Farmers’ willingness to adapt to climate change for sustainable water resources management: a case study of Tunisia

Shrinking water resources as a potential result of climate change (CC) creates a challenging tradeoff situation in the north of Tunisia. This study provides valuable insights into the conditions that can promote farmers’ acceptance of regulated deficit irrigation and a new water pricing policy to address CC impacts on the semi-arid irrigated region which will allow for a sustainable irrigation regime and the conservation of water resources at regional scale. Binary logistic regression was used to analyze data collected from 100 farmers in the citrus regions of Beni Khalled and Menzel Bouzelfa, to identify determining factors for farmers’ willingness to accept the proposed water management strategies. Empirical findings reveal that the significant explanatory variables are essentially linked to farmer satisfaction about the current irrigation management in relation to water supply reliability, rather than the social criteria and farmers’ awareness of water scarcity. More efforts are needed to improve the transparency of water allocation systems to motivate the willingness of water users to adopt new technologies or policies. The different stakeholders should agree to take action now about strategic extension and communication plans to enhance awareness on ensuing environmental problems, to take advantage of long-term profitability of the water restriction. doi: 10.2166/wcc.2018.171 om http://iwaponline.com/jwcc/article-pdf/9/3/598/484854/jwc0090598.pdf er 2021 Asma Lasram Higher Institute of Agronomy of Chott Mariem, P.O. Box 47, 4042 Chott Mariem, Sousse, Tunisia Hatem Dellagi University of Economic and Management Sciences of Tunis, P.O. Box 248, El Manar II, 2092 Tunis, Tunisia Bezaiet Dessalegn Integrated Water and Land Management Program (IWLMP), International Center for Agricultural Research in the Dry Areas (ICARDA), El-Rawaby Neighborhood Behind Abdallah Abu Ghosheh street, Yousef el Sukkar Street Bldg. no 8, Amman, Jordan Boubaker Dhehibi (corresponding author) Sustainable Intensification and Resilient Production Systems Program (SIRPSP), International Center for Agricultural Research in the Dry Areas (ICARDA), El-Rawaby Neighborhood, Behind Abdallah Abu Ghosheh street, Yousef el sukkar street bldg. no 8, Amman, Jordan E-mail: b.dhehibi@cgiar.org Netij Ben Mechlia National Agronomic Institute of Tunis, 43 Av. Charles Nicole, 1082 Tunis Mahrajène, Tunisia


