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Morroco case study: socio-economic study of erosion control in the Loukkos Basin
(cf. Alaoui 1992a, b)
A social and economic study of the problems connected with erosion control was recently carried out in the Loukkos Basin by a Moroccan consultancy firm (Agroconcept). The main conclusions of an economist on the team can be summarized as follows:
THEORETICAL RELATIONS BETWEEN FARMERS' ATTITUDES AND ECONOMIC VARIABLES
There is a simple theoretical relationship between farmers' attitudes and such economic variables as price rises, subsidies for inputs, the "risk effect" or landownership. Field studies are the only way to determine the local effect of these variables.
A FIELD SURVEY OF FARMERS' ATTITUDES TO SPR IN FRUIT-GROWING
Importance of the local factor: the attitudes of farm leaders in the same district tend to be fairly similar. Out of 117 farmers in the 22 districts surveyed, 41% were in favour of terracing for fruit-growing, 48% against, and 11% uncommitted, but the views within each individual district were much the same.
TABLE 6
Cost of farm erosion in dirham/ha/yr for a cereal-fallow-grassland rotation on medium slopes ($US 1 = 25 dirham [1995])
|
Erosion t/ha/yr |
Cost DH/ha/yr | |||
|
Min |
Max |
Min |
Max | |
|
Beni Boufrah (eastern Rif) |
0.4 |
2.7 |
0 |
37 |
|
Mda (pre-Rif) |
0.3 |
44 |
0 |
257 |
|
Mokrisset (western Rif) |
2.7 |
24 |
33 |
100 |
For: discount rate = 0.08;
coefficient a = 0.04 to 0.15
FIGURE 13 Production loss as a function of cumulative erosion (cf. Alaoui 1992a, b)
Technical factors (inappropriate techniques, fruit trees and terrain) are less often determinants of attitude than factors connected with land use (right of use, ownership, grazing, etc.).
The State sets up physical structures for erosion control. Farmers will also anticipate future State intervention: shorter fallow periods, cropping on rangeland as a reaffirmation of ownership rights, more intensive use of land or requests for development to take advantage of promised wages.
THE COST OF EROSION
Potential losses in fertilizer equivalent: 680 DH/ha/yr in 1978 in the Tleta Basin, or $US 100 (at May 1992 rates).
Erosion operates by decreasing selectivity of the richest elements in the soil, supporting soil scientists' claims that:
Yt = iY e-aSL
Yt = annual yield in t/ha
iY = initial yield
wherea = initial parameter
SL = cumulative yearly soil loss in t/ha/year
The costs of erosion from yield losses range from 0 to 257 DH at 1990 financial prices for discount rate of 0.08 and a coefficient "a" of 0.04 to 0.15 (Table 6).
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These survey results confirm farmers' views on the low average costs of erosion. Erosion costs are low in comparison with the cost of other production factors, and land values vary little as a result of erosion-related factors (slope, SPR improvements), but widely as a result of factors linked to production costs (distance, status, mechanization possibilities) and yields (soil and plantation type) (Figure 13). Moreover, farmers do not see erosion as a sure and steady factor, but more as a chance process linked to exceptional weather combined with the state of certain plots at a given moment, further reducing the cost of erosion in their minds. |
THE COSTS OF EROSION DAMAGE DOWNSTREAM
The site costs and benefits of water control can be seen in the following curves:
• the benefit curve rises over time as water is put to ever-varied use;
• the cost curve falls with the passage from construction investment to upkeep investment.
In theory, a site with a very steep curve must be seen as a non-renewable resource.
At Loukkos (Morocco), two simulations were produced for management of the reservoir:
• the first looked at the annual rate of siltation for 1979-1990: 35 million m³ per year;
• the second showed an increase of 50% in the siltation rate.
The cost of siltation is then calculated as the difference in production levels in these two situations evaluated at market prices.
