A – Proposal for the creation at UNESCO-IHP of the
“Land Subsidence International Initiative (LaSII)”

B – Official documents of the
“Land Subsidence International Initiative (LaSII)”



Land Subsidence (LS), i.e., the loss of land elevation, is a major problem that threatens viability and sustainable economic development for many millions of people throughout the world, especially, but not restricted to coastal and highly urbanized areas.

The UNESCO Working Group on Land Subsidence (WGSL) is one of the oldest working groups within the International Hydrological Programme (IHP), initiating activities during the 1965-1974 International Hydrological Decade (IHD). In the 1970s the WGLS started its activities to improve and disseminate knowledge on LS, mainly in developed and newly-developed countries and regions, e.g., Japan, The Netherlands, USA, Italy, Mexico, China, Taiwan that were strongly affected by LS following the economic boom after the World Wars. Since 2010 the members of the WGLS established new linkages and collaborations with other international and national hydrologic programs and projects concerned with the sustainable development of global land and freshwater resources and the subsidence hazards accompanying their exploitation, mainly in developing countries such as Indonesia, Pakistan, Egypt, Vietnam, India, Iran, etc. Now, facing global changes, the need to disseminate this knowledge more broadly and to intensify applications of the accumulated knowledge is urgent.

In the IHP-VIII Phase Strategic Plan (2014-2021) which addresses Water Security, LS is considered as a major threat.  Because of the strong anthropogenic component of the prevalent subsidence processes, the activities of the LaSII would be aligned implicitly with the goals elucidated in Theme 1 (Focal Areas 1.1, 1.2 and 1.3), Theme 2 (Focal Areas 2.1, 2.2, and 2.3), Theme 4 (Focal Areas 4.4 and 4.5) and Theme 5 (Focal area 5.1).

Why Land Subsidence (LS) is still a critical societal issue

Society is facing a large number of challenges related to the sustainable use of land and water resources that will increase in the next decades. The effects of climate change in terms of sea-level rise and variation in the distribution and timing of precipitation, runoff and recharge, are compounded by the increasing concentration of population in (mega-) cities and elsewhere along the coasts of the world. The consequences related to the expanding need of freshwater resources in even more concentrated, at-risk zones of the world will inevitably affect a growing number of people.

A few worldwide case studies clarify the present criticality of the LS due to aquifer over-exploitation: 1) in Jakarta, Indonesia, where the population grew from 8.2 million to more than 30 million from 1970 to 2016, groundwater extraction has caused the sinking of land surface at rates of 10-20 cm/yr, with a dramatic increase of vulnerability to flooding from river and sea waters; 2) in many deltaic and coastal areas of the world (e.g., the Bengal, Mekong, Nile, and Mississippi river deltas) LS occurs as a result of compaction and oxidation increasing CO2 emissions to the atmosphere, loosing valuable ecosystems, and enhancing the vulnerability to coastal and riverine flooding; 3) in numerous regions (e.g., China, Mexico, Arizona, Iran, Pakistan) in the world large ground fractures occur as a result of LS with damages to structures/infrastructures and increased aquifer contamination favored by rapid infiltration of wastewaters and pollutants through the fissures; 4) in Mexico City many buildings and houses were severely damaged during the September 19th, 2017 earthquake in areas where the subsoil was strongly weakened by ground fractures that previously developed with the more than 10 m of LS accompanying groundwater exploitation.

Despite the facts that the scientific basis of aquifer-system compaction and LS due to groundwater pumping, and the means to mitigate its occurrence are well known, the process is increasingly affecting more and larger regions and with greater consequences throughout the world. In the IHP-VIII Phase Strategic Plan which addresses Water Security, LS is considered as a major threat.

Nevertheless, the attention afforded by LS in sustainable planning of water services and safe urban development is still undervalued. Although difficult to quantify, the direct and indirect costs associated to damages caused by LS are extremely large. Here a few examples: 2500 M€/year in China; 1092 M€ (1300 M$) from 1955 to 1972 in the San Joaquin Valley, USA; 360 M€/year in Poland; 50 M€ from 1992 to 1995 in Murcia City, Spain; 52 B€/year in The Netherlands (the national planning bureau PBL, Netherlands Environmental Assessment Agency calculated that in the Netherlands, the cost for society of land subsidence occurring in peatlands amounts to billions of Euros). Furthermore, the consequences are expected to increase in the next decades.

