Abstract：
Monitoring water quality and quantity is crucial to be sure that water resources are sustainably used. However, there is no monitoring system of water quantity and quality in southwestern Ethiopia, despite expansion of agricultural activities demanding water resources. The objective of this study was to investigate the effect of agriculture on water quantity and quality with special emphasis on irrigation in southwestern Ethiopia. Data of water quantity was collected from four rivers and four irrigation canals during dry season of 2023. Physico-chemical water quality data was collected from 35 sites. Water quantity was calculated by estimating the water discharge of the rivers and irrigation canals. Weighted arithmetic water quality index was calculated to assess the status of the studied rivers. Principal component analysis was used to identify the relation of the sites with water quality parameters. This study revealed that the average amount of abstracted water for irrigation from the four studied rivers was 22,399 m3/day during the studied period, and the average percentage of abstracted water was 17%. Sites downstream of the irrigation site were characterized by poor water quality compared with the upstream sites. Sites surrounded by agricultural land use were correlated with chemical oxygen demand, electric conductivity, nitrate, orthophosphate, water temperature, and pH, whereas all sites surrounded by forest were positively correlated with dissolved oxygen. This study indicates that agricultural activities have a negative impact on surface water quality and quantity if not managed properly. Hence, we recommend sustainable use of water resources for the planned irrigation expansion.
摘要：
监测水质和水量对于确保可持续利用水资源至关重要。然而,埃塞俄比亚西南部没有水量和水质监测系统，尽管农业活动的扩大需要水资源。这项研究的目的是调查埃塞俄比亚西南部农业对水量和质量的影响，特别是灌溉。在2023年的干旱季节，从四个河流和四个灌溉渠收集了水量数据。从35个地点收集了物理化学水质数据。通过估算河流和灌溉渠的排水量来计算水量。计算加权算术水质指数以评估所研究河流的状况。主成分分析用于确定站点与水质参数的关系。这项研究表明，在研究期间，从四个研究河流中提取的灌溉用水的平均量为22,399m3/天，提取水的平均百分比为17%。与上游站点相比，灌溉站点下游的站点的水质较差。被农业用地包围的地点与化学需氧量相关，电导率，硝酸盐,正磷酸盐,水温,pH值,而所有被森林包围的地点都与溶解氧呈正相关。这项研究表明，如果管理不当，农业活动会对地表水质量和数量产生负面影响。因此，我们建议可持续利用水资源进行计划的灌溉扩展。
