Evaluating the Consequences of Future Changes

The consequences of each alternative future are assessed using a series of interlinked models. The economic models project the likely composition and performance of La Paz’s economy, with economic performance measured by gross regional product, per capita income, and employment. Assessing the hydrological impacts of the region requires two models: one for groundwater and a second model for surface water. The groundwater model predicts the impact of increasing water demands on the quantity of groundwater storage in the underlying aquifer, locates the extent of saltwater intrusion for each scenario, and identifies wells at risk. The surface-water model evaluates the risk of flooding from hurricanes. A marine ecological model assesses the potential impact of land use changes on La Paz’s lagoon that lies along the front edge of the city. The impacts on terrestrial ecology model are estimated through the use of a model that evaluates changes to different vegetation and habitat categories. Changes in the visual landscape are estimated using a model based on the scenic preferences and visual quality of the landscape as reported by local residents and tourists. A recreation model identifies areas of highest recreational value to residents and tourists, and is used to assess the impact of future land use.

Impacts of Groundwater

A groundwater model developed for this study is used to predict the impact of future growth on the condition of the aquifer that supplies La Paz with its fresh water. The model is based on the demands of the growing population for drinking water, in addition to commercial, industrial and agricultural uses.

The largest decline in the groundwater level is seen in the vicinity of the wells providing municipal drinking water. This drop in available water is estimated at around ten meters in Alternative Future A and two meters in Alternative Future C over the twenty-year period. Current water extraction from the aquifer exceeds sustainable levels. Furthermore, according to the hydrological model, future growth in water demand will put about one quarter of the region’s wells at risk of saline intrusion. This risk increases as more freshwater is pumped out of the aquifer, allowing saline water to enter the aquifer.

These results imply that the higher growth scenarios are subject not only to a higher risk of declining water availability, but also to a greater risk of a decrease in the quality of the remaining water stocks. This suggests that new, and likely more expensive sources of water, such as desalinization will need to be developed. Of course, this may have additional economic and ecological impacts. A rising cost of water is economically equivalent to falling personal income, as well as a tax on future business. Desalination also entails potential ecological damage associated with the discharge of highly saline waste into the fragile marine ecosystems and increased air pollution emissions associated with the production of electric power necessary to operate the desalination plant.

	Figure 27. Aquifer area.
Figure 28. Aquifer drawdown. Alternative Future A. Rapid growth, unregulated policy set, high public resources.	Figure 29. Aquifer drawdown. Alternative Future B. Medium growth, legal policy set, low public resources.
Figure 30. Aquifer drawdown. Alternative Future C. Trend growth, proactive policy set, high public resources.

Figure 31. Loss in potable water under different growth projections.

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Surface Water Impacts

Hurricanes have played a profound role in the history of La Paz, periodically causing floods that result in significant economic damage, and at times resulting in the loss of life. As La Paz grows in the future, there will be an increased risk of severe losses if more population is situated within the areas of highest risk. The surface water component in this study estimates the areas at risk of flooding in major hurricane events. In Figures 33, 34, and 35, the projected new land uses are superimposed on the area of 100-year flood plain to show the developed areas at risk of flooding if actions are not taken to either reduce the incidence of flooding in these areas or prevent future development in these areas.

Climatologists are exploring a possible link between human-induced climate change and an increase in the number of major hurricanes. Should these connections prove to be true, the Baja peninsula can expect an increase in the frequency and severity of hurricanes in the future. Rising sea levels is another risk from global climate change. This would increase the severity of coastal flooding associated with storm surges.

Major storms regularly inundate the streets of La Paz with water.	Serious hurricanes hit La Paz on average once every two years.

Figure 32. The one-hundred year floodplain.
Figure 33. Areas at risk of flooding. Alternative Future A. Rapid growth, unregulated policy set, high public resources.	Figure 34. Areas at risk of flooding. Alternative Future B. Moderate growth, legal policy set, low public resources.
Figure 35. Areas at risk of flooding. Alternative Future C. Trend growth, proactive policy set, high public resources.

