Snow Effects on Water Availability

The Guadalfeo River Basin is a mountainous coastal watershed in southern Spain, highly influenced by the snow regime, and vulnerable to future climate variability.

Water users and managers benefit from the easy capability of quantifying future impacts on water availability based on provided climate impact indicators, and needs for actions/decisions.

The C3S climate impact indicators provide an open framework to obtain assessment of the seasonality expected shifts in the river flow regime, and in the long term.

Read Full Technical Report here!


Almond trees in the Guadelfeo River Basin, Spain

Case Study Description
Data Description
Reference information

Water-management issue to be addressed

The Guadalfeo River Basin hydrology shifts from a snow-dominated regime in the North to a warm coastal regime in the South, in a 40-km distance. The climate variability adds complexity to this heterogeneous area. The uncertainty of snow occurrence and persistence for the next decades poses a challenge for the current and future water resource uses in the area. Adaptation plans will benefit from the predictability of water resource availability and regime. The development of easy-to-use climate indicators and derived decision-making variables is key to assess and face the economic impact of the potential changes.

Decision support to client

Results will assess the prevision of water allocation success on an annual and decadal basis in the new planning hydrological cycle, and they have provided a deeper insight on the seasonal future potential regime. Moreover, they are a basis to test the operational rules of the reservoir and the prioriy of use criteria. Regarding the hydropower generation, besides the evaluation of the potential future efficiency and provisions under the expected shift of the snow regime, further assessment on the minimum environmental flows and their impact on the activity is being assessed. Additional concern about the need of an adequate inflow measurement has been achieved and some actions to improve the gauging system are under work at present.

Using the SWICCA indicators has made it possible to quantify in a complex region the extent to which the likely impacts of climate on snow will affect the current water allocation scenario, and to identify the most vulnerable water uses in the area. This helps to foresee and anticipate close in time conflicts of water users, and it will be key in the adaptation assessment under course at the moment.

Temporal and spatial Scale

Each client demanded a different time scale to meet requirements. We used daily scales for river flow indicators at catchment scale in SWICCA, and then aggregated to the desired final scales (monthly, annual or daily). The final local CIIs tailored for each client were obtained on significant control points, relevant for each water issue. Additionally, CIIs related to the energy balance (Snow Water Equivalent and Evapo-Transpiration) were provided on a mean monthly basis, averaged over the catchment area to assess long term changes.

Knowledge Brokering

UCO has had a fluid contact and interaction with the appointed clients in this study case, especially with the water authorities in the river basin both on the regional government and local managers. This propitiated the inclusion of this study case in SWICCA. Initial meetings took place during the preparation of the proposal. Once the project began, e-mail and phone call have been the usual means of interaction during the first stage of the project.

A second stage began after the summer, once the fundamental set of CIIs were already available at different spatial and time scales in the SWICCA Demonstrator. A row of meetings with the three clients in the study case, the Water Office in the Granada headquarters, the Mancomunidad of Municipios de la Costa Tropical in Motril (Granada coast), and the Central South Office of Endesa Generación in Córdoba took place to show them the current version of the SWICCA Demonstrator and check with them what kind of specific information, and the significant scales, could be relevant for their operation on a medium and long term. During this year, contact has been programmed on a 2-months basis, but flexible interaction was developed as the work progressed on. The final period is fully dedicated to assess steps 5 and 6 with the clients.

During this process, two main lessons were learnt by us, as knowledge providers. First, it is key to select and clearly focus both the objective and the type of information to first address climate issues with the clients, not only avoiding too complex and unnecessary issues to transfer but also being capable of listening carefully to their initial questions. This let us on one hand identify their key concerns and needs, but on the other hand provided us with the chance to also identify gaps in their initial questions, and present other views to them not that relevant so far.

Secondly, the clients need to trust the information provided by models before starting to use the indicators we provided them with, and for this it is key to provide them with sound and reliable data regarding not only the results themselves but also their estimated uncertainty.

Climate Impact Indicators

Pan-European Indicators

  • Precipitation (seasonality, 0.5 degree grid and catchment scale)
  • River flow (seasonality, 0.5 degree grid and catchment scale)
  • Snow water equivalent (seasonality, 0.5 degree grid and catchment scale)
  • Wetness 1 (catchment)
  • Wetness 2 (catchment)

Essential Climate Variables (ECVs) time series used:

  • Precipitation (catchments), daily values
  • River flow (catchments), daily values
Local indicators

The final result of this second stage will be a definite final set of local indicators; some of them have been already proposed from the results reached so far. Further analysis about their usefulness and performance is still needed.

Pan-European data to local scale

Read Full Technical Report here!

Lessons learnt

The most relevant lessons learnt are related to the scale effects arising when carrying out this kind of analyses; this applies to steps 1 to 3, and 4 of the workflow. The inclusion of indicators on a catchment scale has been important in the process. Particularly, in mountainous regions this poses a big constraint for a successful implementation of Pan-European data, due to the relevance of the spatial scale issues associated with topography and the snow presence. The existence and accessibility to hydrological tools already validated on a local basis has been crucial to downscale and achieve the current results and prove their usefulness.

