Spanish River Systems: Hydrology, Regimes and Hydrographic Slopes

Summary

This study document describes the hydrology of Spanish rivers, comparing Atlantic and Mediterranean river features and the factors that shape water movement in a river basin. It explains the main river regimes, from Atlantic and Mediterranean to nival and nivo-pluvial, and how the Atlantic and Mediterranean hydrographic slopes are separated by mountain ranges. Students will learn the typical flow patterns of each slope.

Key points

Spain has two main hydrographic slopes, the Atlantic and the Mediterranean, separated by the Baetic System, the Iberian System and the Cantabrian Mountains.
Mediterranean rivers are generally short, with low streamflow, except for the Ebro, and often become ephemeral streams or wadis.
Atlantic rivers crossing the Meseta are long, while Cantabrian and Galician rivers are short and plentiful with more regular flows.
Factors influencing water movement in a basin include climate, size and shape of the watershed, slope, vegetal cover and human action.
The Atlantic regime has maximum flows in winter and minimums in summer, while the Mediterranean regime shows strong irregularity with floods in spring and autumn.
A river regime describes how river flow changes throughout the year; nival regimes depend mainly on spring snowmelt.

Test yourself

Characteristics of Spanish River Systems

Atlantic and Mediterranean River Features

Unlike the distinct characteristics of Atlantic and Mediterranean currents, Spanish rivers exhibit unique hydrological patterns:

Atlantic Rivers

Rivers crossing the Meseta are long.
Cantabrian and Galician rivers are short and irregular, with very intense dry periods in summer and sometimes in winter.
The most abundant flows occur in autumn and spring, which are also the times when high water levels concentrate.

Mediterranean Rivers

Generally short rivers with low streamflow, except for the Ebro.
Irregular, with intense dry periods and large floods caused by heavy rainfall in spring and autumn.
Often ephemeral streams or wadis, characterized by channels where water flows intermittently.
The Ebro River is a notable exception to these general characteristics.

Freshwater Systems: Spanish River Basins

Factors influencing the movement of water in a river basin include:

Climatic Factors: Rainfall and temperatures.
Size and Shape of the Watershed: The nature of the rocks.
Slope: The gradient of the terrain.
Vegetal Cover: The presence of vegetation.
Human Action: Anthropogenic influences.

River Regimes

A river regime reflects the change in river flow throughout the year:

Atlantic River Regime: Maximum flows in winter and minimums in summer.
Mediterranean River Regime: Very pronounced irregularity and dry periods, with floods in spring and autumn.
Subtropical River Regime: Marked difference between high water and low water periods.
Pluvio-Nival Regime: Presents a secondary maximum due to snowmelt.
Nival Regime: Throughput depends primarily on contributions from spring snowmelt.
Nivo-Pluvial Regime: The main maximum is due to thaw, and a secondary maximum is due to precipitation.

Hydrographic Slopes

A hydrographic slope is formed by all the basins whose waters flow into the same sea. In Spain, there are two main slopes: the Atlantic and the Mediterranean, separated by mountain ranges that include the Baetic System, the Iberian System, and the Cantabrian Mountains.

Mediterranean Slope

Characterized by many short, irregular rivers with low flow, though the Ebro is an exception.
Presence of ephemeral streams and ravines is common.

Atlantic Slope

This slope has two distinct sectors:

Rivers Crossing the Meseta: These are long and irregular.
Cantabrian and Galician Rivers: These are short and plentiful, with more regular flows.
The Canary Islands have regular watercourses.
The Balearic Islands have intermittent watercourses.

FAQ

What is a hydrographic slope?

A hydrographic slope is formed by all the basins whose waters flow into the same sea. In Spain there are two main slopes: the Atlantic and the Mediterranean.

What is a river regime?

A river regime reflects the change in river flow throughout the year. The document lists Atlantic, Mediterranean, subtropical, pluvio-nival, nival and nivo-pluvial regimes.

Which Spanish river is an exception on the Mediterranean slope?

The Ebro River is a notable exception, since most Mediterranean rivers are short with low streamflow.