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Impacts on Marine Ecology

The La Paz Lagoon is formed by the 11 kilometer barrier beach – the Mogote – and covers an area of 45 square kilometers. A narrow cut in the northeastern end connecting the lagoon to the Bay of La Paz allows for the exchange of water with the Sea of Cortez. The lagoon is especially valuable because of its roles in support of mangrove habitat and fish populations. The lagoon is also the waterfront for most of the city, such that its water quality is important for public health, recreation, and the visual aesthetic of the city.

A majority of the run-off from La Paz flows directly into the La Paz Lagoon. Pollution and sedimentation associated with this surface water run-off has had important impacts on the ecology of the lagoon system. This process was particularly evident with the dangerously high levels of bacterial pollution in the lagoon in the 1980s. Investments in water treatment have greatly improved water quality. Other more direct impacts on these fragile ecosystems include the clearing of mangroves and the damage to benthic communities from fishing and collection of mollusks.

Although considerable scientific research has been carried out on the lagoon system, there are no comprehensive studies that would permit a quantitative assessment of aggregate changes in the lagoon marine ecosystems. In place of such a quantitative model, this study relies on a qualitative assessment of the likely changes in the lagoon resulting from land use change.

Five criteria were selected to measure the impacts of future changes:

Eutrophication: the physical and chemical changes associated with excessive nitrogen and phosphorus concentrations, and the corresponding surge in aquatic plant growth.

Pollution: undesirable changes in the physical, chemical, and biological characteristics of the water potentially damaging to human and ecosystem health, and to the aesthetic quality of the lagoon.
Direct and indirect impacts: impacts resulting from the physical modification of the lagoon and adjacent land.

Stability: changes in the resilience of the lagoon’s natural systems to respond to external changes.

Figure 36. Marine ecology impact index.

Impacts on Terrestrial Ecology

The terrestrial ecology of the La Paz region is directly impacted by development through the loss of natural habitat. In this study, a terrestrial ecology model assesses the consequences of the alternative futures on different vegetation and habitat categories that have been evaluated by their biotic importance. The mayor habitat types in the region include mattorales, cactus forests, mangroves and coastal dune vegetation. The model rates terrestrial ecosystems based upon 5 criteria:

Species richness – the total number of different species found in the area

Endemism – the presence of rare species, species in danger of extinction, or species not found in other locations
Edge conditions – the transition zones between different ecozones are of particular ecological value

Wetlands – mangroves, other wetland habitats, and their area of influence are especially valued for the multiple ecological functions they perform

Natural protected areas – this criterion recognizes existing legal protection based on natural ecosystem values

These 5 criteria are combined with existing land use conditions to form an index of the value of the natural habitats for each location in the study area. A map of these qualitative values is shown in Figure 37, displaying the relative ecological value of different terrestrial areas

The potential damage to these areas depends upon the specific location and type of future land use change. New land uses of the alternative futures are aggregated into groups based upon their impacts associated with construction, maintenance, and future use. Amongst the most severe potential impacts is the destruction of mangrove habitat for waterfront development.

Dryland ecosystems and cactus forests characterize the landscape surrounding La Paz.	Mangroves are critical for protecting animals and supporting marine life.

	Figure 37. Terrestrial ecology priority areas.
Figure 38. Impacts on terrestrial ecology. Alternative Future A. Rapid growth, unregulated policy set, high public resources.	Figure 39. Impacts on terrestrial ecology. Alternative Future B. Moderate growth, legal policy set, low public resources.
Figure 40. Impacts on terrestrial ecology. Alternative Future C. Trend growth, proactive policy set, high public resources.

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Impacts on Visual Quality

Figure 41. Visual model protocol.

