A procedure for planning irrigation scheme rehabilitation

Abstract

The procedure aims to identify those irrigation schemes where targeted, physical rehabilitation of infrastructure is likely to lead to improved hydraulic and agricultural performance, as measured by water supply, cropped area or crop yields. To do this, a reviews a range of possible causes of under-performance are reviewed: Agricultural or economic factors System design or operational factors The condition of infrastructure Land degradation Water supply at the scheme headworks The procedure provides three main diagnostic tools: A checklist of factors potentially limiting scheme performance. A questionnaire for farmers to obtain their views on system constraints and priority needs. Condition assessment formats to determine the 'fitness for function' of infrastructural components. The checklist provides the basis for structured discussion with O&M staff on a scheme and should identify the nature and approximate scale of technical and non-technical factors that influence scheme performance. The farmer questionnaire obtains information from the field about levels of performance, the role of infrastructure and other factors in determining that performance, and their relative importance. The condition assessment formats provide a standardised and consistent basis for determining the impact of condition on the hydraulic performance and structural stability of a given asset. A derived condition score can then be used as a parameter in a priority index to rank the importance of different works. The MARLIN software, also available from HR Wallingford as a research output, utilises basic information and procedures discussed in this document. Appendices to the document provide a number of proformas that can be used in the field in following the procedure