Rapel River Basin, central Chile

Water Infrastructure

The Rapel Basin’s infrastructure features reservoirs, lakes, and hydropower dams such as the Convento Viejo and the Rapel Dam. The Rapel Dam creates the largest reservoir in the northwest of the basin with 695 Mm3. All other reservoirs in the basin are used for irrigation purposes, including the Convento Viejo reservoirs I + II and the Los Cristales Lagoon (Rojas et al., 2020; Cornwell et al., 2020).

Furthermore, the Rapel basin features an extensive irrigation system. However, the irrigation efficiency of the region is considered low with 54% due to the dominance of surface irrigation (INE, 2007).

Figure 8: Water infrastructure in the Rapel Basin (IDE Chile 2020).

Water Use

Water resources per capita were around 6.829 m³/inhabitant/year in the VI region in 2009 (MOP) but do not reflect water availability during drought conditions. In the past, water availability occasionally presented a problem. Water deficits in the Central Valley cause water use and availability restrictions (Novoa et al. 2019; Pena, 2021).

Water demands are mainly driven by agriculture, with a share of 93% of the total water demand in the basin, followed by mining (5%) and domestic water use (1%). The industry and energy sectors accounted for less than 1% of the water demand in 2015. However, irrigation efficiency is considered low at 65.5% due to the dominance of surface irrigation (INE, 2007). The intensification of agricultural activities is projected to increase water demands.

References

Cornwell, E.; Sposito, V.; Faggian, R. (2020): Land suitability projections for traditional sub- alpine cropping in the Australian Alps and Chilean Dry Andes. A combined biophysical and irrigation potential perspective. In: Applied Geography, Vol. 121(102248), pp. 3-18, doi: 10.1016/j.apgeog.2020.102248.

IDE CHILE (2020): Water Bodies. [Shapefile]. Available at: http://www.geoportal.cl/geoportal/catalog/main/home.page [accessed 26.07.2021].

INE (2007): ‘Censo Agropecuario 2007’. Available at: https://www.ine.cl/censoagropecuario [Accessed 27.06.2021].

Novoa V.; Ahumada-Rudolph, R.; Rojas, O.; Sáez, K., Barrera, F.; Arumí, J.L. (2019): Understanding agricultural water footprint variability to improve water management in Chile. In: Science of the Total Environment, Vol. 670 (2019), pp. 188–199, doi: https://doi.org/10.1016/j.scitotenv.2019.03.127

Pena, H. (2021): River Basin Policy and Management. In: Fernández, B.; Gironás, J. (eds.): Water Resources of Chile, Vol. 8, pp. 229-242.

Rojas, R.; Bennison, G.; Gálvez, V.; Claro, E.; Castelblanco, G. (2020): Advancing Collaborative Water Governance: Unravelling Stakeholders’ Relationships and Influences in Contentious River Basins. In: Water, Vol.12(2020), pp. 1-25,doi:10.3390/w12123316