Inventory of farm pond and priority screening the hotspot for improvement in Chung-gang Creek Basin

• Main Authors: Han-Pin Chih, 池瀚斌
• Other Authors: 林昭遠
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5080027%22.&searchmode=basic

碩士 === 國立中興大學 === 水土保持學系所 === 107 === Under the global climate change, due to the high frequency of extreme rainfall events and the characteristics of steep slope terrain, the water resources of the slope land are not easy to cultivate, we must rely on various ways to store water resources. In addition to irrigation, water-preserving spaces such as ponds, terraces and waste farmland on the slopes can also have disaster prevention functions, which can play a key role in water conservation and flood prevention. This study uses terrain homogenous areas to delineate slope units. The maximum water storage difference of the land-use between status and human undisturbed by SCS curve number method is applied as the screening basis for the hotspot of excess runoff. In addition, by using the map of existing agricultural ponds provided by the Bureau of Soil and Water Conservation, number and area of the agricultural ponds of the extraction slope unit can be used for the indicator of available farm pond, the road density is the indicator of waterway connection capacity and the agricultural land area is the irrigation demand indicator. Finally through the K-means cluster analysis, the hotspot where the slope unit farm pond needs to be improved can be selected. The slope unit number 31 is the key area for research, mainly because it has 9 farm ponds with roadside ditches and waterway connection capacity to form continuous flood detention and/or water conservation potential. After on-site investigation and analysis of SCS-CN method, rational formula, universal soil loss equation and irrigation turnover, the amount of flood retention/detention, sediment deposit and available irrigation were reviewed. Results showed that 5 of them had the problem of insufficient depth. Under the consideration of rational use of land, the irrigation turnover rate can be reduced from 5.34 times/year to 3.44 times/year by means of dredging depth of farm pond up to 3 meters, functioning of waterway connection, adding valves and using power to regulate water level. This study can be used as a reference for the improvement of farm pond in planning multipurpose of irrigation, flood detention/retention, and sedimentation.