Opportunities and Challenges for Sustainable Water Resources Management in Tanzania

By Mwakalila, Shadrack

Introduction The current national interest in the Great Ruaha Basin in southwest Tanzania (Figure 1) has been driven by major concerns over water availability generally in Tanzania. In particular, water shortages at Mtera hydroelectric power plants have resulted in national power shortages since 1992. In the Ruaha National Park, which covers over 30% of the basin, the Great Ruaha River has dried up during every dry season since 1993, with the dry period tending to start earlier and last longer. This has had severe impacts on the wildlife, especially the aquatic fauna, and so threatens the tourist potential of the park. Within the Great Ruaha Basin itself, there has also been concern over rising conflicts over water availability for irrigation, as well as over access to water for livestock. This paper seeks to address opportunities, challenges and viable interventions for sustainable water resources management for the entire Great Ruaha Basin upstream of Mtera Reservoir, and draws on a number of sources, including DANIDA (1995), Kikula et al. (1996), Mwakalila (2005), and Kadigi (2005).

Research methodology

A combination of data collection methods was used in this study. A desk study of secondary information and data from different project documents and other existing literature from previous studies was carried out. Fieldwork was conducted in the study area to assess the hydrological characteristics of the Great Ruaha Basin, the irrigation systems, agricultural practices, farming systems, geographical characteristics and the size (magnitude) of the study area. During the fieldwork, information from the district, division, ward and village levels was collected to give an insight on the status of various water demand and uses, including irrigation systems, agricultural practices, constraints and opportunities in the different study villages. Participant observation, consultation of key informants and group discussions were used as tools for information gathering.

Opportunities in the Great Ruaha Basin

The seasonally flooded woodland communities of the Great Ruaha Basin are dominated by Acacia seyal, Acacia tortilis and Acacia kirkii, which are typical of areas that are water-logged, or where drainage is seasonal. Fish populations have declined dramatically, with a much lower residual population surviving over the dry season in the remaining pools. The bird fauna, and some species of aquatic invertebrates such as many insects, are able to migrate to other permanent wetlands, and recolonise the mbuga during the wet season.

The Great Ruaha River flows through the Ruaha National Park and forms an important source of water, particularly in the dry season, for wildlife. Under natural conditions, the river is normally perennial, with flows lasting all the way through the dry season. This provides habitat for hippopotami, fish and other aquatic life, and aesthetic wildlife viewing conditions which are important factors affecting the attractiveness of the park for tourists.

As well as its high biodiversity, the Ruaha Basin also has agricultural potential. Irrigated rice produced from the Usangu Plains accounts for about 14% of the total domestic rice production of Tanzania, ranging between 60 000 and 80 000 tonnes, valued at US$16 million, and providing some 30000 households with an estimated income of US$3 per day stretched over the year. This income is vital for lifting many people out of poverty in this area, and is central to supporting a total population of 750 000 people in the region. This production extracts some 576 mm^sup 3^ of water, giving a value of US$0.027 per cubic meter extracted.

The Mtera and Kidatu hydropower plants contribute over 80% of the power supply of Tanzania. The Mtera Dam is the largest dam in the country in terms of height, crest length and concrete volume. Its impounded reservoir is also the largest artificial lake in Tanzania. Mtera Power Station, with an installed capacity of 80 MW, is the second largest powerhouse in Tanzania after Kidatu (204 MW).

Key challenges in the Great Ruaha Basin

Water use conflicts

From farmers’ perceptions, it was observed that water shortages are the single biggest bottleneck for crop production for a number of reasons, such as many water users, drought and destruction of water sources (Figure 2).

Water demand for hydropower generation

Mtera and Kidatu dams are located on the Great Ruaha River, downstream of the Ruaha National Park. They require both inflows and the careful management of releases and reservoir water levels in order to provide an optimum supply of electricity. As indicated in Table 1, the full supply level (FSL) at Mtera reservoir is +698.50 m above sea level (m.a.s.l.) and the minimum supply level (dead storage level) (MSL) is +690.00 m.a.s.l. The water levels in the 1991-2000 period went down very close to the dead storage level. This resulted in serious rationing in the electricity supply in the country. In the year 2004, the observed minimum water level of 690.5 m.a.s.l. (i.e. only 0.5 m above MSL) occurred in February. In December 2005, the level reached the MSL. In January 2006, the water levels went down to 689.5 m.a.s.l., and since then Tanzania has been facing serious power rationing. In September 2006, the situation was even worse in power rationing; in most areas of the country, the power supply was only available for two days (Saturday and Sunday) per week.

