L. L. PADILLA-GIL, J. A. ÁVILA-OLIVERA, G. A. HUAPE-PADILLA & M. E. GRANADOS-GARCÍA
Instituto de Investigaciones Sobre los Recursos Naturales (INIRENA), Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Av. San Juanito Itzicuaro s/n, Col. Nueva Esperanza, CP 58330, Morelia, Michoacán, Mexico
ja.avilaolivera@gmail.com
Abstract The exploitation of an aquifer system causes water table decline when withdrawals exceed the recharge, which in turn activates the process of land subsidence. When sinking is guided by a structural control, the land subsidence is differential and generally is accompanied by earth fissures, fracturing and ground rupturing. All of these effects of the use groundwater generate damages to the infrastructure of cities. In the case of Morelia, Mexico, damages have been observed since 1983, causing economic and social impacts. Reviewing the Mexican legislation, no legal instrument which contemplates the phenomenon of land subsidence and its associate problems was found. Therefore, neither society nor government have legal elements to invoke or claim. However, the proliferation of constructions located in zones identified by scientific studies as risky continues. Accordingly is necessary to incorporate land subsidence into legal instruments in order to establish regulation criteria and include them in the urban development plans. These instruments could be the General Law of Ecological Equilibrium and Environmental Protection, the National Water Law, and the Territorial Ecological Zoning.
Key words land subsidence; legislation; environmental planning; Morelia, Mexico
INTRODUCTION
The exploitation of an aquifer system causes water table decline when withdrawals exceed the recharge, which in turn activates the process of land subsidence (Ávila-Olivera & Garduño-Monroy, 2006). This situation occurs generally in urban areas of rapidly growth where the demand for groundwater increases as a result of population explosion; examples in Mexico are Mexico City (Figueroa-Vega, 1984), Morelia (Garduño-Monroy et al., 1998), Querétaro (Álvarez-Manilla et al., 2004), Celaya (Trujillo-Candelaria, 1991), Aguascalientes (Zermeño-De León, et al., 2005), among others.
In Morelia extractions are carried out through 105 pumping wells, generating an annual average water table decline of 3.67 m (Ávila-Olivera & Garduño-Monroy, 2007). The city has been characterized by urban growth beyond measure, with consequent excessive exploitation of groundwater resources. Currently the drinking water service is being provided to 747 136 inhabitants.
One effect of the groundwater overexploitation is land subsidence and its associated problems (earth fissures, fracturing and ground rupturing), which have caused damages to the city since 1983 (Garduño-Monroy et al., 2001). Nowadays, Morelia is being affected by differential land subsidence with rates of up to -35 mm/year (Farina et al., 2008), and surface faults in a NE-SW direction, with steps of up to 800 mm (the “Central Camionera” Ávila-Olivera & Garduño-Monroy, 2004).
THE PROBLEM
Water supply programmes and projects are not usually planned according to the responsiveness of the geological environment. An extraction greater than recharge, a parameter difficult to estimate, causes lowering of groundwater levels and reduces the water volume available. Overexploitation obligates searching for alternative sources and also consideration of schemes for better resources management. However, there are also side effects to inadequate groundwater exploitation (Rodríguez-Castillo & Rodríguez-Velázquez, 2006). One of these effects is land subsidence.
The damages caused by land subsidence and ground rupturing, to buildings and houses, include the cracking of walls, floors, girders and foundations, and ceiling collapse; in some cases a total loss of the construction is reached. The owners make continuous and expensive repairs, not knowing that the process will not stop in short or medium term. Also the land cost decreases significantly. Naturally, the loss of their heritage affects the quality of their life and creates a social problem.
In Morelia there is a history of complaints to the authorities, submitted by civil society which has been affected by the purchase of houses that in less than three months presents cracks in their structural elements. However, neither the owners nor the government have legal instruments to claim. Instead, construction in zones with problems of land subsidence which has been indentified by scientific studies continues to proliferate.
