This module describe the most common environmental impacts associated with irrigation and drainage project. Under each item, both positive and negative impacts are briefly described and the most usual mitigating measures outlined. The opportunity to identify positive impacts and to propose measures to enhance such impacts should not be neglected. The structure of the learning units generally follows that of the ICID Environmental Check-list and is divided into three major sections. As a slight deviation from the Check-list, human health has been included, in order to present the human health dimensions of the environmental impacts. When considering impacts, two perspectives must be taken into account, those of:
- The project on the environment, and
- External factors on the project (externalities).
In the detailed sections below, many of the impacts described are most extreme in the case of new irrigated areas. However, rehabilitation and changes resulting from alterations to the operating infrastructure, for example, will also have environmental impacts that may not at first be anticipated.
The intensification of agriculture can lead to groundwater pollution related to the increased use of pesticides and fertilizers. Improved efficiency may significantly reduce return flows which are often utilized downstream by other irrigation schemes or wildlife habitats. Similarly, upstream developments are likely to impact on an irrigation scheme either in the form of reduced water availability (surface or groundwater) or reduced water quality.
Upon the completion of this module, trainee’s will be able to:
- To provide information to workers involved in irrigation and related works,
- To assess risks to the environment,
- To implement environment protection procedures.