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Rio Yaqui Watershed, Northwestern Mexico:
Use and Management 1
Luis Bojorquez2,
Raymundo Aguirre3 and Alfredo Ortega4
Abstract.-- This paper describes the uses and community types of the Rio Yaqui Watershed in Sonora Mexico.
The
management problems are interrelated but there are no studies of sufficient regional scope to integrate the uses of
the area.
To cope with this, research activities associated
with management have to be multidisciplinary.
INTRODUCTION
The use of an ecosystems often influ~
ences other natural systems (Ffolliott
1980).
Riparian ecosystems utilization
impact, and is impacted by, other uses of
their basin.
For this reason a study was
made to describe the vegetational community
types that occur in the Rio Yaqui Watershed
and their sometimes conflicting usage.
The State of Sonora, Mexico, is located on the northwestern corner of The
Mexican Republic.
It is limited by the
Sierra Madre Occidental, on the east, by
the State of Arizona on the north, by the
state of Sinaloa, on the south, and by the
Gulf of California, on the east.
Sonora presents two main landforms:
Northwestern Coastal Plain.- It extenrls from the outlet of the Colorado
River to the south along the coast. and
Sierra Madre Occidental.- It is adjacent and parallel to the coastal plain.
It is the longest and most continuous mountain chain of Mexico ranging from the
eastern border of Sonora and Arizona to
central Mexico.
The maximum altitudes in
its Sonoran range arE: of more than 2, 800 m
above sea level (a. s. l) (DETENAL 1982a).
Agriculture, ranching, mining, forestry, and recreation are the principal land
uses at present (SAHOP 1980) and larger impacts and conflicts can be expected in the
future.
Basic research is needed to reconcile apparently antagonistic requirements
of individual components of some multipurpose combinations (King 1980).
DESCRIPTION OF THE WATERSHED
General Characteristics
The Sierra Madre Occidental has a
large influence on the hydrology of the
area since is the zone of recharge of the
Northwestern Coastal Plain (DETENAL 1981a)
where the most important developments are
located.
Rio Yaqui is the principal river
of Sonora.
It originates in the Sierra
Madre Occidental and discharges into the
Gulf of California.
Rio Yaqui Watershed occupies an area
of approximately 73,000 km2 (30/. of the
state).
It originates in the west aspect
of the Sierra M~dre
Occidental and is
adjacent to the Rio Sonora Watershed in
its west limit.
The north limit lies in
Arizona, U.S. A., approximately 40 km northeast of Douglas.
The direction of the
long axis is northeast from the outlet.
Though the area includes two states, 95/.
of the basin is in Sonora (SARH 1979).
lPaper presented at the Riparian Ecosystems Management Conference.
University
of Arizona, Tucson, Az.
April 16-18,
198 5.
2Luis A. Bojorquez-Tapia is Graduate
Student of Watershed Management, University of Arizona, Tucson, Az.
3Raymundo Aguirre-deluna is Graduate
Research Assistant Range Management Department, University of Arizona, Tucson Az.
4Alfredo Ortega-Rubio is Researcher
in Institute de Ecologia, A. C. Mexico, D. F.
The complex drainage pattern in the
mountains is gradually reduced when the
Yaqui approaches to the coastal plain
(DETENAL 198la), where several arroyos
join the main flow.
The principal river
of the watershed is the Yaqui, which has
a mean annual runoff of about 2. 9 billion
m3 (SARH 1979) The principal tributaries
are the Bavispe, the Moc.tezuma, and the
Sahuaripa.
The Bavispe drains in to La
Angostura Reservoir and continues running
south, forming the Yaqui at the junction
with the Sahuaripa river.
The Moctezuma
475
most xeric aspects while P. ayacahuite
prevails on more mesic slopes of canyons.
flows southward on the western limit of
the basin and is connected to the Yaqui
by the Plutarco Elias Calles Dam, better
known as El Novillo.
From here, the Yaqui
runs out southward to the Alvaro Obregon
Reservoir, which supplies water for the
irrigation of 2, 250 km2 of agricultural
land.
Fourteen drains deliver the water
used by agriculture to Tobari Bay
(Bojorquez 1983).
Ciudad Obregon, Agua Prieta, and
Nacozari are the most important cities
the watershed.
