Groundwater CPR governance in presence of different types of extractors. Lab and field experimental analysis

Last registered on November 24, 2023

Pre-Trial

Trial Information

General Information

Title
Groundwater CPR governance in presence of different types of extractors. Lab and field experimental analysis
RCT ID
AEARCTR-0010742
Initial registration date
January 16, 2023

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
January 23, 2023, 5:50 AM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Last updated
November 24, 2023, 6:04 AM EST

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Region
Region

Primary Investigator

Affiliation
CIRAD

Other Primary Investigator(s)

PI Affiliation
ESI Medjez ElBab
PI Affiliation
INAT Tunis
PI Affiliation
CEEM University of Montpellier
PI Affiliation
CEEM University of Montpellier
PI Affiliation
CEEM CNRS University of Montpellier
PI Affiliation
CEEM INRAe University of Montpellier
PI Affiliation
CEEM INRAe University of Montpellier
PI Affiliation
INAT Tunis

Additional Trial Information

Status
Completed
Start date
2023-01-20
End date
2023-06-20
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Common pool resources (CPR) are characterised by free access (non, or limited, excludability) and rivalry in the use of the resource. CPR have the particularity of placing individual and collective interests in apparent opposition as well as creating tension in the choice of action, which is commonly referred to as a social dilemma. (Dubois et al., 2021). Rivalry in extractive CPR like groundwater implies that agents may think they should consume as much of the good as possible, fearing that the others leave nothing. This behaviour, known as ‘free riding’, is conducive to a phenomenon called ‘tragedy of the commons’ by Hardin (1968). Users depleting a CPR typically face several types of appropriation externalities (Gardner et al., 1997). In the real life, two types of externalities are faced by extractors: a static one (i.e.: the extraction cost at t is determined by the total extraction at t), and a dynamic one (i.e.: the extraction cost at t grows with the depth of the water table, depending on the total extraction at t-1). In such a non-cooperative game, the Nash equilibrium is reached when each individual maximizes his/her utility, whilst the Social optimum is reached when the sum of individual utilities are maximized.

Groundwater is a very important source of irrigation water, which alone represents more than 70% of the total water uses on earth (FAO, 2022). In North Africa half of current groundwater water withdrawals exceed natural rates of water recharge (Mayaux et al., 2022). Maghreb Countries depend on groundwater for their development, and public policies in the last decades have triggered radical changes in newly irrigated areas (extension areas) and in traditional oases (Kadiri et al., 2022). This resulted in a quick intensification of local agriculture, like in Tunisia, where oasis are currently facing sustainability concerns due to “uncontrolled expansion of irrigated areas, over-exploitation of groundwater resources, and soil degradation” (Ghazouani et al., 2009; Mekki et al., 2013).

In Tunisia, the Complex terminal Aquifer in Kebili is characterised by an important phenomenon of groundwater over-exploitation, resulting in 1 meter of lowering of the watertable/year. This is due to the almost irrelevant level of water recharge compared with the high water use (Trigui et al., 2021). In Tunisian oases, traditional farmers organised in water users associations, or GDA (French acronym for Agricultural Development Groups), coexist with newly settled extension farmers. Many GDA farmers have also plots in the extensions, where, like the extension farmers they dig illicit private boreholes that are not declared to the local authority for water management (CRDA) (Farolfi et al., 2022). Water extractions in the extensions are considered by many authors as the main cause of groundwater over-exploitation (Mekki et al., 2013), which will lead to the collapse of the system in the short or medium term if drastic measures are not take rapidly (Petit et al., 2017).

Current policies to match the problem are limited to the attempt by the CRDA to reduce access to water by limiting the number of boreholes. However, the overwhelming presence of illicit boreholes in Tunisian newly irrigated areas shows clearly the ineffectiveness of the measure. Alternative governance tools are necessary in order to face groundwater over-exploitation in the Tunisian oases.

To this end, like Gardner et al. (1997), we designed laboratory experiments to assess the performance of various groundwater governance policies and the applicability of game theory to behaviour in such system. We adapted the groundwater extraction dynamic model by Gardner et al., 1997 by introducing in the model the types of players (farmers), as found in a survey in the Jemna oasis, Governorate of Kebili in Southern Tunisia (Farolfi et al., 2022). The model implies a CPR recharge rate = 0, which is adapted to the local situation, as indicated by Trigui et al. (2021). The model is used to run experiments in the lab (France and Tunisia) and in the field, with Jemna oasis farmers, in order to test the performance of various groundwater governance policies in the studied frame.

