Groundwater recharge II - KASAL please see this

[KEVN]

The discussion on groundwater recharge continues, and I don't want to
withhold this from you who are involved in discussions with the KASAL
project! There's new papers on this subject: "groundwater management
in semi-arid hard-rock areas". Please read.
Elise

----

Don,
Thanks for your bringing this to our notice. See my note to the
author below:

Dear PD,

I read with interest your paper on forecasting ground water, along
with another paper "A decision support tool with variable agroclimatic
scenarios for sustainable groundwater management in semi-arid hard-
rock areas " by Benoît Dewandel et al.

I was fascinated that the studies were done at Maheshwaram. I know
the area well as in the 1980's when I was working for the World Bank
we introduced vetiver grass hedgerows to replace ineffective earth
bunds. At that time we noticed that ground water was substantially
improved and that ethemeral stream flow improved too. Another
interesting fact was that some of the small farm tanks were recharged
not from surface runoff but by improved groundwater. Farmers using
vetiver hedgerows at Gundalpet (Mysore District) clearly correlated
vetiver hedgerows with higher water levels in their wells.

In the photo on page 3 of Benoit's paper I think I see that vetiver
hedgerows are still being used in Maheshwaram.

Last month I was in Ethiopia where vetiver hedgerows have been used
quite extensively and where there is a very good connect between
vetiver and groundwater recharge including improved spring and stream
flows and wetland restoration.

Vetiver hedgerow research in India and elsewhere in the world shows
significant reduction (by as much as 70%) of rainfall runoff - and an
obvious link to groundwater recharge. Vetiver acts in two ways. When
planted as a narrow hedgerow it is so dense that it slows down and
spreads out runoff, and because of its very deep (3 meter +) and
penetrating roots, that break through soil hard pans, it enhances
rainfall infiltration.

The Vetiver System, as we call the collective applications of Vetiver
hedgerows, has huge potential in India and other countries for
improving groundwater and water quality. Of course in addition the
hedgerows impact on significant reductions in soil loss and increase
in crop yields. You can find more at www.vetiver.org

I have a couple of questions: (1) when you were working at Maheshwaram
did you come across any vetiver hedgerows, and if you did was there
any link with groundwater recharge (2) would your institution be
willing to undertake research in relation to Vetiver and groundwater.
Some research has previously been undertaken by the Thais. see:
http://www.vetiver.org/ICV4pdfs/DAS01.pdf

I am copying this email to Umesh Lavania - one of India's leading
Vetiver scientists, and P. Haridas, Coordinator of the Indian Vetiver
Network

Best Regards

Richard Grimshaw
On Apr 28, 2009, at 5:36 PM, Don Miller wrote:


Hi All,

Sorry if I am boring you but some might be interested.

This link is also relevant re groundwater in India, particularly for
those with India experience (which I don't have):
http://www.scidev.net/en/news/scientists-develop-improved-groundwater-forecastin.html
More details of the research here: http://www.ias.ac.in/currsci/apr102009/933.pdf

The term "recharge" only appears in a paper in the bibliography
(Ahmed, S., Engerrand, C., Sreedevi, P. D., Kumar, D., Subrahmanyam,
K., Ledoux, E. and Marsily, G. de, Geostatistics, aquifer modeling and
artificial recharge). Several searches later a 2007 paper by "Benoît
Dewandel, Jean-Marie Gandolfi, Faisal K. Zaidi, Shakeel Ahmed and
K. Subrahmanyam" was located: http://www.ias.ac.in/currsci/apr252007/1093.pdf
This is definitely worth reading for those interested in the use of
the VS in groundwater recharge, as it discusses the role of artificial
recharge structures on groundwater levels in that particular South
Indian geology.

The upper 10-15 metres of material has low permeability but is
underlain by a fissured layer 15-20 metres thick of high
permeability. To my thinking, the role of Vetiver hedges/terraces in
slowing the monsoonal run-off might increase the volume of water
passing through the upper layer. Each terrace could allow rapid
infiltration into its trapped sediment, but retain that water to
slowly seep into and through the upper saprolite layer.

There is discussion in the paper about the estimate of the role of dug
"tanks" on infiltration (page 1098) from which a theoretical figure
could possibly be derived for Vetiver terraces, but the proven impact
in Ethiopia seems to be better evidence. I remain suspicious of
models of catchment behaviour that rely heavily on estimates of many
parameters. At least the authors do admit that artificial recharge
structures will have to be built, although they may have serious
negative impact on water quality. They feel that the artificial
recharge structures could add 2mm to recharge on a catchment scale.
Do we have any estimates from Ethiopia on the depth of recharge
derived from the extensive vetiver plantings?

The authors conclude that if the current cropping patterns persist,
and the only change is the use of artificial recharge structures, that
230ha of the 53 Sq Km catchment will need to be converted into
recharge structures will consequent loss of that land. Some how the
VS seems a very valid answer to their groundwater problems. Maybe
someone should contact the authors?

Regards,
Don


On Wed, Apr 29, 2009 at 9:51 AM, Don Miller <donmi...@gmail.com>
wrote:
Hi All,

Check out this site: http://www.scidev.net/en/news/world-s-major-rivers-drying-up-.html

The hydrological question is - would the reduced run-off and greater
groundwater recharge resulting from widespread Vetiver planting
improve the situation, make it worse, or have little impact on river
flows? It could certainly be effective in smoothing out seasonal
fluctuations, and by improving groundwater recharge the value of wells
would increase, possibly reducing the need to rely on rivers for water
supply.

Note that the areas of greatest river flow reduction are mostly within
Vetiver's climate zone, with the exception of northern China.

Cheers
Don