Charging for irrigation water by volume-electricity would conserve water resources in Greece

A.G. Panoras and I.G. Mavroudis, National Agricultural Research Foundation, Land Reclamation Institute, Thessalonika, Greece

SUMMARY

Most of the area of the Greek plains, which account for 80% of the total irrigable area, is irrigated by collective irrigation networks. The charge for water is based on the area irrigated. This practice results in water and energy losses and other secondary problems like salinity and alkalinity. This paper aims to persuade Greek farmers to accept being charged for water according to the volume or electricity consumed, as this practice saves water resources and energy, improves distribution and application efficiency, increases crop production, and decreases operation and maintenance expenses. To achieve the above-mentioned goal, the case of a collective irrigation network located in north-eastern Greece has been studied. The irrigated area of this network is 7 830 ha and the payment for the irrigation water is based on the electricity consumed for pumping the irrigation water. Comparing the current practice of charging for the water by the electricity consumed with the one used some years ago of charging by area, it is clear that the land reclamation organizations all over the Greek plains, which are responsible for operating and maintaining the irrigation networks, should adopt the system of charging for irrigation water by volume or electricity.

The noticeable reduction in precipitation in the Mediterranean zone in the last ten years (Maheras, 1988; Maheras and Pitsoulis, 1989; Mavroudis and Panoras, 1992; Vafiadis, 1991) along with the increase in the area of land under irrigation has resulted in most of the water resources in Greece being utilized. The search for new water resources of good quality has become a difficult task.

The rational management of irrigation water can reduce the losses so raising the potential for irrigating more land and for supporting the existing irrigation networks in periods of water shortage.

Irrigated agriculture, which is the main consumer of good quality water resources, can substantially reduce water losses, especially in surface irrigation where the losses exceed 50% (Bos and Nugteren, 1983). The main presuppositions for achieving this goal are: (i) knowledge of crop water requirements; (ii) the measurement of water distributed to the network or applied over the field; (iii) the good application over the field; and (iv) the charge for the irrigation water consumed.

This paper aims to demonstrate to Greek farmers and to the land reclamation organizations, through an existing application in north Greece, how charging for the water consumed results in water economy. For this purpose, the case of a collective irrigation network is studied.

ANALYSIS OF EXISTING SITUATION

In the Greek plains, crop water requirements are satisfied from collective irrigation networks. The management, operation and maintainance of these networks are the responsibility of the local land reclamation organizations. The total annual cost of the above-mentioned activities is allocated to each farmer served by the networks on the basis of the area cultivated and not on the water volume consumed. In the case of rice, the farmers pay more per hectare because they use more water.

The irrigation network studied is located in north-eastern Greece and consists of 293 deep wells irrigating 7 830 ha (LRO, 1994; Land Reclamation Service, 1994: pers. comms.). Each well is used by a group of farmers owning neighbouring fields. The sprinkler irrigation system is semi-portable, having fully portable hand-move laterals or travelling machines and permanent buried mains. A pumping plant has been constructed at each well to provide the pressure necessary for sprinkler irrigation. The members of each group irrigate their fields whenever they want. Each well serves 20-30 ha.

Until 1981, the water charges was based on the area irrigated. This meant that the actual overall operation cost was divided by the above-mentioned area without taking into account the volume of water consumed by each farmer. As a result of this system of charging, farmers used to irrigate their fields in a way that resulted in extremely high water losses, especially from runoff.

In 1982, after the Land Reclamation Organization's (LRO) proposal, the charge for water was based on the volume consumed. There were two problems: (i) the flow meter readings were strongly influenced by sand coming from the wells; and (ii) the maintenance cost of the flow meters was pretty high. So, the LRO decided to charge for the volume of water consumed on the basis of the energy needed to operate the pumping stations. More specifically, each pumping plant has a register where the energy consumed by each farmer is recorded. The LRO writes down the readings of the electricity meter at the beginning of the irrigation period. The first farmer to irrigate his field writes down his name, community, the date of irrigation and the readings of the electricity meter at the beginning and the end of the irrigation. The following irrigators of the same group do exactly the same whenever they want to irrigate their fields. In this way, the energy consumed per irrigation is recorded and each farmer of the group checks the written entries of the farmer before. At the end of the irrigation period the LRO checks and analyses the written data and charges each farmer for the total energy consumed by him during the irrigation period. This means that the actual overall operating cost is allocated to each farmer on the bais of the energy consumed.

