12 Water Demand
Meenakshi Suhag
Objectives:
1. Concept of water demand
2. Factors affecting water demand of a country
3. The consequences of unsustainable growth on water demand
4. Impacts of increased global demand
5. Water demand management
Concept map
12.1 Introduction
12.1. 1 Water availability and demand
Although water is a copious and renewable natural resource covering two thirds of the planet, a very minute proportion of this is effectively available for human use (Postel et al., 1996).Two third of it is locked up in glaciers and permanent snow cover, remaining one third is distributed regionally with wide disparities. Water has multifunctional roles. Water is considered as the most significant resource for life as it is linked to the well-being of human societies that need it for industrial activities, agriculture, drinking, hygiene and recreation (Grey and Sadoff, 2007).Water is always an important element in Hindu mythology and it has been enjoying the most respectable and unique status in India. Religious structures are always placed near water bodies. The rivers in India are considered Goddesses and most of Hindu rituals move around water for the religious ceremonies be it birth, marriage, death. Historically, towns and cities have flourished on the banks of water bodies and these have played an important role in their growth and development. India’s water bodies are extraordinarily diverse – ranging from lakes and ponds to marshes, mangroves, backwaters and lagoons. Water is used for energy extraction, conversion, power generation and transport. At the global level and on an annual basis, enough freshwater is available to meet such demand, but spatial and temporal variations of water demand and availability are large, leading to water scarcity in several parts of the world during specific times of the year (Mekonnen and Hoekstra, 2016).
Per capita water demand is defined as the annual average daily requirement of water of one person it includes domestic requirement, institutional needs, water meant for public use (such as street washing, flushing of sewers etc.), industrial and commercial use and fire fighting, etc. The average daily per capita demand (lpcd) can be written as:
As per the international norms, if per-capita water availability is less than 1700 m3 per year then the country is categorized as water stressed and if it is less than 1000 m3 per capita per year then the country is classified as water scarce. In India per capita surface water availability in the years 1991 and 2001 were 2309 and 1902 m3 and these are projected to reduce to 1401 and 1191 m3 by the years 2025 and 2050 respectively. The total utilizable water resources of India, according to the CWC are 1110 BCM.
The various types of water demands (Figure 12.1), which a Country may have, may be divided into (I) Domestic water demand includes water for residential uses like drinking, bathing, cooking, washing etc, (II) Industrial and commercial water demand includes water needed by various industries, commercial institutions and buildings (III) Demand for public uses includes amount of water for public utility excluding domestic (IV) Fire demand and (V) Water required compensating losses in wastes and thefts. Globally, domestic water use alone has grown on average by 2.2% every year for the last 60 years (Flörke et al., 2013). Currently, cities estimate that as much as 40-50 per cent of the water is ‘lost’ in the distribution system.
Every human being should have access to safe drinking water. Generally, water availability of more than 1700 m3/person/year is considered acceptable, while below this level water scarcity occurs regularly. In areas with less than 1000 m3/person/year, the lack of water limits human activities and business operations, while less than 500m3/person/year is viewed as a main constraint to human life (Mueller et al., 2015).The World Health Organization specifies 50 litres per person per day as the recommended ‘intermediate’ quantity needed to maintain health, hygiene and for all domestic uses (WHO, 2003). As per the Bureau of Indian Standards (BIS), IS:1172-1993, minimum water supply of 200 litres per capita per day (lpcd) should be provided for domestic consumption in cities with full flushing systems. Indian Standards 1172-1993 also mentions that the amount of water supply may be reduced to 135 lpcd for the LIG and the economically weaker sections (EWS) of the society and in small towns (Modi, 1998; Shaban and Sharma, 2007).
According to the 12th Five Year Plan the country’s water budget, based on Ministry of Water Resources (MoWR) estimates, shows utilizable water of 1123 billion cubic metres (BCM) against a current estimated demand of 710 BCM. The Standing Committee of the Ministry of Water Resources estimates that this water demand will rise to 1093 BCM by 2025.