LEGAL FRAMEWORK
In 1990 the Organization of American States (OAS) published the document Disasters, Planning and Development: Managing Natural Hazards to Reduce Loss, which contains a first effort to integrate development plans with the mitigation of natural disasters. It refers to environmental planning; the document contrasts environmental projects with development projects and concludes that to achieve a lasting development programme, it must incorporate coherent environmental planning.
In Mexican legislation different legal instruments are issued for environment protection, mitigation of environmental impacts, to regulate building construction, for exploitation and use of groundwater and surface water. Some of these instruments are the General Law of Ecological Equilibrium and Environmental Protection, National Water Law, Housing Law, General Law of Human Settlements. Notwithstanding the existence of these laws, none of their paragraphs cover land subsidence risk prevention, the effect on individuals, protective measures against this eventuality, or the application of administrative responsibility to the authorities charged to regulate the establishment and land uses.
While it is true that the National Water Law provides in its article 18 third paragraph that it will issue the regulation for the extraction and use of national water, in relation to groundwater there is no reference to an issue. Maybe a section dealing with the effects of groundwater withdrawal, as a cause of land subsidence, and its associated problems could be inserted in this bylaw.
CONAGUA (the National Water Commission) has issued standards which establish the provisions, specifications and test methods to help ensure that products and services supplied meet with the aim of harnessing and preserving water quality and quantity. However, it has not specified any management for the exploitation and use of groundwater and surface water causing environmental, social and economic risk phenomena related to this activity, such as land subsidence.
DISCUSSION
In the southwestern portion of Morelia, the authorizations to fractionate are unreasonable; they do not take into account the proliferation of pumping wells and the presence of geological faults, despite the fact that there are studies that have established the potential of the area to develop problems of land subsidence, earth fissures, fracturing and ground rupturing; thus, the supply of housing in that zone is irresponsible from both the perspective of the authorities and developers. As a precautionary measure to avoid irreversible economic and social damage, there must be restricted land use in areas with the possibility of natural or anthropogenic risks.
CONCLUSIONS
The Mexican legislation does not consider land subsidence as a natural or an induced disaster, therefore is not included in the National Water Law, nor in the General Law of Ecological Equilibrium and Environmental Protection; also is not considered in emergency programmes for social assistance. This is due mainly to the fact that the land subsidence effects occur in the long term. Therefore, the affected communities have no legal elements to invoke or claim.
The problems associated with land subsidence should be reflected in the General Law of Ecological Equilibrium and Environmental Protection, and in the Territorial Ecological Zoning, in order to establish the regulation criteria and its inclusion in the urban development plan.
REFERENCES
Álvarez-Manilla, A. A., Fernández-Hernández, F., Poot-Lima, R. M. &Zepeda-Garrido, J. A. (2004) Hundimiento máximo en el Valle de Querétaro en función del potencial acuífero. XXII Reunión Nacional de Mecánica de Suelos.
Ávila-Olivera, J. A. & Garduño-Monroy, V. H. (2004) La subsidencia y las fallas geológicas en la Ciudad de Morelia, Michoacán. XXII Reunión Nacional de Mecánica de Suelos.
Ávila-Olivera, J. A. & Garduño-Monroy, V. H. (2006) El abatimiento de los niveles freáticos es sólo un elemento de los Procesos de Subsidencia-Creep-Falla, caso: la Ciudad de Morelia, Michoacán. Geos 26(1), 186.
Ávila-Olivera, J. A. & Garduño-Monroy, V. H. (2007) Análisis del abatimiento de los niveles freáticos del sistema acuífero de Morelia. Revista Ciencia Nicolaita 46, 105-122.
Farina, P., Ávila-Olivera, J. A., Garduño-Monroy V. H. & Catani, F. (2008) DInSAR analysis of differential ground subsidence affecting urban areas along the Mexican Volcanic Belt (MVB). Rivista Italiana di Telerilevamento 40(2), 103-113.