METHODOLOGY

Although the practice of charging for water on the basis of the energy consumed was applied all over the LRO's area, only a small part of this area (Chimonion village) had reliable data for evaluating the effect of this system of charging on the water economy from 1981 to 1994. For this period, a comparison between the 1981 data (year of charging by area) and the 1982-94 data (years of charging by energy consumed) was conducted.

To have a reliable comparison, the net irrigation requirements of the crops (In) have been calculated in Chimonion village for the 1981-94 period using the field water balance

In = ETc - (Pe + Gw + ÄWs), (1)

where ETc is evapotranspiration, Pe is rainfall, Gw is groundwater and ÄWs is the decrease in soil water that can be used during the period. The variable Gw is zero because the groundwater table is deeper than three metres. Moreover, the variable ÄWs is considered zero for practical purposes.

The use of combined equations (Doorenbos and Pruitt, 1977; Jensen et al., 1990) to estimate reference evapotranspiration (ETo) is not applicable in this area because the available climatic data are for air temperature and rainfall only. So, the Blaney-Criddle equation (Blaney and Criddle, 1950, 1962) was used:

ETo = (0.46 T + 8.13) p, (2)

where T is the mean daily temperature in degrees Celsius for the month under consideration, p is the mean daily percentage of total annual daytime hours obtained from tables for a given month and latitude. The ETc was calculated using the appropriate crop coefficient (kc) for the area (Papazafiriou, 1991):

ETc = ETo * kc, (3)

The crop coefficient of potatoes has not been calculated by Papazafiriou (1991), so it has been estimated on the basis of crop characteristics, sowing data, stages of crop development, length of growing season and climatic conditions (Doorenbos and Pruitt, 1977).

The mean monthly effective rainfall was estimated by the evapotranspiration/precipitation ratio method (USDA, 1967). The crop area data was obtained by the Land Reclamation Organization at Orestias (LRO, 1994).

RESULTS AND DISCUSSION

TABLE 1 - Consumption of electricity in an irrigation network of northeastern Greece during the irrigation period

Irrigation period	Consumption of electric energy kWh	Consumption of electric energy per hectare kWh/ha	Percentage of energy consumed in terms of 1981 (%)
(1)	(2)	(3)	(4)
1981	387639	609.5	100
1982	284535	406.3	67
1983	194338	295.6	49
1984	291127	417.1	68
1985	361627	519.0	85
1986	357765	520.8	85
1987	333814	511.7	84
1988	277474	428.1	70
1989	246374	369.8	61
1990	371830	579.7	95
1991	322805	528.6	87
1992	280505	443.4	73
1993	351274	570.7	94
1994	367875	531.9	87
1982-94	307637	470.9	77

1981 = Charge according to area irrigated
1982-94 = Charge according to energy consumed

The energy consumed per hectare (Table 1, column 3) shows that since implementing the charging for irrigation water by volume, energy consumption has decreased by from 5 to 51%. The mean reduction was in the order of 23%.

It should not be said that the energy reduction is due to the new way of payment without taking into account the net irrigation requirements of the crops during all these years. The data of Table 2, column 6, show that for most of the years a relationship exists between the consumed energy (Table 1, column 4) and the net irrigation requirements (Table 2, column 5).

The case of 1992 and 1993 is a typical one. The net irrigation requirements are almost the same (Table 2, column 4) while the energy consumption differs significantly (Table 1, column 3). This fact is not due to the amount of effective rainfall, which was almost the same (Table 2, column 3), but to the dates of rainfall during the irrigation period. So, in 1992 88% of the rainfall during the irrigation period was recorded during the peak period of crop water demands, whereas in 1993 this percentage was only 34%.

Comparing the data of Tables 1 and 2 shows that the electricity (volume of water) consumed during the 1982-1994 irrigation periods was less than in 1981 in spite of the fact that the net irrigation requirements of the crops in the same time period were greater or slightly smaller (1992, 1993) than those of the 1981 irrigation period. Even in 1983 and 1989, when the net irrigation requirements were significantly lower (22 and 13% respectively) than in 1981, the reduction of the energy consumed was so intense (51 and 39% respectively) that a part of it may be attributed to the new way of charging for water.

