Reduce surface water abstraction with return

Reduce surface water abstraction with return

Category 01. Water flow quantity improvement

General description

There are many water uses with return: cooling water systems, hydroelectric power stations, agriculture, etc. To reduce surface water abstraction for hydropower and let more water flowing at the bypassed reaches, the first measure would be to decrease energy demands and use alternative energy sources. Environmental policies and agreements with energy companies are essential for achieve the environmental objectives.

Industrial water use efficiency can be increased with improvements in the design of water systems, reductions in water consumption (e.g. in pulp mills a reduction of water consumption results in increased potential for energy integration and energy saving (Wising et al., 2005)). These technical advances entail environmental and economic benefits (water and energy savings). Once-through cooling systems in indutry should be replaced by cyclical water cooling systems (which can consume 20 -30 % of the total water consumption of the industrial plant anyway) or air cooling systems (relatively expensive if compared to water cooling systems).

In agricultural water uses with returns it is necessary to reduce the water expend in irrigation, trying to satisfy the water needs of the crops and maximizing water use efficiency (WUE). Some studies have shown the suitability of WUE like an instrument for an efficient use of water. Since ET is linearly related to the amount of irrigation, it doesn´t happen the same with the grain yield (GY) (figure 1). A study developed in China North Plain revealed that higher irrigation decreased WUE and WUEet of crops (winter wheat), therefore excessive irrigation might not produce greater yield or optimal economic benefit (Sun et al., 2006) but a depletion of water resources and excessive loss of water by drainage. In Oweis et al. (2000) it is found that a fraction of the supplement irrigation can maximize WUE regarding to other factors (Nitrogen supply, sowing date).

In irrigated crops it is recommended to improve irrigation practices and systems to maximize their efficiency, although the technology available is extremely advanced and is difficult to improve the localized irrigation and other high efficiency techniques. It is necessary to modernize the infrastructures to reduce water loss during the transport. Traditional irrigation techniques, like open furrow irrigation should be practised according to the best management practices (slope, quantity flow, timing, furrow length, etc). For example, in two-slope furrows, with the minor slope in the lowest part and slope transition at ¾ of the furrow length the efficiency is increased around 13% regarding to single-slope furrows (Vázquez, 1999). Other BMPs are:

• Straw mulching to reduce soil evaporation.
• To hoe the soil surface that cut down the soil moisture transfer to soil surface.
• Irrigation scheduling for reducing soil evaporation

Fig. 1 – Relationships between grain yield (GY) of winter wheat and irrigation in 1999/2000, 2000/2001 and 2001/ 2002 (Figure from Sun et al., 2006)

Applicability

The applicability of this measure, like it happens to Reduce surface water abstraction with return depends on management, technological, political and social issues. A method to improve water use efficiency is water pricing and full cost recovery impulsed by the Water Framework Directive, and the clear definition of water rights.

Anyway, water pricing may not always be enough incentive for achieve water use efficiency. This happens when price elasticity for water demand is almost zero (e.g. when water bill supposes only a small fraction of production costs or incomes), when alternative crops or water resources are not possible due to technical, social or economical constraints or when the greater part of water costs are fixed expenses. Increasing water price would reduce water demand when price elasticity is high, and there are a large number of studies showing that irrigators’ water demand is highly inelastic in the short term, at least at low prices. Water consumption does not fall until prices reach such a level that farm income and agricultural employment are negatively affected (Berbel, Gomez-Limón, 2000). Response to price increases is not continuous as there is an optimum supply of water for each crop and the water production function implies that the optimum is not sensitive to price increases until a break-even point is surpassed, when a new crop is introduced or farmers simply go for rain-fed crops (Berbel et al., 2007).

Expected effect of measure on (including literature citations):

• HYMO (general and specified per HYMO element)

In general, there is expected a positive effect on HYMO elements. Increasing flow quantity in bypassed reaches in detriment for hydropower station would have the same effects as those from Increase minimum flows

• physico � chemical parameters

A reduction on water for irrigation combined with an efficient use of fertilizers would reduce nutrient leaching deeper into the soil.Replacement of once-through cooling systems to closed-cycle systems would reduce the impact on stream water temperature.

