Improved yields and revenue
The challenge for Vassilis
Intensive agricultural activity in the Messara valley, Crete, Greece, has a great impact on the availability of water resources. The overexploitation of the aquifer and the unregulated use of the local dam is leading to severe water shortages, creating tension amongst the local water distribution authorities.
At the same time, the use of weather and climate information to support coordinated water resources management at the regional level is very limited. Vassilis, 45, is the head of a water managing committee of the local dam and is in charge of setting the management regulations (typically the quantity of water to be directed to the downstream districts in each growing season) and water price. Using Vassilis’ instructions and data, IMPREX will build and assess a forecasting tool that provides a seasonal outlook for the water that will flow into the dam over the following months, as well as a groundwater status prediction for the Messara valley.
During the summer season, olive tree fields in the Messara valley are generally deficit irrigated regardless of how wet the past winter was. Hence, farmers ask for as much water as possible, as this extra water that is provided to them can be translated into potential profit.
However, the dam basin and the Messara valley often experience dry years during which the stored water in the dam can mitigate an agricultural drought. Due to a lack of reliable information, water managers like Vassilis do not know whether saving water is the right decision, as a potentially wet winter can exceed the storage capacity of the dam and cause it to overflow.
In 2016-2017, when the Messara region suffered a drought period, the ineffectiveness of water management policy led to the draining of the dam resulting in little to no water being stored in the basin. Moreover, the European Centre for Medium-Range Weather Forecasts' (ECMWF) seasonal forecast predicted a warmer and dryer than average 2017-2018 winter that would further increase the risk of severe water scarcity and lead to a potential overexploitation of the local aquifers.
Currently, the water management authorities do not use any monitoring tool for operational water resources. Additionally, no weather and climate service is implemented at any decision-level in the area. Hence, water management is conducted without advanced planning and simply with considerations of the already stored volume of water in the dam and the current user needs.
Solving the challenge with IMPREX
IMPREX will provide the Messara basin water management authorities with a hydrological model tool that will aid better decision-making: by supplying a six-month outlook on precipitation and temperature, this will provide the necessary input to this IMPREX hydrological model allowing for an estimation of water flowing into the dam to be made and the level of drought based on the resources within groundwater to be predicted. This information will support better allocation of water resources, maximising the regional agricultural growth and minimising the risk of decreasing water availability. Furthermore, the water management authorities can adopt more efficient water-use rules, ensuring optimal water turnover for agricultural production.
Figure 2 presents an overview of the Messara drought decision support system which provides seasonal hydro-meteorological forecasts for local water management and demonstrates available weather/climate/hydrological sources of information. It consists of three pillars of information. The first provides specific sources and guidance for additional available weather and climate information not familiar to the local users. The second will be an operational seasonal forecasting of the local dam storage level as an output of hydrologic simulation forced by locally adjusted seasonal forecasts. The system will also provide operational, locally adjusted information for precipitation and meteorological and groundwater drought indices.
Vassilis is in close contact with IMPREX project partners at the Technical University of Crete (TUC), who will produce a probabilistic forecast system for the dam inflow and the drought state for the forthcoming winter. On the basis of the new forecasts, the water managing committee will discuss alternative management choices that will lead to larger water availability when the olive cultivations need it most. The alternative policy choices can result in economic benefit to the farmers through an improved olive yield.
Thanks to better anticipation of water management by Vassilis, olive tree farmers and other agricultural workers in the Messara valley can gain more trust in forecasting predictions and ensure yields and revenue increase.