12.2 Global water demand-Some facts
In the present developmental era, the utilization of water has increased many folds in agriculture, industry and domestic purposes. By 2050, the world’s population is expected to grow to 9 billion and combined with increased wealth and growing urbanization and industrialization worldwide, the demand for water is accelerating dramatically (Bakker, 2013). Global water demand (in terms of water withdrawals), illustrated in Fig. 12.2 , are projected to increase by 55% by 2050, mainly because of the growing demands from manufacturing (400%), thermal electricity generation (140%) and domestic use (130%). As a result, freshwater availability will be increasingly strained over this time period, and more than 40% of the global population is projected to be living in areas of severe water stress by 2050.
12.3 Factors affecting water demand and consequences of unsustainable water demand
The increasing world population, improving living standards, changing consumption patterns, and expansion of irrigated agriculture are the main driving forces for the rising global demand for water (Vorosmarty et al., 2000 and Ercin and Hoekstra, 2014).
12.3.1 Population
Regarded as a driving force in the demand for water, food and energy, the world’s population has been increasing rapidly since the beginning of the 20th century, from about 1.6 billion in 1900, 2.5 billion in 1950, 6.1 billion in 2000, to 7.0 billion in 2011, according to estimates by the United Nations Population Fund (REN21).Increasing populations enhanced per capita water use. Drinking water is demanded for different purposes and it is continuously growing. Population, commercial units, educational, health institutions have increased in the city. Globally,3.6 billion people live in urban areas (UNPD, 2011). The next few decades will be the most rapid period of urban growth in human history, with 2.6 billion additional urban dwellers expected by 2050 (UNPD, 2011). All these new urban dwellers will need water. Currently around 1.2 billion people in the world have limited access to drinking water, which means that one in six people do not have drinking water for your needs, because the demand for water exceeds the supply (Rogers, 2008).The daily supply of drinking water to city population is inadequate and there is a mismatch between demand and supply. Water supply is disrupted regularly in the city. It gets disrupted because of repairing, burst and joining new pipeline etc. Irregularity of water supply forces urban people to store water in iron, plastic drums or large earthenware. Every day they struggle to obtain few litres of water. Urban water demand varies with a range of factors (See Figure 12.3) including Demographic factors (Fox et al., 2009), Climatic factors (Cole and Stewart, 2013) and Socio-economic factors (Qi and Chang, 2011). According to NCIWRD, the population of India is expected to be 1333 million and 1581 million in high growth scenario by the year 2025 and 2050 respectively. This eventually would be major cause of water crisis and water quality deterioration (Bhattacharyya et al., 2015). Meeting the water demand of a growing population at the existing level of per capita water use requires increasing water withdrawal.
12.3.2 Agriculture and Industrial growth
Agriculture industry is the largest user of fresh water as water withdrawals for irrigation account for 70% of all water use globally (Fisher et al., 2007). Today 40% of the world’s food comes from the 18% of the cropland that is irrigated. Irrigated areas increase almost 1% per year (Jensen, 1993) and the irrigation water demand will increase by 13.6% by 2025 (Rosegrant and Cai, 2002). Continued increase in demand for irrigation water over many years has led to changed water flows, land clearing and therefore deteriorated stream water quality (Hanjra and Qureshi, 2010). Industrial water demand has been increasing with the pace of industrial development. In India, industry is the second highest consumer of water. The main sources of water for the industrial sector are groundwater and surface water. Large water consumption relative to water availability results in decreased river flows, mostly during the dry period, and declining lake water and groundwater levels. India is the largest user of ground water in the world. Over 90% of rural domestic water, around 50% of urban domestic water and 60- 70% of agriculture are ground water dependent. This has resulted in the overexploitation and acute depletion of the resource in many parts of the country. Due to paucity of surface water, there is dependency on ground water resources to a great extent in arid and semi-arid region in India. Indiscriminate tapping of ground water for agricultural production is the main reason for the scarcity of ground water resources in different parts of Rajasthan.
