Solving water problems or creating a new one? Alternative water sources (desalination/reclaimed water)
The gap between water availability and demand (mainly due to increasing pressures and climate change impacts) requires the exploitation of non-conventional water resources to cover freshwater and (high) irrigation demands. Desalination and wastewater reuse are increasingly being put forward as sustainable local solutions to water scarcity. However, it is not entirely certain whether these two alternative water sources (AWS) are viable innovations for solving the problem of irrigation at a local/regional level.
We wanted to learn what are the technological, environmental and social challenges/keystones for a successful EU reuse water strategy for food. We realized we had to choose where to analyze the use of AWS for irrigation and that is why we proposed the islands of Gran Canaria and Tenerife (Canary Islands- Spain) as our case studies, since both cases are in areas where desalted and reclaimed water are used for agricultural purposes (either for individual uses; joined or mixed with natural waters).
During the first phase, a systematic review of the use of alternative water sources for irrigation has been conducted. The second phase is conducting Quantitative Story-Telling to anticipate the role that desalination and treated wastewater reuse can play in the metabolic pattern of European regions with water scarcity.
Several questions will be answered for this innovation. For example:
- What are the implications for the WEF Nexus the use of non-conventional water? How does it affect food sovereignty? Does alternative water have a high cost?
- What is the validity of the narrative in this innovation vis-à-vis societal expectations and insights?
- Are there any alternatives to this type of innovation?
One of the objectives of this study is to determine the typologies of agricultural holdings in both study areas, allowing their classification into units of agricultural production, with the aim of obtaining more adequate analysis of the farm structures, the diversity of agricultural production and the sustainability (water-energy) of the activity in the chosen areas.
The following map shows the agricultural crops found in the studied area of Gran Canaria:
Figure 1: Agricultural Crops in the South-east of Gran Canaria
Another research question is to find the typology of water resources used to irrigate the farms of both islands (Tenerife and Gran Canaria). For Gran Canaria, we have found the following water resources:
Figure 2: Typology of water resources used in farms in Southeast of Gran Canaria.
In the south-east of this island, there is a network of irrigation with reclaimed water that is at an approximate height of 200 meters above sea level (as can be seen in the second map). The third map shows a selection of the studied agricultural holdings, which are downstream the main irrigation network.
Figure 3: Reuse water for irrigation, pipping system.
Figure 4: Crops downstream the irrigation network.
For the case of Tenerife, a similar strategy has been followed. The relevant environmental and socio-economic components have already been distinguished. To contextualize this, the technical elements of the water used for irrigating the crops in each of the analyzed agricultural holdings and the perception that the stakeholders have with its use are being contrasted. For example, it is evident that water conductivity is a crucial parameter to assess the water quality. Several crops require higher or lower conductivities to grow adequately. This has an effect on the choice of water used to irrigate the agricultural crops. If the available water has a different conductivity than the needed, the farmer will not be satisfied and will be willing to change its water source.
The idea is to establish a bridge across the information that has been collected these past months, to understand the relation that the studied system has in biophysical and socio-economic terms. That way, we will find out the environmental pressures and impacts from the use of alternative water sources. Here, you can see some of the water resources captured during the participatory process carried out in Tenerife:
Figure 5: Irrigation system in one of the studied agricultural fields in Valle Guerra (Tenerife).
Figure 6: Valle Guerra wastewater treatment plant that provides water in the studied area of Tenerife (CIATF).
Tools / Methodology
A variety of information inputs have been developed to engage stakeholders from both islands. During these past months, the chosen stakeholders (regional Governments, local exploitation water companies, farmers, …) have become part of a participatory process in which they have had several interviews. Since April, the tool ODK Collect (Open Data Kit) has been used to collect data from agricultural farms (through agricultural surveys), for the case studies, linked to NIS application and that will allow the processing of information and analysis with MuSIASEM and its multi-level statistical analysis. The ODK community produces a free and open source software to collect, manage and use data in regions with limited resources. In a few months, there will be an engagement event in which the stakeholders will provide feedbacks and that way, we will be able to fulfill a quantitative research of the real use of alternative water resources for agriculture in the Canary Islands.
If you stay with us in the coming months, you will be able to find out the answers to all these intriguing research questions related with water issues. You will definitely feel refreshed with the results!