview of the Vilcanota basin and river with its main features in Peru (red rectangle defines dimensions of upper right detailed map). The table indicatesthe characteristics of the most important installed and projected hydropower plants in the Vilcanota area.

Sources used: SRTM v.3 USGS; MINAM geoserver; personal communications of EGEMSA and Luz del Sur, 2014

Increasing water demand: population growth

References:

Andres, N., Vegas, F., Lavado, W. & M. Zappa (2013): Water resources andclimate change impact modelling on a daily time scale in the PeruvianAndes. - Accepted manuscript, Hydrological Sciences Journal.

Baraer, M., Mark, B. G., McKenzie, J. M., Condom, T., Bury, J., Huh, K.-I.,Portocarrero, C., Gómez, J. & S. Rathay (2012): Glacier recession and waterresources in Peru’s Cordillera Blanca. – Journal of Glaciology, 58 (207), pp.134-150, Cambridge.

Hanshaw, M. N. & B. Bookhagen (2014): Glacial areas, lake areas, andsnowlines from 1975 to 2012: status of the Cordillera Vilcanota, includingthe Quelccaya Ice Cap, northern central Andes, Peru. - The Cryosphere, 8,pp. 359-376, EGU.

Huggel, C., Haeberli, W., Kääb, A., Hoelzle, M., Ayros, E. & C. Portocarrero(2002): Assessment of glacier hazards and glacier runoff for differentclimate scenarios based on remote sensing data: a case study for ahydropower plant in the Peruvian Andes. – Proceedings EARSeL Workshop,Observing our cryosphere from space, Vol. 11 (13.3), Bern, Switzerland.

INEI 2008: Censos Nacionales 2007: XI de Población y VI de Vivienda. PerfilSociodemográfico del Perú. – Instituto Nacional de Estadística e Informática,2a ed., 474 pp., Lima.

INEI (2013): Evolución de la pobreza monetaria 2007-2012. – Informetécnico, Instituto Nacional de Estadística e Informática, 2a ed., 474 pp., Lima.

MINEM (2013): Avance estadístico del subsector eléctrico: Cifras en octubre2013. – Ministry of Energy and Mining, Peru.

Salzmann, N., Huggel, C., Rohrer, M., Silverio, W., Mark, B. G., Burns, P. & C.Portocarrero (2013): Glacier changes and climate trends derived frommultiple sources in the data scarce Cordillera Vilcanota region, southernPeruvian Andes. – The Cryosphere, 7, pp. 103-118, EGU.

Contact

Fabian Drenkhan: fabian.drenkhan@geo.uzh.ch

With 279 km2 the Cordillera Vilcanota represents the secondlargest glacierized mountain range of the tropics worldwide.Especially as of the second half of the 1980s, it has been stronglyaffected by massive ice loss with around 30% glacier area declineuntil present (Salzmann et al., 2013). Furthermore, glaciervanishing triggers the formation of new lakes and increase of lakelevels and therefore constitutes determining hazardous drivers formass movements related to deglaciation effects (Huggel et al.,2002; Hanshaw & Bookhagen, 2014).

The Vilcanota basin (see Figure 1) still lacks more profoundclimate-related hydrological studies. The upper basin receives anaverage precipitation of about 780 mm/year characterized by highseasonality. Consequently, river flow has a high-level runoff in thewet season (February: ~330 m³/s) and low-level runoff in the dryseason (August: ~40 m³/s) with high interannual variability (Andreset al., 2013). Changes in long-term precipitation patterns andimpacts of ENSO (teleconnections) are still not well understood(Salzmann et al., 2013). It is likely that the Vilcanota river willtranscend its peak water in near-future or might already havecrossed it, as a first study corroborates for the highly glacierizedSanta river basin in the Central Andes (Baraer et al., 2012). Morestudies incorporating bias-corrected satellite data are imperativein a remote and poorly gauged area.

Conclusions

Our conclusions suggest to focus on an integrative risk-oriented supply-demand water balance model scheme inorder to capture the complexity of recent and future waterdistribution. The integration of both physical and social keyvariables considering long-term changes in climate-glacierinteractions as well as economic and demographic trends,plays a determinant role for the performance quality of thatmodel and future adaptation strategies.

Acknowledgements

This study is part of the “Proyecto Glaciares 513” funded bythe Swiss Agency for Development and Cooperation (SDC).

Fabian Drenkhan1, Christian Huggel1, Nadine Salzmann1, Claudia Giráldez 1, Wilson Suarez2, Mario Rohrer3, Edwin Molina4, Nilton Montoya5 & Fiorella Miñan6

1Geography Department, University of Zurich, Switzerland 2National Service of Meteorology and Hydrology of Peru, Senamhi, Lima, Peru 3Meteodat GmbH, Zurich, Switzerland 4Department of Geography, National University of San Antonio Abad at Cusco, Cusco, Peru 5Department of Agriculture, National University of San Antonio Abad at Cusco, Cusco, Peru 6CARE Perú, Lima, Peru

Figure 2: Construction site of the principaldownward tunnel (187 m water fall) of SantaTeresa I hydropower plant. Machine house andtailrace lie within a cavern. Photo was taken onJanuary, 2014.

Figure 3: Santa Teresa site of Luz del Sur.Figure 2

Figure 3

Hydropower station

(C. H.)Turbine Total capacity (MW)

Required

discharge

(m³/s)

Status Operator

Santa Teresa I

Francis

(2 de 49 MW) 98 61

In operation as of

June-July 2014 Luz del Sur

Santa Teresa IIFrancis

(2 de 137 MW) 268 105

Planned

Operation projected

as of 2020Luz del Sur

Machu Picchu IPelton

(3 de 30 MW) 90 31In operation (since

July, 13th 2001) EGEMSA

Machu Picchu IIFrancis

(1 de 101 MW) 101 31Planned

EGEMSA