Water and Soil Management for Water Conservation in a Watershed - Water and Agriculture: Sustainability, Markets and Policies - page 296

2. Strategy for water production or storage in Korea
Water present in soil or above the soil surface, and in streams or rivers, comes
basically from rainfall and snowfall. The formation of groundwater is also made via water
flow into the soil from precipitation. Thus, soil acts as an important media for water
cycling. Therefore, water in soil or above the soil surface is a very important element to
be considered for sustainable water use and water conservation. If anyone or any country
can develop techniques to store water in soil or above the soil surface of lands, countries
that have experienced disasters or damage caused by floods or heavy rains would be free
from these concerns. Korea is a happy country in that aspect, because dykes shutting in
water exist in paddy rice fields. That is, paddy fields, having dykes as mentioned earlier,
act as a kind of water storage facility and are the best important resource for water
storage. Table 3 showed the different height of dykes and the submergence level in paddy
fields formed in an area having topographically different landforms. The dykes were
highest on the plain. Also, water retaining capacity of paddy fields was estimated at
23.8 billion tons for the whole paddy area of 1146 thousand ha. The amount of water
storage was equal to 47.6 times of water to be kept in Youngweol Dam that can store
0.5 billion ton year -1 and was constructed at an expense of one billion dollars. To
maintain the shape of paddy fields can finally produce an effect equivalent to 47 units of
Youngweol Dam, and so the economic value of paddy fields was estimated at 47 billion
dollars, as expressed in the expense to construct 47 units of this dam.
In conclusion, it might be one of the best strategy for sustainable water use to
maintain the dykes and shapes of paddy fields by preventing destruction or encroachment
on farmlands caused by the construction of roads, houses and industrial complexes and
not having a water storage function any more.

Table 3. Bank height and water logged level in paddy land according to geographical condition
(unit: mm)

Valley land Hillside land Plain land

Dyke height 252 198 271

Water Level 45 41 45

Ratio of Area 0.46 0.11 0.42

Source : NIAST, 2000.

The case study for water conservation considering water quality

1. Watershed classification by geological characteristics and mother rocks

The geological and topological characteristics of land in Korea are very complex,
because the land consists of approximately 64% mountainous terrain. Because of the
complexity, it is not easy to study water quality and quantity for sustainable use. The
classification of agricultural fields into watersheds in an area surrounded with mountains