Water scarcity occurs when demand for freshwater exceeds supply and since over the last century water use has been growing at more than twice the rate of the global population. There is an inevitable consequence that there is going to be an increase in the number of regions that are reaching a point at which water services can no longer be delivered sustainably. It is expected that by 2025, almost 2 billion people will be living in countries or regions with “absolute” water scarcity (less than 500 cubic meters per year per person), and two-thirds of the world population could be under “stress” with between 500 and 1000 cubic meters per year per person. This problem is exacerbated by increasing social, cultural, economic and environmental aspects, such as the rapid rates of urbanization, demands from energy production, ecosystems and biodiversity requirements, climate change, and the increased consumption of calories which accompany improved standards of living.
Author
Doug Hobbs
Taking into consideration the situation in Pakistan. There is a ‘Timebomb’ warning for water crisis. Pakistan is the third most water stressed country in the world, with current per capita annual water availability of 1,017 cubic meters. This follows a continued downward trend, 3,950 cubic meters in 1961 and 1,600 cubic meters in 1991 and 1,500 cubic meters in 2009. If this trend continues Pakistan will face absolute water scarcity by 2040 (IMF, UNDP). Pakistan has a growing need for food and would require doubling up its production by 2050 which is less than three decades away.
According to World Water, currently, 47% of the population of Pakistan is living in water-scarce areas.
Source: Water World
When working out a strategy for managing water resources it must be remembered that water is a critical input for agricultural production and plays a significant role in food security. As the global population continues to increase, and issues around increased consumption of calories and demand for more complex foods associated with improved quality of living, it is estimated that agricultural production will need to expand by about 70% over the next thirty years.
Currently around the world irrigated agriculture represents 20% of the total cultivated land and contributes 40% of the total food produced worldwide. It is recognised that irrigated agriculture is at least twice as productive per unit area as rainfed agriculture, which can allow for intensification of production as well as allowing for an increase in crop diversification. Globally however, agriculture already accounts for 70% of all freshwater use and in Pakistan, whilst contributing around a fifth to the national gross domestic product (GDP), it consumes about 95% of the available surface water. So, whilst freshwater use in agriculture is a critical factor to national economic security, as well as being critical for the nation’s food security, it is inevitable that this level of water consumption is not sustainable and as future demand across the all sectors increase, agriculture will be expected to significantly reduce its demands.
At first it may seem too big a task to sustainably maintain (and increase) levels of food production and crop diversity whilst being expected to reduce levels of water consumption. However, there are some areas where improvement in efficiency can be achieved. It is considered that 75% of the additional food we need in the near future could be met by bringing the production levels of the lowest yielding farms up to 80% of the highest-yielding farms on comparable land and one of the tools instrumental to achieving this is better water management. Improving the efficiency of water use in agriculture will be dependent on improving both off-farm and on farm systems. The off-farm conveyance of water requires investment in infra-structure to ensure efficient movement of water. For example, in Pakistan, 45% of the water diverted from the Indus water basin towards irrigating crops is lost before it reaches the field. In addition to the supply of water, the drainage of water from the fields must also be taken into consideration. The effects of diverting river flows for irrigation can have significant impacts on the hydrological balance of the area and as such it is important to ensure an efficient drainage system is in place to sustain irrigated agriculture. In Pakistan, irrigation systems have been developed without any provision for drainage from the fields which, in an area like the Indus Basin, leads to a rising water table which causes an increase in salinity resulting in lower crop yields and degraded water quality, which is clearly counter-productive.
About 70% of the world’s poor live in rural areas where livelihood options outside agriculture are limited and they rely primarily on rainfed farming for food. Improving on-farm water management through more efficient use of rainwater and supplemental irrigation (as well as increased understanding of the importance of good agricultural practices such as soil management, reducing land degradation and conservation tillage) can help them achieve the objective of increasing production to within 80% of the highest-yielding farms on comparable land, as well as giving them the security required to risk investing on other inputs such as fertilisers, improved varieties and consider moving away from the production of low value staple crops to the production of higher value crops such as fruits and vegetables.
Emergency solutions
To achieve the optimisation of irrigation on-farm, developing an understanding of the correct frequency and duration of watering is important as it ensures the correct amount of water is applied in the right place at the right time, increasing irrigation efficiency without compromising agricultural yield. It is also important to understand the physical, chemical and biological composition of the soil and working to improve soil health to maximise water retention and use by the crop. The application of precision irrigation technologies (making use of a wireless sensor network to specifically match soil and plant status and water needs) is a high-tech approach to ensuring the amount of water applied closely matches the crop requirement. However, it does not need to be high tech. It could be a matter of understanding water requirements by testing for soil moisture deficit, using the most appropriate equipment for irrigation and using an irrigation scheduling method or service to apply the correct amount of water. For example, in the Punjab region of Pakistan, it has been shown that a 25% water saving can be achieved and 15-20% increase in crop yields is possible by the application of processes that optimise irrigation.
Resolving the challenges of the future requires the applications of technology, development in knowledge exchange and improvements in off-farm water management. Current projections suggest it will be possible to feed a growing population with a greater variety of foods sustainably whilst making more water available for social, cultural, economic and environmental aspects