Peninsular River Network Characteristics
Hydrographic Network Characteristics
HIDROGRÁFICA. CARACTERES DE LA RED
General characteristics of the river network
Disequilibrium of the river network
The disequilibrium of the river network, i.e., the lack of symmetry with respect to the geographic base. The cause is the tilting or inclination of the plateau toward the west from the Iberian System.
Adaptation to relief
It is due to the great length of rivers that run through plains and valleys (around 1,000 km), contrasted with the short course of mountain streams that do not exceed one hundred kilometres.
Parallelism
In the peninsular river system, the major rivers, except the Ebro, follow roughly parallel courses; their channels are relatively evenly spaced and regularly distributed over the territory.
Intense connection with settlement
This is reflected in ancient cities located near major waterways and in the use of river valleys to establish lines of communication.
Peninsular rivers: flow regimes
The system of peninsular rivers
Oceanic rainfall pattern
These rivers are characterized by abundant water throughout the year and the absence of large floods or long droughts. This regime applies to Galician and Cantabrian rivers.
Pluvio-subtropical and continental Mediterranean regime
This regime occurs in the drier areas of Spain, where annual rainfall is low and there is a very pronounced summer drought.
Mediterranean rainfall regime
The Mediterranean regime is characterized by a distinct rainfall pattern, with a primary maximum in autumn and a secondary maximum in late winter and spring.
Nival regime
The nival regime is restricted to the central and Pyrenean peaks. Its main feature is a pronounced high-water period in late spring and early summer due to snowmelt, followed by prolonged low flows.
Factors determining the river system
Watersheds and peninsular basins
Cantabrian rivers are short and plentiful. They are short because the Cantabrian Mountains are close to the sea and their sources are at considerable altitude and near the coast. They reach the sea quickly and are plentiful due to abundant rainfall and the absence of significant droughts.
Atlantic side contains the great rivers of the plateau. These rivers are long and have a gentle slope. According to the spatial distribution of rainfall, discharge decreases as rivers flow farther south.
Mediterranean coast rivers have mixed regimes. The Ebro is the longest and notable for its flow and relative regularity. In the other rivers, the influence of the relief adjacent to the sea limits the length of their courses. These rivers are not very plentiful and experience large seasonal floods (crecidas).