WGLS role in the development of an IHP-UNESCO Land Subsidence International Initiative (LaSII)

Until now, a still growing group of scientists from all over the world have – on a voluntary basis – joined in the WGLS. They are willing to share their knowledge, mainly collected through individual research projects, and enhance subsidence awareness.

As a LaSII the group of experts and collaborators will seek stronger support from the UNESCO IHP and the governments of the 11 countries that are now participating (see detailed list of Members at the end of the document), to consolidate the development of methodologies for characterization and modeling of LS, monitoring networks, transfer of information to decision makers, advise creation of public policies and ideally, in the end contribute to an increase in the security and resilience of inhabitants of LS affected areas. Moreover, there is an urgent need to transfer the generated knowledge to developing countries with limited access to research studies and monitoring. The main goals are to improve access to scientists and engineers from developing countries, enhance knowledge transfer and achieve a better planning for the sustainable use of the groundwater resources LS-affected regions in view of the expected climate changes.

Objectives and activities

LaSII will focus primarily on four main aspects:

  1. LS due to groundwater resources overexploitation,
  2. LS in coastal areas, related with sea-level rise,
  3. LS related with earth fissures, ground fractures and fault reactivation,
  4. LS related with water security in urban areas.

The main goals to achieve with the creation of LaSII are:

  • to propose effective methodologies for LS identifying and establishing an inventory of subsiding areas in the world;
  • to publish guidelines for the identification, investigation, development and management of LS-related phenomena to be used in emergencies;
  • to support capacity building in member countries in order to gain and advocate better understanding and handling of hazards, vulnerabilities and benefits involving LS and other groundwater-related disasters;
  • to raise awareness of decision makers, implementers, users and the general public of the importance of groundwater as a store of freshwater in order to encourage improved protection and sustainable exploitation of groundwater – through leaflets, publications, the media, education and training;
  • strengthen capacity building and educational capabilities in urban water management aimed at relevant target groups, including decision makers, planners and practitioners, with a special emphasis on developing countries;
  • to facilitate participation of IHP Focal Points and National Committees in the development of case studies and the dissemination of LS mitigation guidelines;
  • strengthen linkages with other IHP Programs: ICHARM (International Centre for water Hazard And Risk Management), FRIEND (Flow Regimes from International Experimental and Network Data), HELP (Hydrology for the Environment, Life and Policy), and Urban Water Management (UWMP) together with international institutions (i.e. International Association of Hydrogeologists, International Society of Soils Mechanics and Geotechnical Engineering, Eurogeosurveys, etc.);
  • to favor financial support from external sources, such as World Bank, UNDP, EU, national founding agencies.

Proposed activities of the LaSII:

  • publishing a guidebook on land subsidence;
  • convening annual WG meetings;
  • organizing, sponsoring and convening a 5-yearly international symposium on land subsidence over five decades (the ninth held at Nagoya, Japan, in 2015 and the tenth will be held in The Netherlands in 2020);
  • establishing a growing number of collaborations with other local, state and national subsidence-interest groups, and several collaborative projects;
  • the improvement and regular updating of the website (https://www.landsubsidence-unesco.org). It contains general informative material, a worldwide map of the land subsidence occurrences, the proceedings of the past nine symposiums on land subsidence, scientific articles and technical reports. Maps production could be undertaken in coordination with the UNESCO WHYMAP programme.
Implications of LaSII on the UNESCO-IHP Programme and Secretariat

Similar to what has been carried out by the WGLS until now (short summary of the activities carried out without any financial support from UNESCO listed at the end of the document), LaSII activities will not have direct financial implications for the IHP Secretariat, as it will rely entirely on extra budgetary.

