I advise you to see these two links

https://www.eolss.net/sample-chapters/c07/E2-16-02-02.pdf

https://foodwise.org/articles/10-ways-farmers-are-saving-water/

In fact among the agronomic measures, there are contour farming, vegetative barrier, strip cropping, off-season tillage in light soils, surface mulching, and adding pond sediment and organic matter into the soils. Some of the most important measures to practice water conservation in arid areas are the conjunctive use of surface and groundwater, the re-use of effluent, artificial aquifer recharge, and the utilization of sand storage dams to reduce evaporation. Rainwater harvesting is being practiced in India from the ancient times. Arid regions with extremes of the temperatures receive a meager amount of rainfall, and there is a great scope for the conservation and harvesting of rainwater. By increasing suitable vegetation on these lands so that soil erosion is avoided. ii. By increasing plantation at places that have some water resources. There are other kinds of water resources, such as soil water and phreatic water. Soil water depends on the water exchanges between rainfall, surface run-off, and groundwater in the soil, which are so complex that it is difficult to make a quantitative evaluation. The phreatic water can be found in deserts.

In various countries, they try to grow highly valuable crops in closed buildings and greenhouses (e.g. Cannabis or medicinal plants greenhouses). To further reduce costs governments could dilute the value of their currencies or subsidise production.

This is attached, a BOOK REVIEW devoted to the fundamental Water-Food Nexus in the Arid Region taking Tunisia as example. "National water security– Case study of an arid country, Tunisia, Ghislain de Marsily, Euro-Mediterranean Journal for Environmental Integration (2019) 4:11". The Previous French version of the book is available in chapters on:

https://www.researchgate.net/publication/356650449_Securite_Hydrique_de_la_Tunisie_Preface_Introduction https://www.researchgate.net/publication/356662490_Les_Problemes_de_l'Eau_dans_le_Monde

https://www.researchgate.net/publication/356663902_Cinquante_ans_de_politiques_de_l'eau_1960-2010

https://www.researchgate.net/publication/356665641_Le_Bilan_Hydrique_National

https://www.researchgate.net/publication/356666107_Le_bilan_Hydrique_Integral_Eau_Bleue_Eau_Verte_et_Eau_Virtuelle

https://www.researchgate.net/publication/356666288_La_gestion_de_la_demande_en_eau_et_les_ressources_non_conventionnelles

https://www.researchgate.net/publication/356674959_Securite_Hydrique_de_la_Tunisie_les_questions_en_debat

https://www.researchgate.net/publication/356678805_Securite_Hydrique_de_la_Tunisie_Conclusion_Postface

Abstract:

This is a short review of a book recently published by Springer entitled: National water security–Case study of an arid country, Tunisia; by Mustapha Besbes, Jamel Chahed, and Abdelkader Hamdane. It shows that around 40% of the water consumed in Tunisia is imported as virtual water, used in other countries to produce goods. Water security is thus strongly linked to food security, but includes protection of the resource from pollution, accidents, malicious acts, and anticipation of extreme hydrologic events. A detailed analysis is made of water consumed by agriculture for food production by both rain-fed and irrigated crops, from which a surprising conclusion can be drawn: the major part of Tunisian food production is provided by rain-fed agriculture. Therefore, optimizing the yield of rain-fed agriculture becomes a priority. Alternative water resources are also discussed, as well as water governance. Results can be integrated into the policy choices related to sustainable water management which should be made in the future in Tunisia, and other regions where water is scarce.

Keywords Water resources · Water demand · Water scarcity · Arid zone · Blue water · Green water · Virtual water · Food production · Irrigation

This paper, tries to answer the following question: is it possible to predict Water Resources only with GCMs, without downscaling, and what would be the resulting uncertainties? "Besbes M., Chahed J. "Predictability of water resources with global climate models. Case of Northern Tunisia", Published online: 12 June 2023, Les Comptes Rendus. Géoscience". Available on:

Article Predictability of water resources with global climate models...

Abstract: The objective of the research is to explore the predictability of water resources directly with GCMs by analysing long-term effects of climate change on Northern Tunisia’s blue and green water. Hydrologic impacts rely on a rainfall-runoff lumped model using outputs of CMIP6 GCMs within the framework of the ssp2-45 scenario. Among the 30 CMIP6 models, the composite cnrm-esm2-1 and fgoals-g3 best restore observed runoff from 1995 to 2014 and give the best GCM. Hydrologic projections 2015–2100 show significant drops in rainfall (9%), runoff (21%), groundwater recharge (15%), as well as for green water (6%). The results show that the use of raw GCMs predictions on large basins is possible and provides precisions comparable to what is produced when using Regional Climate Models in medium size basins.

