Hydrology and Vegetation in Spain: Key Factors
**Influencing Factors**
- The weather plays the biggest influence since water in lakes and rivers comes from aquifers and precipitation.
- The relief and topography influence the organization of watersheds in the erosive capacity of the rivers and the formation of lakes and aquifers.
- The lithology is the rock type, and its characteristics may promote or facilitate surface runoff, water infiltration, and the formation of aquifers.
- The vegetation holds the soil and prevents its erosion.
- Human beings consume water for supply and irrigation and try to offset this expenditure by the construction of works such as dams and transfers.
**River Regime**
Understanding the behavior of the average flow of a river along the year. The regimes are classified according to the system of rivers feeding. Regimen distinguish rain (the water comes from rain) and nival regime (water derives from snowmelt) types of schemes.
A. Oceanic rainfall patterns: rivers of the regions of Atlantic climate, abundant water throughout the year, these rivers belong to the Cantabrian and Galician. – The subtropical rain regime: own land inside the precipitation. Small differences are noticeable in flow during periods of maximum and minimum two seasons, the water and abundance of low water. Mediterranean rainfall regime: maximum secondary flow in autumn and winter and spring, causing dangerous increases suffering from a cold drop.
B. Regime nival: corresponds to the rivers of mountain – 1. Pure: high mountain rivers located near or at altitudes above 2500 meters of water altitude. The snow is delayed. – 2. Mixed: middle mountain rivers situated at altitudes below 2500 meters. There are types of rainfall: nivo-pluvial and pluvial-nival.
**River Basin**
The territory’s orderly functioning of a main river and its tributaries are separated by a dividing line. The major watersheds are the rivers in the north. Within the basin, the water circulates through a channel or bed, showing a concave longitudinal profile and a transverse profile fitted or shaped by a wide valley. The rivers of a watershed form a network that is organized from the tributaries up to the main river.
**Peninsular Hydrographic Slope**
A slope basin is the set of catchments discharging into the same sea.
A. Rivers of the Cantabrian side: they are short and rise in the mountains near the coast. They possess great erosive force, and their slopes would be greater if not protected by vegetation. The rivers of this scenario are numerous and plentiful, with a regular regimen. Taking advantage of these circumstances, wetlands are constructed for energy production.
B. Atlantic watershed: they are long since they are born near the Mediterranean and end in the Atlantic, forming gullies on the slopes. Their regime is irregular. They present summer drought coinciding with the minimum of precipitation.
C. The Mediterranean rivers of the watershed are short except for the Ebro. They are gullied rivers that erode violently deforested hillsides, their status is irregular in the summer, and they have several low-water periods. They can suffer catastrophic increases. As a result, it is possible to build reservoirs there.
In the Mediterranean side, streams are common, intermittent courses that only take water when it rains; much of the year, their beds or wadis are dry.
**Lakes**
In Spain, there are 2474 lakes. They are of small size, and many are seasonal. Lakes are caused by endogenous forces within the earth. Tectonic lakes form in land sunk by the action of the faults. Volcanic lakes are found in craters. Exogenous lakes are caused by external forces such as wind, karstic, or glacial lakes: excavated by the wind or coastal lagoons. Salt lakes are separated from the sea by a coastal ridge. Karst lakes originate in the basins created by the dissolution of limestone. – Arreic lakes: they are the most exogenous type of lake, characteristic of extended arid or semiarid regions. Wind lakes: have been excavated by the wind’s action on soft materials. Lakes or lagoons: salt lakes separated from the sea by a coastal cordon. There are many in the Guadalquivir.
**Vegetation**
The peninsula is divided into several types of vegetable kingdoms: the Holarctic, alpine and boreal to Euro-Siberian, the Mediterranean, and Macaronesian. Influences: the 3 basic types are the forest, scrub, and grassland. They depend on physical factors such as topography, soils, and climate; and human factors such as the introduction of new species and the degradation of existing vegetation.
**Vegetable Landscapes of Spain**
A – Oceanic climate: corresponds to the Euro-Siberian floristic region.