INTRODUCTION
Due to aridity, water resources in Tunisia are subject to high demand pressure especially in the irrigated areas where chronic water shortages have reached critical levels, causing important environmental degradations and serious social tensions among users, as in the case of the Governorate of payments through exports, in addition to its role in securing the food security for the local and national population. In this region, decrease in groundwater level of the main aquifers and water quality degradation are damage resulting from overexploitation, citrus surface extension, and noncontrolled increase of wells. This situation implies important losses of soil fertility due to salt accumulation (Sarraf et al. ).
To mitigate the large hydrological deficits, additional water was brought to Cap-Bon through a canal from the north-western regions of the country, which is better endowed with water resources. By fixing an annual transfer quota of 80 Mm 3 (National Center of Agricultural Studies ), the canal was supposed to solve the problem of water imbalance. However, the plan failed because it did not account for the needs of new expansion in cultivated areas. Other measures taken to mitigate water shortages in the irrigated areas include up to 60% subsidies extended to farmers who adopt drip irrigation. However, despite the intentions of the modernization efforts to promote water saving and conserve quality resources, on-farm water use was not significantly reduced (Al Atiri et al. ), surface irrigated areas have been extended (Regional Agricultural Development Center of Nabeul ), groundwater resources continue to be degraded (National Center of Agricultural Studies ) and hence the government has not managed to curb the demand for more irrigation water.
With the increase in groundwater salinity in the Cap-Bon region and as citrus trees have been classified as a salt-sensitive crop (Syvertsena & Garcia-Sanchez ), farmers are becoming more dependent on canal water, which is strongly and simultaneously solicited by other economic sectors such as tourism and industry. The availability of canal water during the summer season is then exposed to large fluctuations, making unplanned water cuts a serious threat to the entire region. This challenging tradeoff situation is making water allocation for agricultural purposes a real dilemma for local water managers. The paradox is that farmers who are complaining of water shortages are, at the same time, blamed for wasting too much water.
Indeed, Dhehibi et al. () found, on the basis of a survey, that the technical efficiency of citrus growers was too low in Cap-Bon and that farmers could have the same yields with reduction of the water supply by 47%.
The prospects of increasing temperature and decreasing precipitation in the region, due to CC (Ludwig et al. ; Dakhlaoui et al. ), are expected to constrain more water availability for agricultural uses and lower the supply reliability (Nunes et al. ), exposing the sustainability of the entire production system to imminent risk. Quantitative and price control policies are the two most commonly used mechanisms for water demand management, as underlined by many authors (Wietzman ; Feike & Henseler ), and could enhance the adaptive capacity of communities. For quantitative control, it was proved through many studies that the application of regulated deficit irrigation (RDI) is appropriate for managing water scarcity in citrus-planted areas and could save between 25 and 30% of water resources in Mediterraneanlike climates and others, with an improvement of the fruit quality and no significant reduction of the yield (Ballester et al. ; Panigrahi et al. ; Panigrahi & Srivastava ). The planned restrictions of irrigation water are applied in order to avoid random water cuts, imposed by reduced supplies. RDI is considered to be a promising technology for ensuring the distribution of canal water among farmers with more equity, avoiding over-irrigation, and increasing water productivity. Likewise, with less irrigation water, inputs of dissolved salts into the soil are expected to be reduced.
For pricing control, and in order to improve the adaptive capacity of both stakeholders and policymakers to cope with climate impacts on water resources, a new water pricing policy (WPP) could be also used as an incentive mechanism for farmers to enhance the sustainability of water use (Turner et al. ; Iglesias et al. ; Ziolkowska ). In Tunisia, water prices (the equivalent of €0.045/m 3 according to Tunisian exchange rate on 15/09/2015) were subsidized and not related to the marginal values of crops grown by irrigation and were set too low to affect farmers' irrigation behavior significantly or act as an incentive to limit water demand (Chebil et al. ). Higher prices could be applied for water amount beyond the crop requirements to reduce overirrigation and enhance rational use of this valuable natural resource.
However, current water irrigation price inelasticity the strategies that should be undertaken by policy designers, and the profile of farmers who must be more targeted by institutional extension to foster optimal water allocation and efficient productivity.
The paper is structured as follows: the next section presents the methodological framework. This is followed by the results and discussion on the farmer water delivery, qualitative analysis of the survey, and the econometric model results. Finally, conclusions and policy recommendations are presented.

METHODOLOGICAL FRAMEWORK Study area and data collection
The study area is located in the peninsula of Cap-Bon, corresponding administratively to the Nabeul Governorate, in the north-eastern part of Tunisia. The region is characterized by a semi-arid Mediterranean climate with a long-term annual reference evapotranspiration of 1,100 mm and rainfall aver- According to this method, the farmers were more likely to adapt their water management strategy by accepting the new one if the logit (Z), derived from the agreeable respondents, exceeds that obtained from the disagreeable respondents. Z i of the ith farmer is a linear function of n explanatory variables X ¼ (X 1 ,…, X n ): where x i is the observed value of the explanatory variables for observation i and where β 0 is the intercept term, and β k are the coefficients associated with each explanatory variable X k . They are estimated by maximum likelihood estimation (MLE) method.

