荖濃溪和楠梓仙溪是高屏溪上游的主要兩條支流，荖濃溪發源於中央山脈和玉山山塊及向南延伸的內麓山帶之間，楠梓仙溪則貫流於荖濃溪流域東側地區。本研究的目的是要由野外階地等地形面的調查、對比、分析，探討兩支流域階地發育的共同特徵，及影響區域地形發育的構造連動特徵，包括斷層或其他構造線的活動性。由野外階地等地形面的調查、對比、分析，荖濃溪和楠梓仙溪的河階地可以對比於四個發育期。第一期階地發育於更新世末期，第二期階地發育於更新世、全新世交替時期，第三、第四期階地發育於最近4000年以來的全新世晚期。於地形演育早期，流域上游發育較多的沖積扇階地，同時期下游對應發育的主要是岩石階地，晚期則均以岩石階地為主。而楠梓仙溪上游的沖積扇階地發育於第一、二階地發育期，荖濃溪的沖積扇階地則發育於第二、三階地發育期。兩流域最近期的河川下切均切入岩盤，上游的下切量較高，河川下切切入岩盤的平均下切速率大約5rnm/yr；下游的六龜、旗山附近，平均下切速率則降至約1-2rnm/yr，或者更低。若河川平均下切速率約略相當於地盤抬升速率，則區域構造運動是北高、南低的傾動式的。至於楠梓仙溪下游傾斜的階地面，極可能是由更小規模的活動構造造成的，是否與旗山斷層有闕，有待進一步研究。

The aims of this study are to investigate and analysis the river terraces of the Nantzuhsien and the Lanonong River, which are the major tributaries of the Kaoping River, to model their geomorphic evolution, and to discuss the regional neotectonic activities involved. Field evidences show that there are four stages of terrace development in this area. The first stage occurred late Pleistocene, maybe before 30 ka. The second stage is maybe in several hundreds to one thousand years earlier or later than 10 ka. The third and fourth stages are after 4 ka. In upper reaches, alluvial fan terrace is the main terrace type of earlier stages, which are the first and second stages in the Nantzuhsien and the second and third stages in the Laonong River. In lower reaches or in later stages of upper reaches, that is strath terrace. The average bedrock incision rate of upper reaches that estimated from the ages of terrace sediments and the height of rock-cut surface beneath terrace sediments is about 5mm/yr, and about 1-2mm/yr in lower reaches. The continuous uplifting and tilting are interpreted as the major causes that lead to the incision of rivers, and whether the tilting of some terrace surfaces is the evidence of active fault movement is left for further study.