Understanding Spanish Water Resources
Water Stress Diversity
The Peninsular Rivers
A river is a continuous stream of water, more or less abundant, which flows into the sea, another river, or lake.
Factors Influencing Peninsular Rivers
The peninsular rivers are conditioned by various factors that influence the flow and organization of river basins and watersheds. Factors influencing the rivers are climate, terrain and topography, lithology, vegetation, and human action.
Flow and Flow Regime
Flow: The amount of water passing a given point per second by a river. The river system is the seasonal variation in river flow.
Hydrographic Basins and Watersheds
The watershed is the land whose waters pour into a main river and its tributaries. The characteristics of the features are as follows:
- It is separated by a division of water.
- Peninsular basins are Northern Miño, Duero, Tajo, Guadiana, Guadalquivir, Pyrenees, Ebro, Jucar, Segura, and South.
- The watershed basin is the set of basins whose waters flow into the same sea.
There is a large asymmetry between the Atlantic and the Mediterranean due to the inclination of the plateau to the west from the Iberian system. Springs are the Cantabrian, Atlantic, and Mediterranean.
Balearic and Canary Islands
Balearic and Canary Islands lack rivers themselves. They have streams or low-flow streams, fed by springs. Floods are also common in both archipelagos.
Spanish Lakes and Wetlands
Lakes are natural bodies of fresh or brackish water accumulated in depressed areas that reach a certain depth. Depending on their origin, there are two types of lakes: endogenous and exogenous. Endogenous lakes are caused by forces within the Earth. Exogenous lakes are caused by forces such as the action of ice, water, or wind.
Wetlands
Wetlands are areas of land covered by shallow water, often intermittently, since during the low summer level, they may even disappear. They include ponds, marshes, deltas, and bogs.
Lagoons
Lagoons are natural bodies of fresh or brackish water, accumulated in depressed areas, that reach a certain depth. Lagoons have a lesser size and depth than lakes, but the difference between them is not very accurate.
Aquifers
Aquifers are underground water sacs. They form when water infiltrating precipitation finds a waterproof layer and accumulates. You can access their waters through rivers and springs, or directly into the sea. In the Balearic and Canary Islands, most water comes from aquifers whose formation is favored by the permeability of limestone and volcanic rocks.
Water as a Resource
Water is essential for life on Earth and many human activities. For this reason, people have preferred settlements near water. Among the consumer uses of water are agricultural irrigation, which absorbs more than 80% of consumed water, economic sectors, and households and municipalities. Non-consumptive uses of water include fisheries, aquaculture, navigation, hydropower, and water sports.
The Water Balance
In Spain, water resources come from precipitation that feeds surface waters and aquifers. Although this amount is still above the water demand, there is an annual water deficit of around 3000-4000 hm3 due to several problems:
- Uneven distribution of resources: Rivers, the main source of supply, have strong seasonal and interannual irregularity and an unequal spatial distribution. This determines the presence of basins with a surplus.
- Uneven distribution of demand: Concentrated in areas of economic and demographic dynamism, the Mediterranean, where resources are scarce.
- Failure of reservoirs and water loss: Water stored in reservoirs is insufficient to meet rising demand. Annual water losses are significant due to inadequate irrigation systems and leaking pipes.
Hydraulic Infrastructure
Hydraulic infrastructure is built to regulate water resources and improve water quality. Rivers have been regulated by dams, canals, and diversions. Reservoirs are large areas of artificially stored water behind a dam or barrier across a stream. Distribution channels or water courses add up to more than 15,000 km. Their main problem is the age or poor condition of many sections, leading to heavy water loss. Transfers are movements of water between surplus and deficit basins. Some Pyrenean lakes, aquifers, and seawater are other water resources utilized. Water policy has two main purposes: the regulation and management of water resources. The regulation of water corresponds to the Water Act.
Overexploitation and Pollution
Overexploitation is due to increased consumption for agricultural, urban, and industrial use. This has driven massive collection works of water reservoirs and wells. As a result, some wetlands and aquifers are at risk of desiccation. To address this, water-saving irrigation techniques and the reuse of treated water are encouraged. Regarding rivers and aquifers, the aim is to define over-exploited areas, limiting the use of aquifers during times of scarcity. For wetlands, the goal is to protect them by promoting their rational use and the recovery of degraded areas.