AN INCENTIVE POLICY FOR SUSTAINABLE MANAGEMENT
OF IRRIGATION WATER
IN THE LOIRE-BRITTANY BASIN

François DUBOIS DE LA SABLONIERE

INTRODUCTION

The six Water Agencies in France are state owned public agencies under the supervision of the Ministry of the Environment and Land Use Planning which have for their objective to protect water resources in each of their respective hydrographic basins.

For that, they collect financial charges from water users. These charges are then reallocated by means of financial aid, either for pollution control (quality), or for the improvement of the resources (quantity).

It constitutes, therefore, a financially incentive policy. Each agency is autonomous. It’s the application of the « polluter-pays » and « user-pays » principles.

It is important to point out that the agencies are neither a contracting authority nor in charge of law enforcement. This system has been functioning for a little more than 25 years.

Included in the Water Act of the 3rd January 1992, the protection of resources and its implementation in respect to the natural equilibrium are thus the essential justification of the Water Agencies intervention programmes which take part in a sustainable development policy.

This following paper concentrates on the action launched by the Loire-Brittany agency for a careful management of water for irrigation.

1) The Loire-Brittany basin

A hydrographic network of 80.000 km with diversified hydrological features.

Little underground water under the ancient massifs ; some important resources but at times too strongly used on the plain.

120 billions of m³/year of rainfall and a yearly flow of 30 billions m³.

Average rainfall : 700 mm/year

Rains filtering through to ground water on the plains : 150 mm/year

The Loire-Brittany basin incorporates two thirds of french breeding activities (and 50 % in the Brittany counties alone), but also almost 50 % of cereal productions especially the Centre and Poitou-Charentes regions.

2) Present state

Abstraction

The yearly water abstraction in the Loire-Brittany basin is divided according to 4 large categories of users :

§  Local communities (towns, communities, community unions ...) about 1 billion m³ taken yearly, of which 360 million are consumed, that is to say not returning to the natural environment ;

 

§ Industry : about 220 million m³ of which only 28 million consumed ;

§ EDF (Electricity Board) : 1,5 billion m³ of which 340 million consumed ;

§  Agriculture (irrigation) : 450 million m³ wholly consumed corresponding to about 320.000 ha (hectares) irrigated.

 

Irrigation is, therefore, the top water consumer of the Loire-Brittany basin, even if it isn’t the main user. This statement is even truer if we consider the summer period during which irrigation is practiced.

The attached documents give the sharing of the quantity taken and consumed by different water users according to the type of water resource.

Irrigation by spraying practiced in the Loire-Brittany basin is a complementary irrigation allowing to secure yields on soils with low water reserves or to cultivate products that need a great deal of water such as corn.

The attached document represents different types of irrigated crops.

Corn, wheat, sugar-beet, proteaginous peas make up the main irrigated crops.

It mainly concerns individual irrigation, the withdrawals being done in an aquifer, a dam or a river.

The succession of dry years (1976, 1989, 1990, 1991, 1996...) and the agricultural economic context have generated a very strong growth of irrigated surfaces in the regions of the Centre, Loire Country and Poitou-Charentes.

The rapid evolution of the demand has locally led to some over exploitations of resources with conflicts of use and the drying up of rivers (near to 1000 km in 1996 in the Poitou-Charentes area ...).

Some administratives measures (water law enforcement) for limiting abstraction are taken each year (limited pumping time, days of prohibition). In some extreme cases, it isn’t allowed anymore to pump water even though irrigation might still be necessary for the plants.

3) The main principles of sustainable management of irrigation water in the Loire-Britanny basin

The strategy for sustainable management of irrigation water in the Loire-Britanny basin relies on 6 main principles :

- knowledge of volumes taken

- knowledge of available resources

- satisfying the needs of the natural environment (minimum flow of rivers)

- volumetric management

- accompanying programs for farmers to a careful management of water

- incentive pricing

3.1. Knowledge of abstracted volumes

As from April 1991, before the Water Act of 3rd January 1992 which made it compulsory, the metering of water for irrigation became a priority for the agency.

If the volumes were metered in the local communities and industries, the biggest part of the volumes taken for irrigation was not metered.

Now, water metering is one of the ways of a sound water management.

The quantification of water taken is indeed a necessary measure :

- for the farmer himself to manage water better for a plot of land by validating the supposed doses to be carried by his irrigation installation ;

- to create water resources management tools ;

- for local authorities to manage on a county scale or in the future at river basin level, to plan, share and arbitrate, especially in times of crisis ;

- for the Water Agencies to produce more reliable data allowing :

1) a realistic computation of the basis of withdrawal charges,

2) to carry out a better balance-sheet for resources and needs.

A study has been entrusted by the Agency in 1991 to the Society of the Canal de Provence.

As a result of this study, the Agency has built an intervention program of the installation terms for the meters. Thanks to its very high financial assistance (75-80 % subsidy), and a network of qualified fitters, the meter stock has rapidly increased : 40 % of withdrawal points representing 65 % of irrigated surfaces are equipped up to the 1st July 1997. In the most intensively exploited groundwater, these rates are respectively 55 % and 80 %.

