|
2.2 Summary of current analysis of use
2.2.1 How water is used
An analysis of how water is used in the Scottish river basin has been undertaken to identify the sectors making the greatest use of water. This also helps us to identify and prioritise the sectors where additional economic information needs to be collected as a priority in order to support the development of programmes of measures.
This report examines the four main water uses that affect the condition of the water environment in the Scottish river basin district: abstraction, impoundment, discharge (both point source and diffuse) and engineering.
The main abstracting sectors are energy, using water for cooling, and water supply, both domestic and as part of a production process. These same two sectors are also major impounders although for different purposes; energy is generated through hydropower and water is stored in reservoirs (other examples of impoundment include flood defence and canals).
Over 90% of clean water used by households is discharged to mains sewers and many other water uses are non-consumptive with water being returned in an altered state and used to dilute pollution or to dissipate heat. The most significant sectors for point source pollution, after sewage and refuse disposal, are fish farming, and manufacturing.
Harbours, canals, flood defence, river straightening and alteration through towns are all good examples of engineering activity.
2.2.2 How water use is valued
It may sometimes be difficult to decide if the costs of achieving a particular environmental objective would be justified. In such cases, information on the value of the water usage of the industrial process affected by the improvement measures may be useful in reaching a decision. This section discusses the quality and extent of existing data on the value of water usage in the Scotland river basin district.
Due to the complexity of many industrial processes, placing a value on their usage of water is not straightforward. The most appropriate methods are discussed in the Water Use report10 but unfortunately there are not sufficient data on the water use and non-water costs of businesses to be able to apply this model to Scotland or to further local scale analyses. Therefore, it has been necessary to partly rely on estimates originally derived for Canadian industry and transfer the values to Scotland11. The results are given in Table 2 and Figure 3. Inflation factors and exchange rates have been applied to transfer the values to 2004 UK pounds.
Table 2 Industrial value of water use
| Manufacturing industry |
1991 values ($Can) |
2004 values ($Can) |
2004 values (£UK) |
| Food |
0.017 |
0.30 |
0.125 |
| Beverage |
0.038 |
0.50 |
0.21 |
| Rubber products |
0.006 |
0.10 |
0.04 |
| Plastic products |
0.032 |
0.40 |
0.16 |
| Textile products |
0.005 |
0.10 |
0.04 |
| Wood |
0.020 |
0.30 |
0.125 |
| Paper and allied products |
0.031 |
0.40 |
0.16 |
| Primary metal |
0.107 |
0.13 |
0.055 |
| Fabricated metal products |
0.048 |
0.60 |
0.25 |
| Transport equipment |
0.025 |
0.30 |
0.125 |
| Non-metallic mineral products |
0.023 |
0.30 |
0.125 |
| Refined petroleum and coal products |
0.288 |
0.36 |
0.15 |
| Chemical and chemical products |
0.072 |
0.90 |
0.375 |
The information available and the needs of the research meant that the report focused on particular methods and users. Table 3 summarises the values calculated. However, it should be noted that the values were calculated using different methods and based on different assumptions and, therefore, the results for sectors are not directly comparable. This was necessary due to differing data availability and different ways of using water. For example a high volume user such as aquaculture may have a low per m3 value whereas another use such as irrigation may have a much higher m3 value. The figures do provide a measure of the importance of water for certain sectors and will provide a means of tracking changes in the value derived from particular uses. Values are expressed in units appropriate to the nature of the usage under consideration.
Table 3 Summary of the valuation techniques and results for sectors considered
| Sector |
Valuation technique |
Key assumptions |
Value* |
| Households |
Gibbons’ willingness to pay formula |
Assumes all consumers pay volumetric charges levied to metered customers in England, Wales and Scotland |
0.102–0.244 p/m3 |
| |
|
Includes value of both clean and dirty water |
|
| |
Benefits transfer from stated preference study |
Only considers value of supply of clean water |
0.067 p/m3 |
| Agricultural irrigation |
Net-back analysis |
Assumes that the West Pfeffer catchment is representative of other areas where potatoes are irrigated |
£5128 /ha |
| |
|
Value includes both naturally available water and water applied through irrigation |
|
| |
Transfer of net-back analysis |
Data from England and Scotland combined despite different agricultural support arrangements and climate |
23–138 p/m3 |
| Aquaculture |
Avoided Cost |
Costs calculated based on running costs of the largest effluent filters bought without a loan |
0.126 p/m3 |
| |
|
Considers water use for disposal of solid waste only |
|
| |
|
Assumes filters remove all solid waste |
|
| Salmon angling |
Benefits transfer of travel cost method study |
Assumes salmon anglers in Donegal are representative of others throughout Scotland and Northern Ireland |
£175 /day |
| Industry |
Benefits transfer from marginal productivity approach study |
Industrial water use in Scotland and Northern Ireland assumed to be the same as for Canada |
4–37.5 p/m3 |
| |
|
Assumes no improvements in water efficiency since 1991 |
|
Results are based on the information available and the techniques developed at the time. However, there are a number of areas in which understanding can and should be improved. In particular, the understanding of the volume of water supplied to and discharged from different sectors could be improved. In turn, this could help to identify issues of water use at a more precise geographic level in order to facilitate assessment of the individual RBDs, such as the Solway-Tweed. As we progress towards river basin management planning this information will be refined and we will be able to use it to inform our decision-making.
|
