An African Renaissance

The Zambezi River in northern Mozambique historically provided the gateway to Central Africa. Due to damming, coinciding with twenty years of civil war, the use of this trade route collapsed. Upon its recovery, Mozambique is showing renewed interest in the rich agricultural prospects of this region and thus also in again utilising the river as a means of accessibility. This article illustrates how modern survey technology can be applied in a third world environment, contributing to the success of one particular project and indirectly influencing the development of inaccessible communities

The company Sena Sugar is investigating the rehabilitation of an abandoned sugar mill in Mozambique The mill is situated on the Zambezi River at Marromeu, some 90km inland and 250 from the nearest town. Sena is a 25/75 per cent joint venture between the Mozambican State and a Mauritian consortium. The 25 per cent held by the State consists mainly of physical assets, most of which are in very poor condition. To make the Marromeu mill and plantation fully operational, a total investment of US$ 90 million has been set aside.
Due to the absence of infrastructure and inaccessibility of the location, due primarily to recent catastrophic floods in central Mozambique, sights fell on the river as an access and export route. In the mid-1800s David Livingston (Scottish missionary and explorer of the Victorian era, now best remembered for the meeting with Henry Morton Stanley which gave rise to the popular quotation, 'Dr Livingston, I presume') used the Zambezi as his gateway to central Africa by navigating to Malawi. His wife died of malaria during his expedition on the Zambezi and is buried not far from the sugar mill.

Sitting up the River
During the early 1900s the British Sugar Company established the sugar industry in the Zambezi valley but during the Second World War this was abandoned and severe plundering occurred during the subsequent civil war. Furthermore, the construction of the Cabora Bassa Dam led to a reduced flow downstream, causing silting-up of the river and making it very difficult for vessels to navigate.
River transportation was deemed to be the only economical means of transporting construction materials and chemical fertilisers in and the final product, sugar, out. The objective was to ensure that a work boat could safely tow 150,000 ton barges from Chinde at the mouth of the river, to Marromeu, a distance of 90km inland, and back. A river flow of 2m/s and sandbanks of <1m clearance made this a very challenging task. as final product, the client required low-skill navigational package capable of enduring harsh african environment, to safely navigate tug during towing operations, especially down-river when stranding on sandbank with barges in-tow can have devastating consequences. project was also be funded by world bank, outcome accessibility study could determine future rehabilitation concerning marromeu sugar mill.

A Survey with Hippo's and Crocodiles
Thales GeoSolutions together with Geoinformatica Limitada, Thales Mozambican partner, was contracted to conduct a feasibility study to determine the navigational potential of the lower Zambezi River. The objective was to conduct a hydrographic survey of the entire river, from the mouth to the sugar mill site, to determine if a safe navigational route could be identified, to install a navigation system on the tow-tug and to demonstrate that the system would resolve their problem.
The study was conducted by the present author, with an overview of historical data and local assistance provided by the late David Chemane of Geoinformatica. A 4m ski-boat was used as the bathymetrical survey vessel equipped with a satellite-derived Differential GPS, survey echo-sounder and a navigational display aid, all fully integrated. The work consisted of surveying cross-sectional profiles at 200m intervals, at higher intervals on river-bends and when variation occurred in river topographical outlay. The deepest point on each profile was identified to make up the navigation route. Two major sandbanks were encountered on-route and required a more detailed survey. Local water levels, at Sena and Chinde, were recorded by direct staff readings and the water release figures for the Cabora Bassa dam were logged during survey periods. As the maximum tidal difference on spring is 5m at the river mouth, tidal influence is encountered up to 30kms up-river. Further, recorded tides at the Port of Beria were compared with those predicted for the river mouth.
A motorised barge accompanied the survey crew to act as mobile base and logistical support. Besides the customary survey logistical problems, this survey brought with itÕs own complications: crocodiles and hippopotamus in the work area. Many a survey line was abandoned due to hippo obstruction and rumours of local people being taken by crocodiles while collecting water provided interesting diversions. The local population is very dependent on the river for their livelihood and their way of life goes back centuries, making this survey a very memorable experience.

Way Points
The fieldwork was conducted within seven days and the result was identification of a navigation route by multiple 'way points'. A navigation system (DGPS c/w Screen display) was installed on the tug, displaying the predetermined 'way point' route. Performance trials were then conducted, towing a fully loaded barge down and up-river. The main complication, strong down-river flow during the down run, required the vessel to steam at full throttle in order to maintain steering control and follow the pre-determined route. The trial was very successful and the client expressed satisfaction by commissioning the system. Routine maintenance surveys of problematic areas will have to be conducted, especially during the rainy seasons, when sandbanks and river-flow can change. As for the dry seasons, dam release can be manipulated to coincide with planned shipments and thus provide additional bottom clearance. The idea is to sail down-river with the dam release waterwave. For this, a module of timephase versus dam release volume was drawn up to assist with the scheduling. Up-river passage is not a major problem as, firstly, vessel draft is minimal and, secondly, navigating against the current makes steering and ground speed more controllable.
Thales has subsequently been commissioned to conduct a similar exercise applying the same principles a further 80km up river for accessibility to a proposed forestry export project.

Open Up Central Africa
Transportation on the Zambezi dating from Livingston's days opened up central Africa but since the construction of the Cabora Bassa Dam this route has lost its capability to serve as a trade route. It is hoped that by applying modern technology the route will now be reopened and help to develop a sector of Africa that suffers as a result of its inaccessibility. Until recently, Mozambique was the country with the fastest growing economy in Africa but recent freak floods affecting central and southern Mozambique have set back their economy drastically. Fortunately, the survey area was not badly affected by these floods, in which an estimated seven hundred people died. The Marromeu Sugar mill and plantation will create an estimated twenty thousand new jobs, raising living standards of people in the area. Thales was very gratified to share in a project that will change people lives for the better.