Free Flow

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ater

ooperation

, S

ustainability

and

overty

radication

groundwater recharge, which was mostly caused by

changes in land use in the recharge area over the past

30 years. The decline in groundwater recharge levels

from paddy fields was due to the practice of converting

paddy fields to dry fields, and this accelerated the fall

in groundwater levels.

As a result, the city saw that it needed to cooperate

with neighbouring municipalities in order to conserve

groundwater. To tackle issues that cannot be solved

within one administrative district or one munici-

pality alone, cooperation with concerned adjacent

municipalities is indispensable. The city formulated

an agreement to maintain and increase groundwater

recharge through cross-municipal cooperation. Major

cooperative initiatives started in 2004, including

a project to flood the converted paddy fields of the

Shirakawa river mid-basin and to maintain the water-

shed protection forests in the upper basin.

Cooperation on the project to flood the paddy

fields was carried out through the Council for

Sustainable Water Use in Agriculture, which consists

of Kumamoto City, Ozu and Kikuyo towns, four

local agricultural land improvement districts, Japan

Agricultural Cooperatives (JA) Kikuchi and JA

Kumamoto City East Branch. The project provides

subsidies to encourage farmers to flood their

converted paddy fields with water from the Shirakawa

river every day for one to three months between May

and October. Farmers may flood their fields after

harvesting and before planting and growing crops.

The amount of subsidies depends on the length of

the flooding period. The flooding is effective not

only to recharge groundwater levels, but also to limit

the negative effects of weeds, insects, diseases and

continuous cropping issues. Moreover, flooding helps

to reduce the use of agricultural chemicals, prevents

groundwater pollution and reduces financial costs.

Important watershed forests, which are vital to

Kumamoto City, are located in the upper basins of the

Basin-wide groundwater management using the system of

nature in Kumamoto City, Japan

This has been the case in Kumamoto City in the centre of Kyushu,

the southern major island of Japan. In cooperation with neighbour-

ing municipalities, Kumamoto City government has managed an

artificial groundwater recharge system using abandoned paddies and

protected watershed forests. Drinking water for the city’s 730,000

citizens is totally supplied by this abundant groundwater, which

is chlorinated only at a minimum level without further purifica-

tion. By protecting the natural systems and conserving Kumamoto’s

high-quality groundwater, the city can provide its citizens with high

quality ‘mineral water from the tap’.

The city has undertaken various efforts to maintain its abundant,

pure and crystal-clean groundwater so it can pass down this treasure

to future generations. Between 90,000 and 270,000 years ago, the

volcanic Mount Aso experienced four violent eruptions with pyro-

clastic flows. These flows deposited and accumulated to more than

100 metres in thickness, and became an ideal groundwater aquifer

for the region. In addition, about 400 years ago, Kato Kiyomasa, the

feudal lord of Higo (now Kumamoto), promoted the development

of paddy fields along the Shira river alluvial low land, where it is

easy to permeate and recharge the local groundwater aquifer. This

situation worked well and allowed Kumamoto access to a far greater

amount of clean groundwater. Kumamoto City does not have an

alternative source for groundwater, and can face a crisis when the

resource dries up or is polluted. With rapid urbanization since the

early 1970s, the amount of percolated groundwater has decreased

while water use has increased.

Kumamoto has carried out various initiatives to conserve its

groundwater, including the adoption of the Declaration of the

Groundwater Preservation City in 1976 and the installation of

groundwater observation wells in 1986. As part of these efforts,

the city has conducted research on groundwater flow systems

in the area and identified a trend towards long-term decreases

in groundwater levels. This was mainly due to the decrease in

Promoting cooperation in Bogota, Colombia

The Río Bogotá is highly polluted. The project focused on

this issue and specifically preventing pollution by small-

scale and informal sector tanneries on the upper part of

river. Key players, including an association of tanners,

the environmental regulator, local government, an NGO, a

university and the Chamber of Commerce, were engaged

throughout the project.

The Sustainable Water Management Improves

Tomorrow’s Cities’ Health project of the United Nations

supported a process of conflict resolution, capacity building

and dialogue, and the regulator is now pursuing these

alternatives to a punitive, legalistic and failing approach.

Almost half of the informal small enterprises that were

polluting have now implemented cleaner production

principles, thereby removing much of their pollution.

This has also led to an increase in their productivity. The

research supported the tanners in making changes and a

follow-up project is now expanding this approach across a

wider catchment area.

Paddy fields along the Shira river helped to recharge Kumamoto City’s local

groundwater aquifer

Image: Kumamoto City, Japan