Cost–Benefit Analysis of Soil Degradation and Restoration - Principles of Sustainable Soil Management in Agroecosystems - page 240

about the study area has been presented, the method used to estimate reservoir
sedimentation under different assumptions regarding land resource management
upstream as well as the approach for estimating the benefits and costs of soil con-
servation are outlined. A more complete description of this research can be found in
Veloz et al. (1985).
Like many other LDCs, the DR has looked to hydroelectric development to
reduce fuel oil imports. Many promising dam sites are found in the Cordillera
Central, where most of the country's major rivers originate. Elevations vary in that
region from 100 to 3000 m above sea level, and precipitation in many areas exceeds
1500 mm/year.
As late as the 1950s, most of the Cordillera Central was forested. But after the
death in 1961 of the country's longtime dictator, Rafael Trujillo, who owned most of
the country's standing timer, many forested areas were clear cut. Peasants then set-
tled on the newly cleared land. The CRIES Study (1980) shows that by the late 1970s,
most of the region had been converted to rangeland and cropland. High rates of soil
loss are now a problem throughout the Cordillera Central, according to Hartshorn
(1981).
The Valdesia Dam is one of several projects initiated in order to decrease the
DR's dependence on imported oil. By developing Valdesia and one other site dur-
ing the 1970s, de La Fuente (1976) states that the DR reduced the share of elec-
tricity generated at oil-burning facilities from over 90% to less than 80% by 1981.
However, the Direccion General de Foresta (1976) suggests that sedimentation has
been a continuous concern at the reservoir. Even before a major hurricane swept over
the island in 1979, annual sediment yield in the reservoir watershed was estimated to
be 1.4 million metric tons.
10.4.2.1 Study Methodology
Although the Dominican government had determined that the Valdesia reservoir
catchment area would have a watershed management program in the near future, a
specific plan for reducing soil erosion there had not yet been developed. Without a
more detailed plan, it was possible to characterize in a general way the land uses and
land management techniques to be encouraged under the project. Consultation of the
literature wand with professionals who have worked in the DR suggested the follow-
ing guidelines for four slope classes:
Slope class A (3%-20% slope): Continue crop farming on existing cropland.
Encourage mulching and contour farming. Renovate all rangeland with a
slope of 13% to 20%.
Slope class B (21%-35% slope): Encourage mixed cropping/agroforestry enter-
prises on existing cropland. Renovate all rangeland.
Slope class C (36%-50% slope): Convert all existing cropland to agroforestry.
Renovate all rangeland.
Slope class D (over 50% slope): Reforest all existing cropland and rangeland.
To estimate the impacts of project implementation on resource management, a
1:50,000 scale topographic map of the 85,090-ha watershed was consulted. The