This case study is focused in the water exploitation system of Jucar River Basin that is placed in the east of Spain and flows into the Mediterranean Sea. This territory has always presented water scarcity problems related with prolonged drought episodes due to the high seasonality, which is typical of the Mediterranean climate.
It is for this reason that the Jucar River Basin District Agency (CHJ) is interested in the predictability of extreme events (droughts specifically) and their possible impacts for future periods, to anticipate specific management measures for droughts impacts on water users and suppliers.
In this system, water management is based on the reliability criterion for water allocation and reservation and on the Status Index (SI) used in the Special Drought Plan (SDP). Thus, climate services provided by SWICCA will allow us to communicate possible impacts of climate change in water resources to improve water management. The main message to keep in mind from our case study is: a modeling chain with climate change data could be the key of future water management in areas with water scarcity problems.
Case Study Description
This area has suffered several episodes of drought, in the last 30 years the most remarkable drought events were in 1992-1995, 2005-2008 and 2013-current periods. The importance of these events are the impacts to sectors such as agriculture, hydropower, urban, water quality, environment, etc that leads to huge economic losses for the administration as well as for the users. For that reason, each basin has its own Special Drought Plan (SDP) that is based on the State Index (SI), a system of indicators that relates the amount of water resources of the basin with the level of risk and the measures to be applied.
These dry periods are difficult to manage in adjusted systems. In addition, it seems that climate change will make the management harder due to the increase of temperature and the decrease of precipitation, based on many scientific papers. Thus, it will be a huge improvement to know in advance that a drought episode is coming and try to avoid the possible impacts to be more efficient in water management within these situations. That could be possible with climate change data provided by SWICCA project.
The analysis showed inconclusive results, but if they would be reliable at the end, it could be a good starting point in water management for future periods. The client (CHJ), who is a decision-maker, could base its decisions on these results, which were based since the beginning on the Essential Climate Variables (ECV) provided by SWICCA. The statistical results could be integrated in the next River Basin Management Plan to take into account the reduction of inflows due to climate change and its possible effects in all system. In addition, results could be linked to the SI of the SDP to know the level of risk that could be real in a near future.
Thus, with reliable results, our client could start to apply new techniques to save water in all uses and to be ready to face more severe dry periods. If the results could capably show an approximation of the future reality, the CHJ would be ready to avoid huge economic loses and minimise the impacts on water resources consumers.
The time scale varies according to the objectives of decision-making: for purposes of water planning, the time scale is long term (5 to 20 years), on the other hand, for purposes of water management under drought episodes, the time scale is 3 or 6 months (short term).
The water exploitation system is treated at sub-basin or catchment scale, five in this case.
Currently, UPV has a fluid relationship with the CHJ via e-mail, phone calls, interviews and regular meetings that ensure strategic overall coordination. This relationship provides the knowledge of the client needs and the exchange of information about methodologies, last developments, actions taken, how to face future problems and the advances in improving water management.
In addition, annual workshops are organized by both entities, where is required the presence of water users to improve water management. In this type of meetings, the results obtained during the working period are communicated through slides and reports to ensure the right understanding, moreover, a better feedback is provided by all components involved in water management.
This participative approach embraces all parties involved in water management and results in a better understanding, with the needs of all sectors being considered and covered where possible.
We used ECVs (Essential Climate Variables) daily time series of Precipitation, Temperature and River flow at catchment and 0.5 degree grid resolution. However, after several tests, we decided to use that data from E-HYPE model at catchment resolution.
UPV will provide the SPI and the Status Index from the National Drought Indicator in Spain. This represents a composite indicator of diverse meteorological, hydrological and water bodies states standardized variables. This system of indicators consists of spatially distributed control points in the area of the river basin and collects information about reservoir storages, groundwater piezometric levels, streamflows, reservoir inflows and precipitation.
Step 1: Pan-European and local data collection – The data required come from Pan-European and local databases. This information includes: water supply, river flows, air temperature, precipitation, potential evapotranspiration, water requirements, environmental flows, population density, fresh water demand, drought indicators, infrastructures and management rules, among others.
Step 2: Pan-European model and Basin model – In this step two ways can be followed: 1) use the streamflows from Pan-European models, 2) use the basin model (calibrated with local data) with climate data from Pan-European datasets to extract streamflows.
Step 3: Data validation: Comparison of series from the reference period - This process is used to verify that local and Pan-European data are similar in the reference period. It is compared streamflows, precipitation and temperature from both data for the same points of the basin.
Step 4: Bias correction for future periods and inflows extraction – From the comparison of both data, an average coefficient is extracted to do the bias correction. This coefficient is applied to the series of future periods to extract more reliable inflows series from the Basin model.
