The Tugwi Mukosi project involves a dam and downstream infrastructure aimed primarily at irrigation development in the South — Eastern lowveld of Zimbabwe. The Dam, with a capacity of 1 802 600 megalitres and a yield of 340 000 ML per annum, was officially opened in May 2017.
While existing downstream commercial development is able to benefit from this considerable resource, no additional abstraction infrastructure is available for the expansion of irrigation to fully utilise the water.
Studies undertaken in the 1990’s that identified potential areas for irrigation development are now superseded by events on the ground, particularly the change in land ownership models, the potential change in crops, modern irrigation and conveyance options and importantly, much of the data informing those plans was lost.
As a result of these changes, the Government initiated a review of previous work and planned for the upgrading of infrastructure to fully utilise the water. This exercise commenced in 2017 when MBB Consulting Engineers, in partnership with Pricewaterhouse Coopers (Zimbabwe), were contracted by the Infrastructure Bank of Zimbabwe (IDBZ).
A review of past work, was completed in March 2018, and the next phase was approved for commencement in May 2018. Phase 1 identified that very little of the prior studies remains relevant and it discovered that much of the information presented in prior studies no longer have raw data available for checking the validity of assumptions. As a result, almost all the prior work is of little value and the feasibility investigation essentially has to start from the beginning.
Phase 2 investigation encompasses the inter-related fields comprising the proposed development, as follows:
Environmental and social
Engineering and Infrastructure
Crops, agronomy and soils
Economics, financial, markets and legal.
The duration of the study is critically affected by the need for base information before detailed technical work can take place.
This has a knock-on effect on all sections of investigation.
A mapping exercise has already been initiated to obtain satellite-derived contours and maps — that will be used in the selection of soils and subsequent infrastructure design. Design work will be carried out and budgets derived from preliminary designs that incorporate the latest irrigation technology that is suitable for the environment and crops.
It is noted that the technical team will endeavour to identify a small irrigation scheme on good soils that can benefit from early implementation using Tugwi Mukosi water.
This scheme will be treated as a pilot project, helping to identify opportunities and options during the course of the study whilst also showing resident farmers that progress is being made. This will be managed as a separate exercise after approval, once suitable land is identified.
Another important feature of Phase 2 is to investigate opportunities for inclusion of the Chingwizi settlers. It was noted in Phase 1 that this is technically feasible; however, the soils need to be assessed along with financial viability before a recommendation can be made.
Progress to date
Phase 1 of the feasibility study was completed in March 2018 upon submission by MBB Consulting Engineers of a Phase 1 Irrigation Feasibility Study Report.
The Phase 1 Feasibility Study Report concluded that there is absence of complete documentation of soils investigation and study in the previous feasibility study which results in the need for large areas having to be re-evaluated in Phase 2.
Also, very little environmental study was carried out in the previously study and does not meet current environmental legislation and current international standards. Therefore, all of the environmental and gender mainstreaming processes will have to re-commence.
A decision to proceed to Phase 2 was granted by the Government in June 2018. The biggest drawback and source of delay has been lack of foreign currency resources to meet overdue interim payment fee notes to the Consultant.
Progress in Phase 2
The Consultant, MBB Consulting Engineers, have covered the following study activities and herein below is the status of progress under Phase 2:
Crops, Agronomy and Soils identification tasks
A typical cropping model has been developed for the purposes of engineering design, in particular the selection of design capacities for irrigation water.
The investigation of soils and reports in the Chingwizi, Matibi 2, Tokwe and Mutirikwe areas have been completed. The total irrigable area identified currently is at 14 993 ha (out of a total of 20 386 ha sampled).
Field work was at one time interrupted by heavy rains resulting in lack of access to the field in January and February 2020; the outbreak of the Covid-19 pandemic and Covid-19 lockdowns. The completion of soils studies is now dependent on relaxation of travel restrictions.
