Spate Engineering

Spate irrigation systems are based on floods and related phenomena, which makes them very different from normal irrigation practices. Design considerations that apply to other irrigation systems do not apply to them. This difference, however, has not been appreciated by a number of interventions carried out to modernize or improve existing spate systems. Many of them ended up not improving or worsening their performance.

Some of the factors that make spate systems unique are:

  1. The large amount of sediments that ride on the flow
  2. The large amount of trash that comes in with the flood waters
  3. Scope for abrasion and impact damage
  4. An intricate system of water rights of various users.

Having evolved over hundreds of years, traditional spate systems take all of these into account. Any intervention to increase their efficiency should be based on these considerations.

Lecture 1:
Spate Diversion Structures and Intakes

Dr. John Ratsey

Sediments are a fundamental feature of most spate irrigation schemes. Developing a strategy for sediment management is the first requirement in the planning of spate irrigation schemes. This lecture focuses on this issue.

Lecture 2:
Diversion Bunds and Spillways in Spate Irrigation

Dr. Noman Sadozai

In this presentation, Noman Sadozai, Senior Engineer at Pakistan Agricultural Research Council, takes us through a recent project that could successfully restore such structures and protect them from future damage, in Dera Ismail Khan. He explains what kind of engineering inputs and social mobilization have to go into such an effort.

Lecture 3:
Improved Traditional Engineering in Yemen

Dr. Frank van Steenbergen

In this video, Frank van Steenbergen takes us through examples of traditional engineering in Hadramawt, Yemen. Designed to manage flood discharges from an inland river, the origin of these structures is centuries old. The farmers, however, have also been using modern construction material and techniques to reinforce them and enhance their utility.

Lecture 4:
Lessons from Past Interventions

Dr. John Ratsey

Too often, top-down technocratic interventions are based on hydrological assumptions that are not field-tested. Therefore, it is important that the design process is informed by the farmers’ knowledge and experience. Besides, unless they are involved, they have no motivation to rectify the government’s mistakes. In this presentation, spate-irrigation expert John Ratsey presents and these and many other related issues.

Lecture 5:
Treating Dryland Valleys with Water-spreading Weirs

Dr. Jozias Pieterse

Over the last five decades, the environmental situation in the Sahel has deteriorated dramatically for several reasons (overgrazing, deforestation, and droughts). This leads to food insecurity and higher vulnerability to the effects of climate change. This lecture addresses these issues.

Last modified: Thursday, 11 September 2014, 09:47 AM