Sustainable development and protection of water resources
in the irrigated land of the Ily river delta
(Project TA-MOU-01-CA21-021 funded by the USAID)
The results of field investigations and simulations with mathematical models in the study area led to the following conclusions and recommendations:
- The efficiency of the irrigation network (mainly unpaved canals) of the Akdalinsky land is very poor. Water losses from irrigation canals are large, leading to the development of close-to-swamping conditions. Therefore, reconstruction works are recommended to decrease water losses by infiltration from the transmitting canals.
- The performance of the drainage canals is not always efficient. Some collectors discharge water to the aquifer. Regular cleaning and deepening of drainage canals and collectors is recommended.
- In 2002, the area occupied by rice fields in the Bakhbakhty part of the Akdalinsk irrigation land was 4165 ha. Results of simulations indicate that, on one hand, increasing this area will lead to further swamping of the land; on the other hand, decreasing the proportion of rice fields will lead to lowering of the groundwater level to 3-5 m below surface. Taking into account the critical groundwater depth of about 3.75 m, and the high potential evaporation, this will lead to the secondary salinization of a significant part of this land. Keeping an area of rice fields of 4200-4500 ha is the most rational solution for this region.
- Most dangerous pollutants of surface and subsurface water in the study area are pesticides. Groundwater is polluted by pesticides leaching from the vadose zone during irrigation and by infiltration from imperfect drainage collectors. Simulation results indicate that pesticides are partly degraded, while the rest is removed from fields with surface and drainage water. This process depends mainly on pesticide characteristics and flooding regimes over the rice fields. To decrease pesticide concentration in overland water, the discharge of surface water from rice fields must be minimized. The application of more degradable pesticides is recommended. The application of pesticides of DDT type must be prohibited.
- During the last few years, starting from the post-USSR period in 1993 and owing to the difficult financial situation facing agriculture in Kazakhstan, application of pesticides in the Akdalinsky irrigated land was practically stopped. Nowadays, economics and agriculture are recovering fast. Therefore, an increased application of fertilizers and pesticides is expected in order to increase the agricultural yield. As a result, the problem of ecological safety of the environment becomes more acute. Thus, additional efforts and investments must be made to improve monitoring of soil and water quality, including further development and application of mathematical models.
- The People’s Republic of China plans to increase its water intake from the Ily River in near future. This will lead to a decrease in water discharge to Lake Balkhash and, probably, deterioration in the ecological condition of the area. Thus, existing water policy in this region will require tight regional management and cooperation. Using developed models, it will be possible to simulate consequences of water management policies and to predict hydrological and hydrochemical conditions in the Akdalinsky irrigated land. Actually, the models that were developed and used in this study are a prototype for an automated system of water resources regulation in the region.