Sustainable Water Management and Agricultural Production in Arid and Semi-Arid Regions

While there is more than enough fresh water available on a global basis to meet the needs of the present population, this water is not distributed evenly over time or space. Many areas with the fastest growing populations in the world are arid or semi-arid, and face chronic water shortages. The stress on water resources in arid regions with large populations raises the question of whether agricultural activities in the regions are sustainable.

The overarching goal of this research is to assess and promote sustainable agriculture in a world of limited resources and growing demand. The goal of the first research phase was to develop a method to determine whether agricultural practices in regions are sustainable and to examine the effectiveness of various policy options. The research had the following specific objectives: (1) To develop a general hydrologic-economic model for analyzing the sustainability of irrigated agriculture, which can provide the “virtual environment” to structure debates about the merits of different policy options, and (2) To evaluate and compare policy instruments, including command and control regulation of water and land use, increases in water and drainage fees, and establishment of water markets

The research aimed at developing a dynamic and integrated model that incorporates hydrological constraints, economic forces and technological innovation, which could be used universally.

The goals of the second research phase are as follows: (1) To gain a better understanding of the state of water resources and sustainability of agricultural practices in critical developing regions and (2) To show how new environmental assessment technologies can be used to evaluate the sustainability of current water management practices and to support the formulation of sustainable policies

The research scope has been expanded to apply new technologies in remote sensing, hydrology and resource economics in a package. Cultural dimensions have also been included to assess the effectiveness of policies designed to ensure sustainability of water using practices. A large aquifer in North Africa has been selected for in-depth analysis.

During the first phase, a physical-based modeling approach was developed to assess the sustainability of current agricultural activities, and to explore options for achieving sustainability in the future. A general hydrologic-economic model of agriculture production and environment quality was developed first, to examine soil and water salinization caused by rice irrigation in the Murray-Darling River Basin of Australia. These models were used to examine the consequences of two land and water management policies, namely (a) restriction on the area planted with rice on each farm, and (b) expansion of water trading. This site was selected, as the local climate is similar to the one found in arid and semi-arid regions in developing countries.

The analysis found that irrigated rice area would have to be cut in half in order to stop the salinization process at present levels. There was also evidence of a rising water table in the region, with potentially negative effects on rice yield. The research also found that the negative externalities of rice agriculture may be smaller than generally believed in economic terms. This implies that rice farmers would be sensitive to the negative effects of irrigation because these effects have a significant impact on their own yield. In regions where the water table increases to unacceptable levels, rice farmers would experience decreasing yields and probably cut back on the percentage of land devoted to rice. If the rice restriction were lifted, farmers with low water tables would probably grow more rice while those with unacceptably high water tables would probably grow less. The overall effect should be an increase in sustainable regional revenue.

Field Studies have also been carried out in various countries, including the Kajemaram Oasis (Nigeria), the Palapye Aquifer (Botswana), the Iullemeden basin study (Niger), Rain harvesting study (Thailand), and the Tarim basin water and salt management study (China).

The first research phase generated the following lessons learned:

(1) The climactic conditions and local hydrogeologic condition have to be studied first before coming to conclusions

(2) It is a worthwhile to develop equitable partnerships for mutual learning among AGS researchers and policy makers and researchers at developed countries

(3) The research results need to be formulated in a manner that can be translated into action to enable implementation

The second phase has been based on a case study of the “Systeme d’Aquiferes du Sahara Septentrional (SASS)”, a large aquifer underlying portions of Algeria, Tunisia, and Libya. The SASS aquifer is a classic common property resource. Throughout the region, cultural and religion considerations tend to support the view that water is too important to have its use determined by the impersonal outcome of markets.

Significant progress has been made in modeling the distribution of recharge using remotely sensed data and calibration of the maps by environmental tracers. This has worked well, particularly in the Botswana study in Kavimba. Another important result was that digital terrain models are not exact enough for modeling purposes. The team has found that salinization modeling has to be coupled with ways to account for the uncertainty of models.

AGS research has catalyzed associated research and training support from other sources, including Swiss Development Agency and UN agencies. The group has also been able to make concrete policy recommendations by working directly with the Department of Water Affairs in Botswana. In addition, Australian researches have been using and improving the models developed during the first research phase in their assessments of local policy options, both in and beyond the original study area.