Water for people.pdf - WHO Thailand Digital Repository

L A K E T I T I C A C A B A S I N , B O L I V I A A N D P E R U / 4 6 7Table 21.2: TDPS system sizeBasin Area (km 2 )Lake Titicaca 56,300Desaguadero River 29,800Lake Poopó 24,800Coipasa Salt Lake 33,000TDPS System 143,900Lake TiticacaAverage area 8,400 km 2Average altitude3,810 m.a.s.l.Average volume 930 km 3Maximum length176 kmMaximum width70 kmMaximum depth283 mDesaguadero RiverLength398 kmAverage flow 70 m 3 /sAverage gradient45 cm/kmLake PoopóAverage area 3,191 km 2Average altitude3,686 m.a.s.l.Coipasa Salt LakeAverage area 2,225 km 2Average altitude3,657 m.a.s.l.of desert that runs along the Pacific coast, and to the east arethe Amazon plains that extend to the Atlantic Ocean. The systemis located in the southern part of Peru and the north-west ofBolivia. The source that feeds the lake, situated to the north,belongs mostly to Peru. Of the five major rivers flowing into thelake, four run through Peruvian territory. The southern part ofthe system, which belongs to Bolivia, is drier and ends in theCoipasa Salt Lake, which is formed by the evaporation ofoverflow from Lake Poopó.ClimateThe climate within the TDPS system is that of a high mountainregion with a tropical hydrological regime of great interannualirregularity. In the surrounding area, Lake Titicaca exercises amoderating influence on temperatures and rainfall.Precipitation varies between 200 and 1,400 millimetres (mm),with maximum value of 800 to 1,400 mm at the centre of the lake.The system shows zones of diminishing humidity from north tosouth, going from humid around Lake Titicaca, to semi-arid in LakePoopó, to arid in the Coipasa Salt Lake. There are great seasonalvariations, as the area usually has wet summers and dry winters,with a rainy period from December through March and a dry periodfrom May through August. The air temperature varies within thesystem depending on latitude, longitude, altitude and proximity tothe lake, with minimums of -10 to -7°C and maximums of 19 to 23°C.Humidity is low throughout the system, with an average of 54 percentand variations depending on latitude and season. The area alsoreceives strong solar radiation with an annual yield of 533 caloriesper square centimetre (cm 2 ) per day: this high radiation explains theintense evaporation that occurs in Lake Titicaca.Land typesThere are four types of land in the Lake Titicaca basin, classifiedas follows.■ Arable land: Due to climatic conditions and the altitude of thehigh plateau, special agricultural practices are required. Most ofthe soils have organic matter and nitrogen deficiencies. Only33.9 percent of the TDPS land area is arable land. It covers44,692 km 2 .■ Non-arable land: Such land requires special practices to maintainpermanent plant cover. Non-arable surface covers 28,063 km 2 or21.3 percent of the total.■ Marginal lands: These are characterized by moderate to strongerosion processes, but with potential use for extensive grazing ofllamas and alpacas. The total area is 40,844 km 2 or 31 percentof the whole basin.■ Badlands: Although unsuitable for agriculture or grazing, suchareas can be used for wetlands, recreation and mining. Badlandscover 18,178 km 2 , representing 13.8 percent of the system.Major socio-economic characteristicsPopulationThe pre-Hispanic ethnic groups on both sides of the lake maintainancestral cultural patterns which are unlike those of Western culture.The annual economic growth rate for the system is very low, with adeclining tendency in the rural areas. This is due mainly to extensivepoverty, which results in high infant mortality and rural-to-urbanmigration. A diminishing soil fertility rate can also be observed.Tables 21.3 and 21.4 give an overview of the system’s populations.Poverty is the most critical social problem in the TDPS system,affecting both rural and urban populations. Families have to devoteall their energies to meeting basic needs, and locally availableresources are too limited to offer much hope of improved livingconditions. Extreme poverty and a lack of opportunity compel therural population, especially young people, to migrate to the cities,