Visual quality is unquestionably one of the region’s key assets at risk of further degradation from future development. This potential degradation can have severe negative impacts on La Paz’ tourism and development industries, and the region’s economy. To assess the consequences of future change on the visual landscape, a model of visual quality is produced using the results of a photographic survey of residents and visitors. Survey respondents were asked to order by preference sixty photographs that represent the existing landscape of the La Paz region according to the scenic preferences. The sixty photographs in order of preference are shown in Figure 43.

These results are summarized and translated into a map of landscape quality (see Figure 42) and into a computer model. The model applies these preferences to describe the existing scenic qualities throughout the study area and formed the basis for measuring changes in visual quality associated with each alternative future. In Figures 44, 45, and 46, the mainly negative impacts of Alternative Futures A, B, and C are highlighted. Note especially the impact along the coastline and the roads that are now highly scenic.

A photographic survey asks local residents and visitors to show their visual preferences.	Views out towards the water from La Paz are important for visitors and residents.	Scenes of undeveloped coastline received the highest score in visual surveys.

	Figure 42. Visual quality priority areas.

4.68	4.50	4.45	4.27	4.13	4.09
4.04	4.00	4.00	3.90	3.90	3.86
3.81	3.81	3.77	3.77	3.77	3.72
3.63	3.63	3.63	3.50	3.45	3.45
3.27	3.18	3.13	3.13	3.09	3.09
3.04	3.00	2.95	2.90	2.90	2.86
2.86	2.81	2.77	2.77	2.72	2.72
2.63	2.63	2.63	2.63	2.59	2.59
2.50	2.40	2.40	2.27	2.27	2.18
1.81	1.81	1.45	1.27	1.09	0.36

Figure 43. The sixty pictures of the photographic survey in order of preference.

 

Figure 44. Impacts on visual quality. Alternative Future A. Rapid growth, unregulated policy set, high public resources	Figure 45. Impacts on visual quality. Alternative Future B. Moderate growth, legal policy set, low public resources.
Figure 46. Impacts on visual quality. Alternative Future C. Trend growth, proactive policy set, high public resources.

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Impacts on Recreation

The many recreational areas surrounding La Paz are a key feature in the landscape. These areas attract visitors to the region and add to the quality of life in La Paz. A recreation model identifies areas of highest recreational value to residents and tourists and is used to evaluate the impact of future land use.

The greatest threat to public recreation areas is the development of private housing and tourist resorts that restrict public access to beaches.

These impacts can be seen in Figures 48, 49, and 50 on the coastal areas of the northern La Paz peninsula area including the Balandra and Tecolote areas. These areas that Paceños and tourists have historically used for recreation have been de facto public areas. However, they are not legally defined as either public or recreational areas. Deciding the future of these lands promises to be a contentious issue, and the subject of legal disputes and social conflicts.

Tecolote is one of the few areas on the northern peninsula with permanent structures.	Diving, snorkelling, fishing and windsurfing of among the water sports enjoyed in the area.	El Tesoro, one of several public beaches in the region.

Figure 47. Recreational priority areas.
Figure 48. Impacts on recreation. Alternative Future A. Rapid growth, unregulated policy set, high public resources	Figure 49. Impacts on recreation. Alternative Future B. Moderate growth, legal policy set, low public resources.
Figure 50. Impacts on recreation. Alternative Future C. Trend growth, proactive policy set, high public resources.

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Areas of Conflict

An aggregate spatial analysis allows a projection of the areas in the landscape that are potential sites of conflict in the future. This analysis is carried out with the overlay of two aggregate maps. Figure 51 combines the various attractiveness maps presented earlier. This map shows the areas with the most intense pressure for development. Figure 52 is a combination of the terrestrial ecology, visual quality, and recreational quality maps. This map serves as a measure of the aggregate environmental value of each location in the region.

Overlaying these two maps produces Figure 53, which displays the different possible combinations of development pressure against the ecological, visual, and recreational value of the landscape.