1 – Deciduous forest consists of tall trees with a straight trunk and smooth, large leaves that fall in autumn. Examples include oak and beech. Ferns and mosses grow in the understory. Beech cannot stand the heat, but it can withstand the cold. It requires high humidity and is a mountain tree that adapts to calcareous and siliceous soils. Its growth is fast, and its wood is of high quality. Its main area is in the Cantabrian Mountains and Navarrese Pyrenees. The oak does not support hot summers, has reduced tolerance to cold, and requires less humidity than beech. It grows slowly, and its wood is hard. Its areas are in Galicia and the Cantabrian Mountains. Chestnut is a secondary plant formation that gained ground because it draws more. Another type of forest is called “mascarete” of rebollo and moan with smaller trees whose leaves do not fall until the new outbreak.
2 – The moor and fields: the heath vegetation is a dense shrub type of scrub. The meadows are herbaceous.
**Mediterranean Climate**
The evergreen forest and scrubland are adapted to summer drought.
A – Evergreen forests: These are medium-height trees with thick, rough bark. The most typical species are oak and cork oak. The oak is the most widespread tree; it is resistant to drought and adapted to all soil types. Its wood is hard. The cork oak needs mild winters, some moisture, and siliceous soils. The pine forest is a secondary plant that adapts to extreme cold, heat, humidity, and aridity. It spans wide areas.
B – Scrubs: are the result of forest degradation by human beings. 3 types:
1 – Maquis: dense shrubbery, almost impenetrable, up to two meters in height (heather, rockrose, mastic, and broom).
2 – Garrigue: scrubs formed by shrubs and low rise (thyme, rosemary, and lavender).
3 – Steppes: in semi-arid areas in southwestern Spain where the scrubland was degraded by human action.
**Riparian Vegetation**
It is a landscape that presents constant water, which makes certain species able to live only in the strips located parallel to the river. Riparian forests are formed by species such as alder, willow, and poplar.
The Vegetation of Mountain
In the mountains, the vegetation has floors that vary depending on the height. Accordingly, it can be distinguished between:
a) The Alps or Pyrenees mountain is represented by the Pyrenees. At its upper three floors can be distinguished:
1 – Natural conifer such as pine, black pine, and Scots pine. The spruce forests can be mixed with beech.
2 – Alpine meadow domain, which has a short growing season. At this point, small rupicolous plants grow, i.e., adapted to live in the rocks.
3 – The snowy slope is reduced to spaces in which snow remains all year, and the vegetation is nonexistent. Other areas of high slope, where snow disappears some time. Here there are small rock-dwelling plants, arranged directly on the rock (lichens and mosses), or in cracks and fissures.
B) The rest of the peninsular mountains lack subalpine conifers. The supraforestal floor is formed by small shrubs. In the Atlantic area, heather and broom are abundant, and in the Mediterranean area, shrubs and thorny bushes. Above the supraforestal floor are the meadows.
Canary Islands Vegetation
The vegetation of the Canary Islands has African and South Atlantic influences. In their insular, a large role is played by endemism (own unique vegetation) and relics (vegetation that occupied large areas in other geological eras with different climates).
This original plant is based on the relief, which leads to a succession of floors:
1 – The basement is marked by aridity. Dominated by sparse and rough shrubs.
2 – The intermediate floor is conditioned by lower heat and increased humidity.
3 – The thermocanarian floor. The vegetation is adapted to the fogs caused by the trade winds, the most refreshing and less sunshine. It consists of two original forest formations: the laurel forest, very dense, and the fayal-heath, the result of degradation by human action.
4 – The Canary Island pine forest dominates the Canary Island pine floor. Its main species is the Canary Island pine that must adapt to special conditions of aridity and cold.
5 – The supracanarian floor is only present on Tenerife and La Palma. It is characterized by strong, scattered shrubs but rich flora.
**Soil Types**
1 – Zonal Soil: there are several types according to the climate.
a) Oceanic climate: soils rich in organic matter and acid rain’s constant as rain that washed the surface layers and drag the bases to the lower strata.
b) Mediterranean climate: in these soils are siliceous rocks. The most characteristic is the southern brown earth, limestone, which highlights the Mediterranean red soil and red earth. On the other hand, in the clay and loam land arise or black vertisols.
2 – Azonal Soil: These soils do not have well-defined characteristics because they have not had enough time to form or because they are located on steep slopes.
3 – Intrazonal Soil: These soils, if well developed in Spain, include the brown limestone with abundant limestone, rendzinas on content calcium carbonate, the flood on the banks of rivers and flooded areas endorheic, sandy soils, the salt, and volcanoes.