Reliable subsurface drainage systems for groundwater table and salinity control are needed to maintain or enhance the productivity of irrigated lands and to contribute to the rural development of lowlands in the humid tropic. This publication presents guidelines to assess the need for envelopes and for the selection of appropriate materials (i.e. pipes and envelopes) for the proper and lasting performance of subsurface drainage systems. In addition, it also contains guidelines for adequate installation and maintenance of drainage materials as well as the required specifications and standards of such materials, which may be used in tender documents for implementation of subsurface drainage works. Practical guidelines for the implementation of laboratory and field investigations to evaluate the performance of drainage materials have also been included.--Publisher's description.

The purpose of this manual is to provide clear and helpful information for maintaining gravel roads. Very little technical help is available to small agencies that are responsible for managing these roads. Gravel road maintenance has traditionally been "more of an art than a science" and very few formal standards exist. This manual contains guidelines to help answer the questions that arise concerning gravel road maintenance such as: What is enough surface crown? What is too much? What causes corrugation? The information is as nontechnical as possible without sacrificing clear guidelines and instructions on how to do the job right.

Prepared by the Task Committee on Recommendations for Standards in Hydraulics of the Hydraulics Division of ASCE. This report investigates whether standards or guides are useful to hydraulic engineers and whether additional standards or guides should be prepared. The results of a questionnaire indicate that most hydraulic engineers are not familiar with the procedures used to develop standards or with existing national or international standards. However, responses to the questionnaire show that hydraulic engineers welcome guides or standards as long as some flexibility to use engineering judgment for site specific conditions is allowed. The report recommends that guidelines or consensus standards be developed in the following areas: application of one-dimensional surface water computer programs of the HEC-2 type; prediction of scour at bridge piers; design of pump intakes and sumps; and calculations of friction and form losses in closed conduits. Annotated lists of standards and guidelines produced in the United States and abroad are included.