A Geographical Study on Relationships between Damage of Farm Ponds by Hyogo-ken Nanbu Earthquake in 1995 and Impounded Water Level of Farm Ponds

Abstract

There are many farm ponds in the western part of Japan and they play important and essential roles in rice field cultivation.
Of the farm ponds in Hyogo Prefecture, 1372 were damaged by Hyogo-ken Nanbu Earthquake in 1995.
The author aimed to clarify the features of the damaged farm ponds from an impounded water level of them. The results are as follows. In the case of valley closed ponds (tani-ike), ponds of high water level were hardly damaged and those of low water level were heavily damaged. In the case of flat ponds (sara-ike), ponds of high water level were heavily damaged and those of low water level were hardly damaged. In both cases of valley closed ponds and flat ponds, ponds of middle water level were slightly damaged.
The farm ponds located just near fault lines and those not repaired for more than 100 years were heavily damaged, although their water levels were in safe rangefor the reason above mentioned. Also the farm ponds repaired or built in recent years were hardly damaged, although their water levels were in dangerous range.
Many valley closed ponds were damaged, because their water levels were decreased under the influence of drought of previous summer.