Programme  OS1n Water quality 2  abstract 723

Monitoring to Support Water Quality Management in North-Central Chile

Author(s): Lars Ribbe, Mesenia Atenas, Francisco Meza, Nicole Kretschmer, Ricardo Oyarzún, Eduardo Salgado
• Lars Ribbe, Institute for Technology in the Tropics (ITT), Cologne University of Applied Sciences, Germany • Mesenia Atenas, Dirección General de Aguas (DGA) Head of Section on Water Quality, Chile • Francisco Meza, Instituto Nacional de Investigacio

Keyword(s): Water quality monitoring, decision making, watershed management, Chile, semi-arid environment, Norma secundaria,

Article: abs723_article.pdf
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Session: OS1n Water quality 2
AbstractWater quality management requires

scientifically sound data as a base for the decision making process. This data should be provided by suitable

monitoring systems. In Chile, like in other countries, information requirements with regard to water quality are

determined by the national water policy and legislation.
In addition, monitoring system design needs to take into

consideration the variability of the natural processes as well as pressures exerted to the systems by human activities,

including pollution sources, water abstractions and climate change. At the end, social and political aspects determine

how important water quality monitoring is for the country or region and economic factors will determine which

monitoring intensity is feasible. However, a sound scientific knowledge can help to allocate resources for monitoring

in the most efficient way.

The objectives of the presented contribution are to scrutinize recent water quality

legislation in Chile regarding information demands and to analyse spatial and temporal variability of key water quality

constituents in five river basins in North-Central Chile for the 26-33 ºS realm (Aconcagua, Ligua, Huasco, Limari,

Choapa) based on existing water quality related data through GIS and statistical analysis. This analysis lays down the

basis for suggestions on an improved monitoring system in these watersheds.

The water quality legislation is

analysed according to the stipulated quantitative information requirements regarding water quality constituents. These

requirements belong to the fields of impact, compliance, and trend monitoring, each type having different demands

according to the statistical design. The five watersheds, which differ in size, climate, land use, and development

status, are analysed according to their topography, surface water networks, water flows, point and diffuse sources of

pollution, and land use.

The spatio-temporal analysis on a watershed basis illustrates that in some cases spatial

correlation allows the exclusion of several existing monitoring sites, whereas in other cases the high temporal

variability of parameters asks for higher measuring frequency than the actual (four times a year) in order to satisfy

statistical needs and to support an effective decision-making process. To provide an example the case of nitrate in

the Aconcagua watershed is elaborated in more detail. Modelling results show that spatio-temporal variability asks

for a redesign in terms of monitoring site location and frequency, supporting an optimized allocation of financial

means to satisfy the requirements of the secondary water quality norm. At the same time the study reveals the

existing knowledge gaps regarding the behaviour of constituents within the watershed systems, which inhibits an

improved monitoring design.

Subsequently, concrete suggestions for a future research programme are

elaborated in order to fill the data gaps. In particular it seems necessary to study the behaviour of pollutants like

heavy metals and nutrients at a sub-watershed level.

Finally, some qualitative statements are presented

regarding a possible impact of climate change on water quality issues. Here, special reference is made to the design

of trend monitoring networks in the watersheds under scrutiny.

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