References

Dubois, D., S. Farolfi, P. Nguyen-Van, and J. Rouchier. 2020. "Contrasting effects of information sharing on common-pool resource extraction behavior: Experimental findings." Plos One no. 15 (10).
FAO. 2022. The State of the World’s Land and Water Resources for Food and Agriculture – Systems at breaking point. Main report. Rome. https://doi.org/10.4060/cb9910en
Farolfi, S., Lavaine, E., Morardet, S., Lfakir, O., Khamassi, F., & Willinger, M. (2022). Farmers’ perceptions of water management in Jemna oasis, Southern Tunisia. New Medit, 21(5). https://doi.org/10.30682/nm2205d
Gardner, R., Moore, R., and Walker, J. 1997. “Governing a groundwater commons: a strategic and laboratory analysis of western water law.” Economic Enquiry (35): 218-234.
Ghazouani, W., Marlet, S., Mekki, I. and Vidal, A. (2009). "Farmers' Perceptions and Engineering Approach in the Modernization of a Community-Managed Irrigation Scheme. A Case Study from an Oasis of the Nefzawa (South of Tunisia)." Irrigation and Drainage 58: S285-S296. doi: 10.1002/ird.528
Hardin, G. 1968. "The Tragedy of the Commons." Science (162):1243-1248
Kadiri, Z. , Benmihoub, A., Farolfi, S., Khamassi, F., and Faysse, N. (2022)“Making Sense of On-Going Dynamics and Innovations in Oases and Newly Irrigated Areas of North African Arid Regions: Towards More Sustainable Development Pathways.” New Medit, vol. 21, no. 05, 20 Dec. 2022, 10.30682/nm2205n..
Mekki, I., Jacob, F., Marlet, S. and Ghazouani, W.. (2013). "Management of groundwater resources in relation to oasis sustainability: The case of the Nefzawa region in Tunisia." Journal of Environmental Management 121: 142- 151.
Mayaux, L.P., Lejars, C., Farolfi, S., Adamczewski-Hertzog, A., Hassenforder, E., Faysse, N., Jamin, J.Y. 2022. Enabling institutional environments conducive to livelihood improvement and adapted investments in sustainable land and water uses. SOLAW Background Thematic Report. Rome, FAO. https://doi.org/10.4060/cc0950en
Petit, O., Kuper, M., Lopez-Gunn, E., Rinaudo, J. D., Daoudi, A. and Lejars, C. (2017). "Can agricultural groundwater economies collapse? An inquiry into the pathways of four groundwater economies under threat." Hydrogeology Journal 25 (6): 1549-1564. doi: 10.1007/s10040-017-1567-3.
Trigui M.R., Trabelsi R., Zouari K., Agoun A., 2021. Implication of hydrogeological and hydrodynamic setting of water quality in the Complex Terminal Aquifer in Kebili (southern Tunisia): The use of geochemical indicators and modelling. Journal of African Earth Sciences, 176: 104121. https://doi. org/10.1016/j.jafrearsci.2021.104121.

External Link(s)

Registration Citation

Citation
Dubois, Dimitri et al. 2023. "Groundwater CPR governance in presence of different types of extractors. Lab and field experimental analysis ." AEA RCT Registry. November 24. https://doi.org/10.1257/rct.10742-1.2
Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2023-01-20
Intervention End Date
2023-06-20

Primary Outcomes

Primary Outcomes (end points)
We assess through laboratory and field experiments the performance of various groundwater governance policies to reduce over-exploitation of groundwater CPR.
We analyse the role of communication among players to reduce over-exploitation of groundwater CPR.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
We observe if players' myopic behaviour increases over-exploitation of groundwater CPR.
We observe whether field actors' (farmers) behaviour is different from university students' behaviour.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The following hypotheses are tested:
H1: In the absence of a governance policy (baseline condition of ‘laissez faire’), the appropriation externalities push players to assume a behaviour conducing to a Nash equilibrium.
H2: The introduction of governance policies reduces the depletion rate of the CPR, bringing the system closer to the Social optimum.
H2: Communication among players contributes bringing the system closer to the Social optimum.

