**1. Introduction**

Water satisfies several key roles for environmental sustainability and human development: it guarantees the people health and economic development and constitutes the backbone of ecosystems. However, it is irregularly distributed in space and time and frequently is carelessly used to the development of economic activities. According to different economic sectors, just agriculture uses, on average, more than 70% of the water resources in the world to produce food. Thus, the variation of climate patterns will necessarily have an impact on the food supply and its price.

The evidence that mankind faces hydrological and environmental issues is increasingly frequent and visible to the society. This became especially clearer after the last UN Climate Change Conference COP 25, since several countries (such as Spain or France) have declared the climate emergency. Despite this, the results of this meeting have been criticized by several scientific sectors because of their lack of ambition, so that it is valuable to continue making visible the importance of water resources studies and how they will be affected by future climate variations.

In a national context, available water should not be a problem for Chile since it is one of the countries with the highest amounts of water per person [1]. From the year 1970 to 2000, Chile averaged an annual rainfall of 1006 mm (main input) and evapotranspiration of 311 mm as main output, so it has 695 mm of surplus [2]. In terms of storage, it has supposed to be more than 500 km3 of water susceptible to be used in human activities every year.

Nonetheless, this significant global amount hides a great spatio-temporal variability depending on natural and socio-economic features of each region. A good example of this contrast between regions is the existing difference between the southern regions where water is abundant but people are few and the northern and central ones where population densities are too high in comparison to the availability of water.

There are many situations in which natural conditions are combined with factors, such as economics, to give place to a long water crisis in Chile [3]. For example, if economic activities by sectors are considered, the largest user of water resources in Chile is agriculture, which consumes up to 75% of the water resources at a national scale [4]. This could be justified because it supplies water for an irrigated land of larger than 1 million ha, which is mostly located in the central zone of Chile [5]. Irrigated areas have significantly increased the use of water resources in the last decade. Besides, some products have increased the area for its cultivation.

Among themselves, the crops of avocado (*Persea americana*) have increased 43% in terms of land surface during the last decades, Chile being the second producer country in the world. Avocado is indeed a species that records a water print of 715 l/kg exported, significantly higher than more traditional crops [6]. Most of the Chilean economy is based on natural resources, with a strong export-focused activity [7]. Despite this, in many regions of the country, the uncontrolled exploitation exceeds the actual availability of water resources. This has led to declare numerous regions as depleted in both surface and groundwater [4].

This situation could be even more worrying according to the effects of climate change foreseen by the scientific community. In the particular case of Chile, a reduction between 20 and 40% of total rainfall has been already reported [8]. Added to this, the lack of vegetation management in the upper areas of the watersheds and the elevation of the isotherms have increased water demand and reduced snow deposits, respectively, giving place to a strong decrease of river discharge. An intensive demand for water resources and a decrease in them requires knowing the water availability both in the present and in the future, in order to develop hydrological plans to guarantee economic and environmental sustainability.

Taking into account the abovementioned, this work is focused on the analysis of both the current and future water balance of each one of the administrative regions of Chile since they are the appropriated scale in which decisions on land planning should be made. The reasons of choice this scale work is twofold; on the one hand, Chile is divided into longitudinal regions easily assignable to climatic belts, and, on the other hand, they are the regional governments who are in charge of the regional administrations and consequently in charge of their land and water management. In addition, this research should be also useful to become aware of the upcoming effects of climate change, foreseen by reliable predictive models in every scenario (optimistic and pessimistic), that serve to discuss about the sustainability of many of the current human activities.

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**Figure 1.**

*Geographical distribution of the Chilean regions.*

*The Availability of Water in Chile: A Regional View from a Geographical Perspective*

The study was carried out in the whole continental territory of Chile, excluding its islands and the Chilean Antarctic Territory. The size of the study area is 4270 km of distance from north to south and a width (from west to east) ranging from 90 to 445 km involving a great sort of different climate types (cold, temperate, Mediterranean, desert, and high mountain). The limits of the Continental Chile are Peru and Bolivia in the north, the Andes in the east, the Pacific Ocean in the west, and the Drake Passage in the south, Argentina being the country in whom Chile

This territory is inhabited by around 18 million people with a relatively high standard of living (according to the main macroeconomic indicators) within the context of Latin America. It is divided since 2017 into 16 regions, 56 provinces, and 346 communes. Each region has its own regional government headed by the intendant and the member of the Regional Council (elected every 4 years). These regions keep its original Roman number from I to XII following a gradient from north to south. The Metropolitan Region has the number XIII; and three new

regions recently created have continued this tradition (**Figure 1**).

*DOI: http://dx.doi.org/10.5772/intechopen.92169*

**2. Material and methods**

shares more kilometers of border.

**2.1 Study area**

*The Availability of Water in Chile: A Regional View from a Geographical Perspective DOI: http://dx.doi.org/10.5772/intechopen.92169*