Figueroa-Vega, G. E. (1984) Case History 9.8 Mexico, D.F. In: Guidebook to Studies of land subsidence due to groundwater withdrawal (ed. by J. F. Poland), 217-232. International Hydrological Program, Working Group 8.4.
Garduño-Monroy, V. H., Arreygue-Rocha, E, Chiesa, S., Israde-Alcántara, I., Rodríguez-Torres, G. M. & Ayala, G. M. (1998) Las fallas geológicas y sísmicas de la ciudad de Morelia y su influencia en la planificación del territorio, Ingeniería Civil, 1(5), 3-12.
Garduño-Monroy, V. H., Arreygue-Rocha, E, Israde-Alcántara, I. & Rodríguez-Torres, G. M. (2001) Efectos de las fallas asociadas a sobreexplotación de acuíferos y la presencia de fallas potencialmente sísmicas en Morelia, Michoacán, México, Revista Mexicana de Ciencias Geológicas 18(1), 37-54.
Ley de Aguas Nacionales (National Water Law).
Ley General de Equilibrio Ecológico y Protección al Ambiente (General Law of Ecological Equilibrium and Environmental Protection).
Rodríguez-Castillo, R. & Rodríguez-Velázquez, I. (2006) Consecuencias sociales de un desastre inducido, subsidencia, Boletín de la Sociedad Geológica Mexicana, Número especial de Geología Urbana Tomo LVII(2), 265-269.
Trujillo-Candelaria, J. A. (1991) Fallamiento de terrenos por efecto de la sobreexplotación de acuíferos en Celaya, Guanajuato, México. In: XXIII Congress of the Association of International Hydrologists, Sobreexplotación de acuíferos: España, 175-178.
Zermeño-De León, M. E., Esquivel-Ramírez, R., Hernández-Navarro, A., Mendoza-Otero, E. & Arellano-Sánchez, J. (2005) Influencia de la Extracción del Agua en la Subsidencia y Agrietamiento de la Ciudad de Aguascalientes. Revista Investigación y Ciencia de la Universidad Autónoma de Aguascalientes 32(1), 15-22.
Instituto de Investigaciones Sobre los Recursos Naturales (INIRENA), Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Av. San Juanito Itzicuaro s/n, Col. Nueva Esperanza, CP 58330, Morelia, Michoacán, Mexico
ja.avilaolivera@gmail.com
Abstract The exploitation of an aquifer system causes water table decline when withdrawals exceed the recharge, which in turn activates the process of land subsidence. When sinking is guided by a structural control, the land subsidence is differential and generally is accompanied by earth fissures, fracturing and ground rupturing. All of these effects of the use groundwater generate damages to the infrastructure of cities. In the case of Morelia, Mexico, damages have been observed since 1983, causing economic and social impacts. Reviewing the Mexican legislation, no legal instrument which contemplates the phenomenon of land subsidence and its associate problems was found. Therefore, neither society nor government have legal elements to invoke or claim. However, the proliferation of constructions located in zones identified by scientific studies as risky continues. Accordingly is necessary to incorporate land subsidence into legal instruments in order to establish regulation criteria and include them in the urban development plans. These instruments could be the General Law of Ecological Equilibrium and Environmental Protection, the National Water Law, and the Territorial Ecological Zoning.
Key words land subsidence; legislation; environmental planning; Morelia, Mexico
INTRODUCTION
The exploitation of an aquifer system causes water table decline when withdrawals exceed the recharge, which in turn activates the process of land subsidence (Ávila-Olivera & Garduño-Monroy, 2006). This situation occurs generally in urban areas of rapidly growth where the demand for groundwater increases as a result of population explosion; examples in Mexico are Mexico City (Figueroa-Vega, 1984), Morelia (Garduño-Monroy et al., 1998), Querétaro (Álvarez-Manilla et al., 2004), Celaya (Trujillo-Candelaria, 1991), Aguascalientes (Zermeño-De León, et al., 2005), among others.
