Performance evaluation of the subsurface drainage system in a Dakahlia Region, Egypt

الملخص EN

This study is conducted to evaluate the performance of subsurface drainage system in the 30000 hectares Integrated Soil and Water Improvement Project (ISAWIP) Dakahlia, Nile Delta, Egypt (ISAWIP, 1994).

The drainage collectors rates and its relationship with collectors hydraulic gradient.

The overpressure in the drainage system and the fluctuation of groundwater table were measured as indicators for the performance of the subsurface drainage system.

Three cropping seasons, summer 1996, winter 1996-1997 and summer 1997 were considered.

Results show that the drainage collectors rates are under the design one in most of the time except in summer season in the case of cultivation rice in majority of the area served by the drainage system.

The collector drainage rate based on the measured hydraulic gradient did not represent the actual drained rate of the system and the overpressure in the collector pipes was observed in the summer season only.

The groundwater table depths were acceptable most of the time except the areas cropped with rice or adjacent to rice fields.

The lateral drain spacing was underestimated in both the winter season and in the non-rice fields of the summer season.

However, the lateral spacing required to manage the rice cultivation was three to four times the designed spacing.

Results, which were achieved, could be widely applied under similar conditions.