Comparison Assessment of Water Use and Damage between Modern and Traditional Rice Irrigation Schemes: Case of Usangu Basin, Tanzania
Abstract
:Introduction
- It is home to over 200 000 people, most of whom depend for their livelihoods on the natural resources (water) of the basin and 30,000 household directly depending on rice farming in the basin [19];
- It has extensive water abstraction for rice irrigation achieved through improved intakes in modernized irrigation schemes;
- Multiple water use sectors apart from irrigation exists including domestic, livestock, river line environment and wetlands, wild animals and ecological functions in the Ruaha National Park, fishery in the rivers and the wetlands and hydropower generation which contribute over 50% to National Electric Grid in the dry season.
Material and Methods
Description of the Study Area
Data Collection and Analysis
Results and Discussions
Field Water Balance Analysis
Competition for Water and Water Damage
- (i)
- Over-irrigation does occur in the field, with intakes which can abstract water from the river, indefinitely. But contrary this reduces the productivity of water since too much water results on low yield but also too much gross water use results in low rice productivity (expressed in yield per gross annual water use)
- (ii)
- Since each crop type has a defined water requirement in a particular environment, the excess water abstracted is seldom useful for the crop and thus it is lost through natural processes such as evaporation, deep percolation and in this way losses of water resources occurs
- (iii)
- Also, as less water is left for the traditional systems which are often located downstream of the modern systems, the cropped area is reduced and again either the yield per year is reduced or the crops attain their wilting point before maturity. This creates feelings to traditional farmers that upgrading of traditional intakes is the way to enable sufficient abstraction of water (the way to win water competition) – But indeed it has caused more competition in the basin and the traditional farmers they still manage the little water they get.
- (iv)
- The competition does not end by the two users only (modern and traditional). As it was mentioned earlier that all the users in the USB get water from common sources, the effect of competition reaches other users like hydropower, livestock keepers and domestic in the downstream of the systems.
Strategies for Water Resources Management
Water Management in Irrigation
Technology and Policy
Structural or Hydraulic Effects of Improved Intakes
Operation and Maintenance (O&M)
Patterns of Rice Production
Reduced Land and Crop Water Productivity
Equity of Water Supply within Systems
The Upstream/Downstream Effects
Conclusions and Recommendations
Site Name | Seasons | Mean net annual water use (mm) | |
---|---|---|---|
1999/2000 | 2000/2001 | ||
Modern | 985 | 1063 | 1024 |
Modern | 989 | 986 | 988 |
Traditional | 1151 | 1095 | 1123 |
Traditional | 999 | 976 | 988 |
Mean | 1031 |
Site Name | GAWU (mm) | NAWU (mm) | Efficiency (%) |
---|---|---|---|
Modern | 2038 | 985 | 48% |
Modern | 1993 | 989 | 50% |
Traditional | 1668 | 1151 | 69% |
Traditional | 1789 | 999 | 56% |
Site Name | GAWU (mm) | NAWU (mm) | Efficiency (%) |
---|---|---|---|
Modern | 3010 | 1063 | 35% |
Modern | 2327 | 986 | 42% |
Traditional | 1722 | 1095 | 64% |
Traditional | 1730 | 976 | 56% |
Site | Field Operations | |||
---|---|---|---|---|
Pre-saturation | Water depth (mm) | Duration of water in field to maturity (days) | ||
Amount (mm) | Duration in days | |||
Modern | 665 | 19 | 121 | 200 |
Traditional | 156 | 4 | 116 | 165 |
Acknowledgement
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Machibya, M.; Mdemu, M. Comparison Assessment of Water Use and Damage between Modern and Traditional Rice Irrigation Schemes: Case of Usangu Basin, Tanzania. Int. J. Environ. Res. Public Health 2005, 2, 335-342. https://doi.org/10.3390/ijerph2005020020
Machibya M, Mdemu M. Comparison Assessment of Water Use and Damage between Modern and Traditional Rice Irrigation Schemes: Case of Usangu Basin, Tanzania. International Journal of Environmental Research and Public Health. 2005; 2(2):335-342. https://doi.org/10.3390/ijerph2005020020
Chicago/Turabian StyleMachibya, Magayane, and Makarius Mdemu. 2005. "Comparison Assessment of Water Use and Damage between Modern and Traditional Rice Irrigation Schemes: Case of Usangu Basin, Tanzania" International Journal of Environmental Research and Public Health 2, no. 2: 335-342. https://doi.org/10.3390/ijerph2005020020