The IHP support will mainly include provision of guidance on:

  • the establishment of the Initiative;
  • reporting the progress achieved by the Initiative to the sessions of the IHP Intergovernmental Council;
  • sharing the main results of the Initiative with the UNESCO Water Family and beyond


LaSII Guidelines for the organization and maintenance of membership

Structure of the LaSII

The LaSII is an integrated, world-wide group of specialists in the different aspects related to Land Subsidence. The group is formed by a Chairman, a Vice-Chairman, a Technical Secretary, Members, Observers and Associates.

The LaSII strives to integrate representatives from each country in the world affected by subsidence. Each country may be represented by a maximum of two Members. If Members are unavailable, a country can be represented by one or two Observers. A third category, Associate, is for any land-subsidence specialist or enthusiast practitioner showing an outstanding commitment to LaSII’s activities as evaluated by the Members, even if there are already two Members/Observers of her/his represented country.

Activities of the LaSII

– Meet annually and discuss the status and strategy of the LaSII, as well as other topics

– Organize an International Land Subsidence Symposium approximately every 5 years

– Raise awareness of land subsidence

– Disseminate information (presentations, policy brief, webinars, flyers, etc.)

– Train (courses, summer courses, webinars, presentations, conferences, etc.)

– Encourage development of collaboration projects
– Update and improve the LaSII website

– Contribute to the annual reporting to UNESCO

If the LaSII evaluates and approves the integration of a new Member, she/he generally will be admitted as an Observer and can subsequently be promoted to a Member if LaSII vote results determine the Observer has sufficiently engaged in the activities mentioned in these guidelines.

A potential new Observer is proposed by one of the Members, with the CV and statement-of-interest distributed through the Technical Secretary. To become an Observer, the candidate must demonstrate 1) specific “knowledge” on land subsidence occurrences in the country she/he will represent and 2) that land subsidence is a key field of her/his actual research or work; or 3) In the case (1) and (2) cannot be “accomplished”, the candidate must have strong connections/collaborations with local academic/administrative/technical institutions, especially if he/she will represent a developing country (mainly for Africa, Asia, and Latin America) that are regions of particular interest for UNESCO. An observer participates in the meeting but only members can vote on the LaSII decisions.

If an Observer position is not available (the country is already represented by 2 Members/Observers) or the above requirements are not fulfilled, a land-subsidence scientist/expert can be integrated as an “Associate” to LaSII activities when she/he demonstrates a sufficient interest in land subsidence as evaluated by the LaSII. Associates are expected to follow and participate in LaSII activities. Attendance to every annual LaSII meetings is not mandatory but can be requested. The permanence of associates will be evaluated every five years based on their contribution to land subsidence activities.

The Chairman will send a letter to communicate the new Member/Observer/Associate is admitted and to notify his commitments to the LaSII.

Chairman, Vice-Chairman, Technical Secretary
The Chairman and Vice-Chairman are elected by the LaSII members every five years, generally during the meeting of the International Symposium. The Vice-Chairman can be promoted to Chairman by LaSII members vote. After her/his promotion, the Chairman may propose a member for the Vice-Chairman position. Chairman and Vice-Chairman must be members of the LaSII for at least the previous 5 years.

If the Chairman, during her/his term abandons her/his position, the Vice-Chairman is promoted to Chairman, and a Vice-Chairman is elected for the remainder of the 5-year term. In case of absence during any meeting, the Chairman delegates her/his duties and responsibilities to the Vice-Chairman. The Technical Secretary is selected by the Chairman in agreement with the Vice-Chairman.

Maintenance of membership
Maintenance of membership depends on LaSII activity level. An active member of the LaSII is expected to:

– Demonstrate work on academic or applied research related to the processes associated with land subsidence;

– Participate physically or virtually in the annual meetings of the LaSII. If absent for two consecutive meetings, the permanence of the Member/Observer will be evaluated by the LaSII;

– Develop activities that encourage or promote the LaSII and their achievements;

– Contribute to the LaSII strategies in the short, medium and long term.

The status of the Members that are no longer active in LaSII activities will change to “Member Emeritus”.


