Reclamation Efficiency of Closed Horizontal Drainage in the Shirvan Steppe of the Kura-Araz Lowland of Azerbaijan

The paper evaluates the efficiency of irrigation and drainage systems and their technical level in the Shirvan steppe of the Kura-Araz lowland in Azerbaijan. The study of filter materials used in the construction of the drains under study showed that fractions in the range of 1-20 mm, a cast cover 15-20 cm thick and a filter cover with a non-uniformity coefficient of 8-10 are more optimal for constructing drains in such areas. Analysis of actual data on closed horizontal drains in experimental areas showed that the drainage flow modulus is functionally related to the drainage pressure. The infiltration coefficient of soils in the experimental area in the village of Bychagchi (B = 200 m) is 4.25 m3/day, and in the experimental area in the village of Deligushchu (B = 400 m) it is 4.38 m3/day. It was found that the dependence of the drainage flow modulus q = f (H) on the pressure changes along a parabolic curve. This dependence established that at the maximum possible groundwater pressure (H=3 m), the drainage flow modulus is 1 l/sec ha, and at H=2.0 m – 0.50 l/sec ha.