“The destabilization of the Global Hydrological Cycle (GHC) is causing the steady increase in the frequency of natural disasters, and in particular drought and flooding. Vetiver impacts water quantity and quality, and in the process restores soil health. Most countries with tropical and semi arid climates are being severely affected by GHC changes, and will need to use all opportunities to mitigate drought and flooding. In many regions rivers, lakes and aquifers are at an all time low; cities, towns and villages are either without drinking water, or with water rationing, AND in many instances the quality of the water that is available is seriously contaminated. The Vetiver System with its capacity to manage rainfall precipitation runoff, particularly for the recharge of essential ground water and its ability to reduce the contaminates (especially those generated by the agricultural sector) that lower water quality, should be seen as one of the most practical and efficient means of mitigating these problems, and should be promoted as such.”
Soil erosion control (soil conservation) and water conservation are closely linked. The impact of the effects of climate change on farm water supplies and soil moisture for plant growth is becoming critical. Rainfall events are tending to be fewer but more extreme, resulting in increased flooding and rainfall losses to the farm , as well as longer periods between rainfall events when soil moisture is not replenished. Related to this is the diminishing ground water that effects many aspects of farm water requirements.
Redistribution of rainfall runoff — Soil moisture is an essential component of improving the performance of soil macro and micro fauna/flora and the enhancement of soil health and fertility. Vetiver hedgerows will often reduce rainfall runoff by as much as 70% – especially important where rainfall events are few and far between.
Concentrated flows (from eroding rills and micro gullies) reduce the rainfall runoff distribution over a crop field resulting in lower and patchy soil moisture content and increased crop stress. The combined flows, that occur at the upslope face of the hedgerow spread laterally behind the hedge, seep evenly through, and flow with better distribution over the down slope land area – the trick is to establish a hedge at the point where rilling starts again, in order once again to slow down and spread out the rainfall runoff. As a rule of thumb the placement of another hedge is generally at a 2m Vertical Interval (VI) below or above an existing hedge. Soil moisture is often improved to the extent that the wilting point of a plant under drought stress can be extended by 10 days or more – often the difference between a good crop or a total failure!
Use of Vetiver Grass for Soil and Water Conservation in Nigeria , an abstract of a paper by O. Babalola of Ibadan University, Nigeria, demonstrates the effectiveness and the psoitive impact of vetiver on soil loss, soil moisture and crop yields — such results have been obtained in most other countries that use vetiver for soil and water conservation
Ground water – Vetiver hedgerows have been proven to increase ground water recharge by as much as 20%. This is because vetiver’s deep penetrating roots open up infiltration pathways for the water passing through the hedge as well as creating better distribution of slowed down rainwater. This is a very low cost and effective way to recharge water tables. There are many examples from the field of this. One example is from Ethiopia, where vetiver protected farmland results in the rehabilitation of dried-up wetlands, renewal of annual spring flows, recharge of pond water, and permanent domestic well water.
Potential for Increasing Groundwater Recharge – Thailand Microsoft Word – DAS01 Boonma Deesaen#153875.doc (vetiver.org)
Vetiver System: Ethiopia – Ground Water Recharge – Ano Farm (movie)
Vetiver System: Ethiopia – Wetland Restoration – Wichi Wetland. (movie)