| dc.description.abstract | World over, there has been a great shift from rain-fed agriculture to irrigation farming. Part of the farming takes place in wetlands, however, the impact of such form of farming on wetland services is entirely underestimated and, in most cases, unknown. Therefore, this study was conducted to investigate the impact of Doho Rice Irrigation Scheme (DRIS) on water quality and wetland services to the surrounding communities. Wetland ecosystem services are benefits people obtain from wetland ecosystems. This study focused on availability and scarcity of water for domestic use within DRIS dependent community. Doho wetland is located in eastern Uganda on River Manafwa and is utilised by local communities as a domestic water source. DRIS is entirely utilised for rice growing measuring 2500 Ha currently from the initial 3200 Ha in 1990. The use of Doho wetland area for irrigation farming has had detrimental impact on wetland coverage from 4,898 Ha in 1990 to 4,250 Ha in 2017. The approach used in this study included cross-section survey where at least 120 farmers were interviewed to collect primary information on water usage and wetland services. Key-informant interviews were also carried out to collect information on how other schemes are affecting wetlands elsewhere. The study was supplemented by water quality tests to assess the impact of DRIS on the water quality and the wetland services. Water quality monitoring was carried out over a period of two seasons where 7 samples were collected every season and analysed for different water parameters onsite and in the Laboratory. The findings showed that DRIS has had major impacts on the service provided by the wetland. This included 87% diminished availability of water. This water scarcity is mainly attributed to 60% diversion of streams, 70% pollution of water, 10% drying out of dug wells and 20% restriction of upstream users. Water quality in DRIS varied among seasons with wet the season having low water nutrient concentration than the dry season. There was a significant difference between TN (p=0.038), Temp (p= 0.00033), DO (p=0.0044), EC (p=0.0016), and pH (p=0.028) across the dry (December to March and June to August) and wet season (March to June and August to December). The dry and Wet season across all the sampling points showered no significant difference for TP (p=0.085).
Therefore, the findings showed that growing of rice in wetlands can have significant impacts on wetlands services in terms of water quantity and quality. The surrounding rice growing on non-irrigated wetland areas together with surface runoff contribute to deterioration of water quality in the wetland especially downstream of the scheme. The study therefore, recommended, there should be no irrigation schemes establishment within wetland areas and only be used as water reservoirs to support agricultural production in the uplands. The communities around the schemes need to be availed with alternative water sources and not depend on wetland only. There is a need to have a close monitoring of the fertilizer and chemical application activities in the scheme to minimize nutrient loading of scheme waters beyond the thresholds for ensuring water quality. | en_US |
