Given the Limpopo river may stop flowing within the basin in Mozambique for up to 8 months per year, the irrigation potential of 148 000 ha is considered the upper limit, requiring storage works and cooperation between basin countries (FAO 2004). The risk of losing a harvest in rainfed agriculture in the Gaza province of Mozambique can be as high as 75 %.
Historically the irrigation sector concentrated on government estates with little attention paid to their financial sustainability (FAO 2004). Management issues arose and infrastructure deteriorated due to inefficiencies.
Until the early to mid 1980s, very little effort was directed towards the development of sustainable smallholder irrigation schemes (FAO 2004). In 1983 a policy was initiated recognizing the importance of family enterprises and redistributed the land. In 1988/89 the FAO was involved in rehabilitating and improving the irrigation and drainage infrastructure of family enterprise plots.
According the draft national irrigation policy and strategy the following factors contributed to the decline in irrigation (FAO 2004):
Irrigated lands were abandoned just after national independence and the new owners, through inexperience, contributed to the inefficiencies
Irrigation infrastructure was destroyed or abandoned during the civil war
Public funds were gradually reduced for irrigation
Lack of technical assistance and inputs in rural areas to ensure maintenance and improvement of the irrigation schemes.
Chokwé Irrigation Scheme
The Chokwé irrigation scheme was constructed in the early 1950s is located in the Gaza province and is the largest in all of Mozambique occupying a total area of approximately 33 000 ha (Barros 2009; FAO 2004). It lies 8 km upstream and 50 km downstream of the Macarretane Dam with a width varying from 3 to 18 km. The irrigation scheme only functions within 25 % of its total area as the system has deteriorated due to previous droughts, floods, political and institutional reforms, war, and poor management. The system was conceived to work by gravity through upstream flow regulation at Macarretane Dam (Barros 2009). In the late 1980s this area was the main water consumer in the basin at 523 Mm3/year.
Salinity is a major factor limiting the use of land developed for irrigation in this portion of Mozambique. Saline soils occupy as much as 70 % in the
lower Limpopo River Valley, where the Chokwé irrigation scheme is located (FAO 2004).
Agriculture in the Chokwé District of Mozambique.
Source: ARA-Sul 2009
( click to enlarge )
Irrigation methods vary according to crop topography, and soil (FAO 2004). Sprinkler irrigation is used in sugar cane, citrus, fruit and vegetables production. Surface irrigation is used for rice in basins and in furrows for maize and vegetables. Smallholders also used sub-irrigation with control of the groundwater table, although the efficiency is relatively low.