The similar ecological requirements of
pines and oaks, their entangled successional relationships, and the diversity of
microhabitats produce a mosaic of forest
types hard to delineate (Rzedowski 1978).
Oak forest components often can be found
above the lower limit of the pine forest
specially in xeric aspects so it is possible to recognize the following
associations:
in
Climate
The anticyclonic high pressure system
gives to Sonora its arid and semi-arid
characteristics.
The general trend is a
gradient of aridity from the coast to higher elevations.
Thus, for the watershed:
mean annual precipitation
is about 559. 8
mm, from which 92. 07. is lost by evapotranspiration, 0. 47. infiltrates, and 7. 67.
leaves as runoff (DETENAL 1983b).
Total
annual precipitation ranges from 100-200 mm
around the outlet to 1, 000-1, 200 mm in the
Sierra Madre (DETENAL 1981c).
Mean annual
temperature ranges from 24-26°C in areas
close to the ocean to 6-8°C in the highest
elevations (DETENAL 1981d).
However, the rugged topography in the
mountains causes combinations of climate
types within this gradient (Rzedowski
1978).
According to the classification by
Koeppen, the Northwestern Coastal Plain has
subdivisions of climate types BS and Bw
while the Sierra Madre Occidental has subdivisions of climates BS and Cw (DETENAL
198la).
VEGETATIONAL COMMUNITIES
The variety of microenvironmental
conditions in the watershed causes a high
overlapping of communities distributions.
On the other hand, present knowledge of the
vegetation in Mexico does not allow comparisons between community types in great
detail (Rzedowski 1978).
In the present
paper, the classification by DETENAL
(1981a) was followed.
The watershed presents the following vegetational types:
Forest
Bosque de Pino
The pine forest includes the following species distributed in the Sierra
Madre Occidental between 1500 and 3000 m
a. s. l.: Pinus reflexa, P. arizonica, P.
lumholtzi, P. ayacahuite, and P. pondero~Microhabitats are important for the
predominance of a particular species, by
example, P. reflexa is dominant on the
Bosgue de Pino-Encino.The pine-oak
association is formed by t~e same species
of the pine and oak forests but with dominance of pines.
It is found in the
lower, more xeric areas of the pine forest.
Bosgue de Encino-Pino.- This community establishes in disturbed zones in
both the pine and the pine-oak forests.
Quercus and Pinus are the two main genera,
but oak is more abundant.
The following
species are common: P. cembroides, L
arizonica, P. emoryi, Cupressus arizonica,
and Juniperus deppeana.
Bosgue de Encino.- Deciduous oaks
dominate between 1000 and 2000 m a. s. l.
in slopes and plateaus.
The most abundant
species is Q. chihuahuensis, although is
displaced locally by Q. tuberculata and
Q. albocinta in more mesic habitats.
Other important species are: Q. fulva,
Q. sipuraca, Q. santaclarensis, L
hypoleuca, and Q. duranguensis.
Bunchy
grasses are also important.
Selva Baja Caducifolia
This deciduous forest is typical of
subhumid hot climates.
The majority of the
individuals (757.-1007.) lose their leaves
for long periods (6-8 months).
The dominant trees lack of spines and the highest
are 15 m tall.
It is widely distributed on
hillsides with good drainage between 300 to
1200 m a. s. l.
Common genera of this community are Ceiba, Bursera, Conzattia,
Ipomea, Lysiloma, and Ficus.
Bosque de Galeria
The riparian forest exists in areas
where soil moisture is sufficiently high
to support a different community from the
drier surroundings (Johnson and Carothers
1982).
Populus, Platanus, and Taxodium
are the most widely distributed along perennial streams upland.
Prosopis and Acacia
are present in arroyos (Rzedowski 1978).
Scrub
Matorral Desertico Microfilo
This desert scrub vegetation type is
composed of shrubs with small leaves or
476
USES OF THE COMMUNITY TYPES
folioles.
Found on alluvial soils at
elevations from sea level to 800 m a. s. l.,
it can be divided in:
Forestry
Matorral Subinerme.- Thorny plants
(30/.) and plants without spines (70/.)
form this vegetational type.
Important·
species are: Fouguieria splendens, Yucca
~.