Rice irrigation and dry season abstraction in the Usangu Plains

For the perennial rivers flowing from the high catchment, upstream of any irrigation abstractions, the flow at the end of the dry season is low and decreasing slowly with time. At the start of the wet season, the first light rainfall showers in the high catchment are absorbed by the dry soils, but once the rain starts in earnest, the flows in the rivers rise quickly, soon reaching rates comparable to those mid-way through the dry season. In recent years, there has been a tendency for rice irrigators to start their cultivation earlier and earlier in order to gain from the higher prices for their product in the market. This means that all, rather than most, of the early wet season rising flows are diverted. This causes longer delays before the river downstream starts to rise.

After the main rice crop has been harvested, a minority of farmers practice dry season irrigation of vegetables, such as beans and tomatoes. These crops are normally planted in fields close to the top end of the wet season irrigation schemes, where the supply of water from the river is more reliable when flows are low. However, abstraction remains high during the dry season; between 10 cumecs in a dry year and 16 cumecs in an average year. This water is used for purposes other than irrigating crops such as growing vegetables and fruit trees, giving water to livestock and making bricks.

Changes in the perennial swamp of the Eastern Wetland

The Eastern Wetland (Ihefu Swamp) consists of an enclosed area full of alluvial deposits (Figure 1). Two main perennial rivers, together with several ephemeral ones, flow into the wetland, with a single outflow at N’Giriama to the north. The Eastern Wetland slopes gently between the southwestern upstream end at Nyaluhanga and the outlet sill at N’Giriama, with a total drop of 3.6 m over a distance of 50 km along the main channel. These conditions allow for an unstable hydraulic regime affected by deposition and erosion, with much evidence of previous river channels, now long since abandoned, and changes in size, volume and location of open water lagoons in the perennial swamp. These changes to river channels are not all natural, as fishermen and livestock herders working in the wetland have played a part in both opening and closing off smaller channels at different times for their own benefit.

Water allocation procedures

Although the process of allocating water resources has improved in the Great Ruaha Basin, it is rarely supported either by a monitoring programme or by enforcement of the water law. Consequently, overlicense abstractions are common in this highly stressed river basin. Water rights are sometimes allocated without adequate consideration for water availability, especially during periods of drought. This is partly a result of poor monitoring, and a consequent lack of information, and partly a result of a lack of transparent administrative procedures for issuing water rights. However, the real situation in the basin indicates that about 38% of abstracters of water do not have water rights (Table 2). This lack of water rights is attributed partly to the ignorance of the requirements of the law by small-holder farmers, and partly to the long and cumbersome procedures that the applicants have to go through before water rights are granted.

Framework for establishing environmental flows

There are no standards, criteria or guidelines established for setting river flows for environmental purposes. In the Great Ruaha Basin, excessive upstream irrigation abstractions have severely reduced flows in the Great Ruaha River to the detriment of the Ruaha National Park and the water users on the Usangu Plains. Although the national water policy promotes the participation of sectoral agencies in water resources management, the reality is that these agencies still deal with the management of water resources according to their specific sectoral mandates and priorities and do not take a cross-sectoral, basin-wide perspective when making decisions. Conclusions

Water is the key resource in the Great Ruaha Basin in Tanzania in that, without it, other resources, natural and human, cannot be sustained. A variety of stakeholder groups depend on water for drinking supplies, irrigation, livestock watering and hydropower generation. The wetlands in the basin owe their existence and nature to the balance between the inflow and outflow of water. The distribution of flora and fauna in and around the wetlands is also largely controlled by water availability. The amount and timing of water in different parts of the basin controls the seasonal rhythm of life in the Great Ruaha Basin.

Sustainable water resources management in the Great Ruaha Basin of Tanzania is of national importance in terms of utilisation of its water resources for significant crop production, maintaining a RAMSAR wetland site, meeting the ecological needs of the Ruaha National Park and the generation of hydoelectric power.

References

DANIDA 1995 Joint study of integrated water and land management in the Great Ruaha Basin. A final report DANIDA/World Bank

Kadigi R 2005 The value of water for irrigated paddy and hydropower generation in the Great Ruaha Tanzania in Proceedings of the East Africa Integrated River Basin Management Conference Sokoine University of Agriculture, Morogoro, Tanzania 247-63

Kikula I, Charnley S and Yanda P 1996 Ecological changes in the Usangu Plains and their implications on the downstream flow of the Great Ruaha river in Tanzania Research Report No. 99 (new series) Institute of Resource Assessment, University of Dar es Salaam

Mwakalila S S 2005 Water resource use in the Great Ruaha Basin of Tanzania tournai of Physics and Chemistry of the Earth 30 903-12

SHADRACK MWAKALILA

Department of Geography, University of Dar es Salaam, PO Box 35049, Dar es Salaam, Tanzania

E-mail: smwakalila@yahoo.com

This paper was accepted for publication in April 2008

Copyright Royal Geographical Society Jun 2008

(c) 2008 Geographical Journal, The. Provided by ProQuest Information and Learning. All rights Reserved.