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Framework for effectiveness and resilience of small- and medium-scale irrigation systems in Nepal

Published: 11th October 2017 11:25Last Updated: 11th October 2017 11:25
irrigation in nepal

© CDKN.

Introduction

Out of 2.7 million hectares of agricultural land in Nepal, only 1.3 Mha have irrigation facilities. The majority of irrigation systems are small and medium scale. Agriculture is a mainstay of the economy of Nepal, providing about 33% of the gross domestic product (GDP) and supporting the livelihoods of most of the population. Livelihoods based on agriculture are vulnerable due to the monsoon climate and the topography.

A recent study funded by the Climate and Development Knowledge Network (CDKN) revealed that about 0.8% of agricultural GDP is being lost annually due to climate change and extreme events. There is a need to both improve agricultural productivity and make it more resilient to climate uncertainty and change in general.

In light of these concerns, a project was undertaken for CDKN in 2015-2016 to develop a framework for the effectiveness and resilience of small- and medium-scale irrigation. It was delivered by Mott MacDonald working with the Farmer Managed Irrigation System Promotion Trust (FMIST), the Centre for Engineering Research and Development (CERD), and ADAPT-Nepal, in conjunction with the Department of Irrigation, Government of Nepal, with funding from the United Kingdom (UK) Department for International Development (DFID).

This paper* synthesises the findings and recommendations from the project and is intended for policy-makers, planners and implementers working in Nepal’s irrigation sector under uncertain conditions induced by climate change. It provides guidance to irrigation sector project designers and policy- makers on assessing climate risks at the project and system levels, and on mitigating the risks using the resilient approach.

*Download the full report from the right-hand column.

Methods and Tools

The study adopted a two-pronged approach involving both top-down and bottom-up analysis. These approaches are summarised as follows:

  • The top-down approach focused on understanding Nepal’s specific climate vulnerabilities and the overall performance of the irrigation sector in the country, including the challenges and opportunities for sustained agricultural growth brought on by climate change phenomena in Nepal.
    • The top-down approach helped develop broad knowledge on irrigation performance from the perspective of climate change.
  • Because of the diverse biophysical and socioecological systems in Nepal, the information derived from the top-down analysis needed to be verified through location-specific studies. So, the study undertook a bottom-up approach to understand climate vulnerability and performance of irrigation systems at field level.
    • For this, reconnaissance field visits were made to 17 irrigation systems, and two river basins were selected for detailed case studies.

Key messages

The main findings of the study are briefly summarised as follows:

1. Climate change is predicted to affect seasonal water availability, which could have serious impacts on irrigation systems, and consequently on Nepal’s overall economy.

2. The case studies of the two river basins revealed that their irrigation systems are severely affected by climatic and non- climatic factors.

  • The impacts of climate change include:
    • reduced run-off in rivers, due to changing rainfall patterns in the catchment
    • increased flood flows, due to more intense rainfall
    • increased demand for water, due to higher temperatures and more erratic rainfall
    • changes in crop suitability.
  • The impacts of non-climatic factors include:
    • land use change
    • increased water consumption upstream
    • resource mining (sand, gravel) in the rivers
    • migration from rural areas with adverse consequences for irrigated agricultural practices.

3. The study showed that the impacts of non-climatic factors are more important in the short term for most small- and medium-scale irrigation systems, with the possible exception of the impact of increased rainfall intensity on flood risk. In the longer term, climate impacts will become much greater than they are today.

4. It was determined that groundwater irrigation is relatively more resilient to climate change than surface irrigation.

„5. For longer-term water availability and water demand, it is vital to consider the entire basin rather than looking solely at individual systems.

„6. To make the irrigation systems climate resilient, there is a strong need to enhance technical design, improve water use efficiency, adapt agricultural practices, improve water use governance and build robust institutions.

Recommendations

Although the concept of resilience in irrigation systems is evolving, the project has proposed a framework to make irrigation systems resilient:

At irrigation system level

  • Climate data collection stations should be improved, at least for key parameters (minimum and maximum temperatures, daily rainfall), with river flow monitoring introduced in representative small basins.
  • More reliable methods should be derived for flood and low-flow forecasting in unmonitored catchments, along with estimation of effective rainfall.
  • „Research should be undertaken on the impact of soil and water conservation in upper catchments, including small- scale water harvesting.

At institutional level

  • Water management should be improved (at system level and on farm), with the use of appropriate operating rules.
  • There should be a value chain approach to agricultural development, linking producers to markets, and addressing constraints at all levels.
  • „Institutional arrangements for river basin management should be developed and strengthened.

At agent level

  • Actions should be taken to promote understanding of climatic and other changes, their impacts, and coping mechanisms in the context of irrigated agriculture.
  • Better use should be made of short-term and seasonal forecasts on water availability and floods, and crop and water management decisions should be adapted accordingly.

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