C o n d a 1 i a s p. , Mi mo s a s p. , an d P r o s o p i s
glandulosa.
Matorral Espinoso.- The proportion
of thorny shrubs in this community is
higher than 707..
Prosopis spp., Acacia
~.
C o n d a 1 i a s p p. , At r i p 1 e x s p p. , a n d
Fouguieria spp. are common.
Matorral Subtropical
The subtropical scrub is typical in
areas of ecological transition between
relatively humid conditions and more xeric
scrubs.
The majority of the plants lose
their leaves for long periods.
This community is denser with clearings occupied by
grasses in places of high human activity.
The principal species are: Ipomea spp.,
Bursera spp., Eysenhardtia polistachia,
Acacia pennulata, Forestiera spp., Mimosa
~.
0 p u n t i a s p p. , L y s i 1 om a s p p. , and
Mirtillocactus geometrizans.
Matorral Sarcocaule
The Arid Tropical Scrub is found on
rocky, shallow soils close to the coast.
Characteristic species are:
Bursera
hindsiana, Bursera microphylla, Bursera
odorata, Jatropha cinerea, Jatropha
cuneata, Ambrosia dumosa, Cercidium
floridum , Encelia farinosa, Fouguieria
~.
La r r e a t r i d e n t at a, 0 1 n e y a t e s o t a,
Opuntia c.holla, Pac.hyc.ereus pringlei, etc..
Pine communities were not exploited
at the level programmed for 1984 (SFF
1985).
Pinus spp. were the most valuable
trees in Sonora.
Total volume obtained in
1984 was about 43,300 m3.
Sawlogs was the
main product, but others were cellulose,
posts, and c.rossties.
Populus spp. sawlogs were also obtained but on a muc.h
lower scale.
On the contrary, scrub communities
were overexploited.
Th~ ~otal for the
state was 113,300 m3 or 175/. the programmed volume (SFF 1985).
Fuelwood and charcoal were the principal products.
Prosopis
~ and Olneya tesota were the most
utilized for that purpose (SAHOP 1980).
Major problems of the forestry
industry in Sonora are lack of product
classification systems and modern
technology, combined with a deficient
enforcement of forestry polices.
Agriculture
Agriculture is the most important
activity in Sonora and accounts for more
than 25/. of the state's gross internal
product (SARH 1979).
The Rio Yaqui contributes to the most
important agricultural development in
Sonora.
The communities of Matorral
Sarc.ocaule and Mezquita1 near the c.ost
were replaced by 2, 250 Km 2 of irrigated
land.
The main crops cultivated on the
watershed in descending order of importance are:
wheat, cotton, saffron, soy,
corn, and sesame (SARH 1979).
Mezquital
This community is characteristic. of
deep, alluvial soils or in areas with
poor drainage.
The principal species is
Prosopis spp. (mezquite), but Olneya tesota
and Cercidium spp. are also common.
The water supply is mainly from the
river, but now groundwater irrigation is
also common so aquifer overexploitation
and marine water intrusion is a potential
problem (SAHOP 1980).
Agriculture also pollutes water.
Pesticides and fertilizers are discharged
into the river c.ausin~ a negative impact
on estuarin systems and fisheries of Tobari
Bay (Bojorquez 1983).
Grassland
Pastizal Natural
This grassland community is determined by the interaction of local climate,
soils, and biota.
It is found in plateaus
and valleys of moderately deep soils between 200 and 2300 m a. s. l.
Important species
are: Bouteloua spp., Bac.haris spp., and
Hilaria spp.
In disturbed areas by fire,
overgrazing, overc.utting, or abandoned
agricultural lands, Aristida spp. are
common.
477
Ranching
The livestock industry uses about
70/. of the area of the watershed and is
distributed in all the vegetational types.
Overgrazing is a serious problem.
Proper carrying capacities are exceeded by
2 to 10 times, and a common sequence of
deterioration seems to be evident.
Palatable species have being replaced by
undesirable ones, then, if pressure c.onti-
nues, all
is eroded
vegetation is
(SARH 1979).
removed
and
soil
LITERATURE CITED
In recent years poultry .and hog industries have exceeded cattle raising in
economical importance in the state.
Impacts of these activities on the watershed have yet to be determined.