The areas surrounding the existing urban area and road systems are very likely to be developed at moderate to low environmental cost. The outlying areas will continue to experience lower pressure for development and are therefore likely to be protected, even if passively. The areas in dark brown indicate areas of conflict, locations of high development pressure and high environmental value. Examples are the peninsular coastline to the north, which includes the Balandra and Tecolote areas, as well as the Mogote, the barrier beach of the La Paz lagoon. These are the areas of potential conflict that will require the attention of policy makers to resolve.

	Figure 51. Aggregate development attractiveness.		Figure 52. Aggregate environmental quality.

Figure 53. Potential areas of conflicting land use demand.

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Economic Impacts

We complete the assessment of impacts with an evaluation of the likely economic changes associated with each of the Alternative Futures. Economic performance – generating new jobs and higher incomes – is an important determinant in the welfare of the region’s inhabitants.

The economic analysis is based upon modifications to the three reference growth projections presented earlier: trend, medium, and rapid growth. The key differences in the three growth projections are the growth rates in the tourism and real estate sectors. These are the two sectors of the economy with the greatest potential for rapid growth, stimulating further growth in the rest of the economy. The economic performance of the tourism and real estate sectors from 2010 to 2020, however, are linked to the results of the ecological, visual, and recreational impact models. The demand stemming from the tourism sector and the most environmentally-sensitive segments of the real estate market will naturally decline with a drop in the quality of the physical environment. Therefore, the results presented here deviate from the reference projections in the second decade.

One of the consequences of the impacts on the ecological, visual, and recreational landscapes, particularly in Alternatives Aand C, is a decline in the rate of growth for the period of 2010 to 2020 (Figure 54). Despite this slowing of growth, Alternative Future A produces the highest growth in gross output and job creation (Figure 55), followed by Alternative Future B.

The economic consequences of a declining environmental base are much more pronounced when viewed in terms of per-capita income. Although the per capita income measures for the three scenarios follow the same path for the first decade, it diverges in the second decade. Alternative Future C produces significantly higher average incomes while per capita income growth is projected to be stagnant for Alternative Future A in the second decade.

When a broader range of scenarios is analyzed, the scenarios that are based on the proactive policy set outperform the unregulated and legal scenarios in economic terms, as well as the natural environmental measures. The unrestricted and legal policy sets exhibit a relative decline in per-capita income. The underlying mechanism driving these results is the combination of higher population growth rates associated with the first decade of high economic growth followed by a drop in economic growth in the second decade.

The rapid growth scenario without adequately protecting public amenities is essentially the same cycle of over-exploitation and depletion of natural resources seen throughout La Paz’ history. It is also consistent with the phenomenon observed in many destinations around the world where an expansion is followed by a subsequent decline. The decline in the tourism cycle is generally prompted by deterioration in the natural and social environment. The most prominent example of this process in Mexico is Acapulco Bay, where congestion and a decline in water quality have been associated with a shift in the tourism market and erosion in the sector’s profitability.

The higher growth scenarios that produce higher incomes and generate more jobs have clear economic benefits. However, these benefits are reduced substantially when accompanied by the degradation of public environmental assets.

Figure 56. Per capita income

Tourism and real estate development will spur future growth of the region.	Small businesses are important contributors to region income.	The economy of the region of La Paz is dominated by commerce and services.

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A Comparison of Eighteen Alternative Futures

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Figure 57. Land use 2020 in the the eighteen scenarios.[Growth projection, policy set, level of public financial resources.]

Projected land use in 2020 for each of the eighteen possible alternative futures is shown in Figure 57. The environmental and economic results are compared using two summary indices in Figure 58. The economic summary index is created using gross regional product and per capita income projections. The visual, recreational, and ecological impacts for each of the scenarios are combined to form an index of environmental performance. Among the many economic and environmental outcomes, the unregulated futures do not perform well. While the alternatives based on existing laws perform better, the proactive policies produce the most best outcomes. Within each policy option, there are trade-offs between economic and environmental outcomes.

Figure 58. Summary results for the eighteen scenarios.

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