TITLE:
Runoff Harvesting and Storage for Rice Crop at Hamelmalo, Semiarid Region of Eritrea
AUTHORS:
Ramesh Prasad Tripathi, Woldeselassie Ogbazghi, Semere Amlsom, Simon Measho
KEYWORDS:
Compaction, Pond, Puddling, Rice, Runoff Farming, Waterway
JOURNAL NAME:
Computational Water, Energy, and Environmental Engineering,
Vol.5 No.1,
December
1,
2015
ABSTRACT: Rice is staple food in Eritrea but it is not cultivated in the country due to semiarid conditions. However, possibilities exist for growing rice using runoff produced from nonagricultural hilly lands, which occupy >50% - 80% area of all agricultural watersheds in Eritrea. Study was undertaken in 6 ha watershed at Hamelmalo to design and develop waterway for safe harvesting of runoff from 5.5 ha catchment into a pond for facilitating runoff farming of rice in 0.5 ha field at the outlet end receiving recurrent floods. Slope of the catchment ranged from 1% to 6%. The waterway was designed to intercept and carry runoff from two major drains in nonagricultural land together and delivering into a pond made adjacent to rice field. The waterway was about 323 m long with 3 m top width, 1.5 m bottom width and 0.3 - 0.8 m depth from surface. The pond was 60 m long, 9 m wide and 1 m deep with 1.5 m high earthen dam towards rice field using soil excavated from the pond. Embankment on the remaining sides was mango orchard land slopping towards pond. The dam base width was 4 m, top width was 2.5 m and height was 1.5 m from the ground surface. Two spill ways were provided in the dam at ends at the ground level to facilitate release of runoff from the pond for irrigation. Gross capacity of pond was >1000 m3. Combined effect of river water, percolation from pond and wetter rice field raised groundwater table from 3.25 m depth in June to 1.4 m by mid-crop season. This resulted in soil wetness exceeding field capacity below 0.7 m depth and greener crop. Rice yields exceeding 2000 kg·ha-1 were harvested under runoff farming conditions. Soil puddling was more conducive to rice crop than compaction under available soil and water resources.