FIGURE 14 Off-site cost of the rise in siltation rate (cf. Alaoui 1992a, b)
Time profile of costs/benefits related to one hydraulic site
y 2
= site of water storage, the rarity/infrequency of which is greater than for y 1
Loukkos: Off-site costs of rise
1. before the still-water section was filled
2. the more frequent overflows increase power production through more frequent turbine action
3. loss of irrigation water
TABLE 7
Cost of siltation
|
Value of m³ of water in irrigation (DH/m³) |
0.4 |
0.8 |
1.0 |
|
Discount rate |
0.12 to 0.08 |
0.12 to 0.08 |
0.12 to 0.08 |
|
Cost of m³ of sediment (DH) |
0.03 to 0.11 |
0.05 to 0.19 |
0.08 to 0.28 |
As long as agricultural demand does not exceed a certain level (50% of the reservoir), the reduced storage capacity due to siltation is reflected in more frequent discharges and greater availability of water at the level recommended for turbine generation of electricity: this is the positive effect of siltation on power production (Figure 14).
With the rise in agricultural demand towards the year 2020, the major effect of siltation becomes the reduction in average agricultural supply.
These cost curves were obtained by valuing energy production and irrigation water at their opportunity cost (0.7 DH/kwh): market cost of substitute energy production and value of lost farm production (0.4 DH/m³).
If the cost of siltation in cubic metres of sediment is calculated on the basis of the discount rate and opportunity cost of water, this gives indicators of the off-site costs of soil loss that can be used to justify investments in soil conservation. Any investment in erosion control can be analysed by reckoning the total cubic metres stabilized over the period under consideration in terms of the major costs (Table 7).
Bearing in mind the site, this indicator is more sensitive to discount rate than to other parameters.
This indicates that on this site the choice of mechanical techniques with immediate impact (civil engineering) cannot be justified by reasons of siltation control if they are more expensive or less reliable in the medium term than less-immediate biological conservation techniques (e.g. reforestation).
ANALYSIS OF AGRICULTURAL POLICIES
Historians have often seen the loss of competitiveness of farming in the upper watershed compared to that in the lower as a major cause of population transfer and pressure on resources.
If such migration is to be reduced, mountain economies need to focus more on their comparative advantages (e.g. tourism, quality mountain produce such as cheese, fruit and honey) (Seznec 1992).
A recent study on production support in Morocco in terms of producer subsidy equivalent (PSE) shows that price policy has provided much less support to traditional farm produce from the foothills and mountain areas (barley, durum wheat, olives and sheep: PSE = 0 to 0.1) than to modern irrigated production (sugar, soft wheat, rapeseed, beet, pure-bred cattle: PSE = 0.3 to 1.5).
CONCLUSION: LINES OF RESEARCH TO BE DEVELOPED
• Improve knowledge of land-use systems in mountain regions.
• Calculate erosion economics in terms of yield losses/cumulative erosion.
• Effect of agricultural policies on integrated watershed development.
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CONCLUSION: NEED FOR A SOCIOLOGICAL AND ECONOMIC ANALYSIS OF EROSION CRISES AND FARMERS' EXPECTATIONS In world terms, soil degradation is worrying, but has not yet reached disastrous proportions. However, in local terms, losses in yields and potential production wipe out the profits of smallholders and/or heighten the risk of famine. And famines are reappearing in many places in semi-arid Africa in the wake of strong demographic pressure, lower rainfall and political instability. Adults are migrating from certain regions (e.g. south of the Sahel) to secure additional income to feed their families. This factor must be taken into account, for these migrants will not be on hand for village-based land-use planning programmes that require a large local labour force. Erosion affects soil productivity to varying degrees, depending, for example, on whether it concerns a deep homogenous soil or a soil in which fertility is confined to the surface horizons. Research is now underway to determine which soils are the most economically viable for investments in erosion control. The first results clearly indicate that it is more profitable for farmers to invest the limited sums at their command to manage land that has not yet suffered too heavily. However, to date RML and SPR have intervened mainly in heavily degraded areas abandoned by farmers, in order to reduce sediment transport ... and - at a very high price - maintain the quality of the water needed for large-scale irrigation schemes and urban expansion. If the intention is to enlist farmers' participation, their perspective must obviously be taken into account (which means rapid improvement in land and labour productivity); otherwise the State must provide them with incentives and compensation for their efforts to achieve the national objectives of land stability and/or water quality. Further study is still needed on the effectiveness, feasibility and comparative costs of the different erosion-control methods and to model the most economic structures for each region. |