Canal water supplies
Making reference to the Beni Khalled and Menzel Bouzelfa GDA records, the average irrigation water supply over the three cropping years 2011-2013 for those using regularly APPRr Farmer opinion about the regional water resource (insufficient ¼ 0; sufficient ¼ 1) Source: Own elaboration from survey (2017). The farmers were quasi-unanimous (86%) on the inefficiency of the current water governance structure, which reflects the lack of trust in public institutions. However,   Nine out of the 17 variables used in the regression explained significantly the agreement of the farmers for adopting RDI. The farmers' attitude is more likely to be positively influenced when they thought they were over-irrigating, their groundwater resources depended on both the canal water and the wells or were affected by salinity, they frequently applied organic manure, they were older, they thought that regional water resources are sufficient, they rejuvenated their citrus trees, they are from Beni Khalled delegation and have no off-farm income. These significant explanatory variables are enumerated in a decreasing positive influential weight according to exponential B values (Table 4). Exponential B indicates how many times would    dependent, Chi square Pearson test p ¼ 0.02) and hence they were more affected by water supply reliability. Digging wells is an expensive investment for the junior farmers who need more time to accumulate enough money for the task. Farmers living on other incomes, apart from farm incomes, are more unwilling to adopt RDI because they are economically more affected by water supply reliability as they are not always available for agricultural work and irrigation management. The significance of the water resource variable reflected also greater willingness to accept practicing RDI by farmers whose water resource depended on both water canal and wells. Pumping water from wells secures a comfortable water delivery for the users when canal water is exposed to intermittent cuts. The farmers are more likely to adopt a positive position if their water resources are affected by salinity because they are already suffering from the potential risk of CC on water resources quality, so they have become totally dependent on canal water.

Willingness analysis
The perception of farmers about their water irrigation supply and the regional water resources availability influenced strongly their position. They were more cooperative when they thought that the water situation is more reliable and water supply is equitable.
As the environment profitability and the well-being of farm communities when adopting these new strategies is not immediate, farmers adhering to agricultural practices for improved water productivity (frequency of manure application, tree rejuvenation) are better prepared and ready for adoption. In this context, the role of extension has to be highlighted to improve water productivity and farmer resilience. However, the logistic models revealed also that the The farmers were more likely to accept WPP when they are from Beni Khalled delegation, for the same reasons mentioned previously, i.e., linked to the inconvenience of local water management that impacts water supply reliability.
The results of the two models emphasize the great concern of farmers of semi-arid regions such as the Cap-Bon where there is irregularity in the equity of water allocation.
However, willingness to adopt RDI, whose results presented more statistically significant indicators, appears more propitious for minimizing farm income loss, as the farmers have already experienced the shortage of water and its poor reliability has been constraining the efficiency of irrigation schedule. For the WPP, the biggest consumers are reluctant to accept this strategy, and even when farmers presented a positive response, their proposed new price is too low to enhance the reduction of agricultural water use. The significant indicators of farmers' responses to RDI reflected more the environmental concern. On the other hand, the farmers' responses to WPP are more related to economic concern.
The mismanagement of water resources induces a negative perception of local water resource reliability and then a lack of trust in local governing institution, and the lack of support for adhering to new water resource management policies.

LIMITATIONS OF THE STUDY
Although the research has reached its aims, there were some unavoidable limitations. First, since the questionnaire is designed and the model is applied with the finality of understanding the main factors influencing the adoption of RDI and the factors affecting the adoption of the option of new WPP, it seems not to provide enough evidence of the farmers' actual behavior to these two most commonly used adaptation mechanisms for water demand management.
Second, we recognize that we did not address fully the issue of adaptation to CC; in general, rather we focused on a special agro-ecosystem (citrus) which is vital to the economy in the Cap-Bon region (study area). In addition, our methodological framework mainly addressed the assessment of the RDI technology, ruling out, knowingly, adaptation options relating to crop patterns. At the same time, we need to stress the relevance of our approach in trying to figure out how citrus growers would adapt to water scarcity imposed by CC.
Finally, we consider the assessment of the proposed RDI technology, as a measure for citrus growers to remain in the orange production business, is more than needed. Otherwise, if they continue doing what they have always done, they will find themselves soon forced to reduce the size of their cropped area and/or to switch to much less profitable crops, such as olive cultivation, or winter vegetables, knowing in advance these less profitable crops could increase farmers giving way to land speculation for urbanization.
Thus, this scenario was not considered in our research paper, because we hypothesized from the beginning that there is a consensus about citrus conservation in the studied area, at least for the foreseeable future.

CONCLUDING REMARKS AND POLICY RECOMMENDATIONS
Water scarcity is a major threat to sustaining semi-arid irrigated regions such as citrus growing areas in Tunisia.
Irregularities in water supply, frequent social tensions among users, and hazardous environmental degradations are some of the critical challenges for a sustainable citrusgrowing system in the studied area.