To test these hypotheses, four Treatments were designed:
T0 (Baseline)
T1 (Simulator)
T2 (Communication + Simulator)
T3 (Expert Advice + Simulator)

In the baseline treatment (T0), players dispose only of a calculator facilitating their extraction choice at every given period.
In the simulator treatment (T1), players dispose of a calculator allowing them to make simulation over all rounds missing before the end of the session (7-T where T = current round). This simulator is a proxy of more information available to players about the consequences of dynamic extractions of the CPR on the CPR availability and subsequent extraction costs. As we can keep record of the use of the simulator by players, this treatment also allows observing the attitude by certain players to investigate dynamic externalities (sophisticated players looking at future extractions) in comparison with myopic players that are interested only in static externalities.
In the communication treatment (T2), players have the calculator like in T1 and in addition can chat (cheap talk) during 3 minutes before rounds 1, 3, 5 and 7 in sequence 2.
In the Expert Advice treatment (T3), players have the calculator like in T1 and T2, and in addition receive every round a suggestion about the global amount of CPR to extract in order to maintain the social optimum in the group.

In T1, T2 and T3, when indicating 'other players extraction', subjects make a prediction that can trigger an additional gain to the gain from their extraction. The prediction gain follows the formula: prediction gain = 1 Euro - 0.013 Euro * | prediction - realization |, where realization is the total n. of tokens actually extracted by the other members of the group in that round.

The model by Gardner et al., (1997) is adapted to groups of 5 players, where 3 types of players (irrigators) coexist: 1 member of the GDA (whose extraction every round is limited to 1 token), 2 members of the GDA that also extract in the extension areas (whose extraction is included between 0 and 24 tokens in addition to the 1 received from the GDA), and 2 members in the extension (whose extraction every round is included between 0 and 25 tokens).

The experimental protocol involves two parts (sequences) of 7 rounds each per session. The first sequence is always the baseline (T0), whilst the second sequence is a treatment (T0 to T3). The experimental design is summarized as follows:

Sessions: Baseline, Simulator, Communication + Simulator, Expert Advice + Simulator
Sequence 1: Rounds 1-7 (T0)
Sequence 2: Rounds 8-14 (T0, T1, T2, T3)
Groups & participants per session: 12 Groups 60 Participants

This experimental protocol will be run twice in the lab (Montpellier and Tunis), and once in the field, with farmers in the Jemna oasis, South Tunisia. A total of 240 x 3 = 720 participants is expected.

Empirical strategy
We use a difference-in-differences estimation to identify the effect of the introduction of policy measures relying on variation in the level of extraction both across groups and over sequences. Extraction levels are compared before and after policy implementation in treated groups with the extraction level of the baseline groups without policy.

Experimental Design Details
Randomization Method
In France, the sessions will be conducted in the Laboratory of Experimental Economics in Montpellier (LEEM). The participants are students from various disciplines of the university of Montpellier randomly selected from a pool of nearly 3,000 volunteers handled with the Online Recruitment Software for Economic Experiments (ORSEE).
In Tunisia, Lab experiments will be conducted at the National Institute for Agronomy in Tunis (INAT) The participants are students from INAT and various disciplines of the university of Tunis Cartage randomly selected from a pool local students. Field experiments will be conducted in the Jemna oasis. The participants are farmers randomly selected from a pool of nearly 2,600 farmers in the oasis, with the help of the local association for the protection of the Jemna oasis.



Randomization Unit
Sessions of 20 participants (4 groups, N =5) will be run.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
24 sessions in the lab; 12 sessions in the field
Sample size: planned number of observations
720 players
Sample size (or number of clusters) by treatment arms
The experimental protocol is composed of 3 sessions/treatment, for a total of 12 sessions (240 participants). Each session runs with 20 participants (4 groups). Thus, each treatment will have 60 participants (12 groups).
It will be run twice in the lab (Montpellier and Tunis), and once in the field, with farmers in the Jemna oasis, South Tunisia. A total of 240 x 3 = 720 participants is expected.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

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