Chapter: Civil - Water Resources and Irrigation Engineering - Irrigation Water Management

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Need for optimum use of water

Water scarcity, together with the increasing global demand for water in many sectors, including agriculture, has turned out to be a global concern.

IRRIGATION WATER MANAGEMENT

 

Need for optimum use of water

 

Executive Summary

 

Water scarcity, together with the increasing global demand for water in many sectors, including agriculture, has turned out to be a global concern. A growing world population and the adverse impacts of climate change lead to an increasing competition for water use by industrial and domestic uses and agriculture for food production. Irrigated agriculture has an important role in total agriculture and provides people all over the world with a wide range of agricultural products essential for life. Effective water management is the only way to optimise irrigated agriculture and limit water overexploitation. Various irrigation and moisture control techniques have been adopted to improve water use efficiency for crop production, reduce the damage caused by drought and the water use for agriculture.

 

Introduction

 

About 3% of the world water is fresh water only. But a large part is stored in polar ice caps, and only 0.5% are easily accessible freshwater (see factsheet [1913the water cycle). The 0.5% of world water reserves, which are available to maintain life, endure a steadily increasing pressure of human activity by agricultural food production, industry or a continuously growing urbanisation. The water use in agriculture is a key issue for the 21st century. Without improvements, will neither the consequences of climate change be manageable nor will the demand of two or three billion additional people for food be met.

 

The global signs for future water conflicts are:

 

Freshwater consumption enlarged twice as fast as population growth in the 20th century. Approximately 70% of all water used by people is for irrigating crops.Groundwater supplies in major agricultural regions are being overdrawn and depleted much faster than their regeneration by

 

precipitation.Drought prompts even greater tapping of stored supplies while dramatically reducing the rate of replacement. The incidence of drought may be increasing. Furthermore, the increase in surface temperatures, and the prospect of further warming, will put extra stress on crops and further enhance demands for water. By 2025, 1.8 billion people will live in a situation of absolute water shortage. 

 

The Role of Agriculture within Future Water Uses:

 

 

 

The extent to which the agricultural sector contributes to water scarcity and the degrading some of the world‘s highest quality surface and groundwater is responsible for the largest water withdrawals and contributes to conditions of local absolute water scarcity

 

and future water conflicts  yet of course the whole humanity depends on agriculture. The way we produce our food uses 70'90% of the available fresh water, returning much of this water to the system with additional nutrients and contaminants. It is a domino effect, as downstream agricultural pollution is exacerbated by human and industrial waste. This wastewater and the way we currently deal with it contaminate freshwater and coastal ecosystems; threaten food security, access to safe drinking water and results in major health risks and environmental degradation. Out of all sectoral water uses, agriculture, together with industrial water use, has the largest capacity to contribute to integrated water resources management through improved agricultural practices and methods. Furthermore, agriculture has to account for its water use in economic and environmental terms. Overall, managing the demand for agricultural water use must be focus on improving water use efficiency and agricultural productivity from the farms to the market. This includes an improved farm water management, better irrigation system performance and adjustments of national water and irrigation policies.

 

Typically, only 30 to 50 % of the water applied for irrigation is actually used by crops. Hence, there is still a large potential for improving management practices and technology for irrigated and rainfed farming systems, increasing the productivity of the water used.


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