Step 5: Stochastic model: synthetic series of streamflows for a future horizon – This model is used to extract synthetic series of different scenarios of river flows for future periods. It is calibrated with local data and corrected with the properties (mean) of the different RCMs, adapting it to the alteration of its characteristics in the future period of interest.
Step 6: Climate impact simulation –The management model (SIMRISK) is run in order to simulate the risk of droughts or the climate impacts on the case study for future periods. This model include the information from the previous step and extract some statistics from the generated series to estimate the performance of the water resources system, in addition to know the evolution of water supplies.
Step 7: Indicators – The use of simulation models allows the acquisition of the different indicators to know the state of the system depending on the water resources stored, as could be the status index from the National Drought Indicator System (PES) in Spain, which is employed by end users and policy-makers.
Step 8: Vulnerability assessment– This step consist on the assessment of the vulnerability of the case study by employing a reliability criterion for the adaptation to climate change. In other words, climate change predictions allow decision makers to adopt the required measures in order to reduce the vulnerability of the system.
First of all, the comparison between river flows of both data showed the need of improving the inflows of groundwater component to the river in the dry season. Similarly, the water allocation model requires better estimations of river flows. Because of that, the best option seemed to be the use of climate data to extract river flows with the Basin model. This change of alternative showed the need of a better bias correction based on the variability and the temporal correlation since they influence the rainfall-runoff process, the availability of resources and the reliabilities.
Based on the statistic results, it is possible that the decrease in the 40% of the inflows registered from the 80s to the present was not considered in the reference period (1971-2000). That could be the reason of the majority of the RCMs showed a huge probability of having the storage of water resources about the 80% of the total capacity of the basin. It is possible that the climate change had already occurred in the Jucar River Basin and it was not considered in initial data.
As a result, it is evident that more research is needed in the use of Essential Climate Variables (ECVs) at local scale in order to implement adaptation measures to climate change conditions.
The ancient tradition of water management and planning in Spain explains the high number of water related infrastructures (reservoirs and channels) and the development of the existing legislation for water management. In this sense, climate change was not traditionally considered or was taken into account superficially. The effect of using the climate service represents the role of technology in facilitating access to information. In addition, this will allow decision makers to obtain a diagnosis of the vulnerability of the system under climate change and to study future scenarios of adaptation.
The Jucar River system has a more and more adjusted balance between water resources and demands, which means that the consideration of climate change for the CHJ is crucial to improve water management, avoid impacts of water scarcity and the economic losses this entails.
From the client’s point of view, the lack of adaption to climate change would produce important damages to infrastructures and environment, economic losses in agrarian and tourism sector, considering that urban access to water is guaranteed. In this sense, a cost benefit analysis is not available yet, but looking previous drought events and their costs estimated at many millions of euros, this analysis could be very valuable to know what is coming and to make people aware of the importance of climate change adaptation.
This may cause some inconveniences and it could mean a huge effort from the society, but it is necessary for a better future where the waste of water resources is not an option.
Policy changes are supported by the transfer of technology and ideas from scientists (UPV) to policy makers. One of the best ways to conduct this transfer, and to build a shared vision of the river basin district, is through the joint development of Decision Support Systems (DSS). DSS integrate in a single model all the relevant surface water elements: aquifers, infrastructures, water uses, environmental requirements on flows, water rights and priorities, and operating rules for the system. The purpose of this model is to simulate the management of the basin for purposes on water planning and management (different alternatives, time horizons and scenarios).
Water policies and decisions will depend on the accuracy of the results presented coming from the use of SWICCA climate services. As Jucar River Basin is a high stressed river basin, knowing the amount of water resources available in the territory in each moment is a basic question in order to distribute them in a sustainable way among all water users. The Spanish Statement of Water Planning considers a reliability criterion for the supply of water demands that determines if demands are satisfied or not depending on their deficits supplies. So, results from SWICCA have to be reliable because uncertainty is not admissible for decision making.
Link to client webpage: http://www.chj.es
Water Resources Engineering Group
Institute of Water and Environmental Engineering
Technical University of Valencia
Camino de Vera s/n, 46.022 Valencia - España
Jucar River Basin District Agency (CHJ)
Relevant EU Policy
Purveyor: Abel Solera
Water Resources Engineering Group
Institute of Water and Environmental Engineering
Technical University of Valencia
Camino de Vera s/n, 46.022 Valencia – España
Value added by Copernicus Climate Change Service:
Client: Jucar River Basin District Agency (CHJ)
Map showing Jucar River Basin district
Orange trees in Jucar River Basin district