The financial investment up to the 1st July 1997 is about 100 MF for subsidies rising to 70 MF, the unitary cost of a metering apparatus being approximately 15.000 F. The electronic flow-meters represent more than 50 % of the stock, the propelled speedometer as well as the proportional meter or diversion meter share the rest of the stock.

At present, the rate of equipment leaves us to hope a full completion of the program in 1999.

3.2. Knowledge of available resources

If the surface water resources are fairly well known, thanks to the age of the measuring network, the grounwater levels are less known. The generalised measure of hydraulic gradient by piezoelectric networks are recent. The master plan for water development and management (in French SDAGE) has identified some groundwaters classified as being intensively exploited. Are considered as such units where taken grounwater per year passes an average ratio of 200 m³/ha of the aquifer surface and where use conflicts and water courses drying are observed.

The attached map shows these zones.

The main concerned geological formations are the :

- limestone in the Beauce and senoturonian chalk between the rivers Loire and Loir,

- limestone of the superior Jurassic period, of Dogger and Lias.

In these zones, the Agency encourages, thanks to inciting aids (80 %), the study of quantitative datas of environment and use.

§ Geometry and functioning of groundwater and river hydrosystems,

§  Setting up the networks of local complementary measures of management : gauging stations for rivers, piezoelectric meter for groundwater,

§  Total knowledge of the uses of water : intake structure, metering the abstracted volumes,

§  Modelisation of a system permitting forecast management,

§ A minimal flow for biological purposes in river.

Simple (piezoelectric levels, flow of draining rivers) or sophisticated (mathematic models), management tools become a necessity as soon as the intensive exploitation of an aquifer threats to unbalance its equilibrium.

These tools allow to decide for the best and at the earliest (end of winter to the beginning of spring) the volume of water theoretically exploitable in the year by the whole of the users and at the same time preserving minimum low water acceptable for the springs and the water courses.

It is a question of a fundamental technical aid to establish some rules of equal water sharing between various users and to check their impact.

3.3. Volumetric management

The final goal for the intensely exploited aquifers is the determination every year of the amount of water that can be exploited in keeping with the patrimonial and environmental value.

The irrigating farmers will be led to manage the water quota which will avoid a management crisis, which is always difficult to put into practice and to be respected. Rotation shift and the practice of irrigation will then be the privileged management tools of limited volume.

Farmers of these zones concerned by these measures are at present considering the water sharing and the allocation of quotas.

3.4. A program for irrigation farmers to promote thrifty management of water

Thanks to aids rising to 50 % of expenses, the Agency provides a substantial assistance to carry actions of irrigation farmers to a thrifty water management.

Targeted aids

1) on the technical support to irrigation farmers

- the completion of water schedules,

- following up of the hydratation of the ground (tensiometers, in situ dryoven measures),

- agronomical diagnosis,

- varietal behaviour analysis to water stress,

- determination of the real needs of the crops (measurement of real evapo-transpiration of winter wheat),

- dissemination of information.

2) on water saving

Since the 1997 irrigation campaign, the Agency has brought help to irrigating farmers drawing water from intensively exploited groundwaters and recharged rivers and consuming less water per hectare. This assistance amounts to a certain percentage of the financial charge and is all the more important since the consumption of water per hectare is weak.

The table below represents the rate of aid for intensively exploited grounwater.

3.5. An incentive princing policy

The inclusive fixing rate becomes exceptional and the basis of the financial charge is commensurate to the volume measured by the meter. In order to involve farmers and other users, the basic rate of the charge is raised by 50 % in the intensively exploited groundwaters sectors and by 80 % on recharged rivers.

Thus, by the year 2000, irrigating farmers will pay 5,11 centimes per m³ pumped in intensively exploited groundwater and 6,13 in recharged rivers. In the sectors where the needs and the available resource are balanced, this rate is only 3,4 centimes/m³.

Nevertheless, the amount of the charge is not yet at a sufficient level to set up a limitation factor of quantities of water abstracted.

Indeed, the total cost of irrigation for the farmer is about 1 F/m³, brought on the field.

One can imagine a development of the system towards a differentiated fixing rate with a weak charge up to the value of the water quota, then very dissuasive beyond that value.

It would seem advisable to fix a basic charge at a level which will allow the coverage of the costs related to acquisition of knowledge, the functioning of management tools put in place, as well as operation and maintenance of structures (dams, artificial aquifer recharge, water transfer...) of which the costs of the first installation have been covered by the community.

With this type of fixing rate, water users give themselves the means to keep in good condition the heritage which the community has given them.

CONCLUSION

Putting into to practice all these measures aims to make differents water « users » of the Loire-Brittany basin aware, so that they adopt a consistent attitude with the needs of sustainable development.

This policy will be led in close consultation within the River Basin Committee, a real « Water Parliament », and particulary with representatives of the farmers.