Hydraulic performance assessment of Tahtay Tsalit small scale irrigation scheme, Tigray, Ethiopia

Performances assessment of irrigation schemes network is very essential in taking different water management strategies. However, the performance of Mychew irrigation scheme was not assessed and hence, this research was undertaken to assess the hydraulic performance of Mychew small scale irrigation scheme. Moreover, identification of the cause and effect for mal-functionality of irrigation structures was also another objective of this study. Hence, comprehensive field observations, measurements and focus group discussions were held to investigate hydraulic performance, cause and effect of failed hydraulic structures. Simple descriptive statistics was employed for analysis of the data collected from focus group discussions and observations. Eight performance indicators were used to assess the performance of this irrigation scheme. Several factors such as sedimentation, design problem, damage of sluice gates, abstraction of irrigation water by unwanted plants has been identified for mal-functionality of different structures. There were problems in irrigation adequacy (0.75) and equity (0.28) of irrigation water was categorized as poor, while good and fair for dependability (0.08) and irrigation efficiency (0.79), respectively. The average water surface elevation ratio, delivery performance ratio, and delivery duration ratio of the main canal during the monitoring period was less than one, greater than 5% and 150%, respectively. The highest sediment accumulation was observed at head and middle reaches of the irrigation scheme than the tail reaches. Generally, there were a number of irrigation structures which was mal-functioned in this irrigation scheme. Now it needs sustainable solution to improve the performance of the irrigation scheme. Therefore, it was recommended that water should be fairly distributed spatially and temporally. Additionally, capacity building and awareness creation to concerned bodies holds the key to bring a difference in irrigation water management in this irrigation scheme.

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Evaluation of Hydraulic Performance On Lower Areb Small Scale Irrigation Scheme Amhara, Ethiopia

10.21203/rs.3.rs-985549/v1 ◽

2021 ◽

Author(s):

Gashaw Sintayehu Angualie ◽

Alemshet Belayneh ◽

Kibru Gedam Berhanu ◽

Tirunesh Muluken Munye ◽

Kefale Ejigu ◽

...

Keyword(s):

Physical Performance ◽

Performance Indicators ◽

Water Surface ◽

Hydraulic Performance ◽

Water Infiltration ◽

Surface Elevation ◽

Small Scale ◽

Irrigation Scheme ◽

Water Surface Elevation ◽

Small Scale Irrigation

Abstract This study was conducted in the Lower Areb small-scale irrigation scheme for one crop season from March to May 2018 to evaluate the hydraulic performance of the scheme by estimating the hydraulic performance indicators, physical performance indicators, and maintenance performance indicators. The primary data including water flow rate, soil physical properties, and water infiltration were collected. The secondary data collected were climatic, crop data, and data from different reports and design documents including the irrigation water users' interviews. The hydraulic performance of the irrigation scheme was evaluated by estimating adequacy, efficiency, dependability, and equity indicators at nine selected offtakes; three each at the head, middle, and tail reaches of the scheme. The physical performance and maintenance indicators were determined using the irrigation ratio, the sustainability of the irrigated area, the effectiveness of infrastructure, and the water surface elevation ratio. The data were analyzed by using CROPWAT 8.0, ARC GIS 10.1 software, and Microsoft Excel 2013. The overall average values of adequacy, efficiency, dependability, and equity were found to be 0.89. 0.91, 0.096 and 0.07 respectively. Therefore, dependability, equity, and efficiency were under good condition and adequacy was under fair condition. The irrigation ratio and sustainability of irrigated areas were 54% and 123% respectively. The effectiveness of infrastructure and water surface elevation ratios were 73.33% and 94% respectively.

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