Stabilisation of the Queretaro Valley Aquifer
In Querétaro, the main concern on water is
overexploitation of aquifers that since the fifties
have provided water to the inhabitants of this
Valley and are alarmingly experiencing high
levels of exploitation. Being the only source of
supply, solutions must be sought to provide
drinking water to all inhabitants of the entity,
without compromising the water for future
generations.
1. Innovative processes
stabilizing the Aquifer
and
methods
The metropolitan area of the city of Querétaro was supplied with groundwater only until 2010 and
mainly from the Querétaro Valley Aquifer. With the addition of 1.500 l.p.s. of surface water from the
Aqueduct System II, the way we operate the wells has changed, starting with an operational strategy to
replace groundwater volumes for surface water. The extraction of the Querétaro Valley Aquifer is
estimated at 110 million m3/year, which has caused a strong mining of the aquifer since the total
recharge is around 70 million m3/year, resulting in the overexploitation of groundwater.
This imbalance between the difference of recharge and extraction with a deficit of 40 million m3/year
has brought consequences in the area:
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Collapse and subsidence of the land, causing some faults and fractures that threaten the
stability of urban areas in the city, which has a greater exploitation.
Increased groundwater pumping costs, due to a lowering of the levels at a rate of 2.9 m3/year.
Decreased life and performance of the wells.
Deterioration of water quality in some areas of the aquifer, since extraction levels are deeper.
Exchange of 1.500 l.p.s. of surface water of the Aqueduct System II for groundwater
In order to satisfy the constant drinking water demand from the growing population of the state capital
and stabilise the Queretaro Valley Aquifer, the State Water Commission has carried out the search,
identification and evaluation of projects and supply sources to meet these demands.
One such project is the Aqueduct System II, which began operations on 17 February this year, adding a
volume of 47 million m3 (1.500 l.p.s.) annual of surface water for the inhabitants of the metropolitan
area of the city of Queretaro, the investment for the system was MXP$2,854,373,202, including
BANOBRAS FINFRA programme contribution of non-recoverable MXP$800.4 million and the
supplement was obtained through the private sector with the BOT scheme, which is used in
infrastructure in developed countries and allows to carry out high-priority projects for a society without
having to absorb the investment at the time of its execution.
On April 6, 2011, the Alcanfores II well was closed, which marks the beginning of volume reduction of
groundwater extraction in the Querétaro Valley Aquifer.
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Currently the wells operation was
reduced from 24 to approximately 11
hours a day to reduce the extraction
volumes of the Queretaro Valley aquifer
of 47 million m3 a year.
In regard to volumes produced for
February to May 2011 (15.36 million m3)
the extraction in the Querétaro Valley
Aquifer has decreased to 9.4 million m3,
compared to the monthly average
volume for the same period in 2010
(24.76 million m3).
The second action that is being
carried out for the benefit of the
Querétaro Valley Aquifer is the
reduction of demand through flow
recovery in the distribution system.
The water lost in the network represents a high cost to the state of Queretaro, for the investment in
major projects to bring it from long distances, as well as extracting and purifying groundwater before
delivering into the network.
Flow recovery is an important point to reduce leakage incidence, which is performed by replacing
networks in poor condition. Currently, 36% of the network has more than 25 years and/or is in a critical
condition, 20 colonies of the city have been identified that represent almost 50% of total leaks in the
network.
To decrease on leaks incidence during 2011-2015 it is planned to invest 1,100 million pesos for the
replacement of 765 km of network and an estimated recovery of 395 l.p.s., these actions will increase
the physical efficiency of the drinking water network, reduce leaks and stop extracting this volume from
the Queretaro Valley Aquifer.
The third action is rainwater induced infiltration with absorption wells into the
unsaturated Querétaro Valley subsoil
Sites were selected for the absorption wells taking into account the geo-hydrological characteristics and
conditions of the subsurface, which favour water infiltration and movement in the unsaturated layers of
the aquifer, obtaining the rainfall volume that the sub-basins provide.
This project involves the following institutions: CONACYT (National Council of Science and
Technology), CONCYTEQ (National Council of Science and Technology of the State of Querétaro),
CIDETEQ (Centre for Research and Technology Development in Electrochemistry of the State of
Querétaro), Water State Commission of Queretaro, Institute of Geosciences, UNAM (National
Autonomous University of Mexico) and the Faculty of Engineering UAQ (Autonomous University of
Queretaro).
To date we have drilled four wells, three for absorption in: Ciudad del Sol, Corregidora Stadium and
UAQ Sports Complex, and one under study, La Gloria, for rainwater infiltration into the unsaturated
Valley of Querétaro subsoil.
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La Gloria Well is completed at 150.00 metres depth and under implementation process with: Diver to
monitor the static level, tensometers to monitor vertical displacements and piezometers to monitor
water intakes at 20 and 140 metres deep.
The Corregidora Stadium Well is completed at 100 m depth and tests were made to the filling
absorption flow, using a volume of 36 m3, at a filling time of 9.0 minutes and 100 to 50 m depth.
The UAQ Sports Unit Well is completed in full and tests were made to the filling absorption flow, using
36 m3 volume, at a filling time of 9.0 minutes and 100 to 50 m depth.
The Ciudad del Sol Well, is completed at 80.00 m. with an absorption rate of 16.66 l.p.s. and it is
expected, based on the trend curve projection, to reach 100.0 m, with an absorption flow of 25.64 l.p.s.
