干旱区生态环境知识资源中心

Poor availability of water and pastures has been identified as the single most important factor constraining productivity of livestock in Tanzania. Many smallholder livestock keepers have responded to the problem of shortage of water by constructing charco dams (dug out ponds constructed in flat semi-arid areas to store surface runoff). However, most of these charco dams are performing poorly. A participatory problem analysis was carried out in Makanya village in Tanzania in 2001/2002 to identify causes of poor performance of privately owned charco dams and to design appropriate intervention measures for each charco dam. A total of twenty charco dams were investigated, with storage capacities ranging from 20 to 2000 m(3). The retention period of water in the investigated charco dams ranged from 2 to 7 months depending on the capacity of the charco dam, household size and the number of livestock kept. The analysis revealed that major problems causing poor performance of the charco dams were: (i) rapid siltation of the charco dams, (ii) low water retention period, and (iii) lack of or inadequate working tools to carry out maintenance works. Although most of the charco dam owners were aware of the first two problems they were not sure of their causes or their proper remedies. Evaluations done in 2003 and early 2004 has revealed that after improvement of the charco dams, the water retention period has increased by 2 months for the same household size and number of livestock. It was also noted that even those charco dam owners who were at first reluctant to join the initiative; have improved their charco dams accordingly through knowledge sharing with their neighbours. The study has shown that although farmers and pastoralists are endowed with vast indigenous knowledge, their technical know-how has some limitations. They therefore need to be supported by local institutions with the required technical know-how in order to sharpen their skills. This will enable them to realise the anticipated fruits. When a participatory approach is used to build their capacity by imparting new knowledge and skills, the performance and sustainability of rainwater harvesting systems will greatly be enhanced. (c) 2005 Elsevier Ltd. All rights reserved.