The Segura River Basin is located in the Mediterranean south-eastern corner of the Iberian Peninsula. The basin has the lowest percentage of renewable water resources of Spain and is highly regulated. The main water demand comes from agriculture, covering more than 43% of the basin surface, of which one-third is brought under irrigation.
The agricultural water demand from irrigated areas accounts for 85 % of the total water demand. Two water transfers (principally from Upper Tagus Basin in Central Spain) and desalinisation plants are used to partly close the gap between demand and internal available water resources. The problems of water scarcity and droughts are persistent in the basin, affecting the economy of the region and generating conflicts.
The Mediterranean climate and technological development has enabled the agro-food industry in the basin to be highly competitive, modernised and an important source of employment. Export of food industry accounts for a significant share of Spanish agro exports to Europe.
For planning of water resources in relation to the agricultural sector, there are three pivotal stakeholders: (1) the water authority (Confederación Hidrográfica del Segura), (2) Regional agricultural council, and (3) Irrigators' associations. They have to deal with very high variability in available water resources and difficult predictability and planning several months ahead.
In relation to the urban water sector, there is Empresa Municipal de Abastecimiento y Saneamiento de Murcia, S.A. - Aguas de Murcia, which is the municipal company of the city of Murcia for the integrated water cycle (water treatment and management).
Thia case study tested together with end-users several climate services for better-informed water resources and planning, especially for agriculture and urban water supply. There was scope for improvements and better anticipation to drought events and their impacts by developing tools that forecast water quantities and quality based on the latest advances in climate modelling.
For agriculture, the case study developed a water resources accounting and allocation system that allows studying different water scarcity scenarios, climate change scenarios and adaptation measures. A seasonal forecasting system of available water resources for Upper Tagus and Upper Segura should give water resources and agricultural planners the necessary information to be prepared for drought conditions.
For urban water supply, a surface water quality prediction system for the principal Drinking Water Treatment Plant (DWTP) in the basin (La Contraparada) was developed to forecast the development of cyanobacteria communities in a reservoir upstream of the DWTP. This will enhance the operations and reduce water quality risks. Different treatment strategies were tested to solve the problems of eutrophication in the DWTP, driven by extreme weather conditions.
Tools and models
The main developments for this case study were:
- A decision support tool for water resources accounting and allocation that allows studying different water scarcity scenarios, climate change scenarios and adaptation measures, partly developed in IMPREX Work Package 4.
- A seasonal forecasting system of available water resources for Upper Tagus and Upper Segura that will give water resources planners a prediction of inflow into the main reservoirs several months ahead. Climate inputs into the tool will rely on developments in IMPREX Work Package 3.
- Seasonal forecasts of agricultural drought impacts were made based on climate variability indices and new concepts developed in IMPREX Work Package 5.
- A water quality forecasting system for urban water supply providing predictions on critical parameters several months ahead.
- Different treatments were tested in a pilot plant to improve the problems of eutrophication in the inlet water of the drinking water treatment plant (DWTP) La Contraparada (Murcia), owned by Aguas de Murcia.
The Water Authority of the Segura Basin (Confederación Hidrográfica del Segura – CHS) deals with most of the tasks related to water resources management in the basin. CHS is in charge of most of the water-related infrastructure, distribution of the water resources, including those received from the external inter-basin water transfers (Tagus and Negratín).
The planning department of CHS was a key end-user of the developments in IMPREX for the Segura case study. Before, they lacked a tool that provides predictions on the seasonal timescale, several months ahead.
There is a Drought Management Plan that stipulates a set of actions for drought mitigation depending on reservoir level-based drought indices. Seasonal forecasts of these indices are not considered to be relevant in the current management context. But, at the same time they note that their water users are increasingly demanding a seasonal outlook of water resources. Currently, these are done on rough assumptions but IMPREX presented an opportunity to evaluate the possibility of using climate and hydrological forecasts for this purpose. The CHS needed a simple indicator that quantifies how likely it is that over the next months whether the drought situation will improve or not, to some certain level.
Jesús García, Head Planning Department of Segura Water Authority (CHS):
Is the drought situation likely to improve or worsen over the next months? – That´s a question we are dealing with very often. IMPREX investigated how we can get a reliable answer using the latest advances in climate and hydrological modelling. We may then be able to better anticipate droughts.
Photos courtesy of Cetaqua and Future Water
The conditions the forecast saw as the most likely did not match the real-life situation. The perceived lack of accuracy may influence the adoption of the seasonal forecasts for mitigations action and drought management plan in the future.
Read more on this case study.
IMPREX will provide decision-makers tools to plan water resources several months ahead, for the climate of today and of the next decades