Water Use in Agriculture

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Introduction

While 2 litres of water are often sufficient for daily drinking, it takes about 3,000 litres to produce the daily food needs of one person. Around 70 percent of freshwater withdrawals go into agriculture. The uses within the sector are very diverse and include mainly irrigation, pesticide and fertilizer application, and sustaining livestock. Further along the value chain, water is used for food preservation (crop cooling, for example) and processing. Water use in agriculture not only consumes resources quantitatively, but also pollutes the valuable resource with pesticides and fertilizers.

With a growing food demand (especially for water-intense products), agricultural production will need to expand by 70 percent by 2050. Given that irrigated agriculture can be up to twice as productive as rainfed cultivation systems, it is certain that water consumption for agriculture will keep growing. This will allow using land more efficiently, allow for more secure crop diversification, and provide an important buffer against climate variability.

While water use increases yields considerably, it is also associated with negative environmental impacts. Unsustainable resource use can lead to a reduction in water flows, changes in downstream access to water, increased soil salinity or reduction of wetlands that provide important ecological functions for biodiversity, nutrient retention, and flood control. Furthermore, the impacts of climate change are already affecting irrigated agriculture as water demand is increasing, while its availability is becoming more limited where irrigation is most needed.

Incentives created through appropriate policies ensure effective governance and empower farmers to conserve biodiversity, protect ecosystems and minimize environmental impacts. Effective governance takes place through irrigation institutions, who must respond to the needs of farmers. The reliable delivery of sufficient water, achieving efficiency and equity in access, are some of the main targets here. This will also require changes in attitudes among farmers, as well as investments in infrastructure modernization, institutional restructuring, and the upgrading of the technical capacities of farmers and water managers. Agriculture is a major sector of intervention in the nationally determined contributions to the mitigation of climate change, and increasing the efficiency of water use is key for both climate change adaptation and mitigation.

Drip irrigation (GIZ/Böthling).

Sustainable Water Resource Management

Appropriate water resource management strategies allow for the conservation of water and energy while increasing production. These include for example irrigation scheduling or crop specific irrigation management, which can be done by using tools like the Water Requirement Tool or the Soil Tool available on the SPIS Toolbox on Solar Water Irrigation Systems. By using renewable energy for water pumping, farmers can reduce their costs significantly while using climate friendly technologies. However, there are arguments against the utilisation of solar powered irrigation systems concerning groundwater over-exploitation. Several parameters should be evaluated before starting any project concept, including water quality and quantity, recharge capacity, composition of the geological substrata, rainfall patterns, evapotranspiration and runoff, topography and land use mapping. In order to provide an efficient irrigation system, crop water requirements and water source characteristics should be known thoroughly before configuration. Read more…

Understanding the Local Water Resources

Using agriculture water efficiently cannot only save water but also energy resources while improving yields. For this, understanding the local water resources is fundamental. For example, the type of water source determines the extraction method, which varies along surface water, groundwater or non-conventional water. The latter only provides one percent of agriculture water worldwide and includes treated wastewater and desalinated water, which is especially used in the Mediterranean, Middle East, and Andes regions, or on islands, and involves the use of specific technologies, which can also be run on renewable energy.

Another important factor is the elevation or depth of the water body. This determines whether water can be delivered under pressure, which is particularly relevant for surface water, and allows knowing if gravity alone can support pressurised irrigation systems or if it needs to be supported through pumps. Groundwater depth is decisive for the size of the pump and the associated costs. Read more…

Understanding Groundwater

Groundwater is the water found underground in the cracks and pores in soil, sand and rock, called aquifer. It is naturally recharged by precipitation or by infiltration from other water bodies. The underground water movement from areas of recharge to areas of aquifer discharge is called groundwater flow. This occurs generally at low velocities through pore spaces and fractures in rock materials and depends on the geological composition of the aquifer. Groundwater levels may vary seasonally and annually and are usually high after the wet and low at the end of the dry season. Different types of agricultural activities may affect the recharge process negatively, reaching from soil sealing to soil compaction due to the use of heavy machinery, which avoid water infiltration. But also crop choice and vegetation cover can influence infiltration patterns. Regulative measures can help overcoming groundwater shortages and allow sustainable water resource management. Read more…

The module Safeguard Water of the SPIS Toolbox aims to introduce groundwater management and the principles of sustainable water management. It reviews the risks and impacts related to groundwater resource depletion and aims sensitize planning institutions and future users of a (solar powered) irrigation system for a responsible and sustainable utilization of water sources. Further, this module provides a practical guideline for the integration of water management into the planning and operation of irrigation systems. Read more…