Dr Jamel Chahed thank you for your contribution to the discussion

Some of the most important measures to practice water conservation in arid areas are the conjunctive use of surface and groundwater, the re-use of effluent, artificial aquifer recharge, and the utilization of sand storage dams to reduce evaporation.In fact among the agronomic measures, there are contour farming, vegetative barrier, strip cropping, off-season tillage in light soils, surface mulching, and adding pond sediment and organic matter into the soils. Some desert plants store water in their leaves, stems, or roots. Others have thick, waxy skin that helps prevent water loss. Some desert plants have small leaves that help reduce evaporation. Others have deep taproots that help them reach the underground water sources. Groundwater is one of the most important water sources in arid and semi-arid areas. With the increasing world population and the water demand for agriculture and urban use, the need for water resources has increased, especially in arid and semi-arid regions, where groundwater resources play a significant role. By increasing suitable vegetation on these lands so that soil erosion is avoided and by increasing plantation at places that have some water resources. Arid and semi-arid regions are characterized by hostile environmental conditions that include low and erratic rainfall, high wind velocity, intense solar radiation and high potential evapotranspiration during most parts of the year. The semiarid and subhumid zones of the world are often considered dryland farming regions. Agriculture in arid lands is largely confined to grazing by livestock, and even much of the land in semiarid regions is used only for grazing.

Attached is a BOOK REVIEW by Ghislain de Marsily (Académie des Sciences, Paris) devoted to the fundamental Water-Food Nexus in the Arid Region taking Tunisia as an example. "National water security– Case study of an arid country, Tunisia (Authors: Besbes, Chahed Hamdane), Euro-Mediterranean Journal for Environmental Integration (2019) 4:11". The Previous French version of the book is available in chapters on:

https://www.researchgate.net/publication/356650449_Securite_Hydrique_de_la_Tunisie_Preface_Introduction https://www.researchgate.net/publication/356662490_Les_Problemes_de_l'Eau_dans_le_Monde

https://www.researchgate.net/publication/356663902_Cinquante_ans_de_politiques_de_l'eau_1960-2010

https://www.researchgate.net/publication/356665641_Le_Bilan_Hydrique_National

https://www.researchgate.net/publication/356666107_Le_bilan_Hydrique_Integral_Eau_Bleue_Eau_Verte_et_Eau_Virtuelle

https://www.researchgate.net/publication/356666288_La_gestion_de_la_demande_en_eau_et_les_ressources_non_conventionnelles

https://www.researchgate.net/publication/356674959_Securite_Hydrique_de_la_Tunisie_les_questions_en_debat

https://www.researchgate.net/publication/356678805_Securite_Hydrique_de_la_Tunisie_Conclusion_Postface

Abstract:

This is a short review of a book recently published by Springer entitled: National water security–Case study of an arid country, Tunisia; by Mustapha Besbes, Jamel Chahed, and Abdelkader Hamdane. It shows that around 40% of the water consumed in Tunisia is imported as virtual water, used in other countries to produce goods. Water security is thus strongly linked to food security, but includes protection of the resource from pollution, accidents, malicious acts, and anticipation of extreme hydrologic events. A detailed analysis is made of water consumed by agriculture for food production by both rain-fed and irrigated crops, from which a surprising conclusion can be drawn: the major part of Tunisian food production is provided by rain-fed agriculture. Therefore, optimizing the yield of rain-fed agriculture becomes a priority. Alternative water resources are also discussed, as well as water governance. Results can be integrated into the policy choices related to sustainable water management which should be made in the future in Tunisia, and other regions where water is scarce.

Climate Change & Agriculture in the Arid Region, an example of Tunisian Olive Groves adaptation to bioclimatic conditions: The olive tree has been cultivated in Tunisia since Roman times under different bioclimatic conditions in exclusively rainfed groves: in the south with less than 250 mm of rainfall and in the north with more than 600 mm [1]. Apart from the different olive tree species in each of the regions, it is clear that the density of olive trees is strictly correlated with rainfall, ranging from 16 olive trees per hectare in the South to nearly a hundred olive trees per hectare in the North; so that it is possible to faithfully superimpose the density map of olive trees on the map of isohyets. Empirically, over millennia and outside of any protocol or procedure, the peasants have naturally adapted to the natural conditions of the environment, and it is difficult to imagine that things can be otherwise.

[1]

Book National Water Security, Case Study of an Arid Country: Tunisia

See also:

https://www.researchgate.net/post/Water_Footprint_Water_Colors_Blue_Water_Green_Water_Grey_Water_Virtual_Water

https://www.researchgate.net/post/Climate_Change_Water_Resources