Current Status and Problems of the Drainage System in Uzbekistan

抄録

Agricultural productivity in Central Asia has increased with the development of irrigation. In some regions, continual agricultural land use without adequate maintenance of drainage systems, despite using abundant water in the fields, has led to an increase in groundwater levels and soil salinization rate. The salinization level can be changed by controlling the groundwater level. Important countermeasures practiced in Uzbekistan include lowering high groundwater levels through open drainage, sub-surface drainage, and vertical drainage systems. Here, we report the current status and problems of these systems in Syrdarya region, Uzbekistan, which is afflicted with serious salinization issues as per field survey results and existing data. Our results clarify that the functioning of the drainage system should be monitored because (1) the bottoms of the open drainage are too undulated to allow smooth discharge, (2) some outlets of the sub-surface drainage are under drainage water level or covered with soil, and (3) the current operation style of the vertical drainage is different from the conventional one. Thus, it is important to ascertain the effects of the discharge systems in Uzbekistan.