During meetings, voting is accomplished by “raising hand” (or verbal expression for virtual attendees); between meetings, voting can be accomplished by email visible to all the Members. The Technical Secretary will organize the voting and determine voting results. Only LaSII Members may vote.

Member voting about a new Member or removal of a Member will be proposed by the Chairman and evaluated by the LaSII Members during the annual meeting. 50% of the present or virtual Member votes are required to approve a new Member; 67% of the present or virtual Member votes are required to remove a member. Voting is done in the absence of the potential candidate.

An Observer or Associate can be proposed by any Member. This can be done at any time by an email to the Technical Secretary who will be distribute the proposal to all the LaSII Members. The new-Observer/Associate proposal must include a CV and statement-of-interest. After evaluation of the proposal, the LaSII Members will vote on the new observer or associate during the next LaSII annual meeting. 50% of the present or virtual Member votes are required to approve a new Observer or associate. Voting is done in the absence of the potential candidate.

For all other decisions (e.g. the location of the next annual meeting or symposium), approval requires 50% of the present/virtual Member votes. Decisions by ‘normal voting’ generally will be carried out during the LaSII annual meeting.

Procedure for application for new Observers/Associates of the UNESCO Land Subsidence International Initiative (LaSII) from 2019


Candidates for LaSII Observer have experience in research or work related to the exploitation of groundwater and the associated land subsidence phenomena.

A LaSII Member suggests a new Observer by sending the candidate’s CV and statement-of-interest to the Technical Secretary, with copies to the LaSII Chair and Vice-Chair. The Technical Secretary distributes the information to all Members and Observers and collects comments.

Becoming an Observer is subject to member voting during the LaSII Annual Meeting in absence of the applicant. If 50% of the Member votes are in favor of the applicant becoming an Observer, the applicant is acknowledged, the Chairman will send a letter to communicate admission into the LaSII and commitments to the LaSII. She/he also will be invited to the next Annual Meeting.

If the applicant receives less than 50% of the Member votes in favor of the applicant becoming an Observer, is not able to become an Observer. LaSII may decide to propose her/him to collaborate in the LaSII activities as an Associate. The Chairman will send a letter to communicate rejection into the LaSII as Observer, and the invitation to be an Associate (if applicable).

The reasons for no acceptation as Observer, and the eventual invitation to be an Associate, will be explained and sent to the applicant in a letter undersigned by the LaSII Chair.

Observers must contribute to the work of the LaSII and are expected to attend the annual meeting. They have to consider that there is no funding available from LaSII or UNESCO to contribute to the work of the LaSII or to attend LaSII meetings. Observers are encouraged to comment on LaSII topics, but may not vote on the LaSII decisions.

After showing a strong commitment for one or more years with the LaSII activities as an Observer, LaSII members may vote to promote an Observer to Member when her/his country has less than two representatives.


When a country already is represented by two specialists or because the candidate receives less than 50% of the member votes to become an observer, the candidate may be invited to collaborate as a LaSII Associate.

Associates are informed about the LaSII activities and are invited to participate in them. An Associate may be invited to participate in a LaSII Annual Meeting or another LaSII activity.

A LaSII Member suggests a new Associate by sending the candidate’s CV and statement-of-interest to the Technical Secretary, with copies to the LaSII Chair and Vice-Chair.

The Technical Secretary distributes the information to all Members and Observers and collects comments.

Becoming an Associate is subject to member voting during the LaSII Annual Meeting in absence of the applicant. If 50% of the member votes are in favor of the applicant becoming an associate, he/she will be informed by the Technical Secretary.

If the applicant receives less than 50% of the member votes in favor of the applicant becoming an Associate, the Chairman will send a letter to communicate rejection into the LaSII as Associate.

Associates are expected to follow and participate in LaSII activities. Attendance to the annual LaSII meeting is not mandatory but can be requested. There is no funding available from LaSII or UNESCO to participate in LaSII activities or to attend LaSII meetings. The permanence of associates will be evaluated every five years based on their contribution to LaSII activities.