What is sewer irrigation

Huerta of Murcia - irrigated agriculture

overview

Huerta are areas that are used intensively for horticulture and are preferably located in floodplains. The Huerta of Murcia begins west of Murcia after the River Segura, coming from the north, has broken through the foothills of the Betic Cordillera and at Alcantarilla turns a tectonic depression at right angles. It is not far from the Mediterranean, about 80 kilometers from Alicante (see 132.1).

The irrigated areas can be assigned to different development phases. Compared to the traditionally cultivated area in the floodplain, an expansion of the cultivated areas took place initially on the basis of well irrigation, later with water from long-distance pipes. This more than compensated for the loss of land in the floodplain as a result of settlement growth.

Natural conditions

The Huerta has a cultural tradition that goes back more than a thousand years and is one of the oldest irrigation areas on the Río Segura. It is protected against strong winds and cold spells both to the northwest and to the southeast. January temperatures with a mean minimum of 6 ° C and a mean maximum of 16 ° C show the thermal benefit of the region; more than 2900 hours of sunshine are measured per year. These framework conditions allow two to three harvests per year on the same plot. At the same time, agriculture in south-east Spain benefits from a temporary Crop lead of up to two months compared to competing horticultural areas.

The downside of thermal preferential treatment is that it is precarious Water availability in summer. The average annual precipitation in Murcia does not even reach 300 millimeters, the summer evaporation is very high. However, fruit tree crops require an annual average of around 7,000 cubic meters of water per hectare. This made irrigation of intensive agricultural crops imperative. Since the water for this is mainly taken from the Río Segura, the Huerta of Murcia has the character of a river oasis.

The Huerta of Murcia sees itself with natural risks faced. The low gradient of the floodplain leads to episodic rainfall in the event of exceptional heavy precipitation Floodsthat can take on catastrophic proportions in individual cases.

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New irrigation and cultivation methods

The generally increasing demand for water and competing usage demands by the urban resident population, tourism and other trades put agriculture, as the largest water consumer, under increasing pressure in the period that followed. The hallmarks of a new form of irrigated agriculture modern, water-saving irrigation techniques. Above all, drip irrigation increasingly replaced not only traditional furrow irrigation, but also irrigation in horticulture.

Since 1980, water has been discharged from the headwaters of the Tajo (as the crow flies) into the Río Segura via the Júcar river (see 132.1; Tajo-Segura bypass). The province of Murcia is also supplied with water in this way. Thanks to the flexible installation of pressure piping systems, the water can now also be routed on slopes, where it is pumped into decentralized water storage tanks. From there, the slopes at the foot of the mountain ranges were developed for irrigation crops (see map: dark green areas).

The increased demand for winter and early vegetables (see crop rotation bar) led to an important innovation in the Huerta of Murcia, the Accelerated growth through plastic coverings. The technical variants now range from overlying plastic tarpaulins that only leave “windows” open for individual plants, to so-called microtunnels, to accessible, usually unheated plastic greenhouses.

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Decline of traditional agriculture

The traditional "Huerta economy" is based on the Irrigation with river water (see map: yellow areas). The main irrigation channels at the edge, which bring the fresh water, branch off at a weir at the narrow valley north of Alcantarilla (see map). The drainage channels marked in red on the map, which divert the excess irrigation water, flow into the river further down the valley, provided they do not feed relict water into other irrigation channels.

On the basis of this age-old canal irrigation system and a no less old water law, the Huerta of Murcia predominated Small horticultural businesses educated. In the first half of the 20th century, the proportion of winter grain in the irrigated area was increasingly reduced, in favor of fruit and vegetables, which enabled up to three harvests per year. At the same time, the horticultural area in the peripheral areas, which were outside the reach of the canal irrigation system, was continuously expanded through well irrigation (see map: light green areas).

From around the 1950s and 1960s, the trend began to creep up Cancellation process one that was primarily triggered by a selective migration of agricultural workers to the emerging Spanish industry.

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Structural change in the Huerta

In the Huerta of Murcia, the change in irrigated agriculture is linked to a profound socio-economic and ecological structural change. The expansion of the irrigation areas on slopes has forced them to be cleared over a large area. The newly created parcels are around nine hectares in size. On the slopes, erosion processes are intensified, as a result of which the deposition of sediments in the floodplain increases.

The capital-intensive technical modernizations were usually unaffordable for traditional micro-businesses. Therefore now rule Medium-sized companies with two to three hectares of land, which mainly market their products on a cooperative basis. Despite an increased degree of mechanization, the need for labor in the Huerta economy is still considerable. Migrants from North Africa, Latin America and Eastern Europe, who are often employed illegally, are increasingly being used as workers.

The physiognomically dominant feature for the current structural change is Suburbanization. It manifests itself in new construction areas following traditional town centers and in a disorderly expansion of the scattered settlements within the floodplain. In the meantime, more than 50 percent of the former Huerta area has been sealed.

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