**4. Application of sustainability indicators in Baja California Sur, México**

### **4.1 Study region**

Baja California Sur is one of the driest Mexican States, with an annual average 140 mm of precipitation along its 72,000 km2 extension. La Paz, the capital city, is located near the southern tip of the Baja California Peninsula (Figure 2). With a population approaching 200,000, it is the third largest city on this peninsula, after Tijuana and Mexicali. The La Paz region is dominated by desert and arid ecosystems, with a low availability of water resources. The annual mean temperature reaches 24°C with a yearly total rainfall of 180 mm, but with several dry months with null precipitation (Figure 3), with much of water coming in the form of hurricanes (CNA, 1999).

### **Application of sustainability indicators**

Information on quantity and quality of natural resources is essential for sustainable development. In particular, information on freshwater resources, their availability and use is becoming increasingly important with the emergence of regional water shortages and the need to improve water use efficiency.

The factor α is influenced by the quality of the transboundary water, by the consumption of

Critical values of Iwsc identify various ranges for water scarcity and its parameters; the most common range for Q oscillates between 1000 and 1700 m3/p/y. A region is considered highly water stressed if Iwsc is higher than 0.4 (Alcamo et al., 2003), which is a reasonable although not definitive threshold value, because not all the renewable freshwater resources are used by human society. Data with shorter time scales will enable more detailed assessments considering the effects of seasonal variability in the hydrological cycles (Oki, 2006). These values are important because the World Bank and other aid organizations use

R = (C x 100)/(C+F) (3)

An indicator related to the 'efficiency of land cultivation' is the cultivation factor R. The ratio of cultivated to non-cultivated land was defined by Ruthenberg (1976) as:

**4. Application of sustainability indicators in Baja California Sur, México** 

Baja California Sur is one of the driest Mexican States, with an annual average 140 mm of precipitation along its 72,000 km2 extension. La Paz, the capital city, is located near the southern tip of the Baja California Peninsula (Figure 2). With a population approaching 200,000, it is the third largest city on this peninsula, after Tijuana and Mexicali. The La Paz region is dominated by desert and arid ecosystems, with a low availability of water resources. The annual mean temperature reaches 24°C with a yearly total rainfall of 180 mm, but with several dry months with null precipitation (Figure 3), with much of water coming

Information on quantity and quality of natural resources is essential for sustainable development. In particular, information on freshwater resources, their availability and use is becoming increasingly important with the emergence of regional water shortages and the

R the internal water resources in the country in Mm3 Dup the amount of external water resources in Mm3 α ratio of the external water resources that can be used.

them to prioritize and to direct aid to developing nations.

R cultivation factor (years of cultivation as % total cycle)

C length of cropping period, years F length of the fallow period, years

R < 30 as shifting cultivation;

**4.1 Study region** 

R > 70 as permanent cultivation.

For the interpretation of R, Ruthenberg defined:

R = 30 to 70 as semi-permanent cultivation;

in the form of hurricanes (CNA, 1999). **Application of sustainability indicators** 

need to improve water use efficiency.

water resources in the upstream region, and the accessibility of water.

Where:

Where:

Fig. 2. Geographic location of the Mexican State Baja California Sur and La Paz, the capital city. Northwest México

For the application of sustainability indicators to the diagnosis of La Paz watershed, data on water uses, the natural groundwater recharge and the extraction were obtained from the National Water Commission (CONAGUA) reports and other previous studies (Cruz-Falcón, 2007; CONAGUA, 2008). Weather data (temperature, evaporation and precipitation) used in this study for La Paz B.C.S. (México) were obtained from División Hidrométrica de Baja California Sur, of the Comisión Nacional del Agua (CONAGUA, 2008), who collects this information from the La Paz Weather Station, located at 24°09'N and 110°20'W, 3 km south La Paz City. Our analysis indicate that agriculture is the major water consuming activity, in both, Baja California Sur state and the whole Peninsula of Baja California (Table 1).

The natural groundwater recharge was estimated by the method according to the groundwater lever fluctuation method, which is an indirect method of deducing the recharge from the fluctuation of the water table. The rise in the water table during the rainy season is used to estimate the recharge, provided that there is a distinct rainy season with the remainder of the year being notoriously drier (Cruz Falcon, 2007).


Source: Official data base from REDPA - National Water Commission of Mexico (CONAGUA, 2008).

Table 1. Synopsis of the water use in the Baja California Peninsula and related States, according to the consumptive use; unit: Millions m3/yr

Assessing Environmental and Social Dimensions of

**Recharge (Mm³)**

**4.2 Results and discussion** 

marketing policies, others).

**Name of Aquifer** 

Northwest Mexico

and development.

Mexico

Water Issues Through Sustainability Indicators in Arid and Semiarid Zones 75

Factors affecting agriculture in Baja California Sur were found to be water deficit (evaporation dramatically exceeds rainfall): 2,380 mm – 180 mm = 2,200 mm of hydrological deficit, water scarcity (evidenced by absence of surface water with groundwater depletion), high temperatures: Temp avg = 24.5, Temp max = 42 C; Salinity (natural and caused), low fertility of soils, and socio-economical factors (long distance form main markets, complex

The oriented-extensive ground water extractions have caused notorious water depletion in

El Carrizal 16.0 8.60 7.40 861.00 La Paz 27.8 36.95 -9.15 3,200.00 Los Planes 8.5 9.57 -1.10 957.00

Calculation of the index of water scarcity for La Paz watershed and its four microbasins rendered high values, from 1.11 (microbasin La Palma), to 2.74 (microbasin El Novillo) (Figure 1, Table 3). Results suggest that El Novillo faces a critical condition as a result of high extraction rates, over passing the natural groundwater recharge, with a notorious deficit, estimated in -4,450,068.75 m3, which affects the water availability for urban growth

**================= m³ =================** 

The concept of 'sustainable development' as well as 'sustainable agriculture' integrates three main goals: environmental health, economic profitability, and social and economic equity. A variety of philosophies, policies and practices have contributed to these goals. People with many different capacities, from farmers to consumers, have shared this vision. In the case of agriculture, one of the most water-demanding activity, an agroecosystem must be viewed as a source of 'goods' and a sink of 'inputs' (i.e. water). For this activity and for the others, 'nature' (the ecosystem) is the main source of all we consume, but the ecosystem also serves as a sink for all wastes. For production systems, the main resources basically are: water, plants, grains, animals, energy from the sun, wind, and other nonrenewable: oil (from fossil). Human activity is necessarily focused for extracting resources and producing waste to produce, transport to consumer, and dispose of materials. As agriculture and the other socioeconomic activities in arid and semiarid zones depend on water, which mainly is

El Cajoncito 2,233,967.75 3,689,549.00 -1,455,581.25 1.65 La Huerta 7,519,608.13 8,565,189.38 -1,045,581.25 1.14 La Palma 16,524,756.81 18,420,338.06 -1,895,581.25 1.11 El Novillo 2,559,500.39 7,009,569.14 -4,450,068.75 2.74 Table 3. Values of Iwsc calculated for four microbasins of La Paz B.C.S. watershed, Northwest

**Availability (Mm³)**

**Possible has with irrigation 100 cm depth** 

**Iwsc** 

**Extraction (Mm³)** 

Table 2. Hydrological balances for three contiguous watersheds in Baja California Sur,

two out of three contiguous watersheds, at La Paz municipality (Table 2).

**Microbasin Recharge Extraction Balance**

Fig. 3. Pattern of climatic variables for La Paz weather station, (A): maximum, minimum and mean temperature; (B): rainfall, evaporation and ratio E/P