In Morelia extractions are carried out through 105 pumping wells, generating an annual average water table decline of 3.67 m (Ávila-Olivera & Garduño-Monroy, 2007). The city has been characterized by urban growth beyond measure, with consequent excessive exploitation of groundwater resources. Currently the drinking water service is being provided to 747 136 inhabitants.
One effect of the groundwater overexploitation is land subsidence and its associated problems (earth fissures, fracturing and ground rupturing), which have caused damages to the city since 1983 (Garduño-Monroy et al., 2001). Nowadays, Morelia is being affected by differential land subsidence with rates of up to -35 mm/year (Farina et al., 2008), and surface faults in a NE-SW direction, with steps of up to 800 mm (the “Central Camionera” Ávila-Olivera & Garduño-Monroy, 2004).
THE PROBLEM
Water supply programmes and projects are not usually planned according to the responsiveness of the geological environment. An extraction greater than recharge, a parameter difficult to estimate, causes lowering of groundwater levels and reduces the water volume available. Overexploitation obligates searching for alternative sources and also consideration of schemes for better resources management. However, there are also side effects to inadequate groundwater exploitation (Rodríguez-Castillo & Rodríguez-Velázquez, 2006). One of these effects is land subsidence.
The damages caused by land subsidence and ground rupturing, to buildings and houses, include the cracking of walls, floors, girders and foundations, and ceiling collapse; in some cases a total loss of the construction is reached. The owners make continuous and expensive repairs, not knowing that the process will not stop in short or medium term. Also the land cost decreases significantly. Naturally, the loss of their heritage affects the quality of their life and creates a social problem.
In Morelia there is a history of complaints to the authorities, submitted by civil society which has been affected by the purchase of houses that in less than three months presents cracks in their structural elements. However, neither the owners nor the government have legal instruments to claim. Instead, construction in zones with problems of land subsidence which has been indentified by scientific studies continues to proliferate.
LEGAL FRAMEWORK
In 1990 the Organization of American States (OAS) published the document Disasters, Planning and Development: Managing Natural Hazards to Reduce Loss, which contains a first effort to integrate development plans with the mitigation of natural disasters. It refers to environmental planning; the document contrasts environmental projects with development projects and concludes that to achieve a lasting development programme, it must incorporate coherent environmental planning.
In Mexican legislation different legal instruments are issued for environment protection, mitigation of environmental impacts, to regulate building construction, for exploitation and use of groundwater and surface water. Some of these instruments are the General Law of Ecological Equilibrium and Environmental Protection, National Water Law, Housing Law, General Law of Human Settlements. Notwithstanding the existence of these laws, none of their paragraphs cover land subsidence risk prevention, the effect on individuals, protective measures against this eventuality, or the application of administrative responsibility to the authorities charged to regulate the establishment and land uses.
While it is true that the National Water Law provides in its article 18 third paragraph that it will issue the regulation for the extraction and use of national water, in relation to groundwater there is no reference to an issue. Maybe a section dealing with the effects of groundwater withdrawal, as a cause of land subsidence, and its associated problems could be inserted in this bylaw.
CONAGUA (the National Water Commission) has issued standards which establish the provisions, specifications and test methods to help ensure that products and services supplied meet with the aim of harnessing and preserving water quality and quantity. However, it has not specified any management for the exploitation and use of groundwater and surface water causing environmental, social and economic risk phenomena related to this activity, such as land subsidence.
DISCUSSION
In the southwestern portion of Morelia, the authorizations to fractionate are unreasonable; they do not take into account the proliferation of pumping wells and the presence of geological faults, despite the fact that there are studies that have established the potential of the area to develop problems of land subsidence, earth fissures, fracturing and ground rupturing; thus, the supply of housing in that zone is irresponsible from both the perspective of the authorities and developers. As a precautionary measure to avoid irreversible economic and social damage, there must be restricted land use in areas with the possibility of natural or anthropogenic risks.
