The Messara valley is located in the central-southern part of Crete, about 50 km south of the city of Heraklion and constitutes the most important agricultural region of the island.

While, the hilly and mountainous areas of the valley were covered with forest in the past, most of these forests are now cultivated with olives, vines, vegetable, fruit and cereals. Groundwater is a very important resource affecting crop production and the local economy.

Messara valley is characterised by dry sub-humid climate with mild moist winters and dry hot summers. Average annual rainfall ranges from 750 to 1000 mm.

Potential evapotranspiration in the Valley ranges from 1481 mm to 1549 mm yr-¹. The eastern part of the valley has the lowest ETo values.

Altitude in the Messara valley is lower than 400m and a large part (39%) is characterised as almost flat. Major types of landforms are composite landforms (36.4%), level land (39.5%) and sloping land (22.4%).

Based on the hydrological boundaries and land use, the valley comprises of two main catchments: the western Messara catchment area (the Geropotamos River discharging near Phaestos) and the eastern Messara catchment area (the Anapodaris River discharging near Demati area). Water flow in Geropotamos is estimated at 14 million m³ per year and the river remains almost dry during the summer period. Anapodaris is the longest river in Crete, discharging about 40 million m³ per year. The main source of irrigation water in Messara Valley is groundwater. Nine main water reservoirs have been identified in the study area, with a total water storage capacity of approximately 25 million m³. The Faneromeni irrigation water reservoir, has a capacity of 19,670,000 m³.

The Messara Valley is predominantly a cultivated ecosystem: 64.6% of the area is covered by olive groves.

Small parts in of the lower and western part are characterized for their unique biodiversity (2.0% of the total area).

Population in Messara over the last 50 years has remained relatively stable, exhibiting, however, a 2% decrease since 1991, which may be partly explained by migration towards the urban center of Heraklion. While population density in Messara, including the communities of Gagales and Protoria, has generally increased, the wide base of the population pyramids in 1960s and 1970s has been replaced by a broadening of the upper age classes in the pyramid. Decreasing birth rates and rising levels of life expectancy for both sexes coupled with the return of the migrants in the 1990s.

Population ageing in Messara and the communities of Gagales and Protoria is more severe than in the former Heraklion prefecture and Crete in general.

The most important LEDD problems in Messara Valley are:

• Soil erosion in the sloping land     
• Water erosion in areas cultivated with vines, particularly during spring.
• Tillage erosion which has evolved into a serious cause of land degradation in the last decades, after the introduction of heavy powerful machines for cultivation of the land.
• Soil salinization in the lowland.
• Increasing water consumption for irrigation and tourism, which has greatly contributed to over-exploitation of ground water.
• Chemical deterioration of water, attributed to fertilizers applied in agriculture affecting both surface (phosphates, nitrates) and ground (nitrates) waters.
• Intrusion of brackish water in the aquifers due to overexploitation.

All of the above interrelated issues lead to land degradation and desertification. Critical areas to desertification cover 21.2% of the Valley, although the majority of these areas are not in extreme risk of desertification.