The importance of water to the basic needs of man is self- evident and needs no particular emphasis. The importance of water to a developing economy cannot be overemphasized.

A few decades ago, hydrology was a division of hydraulic engineering and was a tool for project survey, plan, and design. Today hydrology still remains an important part of planning and management of water use projects, but it is imperative that surface and ground-water basic data networks be designed and operated from the standpoint of both present and future water needs. Water problems are ever increasing and ever changing and preparation for the future water demands of Zambia requires knowledge of the hydrology of the country instead of the examination of piecemeal samples for each water use project.

The hydrologic survey of Zambia needs to be under the guidance of competent and imaginative hydrologists solidly trained in all elements of basic data collection and analysis and not in the hands of water project planners. Hydrology is a science which requires the highest order of teamwork and the hydrologist will need the help and advice of many employees within the organization to operate the network, provide adequate research, and examine the water needs of the country. It must be thoroughly understood that communication is essential between the hydrological survey and water project planners from both the government and private sectors.

It is very important to define the aims and duties of the Hydrological Branch of the Water Affairs Department in a clear cut "Statement of Policy". Personal copies of the statement should be made available to all professional employees and technicians. The reasons for the existence of the Branch may be self-apparent to heads of the organization, but to all other employees the reasons may be vague and unknown. Every member of the technical and administrative staff would benefit by an understanding of the purpose of his work. Nebulous ideas of the function of a hydrological survey of Zambia serve little purpose to the employee making the plans or those who execute them. A dissemination and free flow of ideas in all directions is necessary in any scientific and creative organization.

The primary functions of the Hydrological Branch of the Water Affairs Department of Zambia are twofold:

1. Water resource appraisal which includes the inventory of all surface and ground waters;
   
2. Research, both basic and applied, in the science of water.
   

Possibly some function regarding water law is also conceivable, although attachment of a law enforcement function to water-resource investigations might weaken the position of the Branch as an unbiased scientific organization.

As the collection of basic streamflow data is a primary function of the Branch the following instructions for the collection, analysis and computation of streamflow records have been written.