VARYING HYDROLOGIC ANALYSES TO MATCH LEVEL OF AVAILABLE INFORMATION IN ETHIOPIA

Abstract

Two separate papers are presented as a way to illustrate how hydrologic analyses should be tailored to fit the amount of information available for a watershed and the intended audience.

The first paper highlights two watersheds in the highlands of Ethiopia where participatory water resource management activities were used to overcome a shortage of scientific information. These watersheds brought together many different implementing agencies to address water scarcity, crop production, and soil erosion, but the most important step was enabling local potential through the creation and strengthening of community watershed management organizations. Leadership training and the reinforcement of stakeholder feedback as a fundamental activity led to increased ownership and willingness to take on new responsibilities. A series of small successes ranging from micro-enterprise groups to gully rehabilitation have resulted in the pilot communities becoming confident of their own capabilities and proud to teach others how to manage a watershed.

The second paper describes a simple method of characterizing three other watersheds in the Ethiopia highlands where basic hydrologic data was already available. Effective precipitation and runoff were summed for various timescales, with weekly hydrographs and biweekly comparison plots proving the most descriptive. The latter graphs showed that discharge was linearly dependent on effective precipitation after a certain amount of rainfall had fallen in each watershed. The hydrographs also confirmed the importance of storage in catchment response behaviors, suggesting that the historical tendency to focus conservation efforts on preventing infiltration excess runoff may not be appropriate for reducing overall water loss. Simple analyses like these should be used to gain an understanding of mechanisms before attempting more complicated modeling techniques.