CONCLUSIONS
The Mexican legislation does not consider land subsidence as a natural or an induced disaster, therefore is not included in the National Water Law, nor in the General Law of Ecological Equilibrium and Environmental Protection; also is not considered in emergency programmes for social assistance. This is due mainly to the fact that the land subsidence effects occur in the long term. Therefore, the affected communities have no legal elements to invoke or claim.
The problems associated with land subsidence should be reflected in the General Law of Ecological Equilibrium and Environmental Protection, and in the Territorial Ecological Zoning, in order to establish the regulation criteria and its inclusion in the urban development plan.
REFERENCES
Álvarez-Manilla, A. A., Fernández-Hernández, F., Poot-Lima, R. M. &Zepeda-Garrido, J. A. (2004) Hundimiento máximo en el Valle de Querétaro en función del potencial acuífero. XXII Reunión Nacional de Mecánica de Suelos.
Ávila-Olivera, J. A. & Garduño-Monroy, V. H. (2004) La subsidencia y las fallas geológicas en la Ciudad de Morelia, Michoacán. XXII Reunión Nacional de Mecánica de Suelos.
Ávila-Olivera, J. A. & Garduño-Monroy, V. H. (2006) El abatimiento de los niveles freáticos es sólo un elemento de los Procesos de Subsidencia-Creep-Falla, caso: la Ciudad de Morelia, Michoacán. Geos 26(1), 186.
Ávila-Olivera, J. A. & Garduño-Monroy, V. H. (2007) Análisis del abatimiento de los niveles freáticos del sistema acuífero de Morelia. Revista Ciencia Nicolaita 46, 105-122.
Farina, P., Ávila-Olivera, J. A., Garduño-Monroy V. H. & Catani, F. (2008) DInSAR analysis of differential ground subsidence affecting urban areas along the Mexican Volcanic Belt (MVB). Rivista Italiana di Telerilevamento 40(2), 103-113.
Figueroa-Vega, G. E. (1984) Case History 9.8 Mexico, D.F. In: Guidebook to Studies of land subsidence due to groundwater withdrawal (ed. by J. F. Poland), 217-232. International Hydrological Program, Working Group 8.4.
Garduño-Monroy, V. H., Arreygue-Rocha, E, Chiesa, S., Israde-Alcántara, I., Rodríguez-Torres, G. M. & Ayala, G. M. (1998) Las fallas geológicas y sísmicas de la ciudad de Morelia y su influencia en la planificación del territorio, Ingeniería Civil, 1(5), 3-12.
Garduño-Monroy, V. H., Arreygue-Rocha, E, Israde-Alcántara, I. & Rodríguez-Torres, G. M. (2001) Efectos de las fallas asociadas a sobreexplotación de acuíferos y la presencia de fallas potencialmente sísmicas en Morelia, Michoacán, México, Revista Mexicana de Ciencias Geológicas 18(1), 37-54.
Ley de Aguas Nacionales (National Water Law).
Ley General de Equilibrio Ecológico y Protección al Ambiente (General Law of Ecological Equilibrium and Environmental Protection).
Rodríguez-Castillo, R. & Rodríguez-Velázquez, I. (2006) Consecuencias sociales de un desastre inducido, subsidencia, Boletín de la Sociedad Geológica Mexicana, Número especial de Geología Urbana Tomo LVII(2), 265-269.
Trujillo-Candelaria, J. A. (1991) Fallamiento de terrenos por efecto de la sobreexplotación de acuíferos en Celaya, Guanajuato, México. In: XXIII Congress of the Association of International Hydrologists, Sobreexplotación de acuíferos: España, 175-178.
Zermeño-De León, M. E., Esquivel-Ramírez, R., Hernández-Navarro, A., Mendoza-Otero, E. & Arellano-Sánchez, J. (2005) Influencia de la Extracción del Agua en la Subsidencia y Agrietamiento de la Ciudad de Aguascalientes. Revista Investigación y Ciencia de la Universidad Autónoma de Aguascalientes 32(1), 15-22.
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