Glossary of Hydrological and Vegetation Terms
River
Natural water current, continuous and more or less abundant, which flows into another river, a lake, or a sea.
Drought
Period during which a stream of water reaches its lowest flow.
Flood
A moment of maximum river flow, which is usually an abnormal increase with catastrophic effects.
Nival Regime
Fluvial type of rivers whose flow is determined by the input of water from melting snow. Corresponds to mountain rivers that reach their maximum during the spring thaw, and their minimum in winter when water is retained in the form of snow or ice. Depending on receiving, or not, contributions from rainfall, they may be pure or mixed.
Rainfall Regime
Fluvial type of rivers whose flow is determined by water inflows from rainfall. The main types are: ocean, pure Mediterranean, continental Mediterranean, and subtropical areas.
Watershed
Territory whose waters pour into a main river and its tributaries, separated from each other by watersheds, which coincide with the change of slope areas. Within the basin, the rivers draw their own course – the space along which they flow – and create a hierarchical river network from the tributaries and streams to reach the main river.
Hydrographic Areas
Joint water catchments that pour into the same sea. On the Iberian Peninsula, there is an important asymmetry between the Atlantic and Cantabrian slopes – into which 69% of the rivers flow – and the Mediterranean coast – into which the remaining 31% empties – due to the slope of the plateau to the west from the Iberian system.
Lakes
Masses of fresh or salt water accumulated in depressed areas that reach a certain depth. In Spain, there are many lakes, nearly 2,500, but of little importance, since most are small, seasonal, or short-lived, due to silting or exploitation by wells for human uses.
Exogenous Lakes
Masses of fresh or salt water accumulated in depressed areas that reach a certain depth, and that originate from external forces of nature, fundamentally different types of erosion. They cover a wide typology: glaciers, karst, arreicos, wind, and coastal.
Wetlands
Tracts of land covered by shallow water, and even intermittent, that disappear with the summer drought. They form lakes, swamps, deltas, lagoons, or peat bogs of major biological interest, due to the presence of species adapted to an environment of transition between water and land and the traffic and nesting of migratory birds. The most prominent in Spain are the Tablas de Daimiel, the Ebro Delta, the marshes of the Guadalquivir, the Mar Menor, or the Albufera of Valencia.
Aquifer
A sack of groundwater formed due to the seepage of water from rainfall, which accumulates over a waterproof layer. They usually discharge their waters into rivers, springs, or directly into the sea. Their waters are of high quality for human consumption due to the lack of harmful organisms and their regularity, but they have been subjected in recent years to overfishing and pollution processes.
Evergreen Forest
Vegetation type characteristic of Mediterranean Spain. Its trees are of medium height, with trunks that are not straight, thick bark, and large branches and tops that provide shade under which a rich understory of serrano and broom grows. The main species are oak, cork oak, olive, and pine.
Garriga
Vegetation characteristic of Mediterranean Spain, consisting of shrubs and bushes of low height, leaving bare spots where rocks appear. They are the fruit of evergreen forest degradation, primarily by human action. Its most characteristic species are thyme, rosemary, and lavender.
Beech
Plant species characteristic of deciduous trees that can be found in the Atlantic regions of Spain. It is typical of high mountains, cold, moist, calcareous soils, although it also adapts to siliceous and calcareous soils, but not heat. They form specific forests or mixed forests with oak in the Cantabrian Mountains and Pyrenees, where its wood, hard and of high quality, is used in manufacturing furniture and various utensils.
Landes
Vegetation characteristic of the Atlantic regions of Spain, consisting of a dense thicket based on heather, gorse, and broom, which can reach four meters. They are the result of the degradation of the ocean deciduous forest or a supra-forest adaptation between 1600 and 2000 meters. These spaces are used for animal bedding and compost.
Laurel Forest
Canarian forest formation made up of more than twenty species, mainly laurel trees, and can be degraded by human action into Fayal-Heath. It is formed on the termocanario floor, between 800 and 1200 meters.
Bedrock
The substrate mineral from which soil is formed, influencing its color, texture, structure, permeability, and acidity. Depending on the bedrock, soils may be siliceous (loose and permeable), limestone (pasty and permeable), and clay (compact and waterproof).
Soil Profile
The set of soil horizons. Horizon D is the bedrock, C the altered bedrock, B the zone of accumulation and alteration, and A the surface.
Terra Rossa
Soil characteristic of the Mediterranean climate on hard limestone with a clay horizon that lies directly on the bedrock. This causes frequent rock outcrops that hinder its mechanization, which determines their exploitation as dehesa forests and marginal crops such as almond or olive.
Rankers
Soil characteristic of the ocean climate on siliceous rock in higher areas or steep slopes. The constant erosion processes they are under make their development and thickness difficult and therefore their fertility. Therefore, they are never used as crops, but as pastures or forests.