Assess Environmental and Socio-Economic Impacts of Irrigation

While water quantity is key to guarantee long-term sustainability and further determines which crops and which irrigation systems are most suitable given environmental (climate, soils, and landscape) and agricultural context, water quality has a significant influence on crop suitability. The presence of certain elements in the soil in combination with a specific irrigation system can affect some plants either positively or negatively and further lead to environmental damages in the agro-ecosystem. Read more…

Irrigation Efficiency Tips

The wise use and conservation of irrigation water is essential, as it is not only a limited and energy consuming resource (energy is needed for water extraction, preparation, treatment, etc.), but also competes with surrounding ecosystem water requirements. Measures that allow improving irrigation efficiency include

•  mapping the optimal placement of irrigation piping, which helps fulfilling the soil and crop water requirements;
  
• preservation and integration of large trees within the crop area, which not only provide shade and thus slow down evaporation processes, but also enhance water availability in the crop rooting zone;
  
•  soil testing, in order to determine soil moisture content and field capacity;
  
• irrigation scheduling, based on soil-plant or atmosphere measurements improves yields and decreases water use;
  
• mulching, as an effective technique to reduce evaporation of soil moisture and protects the soil against extreme temperatures and compaction, acting additionally as a soil conditioner;
  
• intercropping, producing higher yields by making use of resources or ecological processes that would otherwise not be utilized;
  
• rainwater catchment, avoiding soil erosion and improving groundwater recharge; monitoring water consumption regularly;
  
• and improving furrows and avoiding evaporation by covering water storage and water conveyance systems.
  

Irrigation efficiency can only be ensured through active and regular monitoring. Any improvement measure should be scrutinized carefully before implementation and baseline information captured. Read more…

Publications & Tools

A Comprehensive Assessment of Water Management in Agriculture

The Comprehensive Assessment of Water Management in agriculture is a critical evaluation of the benefits, costs, and impacts of the past 50 years of water development, the water management challenges communities face today, and the solutions people have developed around the world. This assessment describes key water-food-environment trends that influence our lives today and uses scenarios to explore the consequences of a range of potential investments. It aims to inform investors and policymakers about water and food choices considering such crucial influences as poverty, ecosystems, governance, and productivity. It covers rainfed agriculture, irrigation, groundwater, marginal-quality water, fisheries, livestock, rice, land, and river basins. Read more…

Navigating Pathways to Reform Water Policies in Agriculture

This report offers a guide on potential reform pathways towards sustainable agriculture water use, based on a thorough review of selected past water and agriculture reforms and extensive consultation with policy experts. A theory of change is developed that emphasises the importance of flexibility in the timing and design of reform processes to achieve practical and effective policy changes. Governments should prepare future reforms via continued research, education, and governance efforts, to help take advantage of reform opportunities when the timing is right. Five necessary conditions are identified for a successful reform process: support evidence-based probem definition, objective setting and evaluation; ensure that governance and institutions are aligned with the policy change; engage stakeholders strategically and build trust; rebalance economic incentives to mitigate short run economic losses; and define an adjustable smart reform sequencing that provides flexibility in the long run. These conditions are found to be necessary to implement four challenging policy changes: charging water use in agriculture; removing subsidies that negatively impact water resources, regulating groundwater use and addressing nonpoint source pollution. Read more…

Towards a Water and Food Secure Future – Critical Perspectives for Policy-Makers

This White Paper by FAO provides policymakers with an overview of the main trends for agriculture water use, with particular emphasis on crop and livestock production. By 2050 agriculture will remain an important determinant of economic growth, poverty reduction, and food security, despite the proportional decline of agricultural revenues in national gross income. Water use in agriculture will remain substantial, irrigated areas will expand and competition for water will increase in all sectors. Despite overall supplies of land and water will most likely be enough to achieve global food production goals in 2050, poverty and food insecurity will remain pressing challenges in several regions. While water will be sufficient to satisfy global food demand, an increasing number of regions will have to cope with growing water scarcity due to increasing competition. The outlook for 2050 provided by this paper reveals the demand for innovative and effective governance mechanisms to mitigate the impacts of growing water shortages. Investments in water technologies and infrastructure will be required for efficient water use, protecting food security and natural resources. Read more…

SPIS Toolbox on Solar Powered Irrigation Systems

The Toolbox on Solar Powered Irrigation Systems (SPIS) is designed to enable advisors, service providers and practitioners in the field of solar irrigation to provide broad hands-on guidance to end-users, policy-makers and financiers. Risks related to system efficiency, financial viability and the unsustainable use of water resources can thus be minimized. The Toolbox comprises informative modules supplemented with user-friendly software tools (calculations sheets, checklists, guidelines). Modules and tools touch upon assessing the water requirements; comparing the financial viability; determining farm profitability and payback of investment in SPIS; sustainably design and maintain a SPIS; highlight critical workmanship quality aspects and many more. Being mainly conceived for the design and implementation of solar powered irrigation systems, most tools can also assess other types of irrigation systems. Read more…

Some of the tools are specifically suitable for environmental impact assessment, for crop water requirement calculation and to ensure sustainable and efficient water use. These are not coupled exclusively to SPIS deployment and can be used to assess other irrigation irrigation systems.

