圖書典藏及影音數位平台

台北水源特定區位於大台北地區之東南隅，面積共計約717平方公里，本計畫範圍不包括東札溪流域規劃面積約697平方公里，其範圍遼闊約佔台北縣行政區域面積三分之一，橫跨坪林鄉、烏來鄉、新店市、雙溪鄉及石碇鄉，為大台北地區主要供水水源來源之一。有鑒於水土災害日益嚴重，災害成因日趨複雜，因次災害整治也非立竿見影的方式可以解決，必須綜合考量整體治理並配合預先預防之理念，期望能提升本特定區整體治理理念

Taipei Water Source Domain is located at the southeast of Taipei Metropolis with steep topography and fragile geological conditions. The centralized rainfalls in past years affected seriously the soil and water conservation in this area. The eroded soils carrying nitrogen and phosphorus went into water bodies and resulted in water pollution; this is the urgent challenge to be dealt with in water source domains. In order to avoid degradation of water quality due to the natural and human-made damages, health diagnosis model of soil conservation is established under the framework of monitoring, diagnosis and treatment processes. First step at monitoring process is to analyse the watershed characteristic, river characteristic and disaster records for understanding whole watershed characteristic and being references when health diagnosis indicators were set up. Second step at monitoring process is to obtain the watershed related data from hydrology observations at the ground, sediment recorders on the slope and air photos or satellite images. Subsequently, the health diagnosis indicators such as runoff ratio, denudation ratio, ratio of green cover, water quality indicator and sediment concentration were set up. The diagnosis process is using health diagnosis indicators to analyse soil conservation related problems such as soil loss, discharge and water quality. The water resource conservation of a watershed could be evaluated by the runoff ratio; the soil losses of a watershed could be evaluated by the denudation ratio; the plant cover of a watershed could be evaluated by the ratio of green cover; the water quality of a watershed could be evaluated by the water quality indicator and the fine-grained soil losses of a watershed could be evaluated by the sediment concentration. The causes of these problems aboved were also appreciated and were divided into three kinds of driving force, such as watershed inherent conditions, the external environment and human development effects. The treatment process is selecting according management plans for different driving force. First step is to decide the management object; second step is to draft strategic planning such as cutting down peak discharge, decreasing soil losses, and conserving soil-water resource for the sub-watershed; third step is to select suitable programs through analysing sediment completeness ratio, green cover completeness ratio and water quality completeness ratio. From the analysis results of runoff ratio, denudation ratio, ratio of green cover, water quality indicator and sediment concentration, the main problem in Taipei Water Source Domain is that eroded soils always raise the water turbidity when typhoons or storms affected the landslides in Jha-Kong Stream sub-watershed. The runoff ratio, water quality indicator and sediment concentration are chosen as the early warning indicators of first phase, and the denudation ratio and ratio of green cover as indicators of second phase. The operation interface of health diagnosis model can assess the watershed health by inputting runoff, rainfall, water quality and sediment concentration data. Then, the aerial photographs and satellite images are used to analyse denudation ratio and ratio of green cover; subsequently, the problem locations of the watershed are ascertained. Besides health diagnosis model of soil conservation, the sediment yield model suitable for water source domain was established to estimate the soil erosion and landslide volume amount. The model passed verification based on sediment deposit data from Feitsui Reservoir and sediment transport capacity of Nan-Shih Stream and Pei-Shih Stream.