• Biota (general and specified per Biological quality elements)

The contribution to low flows would increase habitat quantity; the duration of low flows is sufficient to engender a biological response (Jowett et al. 2005). The type of ecosystem and the linkages between the trophic levels is usually strongly influenced by the overall nature of the flow regime. However, studies that evaluate biological responses to agricultural BMPs at the scale of the catchment are rare (Allan, 2004).

BQE	Macroinvertebrates	Fish	Macrophytes	Phytoplankton
Effect	+	+	+	o

Pressures that can be addressed by this measure

• Discharge diversions and returns
• Surface water abstraction

Cost-efficiency

• An increase on water pricing to reduce water demand can reduce farm incomes and agricultural employment. Depending on the capacity of reaction and adaptability of the farm system (e.g. cereal farms vs. fruit farm) the adoption of water pricing can improve their management or reduce their benefits without significant environmental improvements (Bazzani et al., 2005).

• Improving water use efficiency for industrial use means reduce water consumption while the incomes and outputs remains equal or even better. Ecological behavior of these enterprises supposes an advantage regarding to other companies. Technological improvement may suppose a high initial investment, but with mid–term profitability.

Case studies where this measure has been applied

No projects apply to this measure.

Useful references

Allan J. D. 2004. Landscapes and riverscapes: The Influence of Land Use on Stream Ecosystems. Annual Review of Ecology, Evolution, and Systematics, 35: 257-284

Berbel, J. Calatrava, J y Garrido, A. (2007). Water pricing and irrigation : a review of the European Experience. In: F. Molle, J, J. Berkkoff; R. Barker (eds), Irrigation Water pricing Policy in Context : exploring the Gap between Theory and Practice. Wallingford, UK: CABI. Cap. 13, Páginas: 295-327.

Berbel, J and Gómez-Limón, J.A. (2000). The impact of water-pricing policy in Spain: an analysis of three irrigated area. Agricultural Water Management 43:219-238; ISSN: 0378-3774/00.

Berbel, J. and Gutierrez, C. (eds.) (2005) Sustainability of European Irrigated Agriculture under Water Framework Directive and Agenda 2000. EUR 21220. Office for Official Publications of the European Communities. Luxembourg.

Jowett I. G., J. Richardson and M. L. Bonnett. 2005. Relationship between flow regime and fish abundances in a gravel‐bed river, New Zealand. Journal of Fosh Biology, 66 (5): 1419 – 1436

Neil C. Turner, 2004. Agronomic options for improving rainfall-use efficiency of crops in dryland farming systems. Journal of Experimental Botany, Vol. 55, No. 407

Sun H.Y. Liu C. M., Zhang X.Y., Shen Y.J. and Y.Q. Zhang. 2006. Effects of irrigation on water balance, yield and WUE of winter wheat in the North China Plain. Agricultural Water Management, 85 : 211-218

Radcliffe, D.E., Tollner, E.W., Hargrove, W.L., Clark, R.L., Golabi, M.H., 1988. Effect of tillage practices on infiltration and soil strength of a Typic Hapludult soil after 10 years. Soil Science Society of America 52, 798–804.

Vázquez Fernández E. (1999) Eficiencia de aplicación en el riego por surcos abiertos al emplear dos pendientes. Ingeniería del Agua,.6 (3): 275-282

Wising U., T. Berntsson and P.Stuart. 2005. The potential for energy savings when reducing the water consumption in a Kraft Pulp Mill. Applied thermal engineering, 25 (7): 1057-1066

Other relevant information

Industry can improve. The technology to do so exists. But does the will? Article about Indian water use in industry, and the technological posibilities to improve it.[1]

World Business Council for Sustainable Development (WBCSD) Water and Sustainable Development projects[2]

How to Conserve Water and Use It Effectively U.S. environmental Protection Agency Practices for Industrial/Commercial and Agricultural Users: engineering Practices (water reuse and recycling, colling water recirculation) and Behavioral Practices. [3]

Dinar A. and J. Letey (1991). Agricultural water marketing, allocative efficiency, and drainage reduction. Journal of Environmental Economics and Management 20(3): 210-223