Development of Structurally Improved Erosion Control Dam Models for Ecosystem Connection in Mountain Streams

Abstract

Non-permeable check dams (erosion control dams) have been constructed to serve specific purposes such as water storage, fire control etc. For example, the gravity check dam serves to block the passage of sediments. Numerous tons of sediments, plant material (e.g. dead leaves) etc. accumulate in these non-permeable check dams, thus rapidly degrading the upstream water. There is need to improve on the permeability of check dams by creating ecological corridors in the non-permeable check dams so as to enable upstream to downstream movement of sediments, animals such as fish, amphibians, control pollution etc. to create ecological harmony in the upstream and downstream environments. This study is therefore very important in that it highlights the challenges associated with the use of non-permeable check dams. It was thus necessary to conduct this study so as to ascertain the importance to improved check dam permeability and as well develop cost effective check dam models.   Structural improvement of the existing non-permeable check dams was carried out via demolition, drilling of dam walls to create drainage holes (Φ100 mm pipe in drainage holes replaced with Φ300mm pipes), and this has necessitated the development of improved permeable check dam models with drainage holes that as well serve as ecological corridors. Thus, there is need for improvement of the existing check dams to more ecologically-friendly structures. The required check dam shapes, construction materials and colors depends on the geographical/environmental conditions of the area. In addition, in landslide vulnerable areas with shallow landslides, especially in mountainous valley areas with constructed houses, it`s usually a big challenge to construct large check dams, thus the new model mini-type or membrane type check dams which are less costly, with narrower width and adequate height could best serve in preventing casualties and damages, and enabling harmony with the environment. Constructing these smaller size check dams in areas were landslides are characterized by smaller mass of material movement is thus best suited in such areas as it is cost effective.

Keywords: Check dams, dead leaves, ecological corridors, landslide, permeability, structural improvement