Moreover, we succeeded in identifying the time scales on which the best performance of Pan-European models in this Mediterranean area was found for key variables as SWE and ET, and river flow, from direct use of their results. This was not expected for some of these variables and allows a more efficient running of local models for future projections.

Importance and Relevance of Adaptation

This region development and economy is highly dependent on the snow regulation of river flows. The impact of the future climate on this water reservoir is expected to produce at least significant changes in the seasonal availability of river flow, and then impacts on the water supply and energy production systems.

Knowledge about changes in this seasonal regime allows the provision of adaptation strategies for more than only adapting water planning rules. For instance,

“the information [provided] will assess our position regarding building or restoring hydraulic structures; if the low-flows season expands and water availability during the  summer season is menaced, we will have to explore new alternatives such as desalination, or limiting irrigation areas by means of soil use planning in the future decades”.

The inclusion of three clients as reference users provide a sound basis to design an integrated river basin management tool, which will further facilitate the development of adaptation strategies.

Pros and Cons or Cost-Benefit analysis of climate adaptation

Water management in Spain, and particularly in Andalusia, is dependent on the operation of reservoir networks and other hydraulic structures, which makes these regions less vulnerable to droughts and floods. However, most of them were designed and built during the second half of the past century; the design values for flow and weather extremes have significantly changed both up- and downstream in the reservoirs. Climate adaptation is essential to revise the current scheme, the operational rules, and the water allocation priorities and time distribution. The economic gain from implementing climate adaptation actions arises from the prevention of structure damage, operational failure in demands’ guarantee, and the consciousness itself of these effects, which makes end-users more apron to protect their economical activity (insurance) and shift slowly to sustainable working conditions, minimizing risks.

The most valued aspects by the clients so far are the possibility to have access to local indicators shaped for their specific conditions and much more feasible to use than global climate indicators. The SWICCA goals bridge this gap between the huge amount of global information generated nowadays and the potentially interested users’ capability of exploiting it. Moreover, the downscaling process is not an accessible task for most of these users; the provision of locally validated information is highly valued by them when using precise data for decision making.

An additional benefit is the possibility of consulting any location in the European space. Even at this scale, the advantages of downloading and viewing data from one-click with sound explanation associated are clearly identified by purveyors and clients. Moreover, the catalogue of SWICCA CIIs is wide enough to attract many clients, and even raise interest on additional issues. For instance, one of the clients showed interest on knowing “whether water quality indicators in SWICCA could estimate potential shift in their supply conditions”, despite this not being their main interest initially.

On the other hand, this easy access might lead to misuse of the data if the downscaling process is not appropriately performed. There are certain conditions and regions in which this is key to guarantee reliable final data. For some potential clients, a language different from their mother tongue is certainly a strong constraint for their access and use to the Demonstrator.

Policy aspects 

Besides the pilot Decision Support System for the Basin Authority that may arise from the integrated river basin management tool, the knowledge about the available amount of water resources for allocation among existing users is the basis for the River Basin Management Plans, which have been just revised in 2015.

At the present stage, the results have been yet used to develop new policies or decisions by the Water Authorities, but they will be included as basis information in the new revisions. Moreover, as they are being provided to the clients, they are increasing their awareness of their usefulness and ask about further capabilities. The hydropower generation company has decided to build a new gauging system towards a more efficient monitoring of the river flow, and they have got involved in new projects regarding the use of CIIs in their managerial and decision making everyday.

The reliability of the local indicators derived from the SWICCA-CIIs is key to obtain successful results and supported by their acceptance by the users’ community.


University of Cordoba

Research Group- Fluvial Dynamics and Hydrology
Andalusian Institute for Earth System Research
Campus de Rabanales-Hydraulic Engineering
Edificio Leonardo da Vinci, planta baja
14014 Cordoba, Spain

Telephone: (+34) 957 21 26 62

Prof. Dr. María J. Polo


Relevant EU policy 

University of cordoba

Purveyor: Prof. Dr. María J. Polo
email: mjpolo‹at›

Value added by Copernicus Climate Change Service: 

Tropical Coast of Granada

Tropical Coast of Granada, Municipalities Community, Spain

Endesa Hydropower Generation

Endesa Hydropower Generation, Andalusian Office

Andalusian Department of Enviroment

Andalusian Department of Enviroment, Mediterranean Area Office

Figure 2. Snow in the head areas of the watershed
Snow in the head areas of the watershed

Figure 1. The Guadalfeo River Basin in Spain (altitudes expressed as m.a.s.l.)

The Guadalfeo River Basin in Spain (altitudes expressed as m.a.s.l.)

Figure 6. Tropical crops in the basin

Tropical crops in the Guadelfeo River  basin

Figure 4. The Béznar reservoir systems

The Béznar reservoir systems

Figure 3. The Rules reservoir systems

The Rules reservoir systems