What part of natural flow can be considered a "water resource"?

In this paper, we discuss an unfortunate semantic shortcut – the use of the expression "water resources" as a synonym for "river/groundwater flow" – which causes great confusion in all Water Security-related discussions. We show that only a part of the flow can be considered a resource, and that the efficiency of the flow-to-resource conversion is a complex function of: (i) the hydrologic regime, (ii) environmental constraints (in-stream reserved flows), (iii) the type of water demand, and (iv) the existence of artificial reservoirs. Last, we illustrate how the flow-to-resource conversion can be affected by future climatic changes. Hydrologic data and climate change simulations for three French rivers (the rivers Vilaine, Durance and Garonne) are used to illustrate this discussion

Karst Aquifers in the Arid World of Africa and the Middle East: Sustainability or Humanity?

Karst aquifers are widely utilized water sources and in many countries represent the sole resource for potable water supply and irrigation of arable land. Tapping of karstic waters from springs and diverting them by gravity channels and then aqueducts has a long history and has been significant for the development of many karstic regions. Many cities were established in the vicinity of major springs. But karst water users in many places are facing problems caused mainly by unstable discharge regimes of dynamic karst aquifers or rapid contamination that takes place when pollutants are present in catchment areas. The situation is especially problematic in the regions with arid climates where, besides having limited aquifer recharge, there has been increased pressure on karst aquifers due to population growth, fast urbanization, or industrialization. There are many locations where aquifer systems are already over-exploited and where local, regional, or transboundary conflicts may further disturb water supply for humanitarian purposes. This chapter discusses some examples from northern and eastern Africa and the Middle East, presents possible technical solutions that could mitigate such a situation, and provides recommendations concerning research methodology and management solutions

Insémination artificielle équine - Guide pratique

Mention d'édition : 3.edNational audienc

Karst waters in potable water supply: a global scale overview

Karst aquifers are one of the main potable water sources worldwide. Although the exact global karst water utilisation figures cannot be provided, this study represents an attempt to make an upgraded assessment of earlier and often circulated data. The main objective of the undertaken analysis is not only to provide an assessment of the utilisation of current karst aquifers, but also to estimate possible trends under various impact factors such as population growth or climate changes. In \u3e 140 countries, different types of karstified rocks crop out over some 19.3 × 106 km2, covering \u3e 14% of ice-free land. The main ‘karst countries’, those with \u3e 1 × 106 km2 of karst surface are Russia, USA, China and Canada, while among those with \u3e 80% of the territories covered by karst are Jamaica, Cuba, Montenegro and several others. In contrast, in a quarter of the total number of countries, karstic rocks are either totally absent or have a minor extension, meaning that no karst water sources can be developed. Although the precise number of total karst water consumers cannot be defined, it was assessed in 2016 at approximately 678 million or 9.2% of the world’s population, which is twice less than what was previously estimated in some of the reports. With a total estimated withdrawal of 127 km3/year, karst aquifers are contributing to the total global groundwater withdrawal by about 13%. However, only around 4% of the estimated average global annually renewable karstic groundwater is currently utilised, of which \u3c 1% is for drinking purposes. Although often problematic because of unstable discharge regimes and high vulnerability to pollution, karst groundwater represents the main source of potable water supply in many countries and regions. Nevertheless, engineering solutions are often required to ensure a sustainable water supply and prevent negative consequences of groundwater over-extraction