Impact Assessment Tool

This excel-based tool is structured as a questionnaire which provides the end user with a socio-economic and environmental impact assessment based on the score reached after answering questions about population change and migration, women’s role, minority and indigene groups, income and amenities, regional effects in country, user involvement, natural resources and environment. Read more…

Water Requirement Tool

This tool serves to calculate the water requirement for crops and livestock according to geographic position and rainfall patterns at the location. After entering all data about cultivation area of each crop, number of livestock head, main soil properties and rainfall and temperature patterns, it provides a summary compiling the main water requirements throughout the whole year, distinguishing between irrigation and water from rainfall. Read more…

Water Resource Management Checklist

This tool helps to get a rough idea of the availability of water resources. This tool guides the user through a checklist form where water resource records and its sustainable management can be checked. Read more…

Soil Tool

Determining agriculture water needs requires knowledge about the soil structure. Knowing the percentage of the different particle sizes (sand, silt and clay) allows knowing more about some relevant soil characteristics: particle size distributions provide information about the water-holding capacity, the ability to store plant nutrients, aeration, organic matter levels, internal drainage, compactability, susceptibility to wind and water erosion, pollutant leaching and many more. This excel-based tool includes a simple soil texture calculator which allows determining the percolation rates and derive optimal irrigation scheduling for a selected crop. By introducing the respective percentages of different particle sizes it can estimate the net and gross irrigation depth, the irrigation water need, the number of irrigation applications and the irrigation interval in days. This again is useful for calculating the water storage tank size. Read more…

Pump Sizing Tool

Once crop and livestock water requirements are known, this tool allows calculating the pumping head and determining the most suitable pumping technology. It further calculates the energetic requirements and thus, the size of the solar panel required to power the pumping system. Input variables are pipeline diameter and length, amount and type of connectors, sustainable extraction rate, and expected water source yield, among others. This makes clear how important it is to thoroughly understand the water resources. Read more…

Water Risk Filter Tool

This online tool is developed by the World Wide Fund for Nature (WWF), and the German Development Finance Institution DEG. The Water Risk Filter tool empowers users to explore, assess, and respond to water risks around four focus areas: exploring, assessing, valuing and responding to risks. Read more...

Aqueduct Tools

Aqueduct’s tools map water risks such as floods, droughts, and stress, using open-source, peer reviewed data. Currently two tools are available: An Aqueduct Water Risk Atlas tool mapping and analyzing current and future water risks across locations and an Aqueduct Country Ranking''enabling comparisons of national and sub-national water risks. In addition two additional tools are to be launched focusing on the interconnection with food and agriculture; and flood risks. Read more...

CropWat - FAO

FAO CropWat is a computer program for irrigation planning and management which serves as a decision support tool. Developed by the Land and Water Development Division of FAO, CROPWAT 8.0 allows calculating crop water requirement and irrigation requirements based on soil, climate and crop data. In addition, the program allows the development of irrigation schedules for different management conditions and the calculation of scheme water supply for varying crop patterns. The tool can also be used to evaluate farmers’ irrigation practices and to estimate crop performance under both rainfed and irrigated conditions. Read more…

AquaMaps - FAO

AquaMaps is the FAO global online spatial database on water and agriculture. It makes accessible through a simple interface regional and global spatial datasets on water resources and water management considered as a standard information resource, produced by FAO or by external data providers. Read More ...

AquaCrop - FAO

AquaCrop is the crop growth model developed by FAO to address food security and assess the effect of the environment and management on crop production. The tool simulates the yield response of herbaceous crops to water and is particularly well suited to conditions in which water is a key limiting factor in crop production. AquaCrop includes reference manuals and training handbooks and a series of 43 tutorials to learn how to use it. Read more…

WaPOR – FAO

Achieving Food Security in the future while using water resources in a sustainable manner will be a major challenge for us and the next generations. Agriculture is a key water user and a careful monitoring of water productivity in agriculture and exploring opportunities to increase it will be required. FAO has developed WaPOR, a publicly accessible near real time database using satellite data that will allow monitoring of agricultural water productivity. Read more…

Groundwater Modelling with MODFLOW

USGS MODFLOW is the USGS's modular hydrologic model. MODFLOW is considered an international standard for simulating and predicting groundwater conditions and groundwater/surface-water interactions. MODFLOW 6 is presently the core MODFLOW version distributed by the USGS. The previous core version, MODFLOW-2005, is actively maintained and supported as well. Read more…