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Accueil du site → Doctorat → Allemagne → 2008 → Modeling crop and water allocation under uncertainty in irrigated Agriculture : a case study on the Khorezm Region, Uzbekistan

Rheinischen Friedrich-Wilhelms-Universität Bonn (2008)

Modeling crop and water allocation under uncertainty in irrigated Agriculture : a case study on the Khorezm Region, Uzbekistan

Bobojonov, Ihtiyor B.

Titre : Modeling crop and water allocation under uncertainty in irrigated Agriculture : a case study on the Khorezm Region, Uzbekistan

Auteur : Bobojonov, Ihtiyor B.

Université de soutenance : Rheinischen Friedrich-Wilhelms-Universität zu Bonn

Grade : Doktor der Agrarwissenschaften (Dr. agr.) 2008

Irrigated agriculture for cotton and wheat production forms the backbone of the rural economy in the Khorezm region. Ecological deterioration and inefficient resource use have resulted in and now present a significant threat to the livelihoods of those most dependent on this sector. Inefficient water use has led to rising ground water tables and widespread water and soil salinization has resulted. The high water demand in the region for crop production renders farmers vulnerable to the recurrently predicted decrease in water supply. Farmers in the Khorezm region are vulnerable to uncertain water supplies due to current policies which restrict their decision making in terms of what type of crops to grow, when and where. Similarly, there are ever increasing risks in terms of yields and price fluctuations due to natural conditions and fluctuations in the market. This study contributes to understanding key obstacles and potential solutions to promoting sustainable development in the region. Moving beyond previous disciplinary approaches in this area, this work includes different crop allocation and water use options in a systems context, where linkages between the environment and socio-economic impacts are considered simultaneously in the analysis of economic and ecological benefits from different agricultural activities. To this end, a static, stochastic model for Khorezm was developed to explore potential risk reducing strategies for farmers, while accounting for the ecological consequences potential policies. Worldwide, mathematical modelling has proven to be an effective instrument for increasing the overall understanding of the complexity of water demand and supply processes, while analysing resource-saving alternatives that are both economically and ecologically sustainable. In order to maximize the utility and applicability of such an approach, each model must incorporate local agro-ecological, social and economic conditions. A stochastic programming model was developed to combine the Expected Value-Variance (EV) approach with chance-constrained programming. Analysis was carried out using data from one Water Users’ Associations (WUA), Shamahulum, located in the Khiva district of the Khorezm region. The developed model considered the optimization of water and land allocation of 300 fields, belonging to 99 farmers in one Water User Association (WUA). The availability of Geographical Information System (GIS) based data allowed the integration of spatial aspects into the model. The model was calibrated using various Constant Relative Risk Aversion levels (CRRA). The CRRA is adjusted as the core parameter in the base run of the model and is set to match the observed activity level in the case study WUA. Following the calibration, various simulations were conducted to account for the impact of different policy scenarios. The combined outcomes of the simulations provided a basis for assessing potential effects of different policy measures given the dynamics of the on-going reform strategies in Uzbekistan. The model findings suggest that allocating the area to less water demanding crops and usage of alternative irrigation methods will help to secure farmer income. However, farmers remain unable to fully utilize these risk coping strategies due to occupation of more than 70% of the area with state order, low income crops, including cotton and winter wheat. Key findings from the study indicate the possibility of improving water use efficiency (WUE) and thus the environmental situation in the region through the introduction of water pricing. Results also showed that economic and ecological development could be achieved simultaneously only under the presence of more flexible decision making at the farm level.

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Page publiée le 11 mars 2009, mise à jour le 1er janvier 2019