Also, the depth of these three wells is up to 100.0 m and not reaching the 140.0 m ± depth of the static
level of the Queretaro Valley Aquifer.
Finally, the stormwater infrastructure projects are completed and under review.
This action not only pursues the primary objective of infiltrating water in the aquifer, but also aims to
manage the flooding problem in the urban area of Queretaro, contributing to control surface runoff
volumes.
The fourth action is the Moctezuma and Santa Maria River surface water reservoir to
supply water to the inhabitants of the State of Querétaro.
There is a Water Supply Plan for the State of Querétaro for surface water future demand and
availability of watersheds in the Moctezuma, Santa Maria and Extoraz Rivers of the Panuco 26
Hydrologic Region.
CONAGUA published on 2 July 2009 in the Official Gazette, the AGREEMENT stating the results of
technical studies of national surface water in the mentioned above hydrologic region watersheds.
Water volumes to be reserved
Santa Maria River
158 Mm³
Moctezuma River
158 Mm³
CONAGUA prepared the document on the water volumes to be reserved to send them to the Federal
Official Journal for publication.
The study’s results of 316 million m3 of surface water availability in the 26 Panuco hydrologic, make it
feasible to supply the national surface water reserves in the Santa Maria and Moctezuma rivers
watersheds and thereby ensure water supply for the population until 2105, i.e., for the next 100 years in
the State of Queretaro, as well as its socioeconomic development.
The fifth action is treated wastewater reuse and water culture.
It should be emphasised that due to its importance, actions have been taken to promote the reuse of
treated water in landscape irrigation, agriculture, industry and in some neighbourhoods of the city; in all
cases, where the replacement of drinking water for treated wastewater is possible. This allows us to
free volumes from the aquifer to prevent its overexploitation. Actually, 16.27 million m3 are being reused
per year in the metropolitan area of the city of Queretaro.
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Developing a broad and updated culture on the rational use of water is one of the State Water
Commission activities, an on-going mission through the school programme in preschool, primary and
junior high school education, the community programme and events such as the World Water Day,
State Competition Children's drawing and painting, in 2010 these events were held for the benefit of
74.455 inhabitants.
Impact on the Queretaro Valley Aquifer
The geohydrological balance of the aquifer would reach a steady trend in its recharge-extraction ratio
and a gradual decrease in the abatement rate
of aquifer levels that are currently of 2.9 m. per
year.
This will stop the progress of subsidence in the
affected areas of the city due to overexploitation
of the aquifer, preventing deterioration.
According to the numerical model of
groundwater flow dynamics, abatement levels
are estimated to be reduced between 0.8 m.
and 1.0 m. a year
Consider groundwater as a strategic reserve to
supply future generations of the metropolitan
area of the city of Queretaro.
2. innovation process Originality
This project is considered innovative as it is not known that there is in Mexico or Latin America an
aquifer stabilisation project and considers groundwater as strategic reserves for future generations.
The actions being undertaken in a comprehensive manner to stabilise the aquifer are:
Exchange of 1.500 l.p.s. of surface water from the Aqueduct System II for groundwater.
Flow recovery through massive network replacement of 765 km and estimated recovery of 395
l.p.s.
Induced rainwater infiltration through absorption pits in the unsaturated subsoil of the Queretaro
Valley.
Surface water reservoir of the Moctezuma and Santa Maria Rivers for water supply in the State
of Queretaro.
Treated wastewaters reuse and water culture.
This project represents a very important experience, being the basis and model for the recovery and
stabilisation of the Querétaro Valley Aquifer and encouraging more organisations and States to
replicate it in other aquifers.
Feasibility of replicating results in other utilities
Overexploitation is the result of excessive water extraction, ever-increasing demand for agricultural,
urban and industrial use, resulting in the abatement of water levels in the aquifer and quality
deterioration and destructive exploitation thereof, which is difficult to recover.
The information and experience generated in CEA Queretaro concerning the stabilisation of the
Queretaro Valley Aquifer will set the technical basis that supports actions and policies for the
development and rational use of water in other cities and states.
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Most of Mexico's urban population depend on groundwater, it is important to consider the experiences
in the recharge of aquifers and stabilisation to reduce abatement in water levels and contribute to a
better and rational use.
3. Impact of the process or technology in environmental care and rational use of water.
The most evident impacts of aquifers overexploitation are the major subsidence of soil and sub soil, as
groundwater is extracted the gaps formed are not filled again by water causes a rearrangement of land
and subsidence that substantially damaged urban structures, apart from making them more susceptible
to geological risks.
Expected results are directly related to the stabilisation of the Queretaro Valley Aquifer by ceasing to
extract the volumes supplied by the Aqueduct System II and flow recovery, reducing groundwater
exploitation, additionally to the artificial recharge to be implemented, thus meeting an ecological
problem and its remediation.
In the State of Queretaro actions are been taken for a better water management, optimisation and
efficient use.
For a society with a greater commitment awareness on environmental stewardship and rational water
use
4. Population served and/or number of intakes by utility.
Currently the system for the metropolitan area of the city of Queretaro is supplied with 212,140 drinking
water intakes benefiting 958,327 inhabitants, with one of the highest growth rates in the country.
The State Water Commission of Queretaro seeks to reverse the adverse trends of resources and lay
the groundwork for Querétaro to be a state with sustainability in drinking water supply, using more
effectively the available volumes of surface water and groundwater, requiring and promoting joint
participation of the authorities, users and society in general in the efficient use of water, protection of
water bodies and preserving the environment for future generations.
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