Bojorquez T. L., G. de la Cruz y S. Gaona.
1983.
Evaluacion de las alternativas
de uso de la Isla Huivulai y la Bahia
Tobari.
Reporte.
Asesoria de asuntos
ecologicos, Gobierno del Estado de
Sonora.
63 p.
DETENAL. 198la.
Carta de Climas, La Paz,
Tijuan.J.
E::·cala 1:1000000.
Direccion
General de Geografia del Territorio
Nacional. Mexico, D. F.
Mining
There are several mines in the watershed.
Gold, silver, tungsten, zinc, coal,
magnesium, and lead are the main products.
Yet, copper mining is the one that
has an
economic impact in the nation.
However,
the side effects on the water and air
quality are high.
DETENAL. l98lb. Carta Hidrologica, Aguas
Superficiales. La Paz, Tijuana. Escala
l: 1000000.
Direccion.General de
Geografia del Territorio Nacional.
Mexico, D. F.
The open pit mine of La Caridad,
close to Nacozari, and the smelter greatly
contribute to the pollution problem that
occurs in the river causing a definite
impact on
riparian ecosystems.
DETENAL. 198lc. Carta de Precipitacion
Total Annual.
La Paz, Tijuana. Escala
l: 1000000.
Direccion General de
Geografia del Territorio Nacional.
Mexico, D. F.
CONCLUSIONS
Riparian ecosystems have suffered
heavy damage from the misuse of the natural resources in the Rio Yaqui Watershed.
Overgrazing in all community types and
fuelwood obtainment in scrublands have
devastated the vegetative cover in many
areas.
Then, erosion has taken its role
reducing soil fertility and increasing
sediment yield in rivers and reservoirs.
Soil mass movement is decreasing water
quality affecting riverine systems and
other users downstream.
Sediment in reservoirs have reached in 25 years the levels
planned for 100 years, reducing their
useful life and making water management
more difficult.
Grazing also has impacted riparian
forests directly.
Recruitment of palatable
species (specially Populus) has been reduced because livestock consumes their
seedlings.
Consequently this stands are
becoming senecent gradually.
Cooper mining pollutes water with
consequences yet to be determined.
Unfortunately because of economics, water
quality is not the main concern.
DETENAL. 198ld. Carta de Temperaturas
Medias Anuales.
La Paz, Tijuana.
Escala 1:1000000. Direccion General
de Geografia del Territorio Nacional.
Mexico, D. F.
Ffolliott, P. F.
1980.
Integration of
wildlife and other natural resources
p o 1 ices.
2 4-2 5 p p. .l!J..:
F f o 11 i ott,
P. F., and G. Halffter (tech. coor.)
Consequences of Natural Resources
Polices with Special Emphasis on
Biosphere Reserves.
USDA Forest
Service Gen. Tech. Rep. RM-88. Rocky
Mountain Forest and Range Exp. Sta.
Fort Collins, Co. 57 p.
Johnson, R. R. and S. W. Carothers.
1 9 8 2.
Riparian habitat & recreation: interrelationships and impacts in the
Southwest and Rocky Mountain Region.
Eisenhower Consortium Bulletin 12,31
p. Rocky Mountain Forest and Range
Exp. Sta., Forest Service, USDA,
Fort Collins, Colo.
King,
Agriculture is the final user of the
river and, consequently, the most affected
by negative impacts on water quality and
quantity.
K. F.
1980.
Multiple- Use research.
3-9 pp.
In:
IUFRO/MAB Conference
Research on Multiple Use of Forest
Resources.
USDA Forest Service Gen.
Tech. Rep.
W0-25.
167 p.
Rzedowski, J. 1978.
Vegetacion en Mexico.
Ed. Limusa.
Mexico, D. F.
432 p.
SAHOP
Demands for good and services are
more intense than ever before so large
impacts on the vegetational communities
are expected in years to come.
Therefore,
problem oriented research is required to
achieve a multi-purpose management of this
watershed.
1980. Ecoplan del Estado de Sonora.
Report.
Gobierno del Estado de
Sonora. 255 p.
SARH 1979.
Prontuario Estadistico Sonora
Agropecuario.
Departamento de
dibulgacion y relaciones publicas.
Gobierno del Estado de Sonora.
168 p.
478