Hydrology-based assessment of environmental flows: an example from Nepal

Abstract

The paper examines the applicability of several desktop hydrology-based environmental flow assessment methods—Tennant, range of variability approach (RVA) and South African desktop reserve model (DRM)—in the specific context of Nepal. Some of these techniques are modified, following the discussion of their limitations. It is indicated that hydrology-based methods of environmental flow assessment represent a necessary first step in planning for environmental allocations in developing countries. It is shown that use can be made of complementary features of existing environmental flow assessment techniques to arrive at justified estimates of environmental flows, even in the conditions of limited basin-specific eco-hydrological knowledge. The methods described in the paper could also be used in other countries—by relevant departments, agencies and organizations, which are engaged in ecosystem management and preservation of aquatic environment. This research intends to promote the need for environmental water allocation planning in river basin development and to streamline the inclusion of environmental water demand assessments into relevant national policies.