In preparation for concept designs for selected regions, design models have been developed for the components below and are being utilised for the concept design of Matibi, Makosiya and Chingwizi:
Canals (Trapezoidal and Parabolic)
Canal Siphon Sizing
Drainage Canal Over-passage
Canal Drop Structures
Canal Level Controls.
The feasibility design for Matibi and Makosiya (1010 ha) is complete. Surface (flood) irrigation has been recommended, owing to the high clay vertisoils of the area. The scheme is based on a weir in the Runde River, a bulk water pump station delivering to four balancing dams from which parabolic concrete canals distribute water to the fields. Drawings and costings to illustrate the development are at an advanced stage.
The Chingwizi Concept Design is also at an advanced stage.
It comprises a pump station located at the existing weir near the confluence of the Runde and Tugwi Rivers, a rising main bulk pipeline delivering to a bulk canal into a balancing dam. Two further bulk lift pump stations are proposed to distribute water to the furthest reaches of Chingwizi. The area under command is estimated to be 4070 ha. The system proposed is a “hop-along” sprinkler laid out on 1 ha plots and served with underground piping. Layout drawings are not yet available.
What is evident is that there is a significant cost premium owing to the remoteness of the irrigated land from the river.
Large bore pipelines have to traverse up to 4km before field edge is reached. Similarly, the static lift to the first area is over 40m, which will cause higher than normal operating costs.
Financial and Market Assessments
Initial selection of potential crops for the commercial and small scale farmers sector has been completed in conjunction with the agronomists, based on the soil and climatic suitability.
The evidence suggests that row cropping (maize, soya bean, groundnuts, sorghum, cassava, sunflower, chillies, paprika, sweet potato), sunflower, cotton, sugarcane, mangoes and cashew nuts are the most suited to these conditions in agronomic terms.
Marketing investigations for pulses, legumes, oil seed crops, and cashews on a regional and an international basis are currently in progress.
Financial models and markets assessments, by virtue of them consolidating the whole project, would normally only be completed when all the infrastructural elements are complete.
Economic and legal
Templates for budgeting purposes are being developed focussing on those crops determined to be most suited to the area from an agronomic and management perspective. This selection of crops will be screened taking into account the market potential at national, regional and international level.
Environmental and Social Impact Assessment
A detailed ESIA is yet to be done and will only be prepared after some key design considerations.
The Environmental and Social Prospectus Report was completed and is ready to be submitted to EMA upon approval of the budget and scope of ESIA services.
Further ESIA activities are pending approval of the budget nearly US$360 000 and programme for the final impact assessments. No further ESIA work is in progress, pending such approval.
Early Development Irrigation Opportunities
In Chingwizi and Matibi II, suitable (2,700 hectares) and marginally suitable (6,600 hectares) land was identified following detailed soils investigation.
Preparation of preliminary designs and drawings for irrigation infrastructure for Chingwizi and Matibi II lands, where soils investigations have been successfully carried out, are currently underway.
The selection of the balance of 10,000 hectares of suitable land for the 25,000 hectares irrigation scheme is yet to be concluded;
Preliminary Engineering designs;
Financial and economic analysis and appraisal
Identification of a small scheme to pioneer as a pilot
Cost and Payments for Feasibility Study
The cost for Phase 2 of the Irrigation Feasibility Study (i.e Detailed Irrigation Feasibility Study and the Environmental and Social Impact Assessments) is US$ 1,448,848.
To date a total amount of US$ 277,000 was paid and until last week, overdue payment invoices for the Consultant amounted to US$ 263,051 (ZAR 4,177,956).
Phase 1 was completed at a cost of US$240 000 The considerable cashflow constraints due to non-payments have retarded planned progress to complete the assignment in time and ahead of the next rain season.
The IDBZ has made efforts to secure foreign currency from the inter-bank market, but nothing materialised until this last Tuesday’s Auction when we managed to secure US$103,000. Previously, despite numerous requests made through our commercial bankers, no allocation was being made available.
Treasury has made available necessary ZWL to clear the outstanding invoices amounting to Us$ 160,051 during next week’s Auction.