12.3.3 Climate Change
As climate change becomes more prevalent globally, the future availability of fresh water for human consumption, agricultural production, and manufacturing becomes more uncertain. Furthermore, changing climatic conditions are expected to aggravate the pressures on water supply systems. The Intergovernmental Panel on Climate Change reported in its 2014 assessment that it is virtually certain that climate change will reduce renewable water resources substantially in most dry, subtropical regions, resulting in scarcity of drinking water and biomass-based fuels. Depending on the crop (among corn, apples, and alfalfa), irrigation requirements were projected to increase by 40–250% by the end of the 21st century, attributed directly to decreases in growing season water availability, increases in evapo-transpiration, and changes in crop phenology (Woznicki et al., 2015).
12.4 Framework of action
12.4.1 Water Demand Management
Demand management is defined as the development and implementation of strategies aimed at influencing demand, so as to achieve efficient and sustainable use of a scarce resource. Besides efficiency, it should promote equity and environmental integrity. Because water resources issues are not isolated in one sector, but are shared by agriculture, sanitation, industry, urban development, etc., and create repercussions in the economic, social, and environmental spheres, integrated management is key.
12.4.2 Integrated approach to water demand management
Population growth, increasing urbanization, industrial growth, climate change, and deteriorating and insufficient water infrastructure are five key macro trends that are simultaneously impacting water supply. In order to cope with these challenges and to secure adequate water supply, the implementation of integrated management options that include identifying new water sources, increasing the efficiency of existing water supply systems (Postel, 2000) and managing water demand (Arbues et al., 2003) is critical. Water demand for everyday domestic uses is met through the use of efficient technologies, effective and equitable tariffs. Implementation and enforcement of water use regulation, in combination with the development and adoption of water efficient manufacturing processes helps in limiting the water demand for industry, prompting economic development.
12.4.3 Water demand forecasting
Water demand can be forecast by a number of methods such as classified households method (CHM) (also known as unit water demand analysis), multivariate regression (MVR), univariate time series analysis (using an autoregressive integrated moving average or ARIMA model), and others (Donger et al., 2014). MVR allows forecasts to be based on the correlation demand has with demographics, weather, and tariffs (Bougadis et al. 2005; Polebitski &Palmer 2010). ARIMA models use patterns of past demand to forecast future demand (Caiado 2010).
12.4.5 Community Intervention programme
The water supply infrastructures of the public water supply departments are of paramount importance and can further be strengthened. It should be equipped with modern technology. Preparedness is necessary to provide bulk quantity of purified water needed especially for the large BPL population of the country is essential to water utilities, both for day-to-day operations and for long-term planning. In recent years, another factor has emerged which can be harnessed to reduce urban water use. This is termed as ‘‘community intervention programmes” and relates primarily to the employment of water saving measures such as water efficient appliances and rainwater tanks for outdoor water use in homes (Beal et al., 2012). These water saving measures are likely to gain increasing importance in managing urban water demand. Moreover, it is found that community intervention and water pricing policy in conjunction can play an important role in managing water demand in order to maintain the balance between water demand and supply (Haque et al., 2015).It is essential that the current and future path of growth and development in India encompasses the strategies to address the water scarcity involving interventions like water demand management, water conservation, enhancing water use efficiency etc., through a participatory and integrated approach. Kayaga et al. (2007) emphasize the need to apply water demand management at the end-use level, in addition to the supply-side. Motivations for such are numerous: deferring and reducing capital works, and downsizing treatment plants and distribution upgrades; reduced cost of pumping due to decrease in frictional energy losses; and flexibility of demand-side solutions in terms of adjusting a given program to meet changing circumstances (Sahely and Kennedy, 2007).
12.5 Summary
Water is one of the most crucial and essential natural resources for sustaining life. In the coming decades it is likely become critically scarce due to rapid increase in population, continuous increase in its demands for agriculture, industries, commercial development and expanding economy of the country. The use of various measures to reduce the demand or water use likely to conserve the existing limited water supply through the practices which require less water and reduces the wastage and misuse of water. These measures are concentrating towards making the existing insufficient supply source (whatever it may be) serve water users as effectively as possible and a balance between supply and demand to be achieved. As per the research the various techniques used for the same are based either on giving economic incentives or penalties or involve rationing, legal sanctions and various other types of social or political pressures. The water supply infrastructures of the public water supply departments are important and can further be strengthened with modern technology.
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