臺灣東部山多平地少，但有許多的沖積扇。沖積扇地勢低緩，居民取其耕作、水利之便，因此成為僅次於花蓮溪與卑南溪沖積平原外之精華區。然沖積扇依其自然發育階段可分為穩定、亞穩定與活動中的沖積扇，具有不同程度之土石災害的潛在危險性。 本研究調查東部花蓮溪河谷沖積扇之結果與發現，本河谷內之沖積扇皆為亞穩定～不穩定沖積扇。重要的聚落集中於兩大扇交會之河間區等沖積扇土砂災害陰影區，此為當地人世代從經驗中學到與自然災害安全相處之道。是以河間地為本河谷較安全可供發展的地區，未來開發必以此為是。沖積扇扇頂是土石易生區，故多為粗放型農作；扇端地下水面較高，喜水性作物如水田或荷池、漁塭等分布於此，但也有時有洪患。 沖積扇區上之河道位置與受災面具密切關連，河道位於扇緣者受災面較其位於扇央者廣。此因後者有較直而有效率之河道以疏解土石洪流之壓力。

In the mountainous eastern regions of Taiwan, there are many fluvial fans where, given their advantages of gentle sloping terrain and the availability of water, villages and arable lands have been developed. The importance of this land is second only to that of the alluvial plains of the Hualien and Peinan Rivers. According to their stages of development, there are three categories of fluvial fans: 'stable', 'meta-stable' and 'active', each having a different degree of potential debris hazard. The present study shows that all of the alluvial fans in the Hualien Valley fall into the meta-stable or active (unstable) categories, and the major towns or valleys are located in the interfluvial areas between large adjacent fans, right in the shadow fo the debris hazards. This natural development of settlements in the safer areas reflects the wisdom of the local people, who have learned from the experience of their ancestors how to cope with unavoidable natural hazards. These interfluvial areas are evidently the most suitable sites for further development in eastern Taiwan. In order for this development to take place, engineering works such as levees have been constructed to increase the safe areas, though there is still a certain level of risk. The central parts of the fans are hazard prone areas, and their land usage is limited to orchards, sugarcane, and betel. At the edges of the fans, where the ground water table is usually closer to surface level, fish ponds and rice paddies are found. These lowlands are also subject to flooding. This study also found that there is a close relationship between the location of the stream channel on the fan and the extent of area affected by debris hazards. The channels running along the flanks of the fans usually inflict damage on a larger area than those running through the center. This is because the latter has a straight and unhindered passage way in which the debris flood pressure is released.