TABLE 2 - Net crop irrigation requirements in an irrigation network of north-eastern Greece

Irrigation period	Crop water requirements	Effective rainfall	Net irrigation requirements (NIR)	Net irrigation requirements per hectare	Percentage of NIR in relation to 1981
	m3	m3	m3	m3/ha	%
(1)	(2)	(3)	(4)	(5)	(6)
1981	3 588 505	580 993	3 007 512	4729	100
1982	4 021 100	402 570	3 618 530	5166	109
1983	3 607 628	1 194 334	2 413 294	3671	78
1984	3 864 892	514 256	3 350 636	4800	102
1985	4 007 873	487 134	3 520 739	5053	107
1986	4106 528	403 381	3 703 147	5390	114
1987	3 700 783	484 840	3 215 943	4929	104
1988	3 723 178	572 972	3 150 206	4860	103
1989	3 614 283	870 009	2 744 274	4119	87
1990	3 627 209	462 132	3 165 077	4935	104
1991	3 437190	426 695	3 010 495	4930	104
1992	3 522 914	629 017	2 893 897	4575	97
1993	3 432 079	644 276	2 787 803	4529	96
1994	3 878 902	381 888	3 497 014	5056	107
1982-94	3 726 505	574 885	3 151 620	4770	101

The new system of charging resulted in a rational use of irrigation water. More specifically, the farmers started using low pressure sprinklers instead of gun sprinklers and laser technique for field leveling in order to improve distribution and application efficiency. Some of them started irrigating during the night to avoid the wind effect during the day. The rational use of irrigation water, resulting from the new system of charging, reduced water losses, energy consumption and the maintainance cost of the pumping plants because their operating time was significantly less than before 1982. The reduction in the operating cost of the irrigation network led to a reduction in the cost per hectare charged by the LRO. Finally, it should be said that the new system of charging had a good effect on crop production (LRO, 1994), both because the problems associated with an uncontrolled water table within one to two metres of the ground surface and with soil erosion were eliminated and, above all, because the farmers started to become professional irrigators.

CONCLUSION-PROPOSAL

The study of the Chimonion irrigation network showed that charging for irrigation water by the electricity consumed for pumping the irrigation water reduced the quantities of water used for irrigation. This reduction had a positive effect on soil erosion, water table, crop production and the operating cost of the irrigation network.

For all the above-mentioned reasons, the land reclamation organizations should adopt charging for irrigation water by volume or electricity on all the collective irrigation networks in Greece. Before implementing this practice, the farmers need to be thoroughly informed about the new system of charging and the benefits it will bring.

Furthermore, in pressurized collective irrigation networks, charging by electricity is better than charging by volume because the latter method needs a lot of water measurement equipment which would increase the cost.

REFERENCES

Blaney, H.F. and Criddle, W.D. 1950. Determining water requirements in irrigation areas from climatological and irrigation data. USDA, SCS-TP 96.

Blaney, H.F. and Criddle, W.D. 1962. Determining consumptive use and irrigation water requirements. USDA Tech. Bull. 1275, USDA, Beltsville, Md.

Bos, M.G. and Nugteren, J. 1983. On Irrigation Efficiencies. 3rd edition. ILRI, Wageningen, The Netherlands.

Doorenbos, J. and Pruitt, W.O. 1977. Guidelines for predicting crop water requirements. FAO Irrigation and Drainage Paper 24. Revised edition. Rome.

Jensen, M.E., Burman, R.D. and Allen, R.G. (eds.). 1990. Evapotranspiration and irrigation requirements. ASCE Manuals and Reports on Engineering Practice 70.

Maheras, P. 1988. Changes in precipitation conditions in the western Mediterranean over the last century. J. Climatol. 8: 179-189.

Maheras, P. and Pitsoulis, N. 1989. Man, environment and climatic changes. Panhellinic Research Congress for Environmental Protection and Agriculture Production. Thessalonika, Greece.

Mavroudis, I.G. and Panoras, A.G. 1992. The distribution of rainfall in the Loudias river watershed. Hydrotechnica 2 (1): 69-80.

Papazafiriou, Z.G. 1991. Experimental application of new irrigation methods: Estimation of crop water requirements in Greece. Ministry of Agriculture.

USDA Soil Conservation Service. 1967. Irrigation water requirements. Tech. Release No 21, Eng. Div. SCS.

Vafiadis, M. 1991. Study of rainfall in different spatial and temporal scales. Application in the valley of Central Greece. PhD Thesis.