Rapel River Basin (Chile)
Two larger rivers constitute the basins river network: The Cachapoal and Tinguiririca River (Cornwellet al., 2020). In addition, the Rapel river basin borders the Maipo Basin in the North and the Mataquito Basin in the South. The discharge regime of the river is mixed pluvial-nival. Average annual river discharges (1981–2010) are 89.0 m³/s for the Chapoal and 50.2 m³/s for the Tinguiririca (Rojas et al., 2020).
Surface Water Quality
The water quality is declining mainly due to the growth of domestic and industrial discharges and diffuse contamination by pesticides and fertilizers (DGA, 2004). According to the Ministerio Del Medio Ambiente (2017), the central valley of the basin has the lowest surface water quality condition compared to water coming from high mountains. The inputs of the primary pollutant’s activities are from Agriculture (Nitrogen, Clorotanil, and 2-4D), Livestock Production (BDO5, Nitrogen, Phosphorus), Food Industry (BDO5, TTS, Grass, and Oil), and Vineyards (BDO5, pH, Mn, and TTS)(MMA, 2017).
Central Chile has highly transmissive alluvial basins with good recharge conditions. However, due to the intensive use of groundwater, the DGA has restricted the water use for most of the aquifers in the Rapel basin.
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
Dirección General de Aguas (DGA) (2004): Diagnostico y clasificacion de los cursos y cuerpos de agua segun objetivos de calidad: Cuenca del Rio Rapel’.
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
Suárez, F.; Leray, S.; Sanzana, P. (2021): Groundwater Resources. In: Fernández, B.; Gironás, J. (eds.): Water Resources of Chile, Vol. 8, pp. 347-364.